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SR530 User`s Manual - Stanford Research Systems

1. Set the reference frequency to 100 Hz Itis convenient to use the SYNC output of the signal generator as the reference input if it is available Connect the sine output of the signal generator to the A input and set the input selector to A With the SENSITIVITY at 100mV adjust the amplitude of the input signal to 100 mV full scale Now set the input selector to A B and connect the signal to both the A and B inputs Set the SENSITIVITY to 20uV the DYN RES to NORM and the BANDPASS filter IN Connect the scope to the SIGNAL MONITOR output on the rear panel Set the scope to AC coupled 0 2V div and 10mS div Externally trigger the scope using the reference input signal The CMRR is adjusted by the single turn potentiometer located at A1 under the single hole at the front of the signal shield The shield is the aluminum box on the left side of the main board Using a small screwdriver carefullv adjust the potentiometer to minimize the 100 Hz output on the scope Set the DISPLAY to R and the sensitivity to 5uV and minimize the R output on the Channel 1 meter Notch Filters Set the reference frequencv to 60 0 Hz 50 0 Hz ltis convenient to use the SVNC output of the signal generator as the reference input if it is available Connect the sine output of the signal generator to the A input and set the input selector to A With the SENSITIVITV at 100mV adjust the amplitude of the input signal to 100 mV full scale Set the LI
2. There are 71 led s on the front panel controlled by 9 serial in parallel out shift registers 8 of the shift registers are written to simultaneously and the 9th is written separately 8 consecutive write operations are required to set the LED s in each case The liquid crystal displays are managed by the display controllers U6101 U6102 and U6103 Exclusive or gates U6104 U6105 and U6106 drive the left over segments Latches U6107 and U6108 provide the logic bits for these extra segments as well as the keyboard row strobes U6109 reads the switch closures as the rows are scanned Microprocessor Control The microprocessor U701 is a Za0A CPU clocked at 4 MHz 16K bytes of firmware are stored in the ROM U702 U703 is a 2K byte static RAM backed up by a lithium battery A power down standby circuit Q701 preserves the RAM contents when the power is turned off The battery has a life of 5 10 years The CPU has power up and power down resets to prevent erroneous execution during turn on or short sags in the line voltage U704 is a 3 channel counter One channel generates the baud rate for the RS232 interface while the other two are used to measure the frequency or period of the reference oscillator U709 provides a gate pulse to counter 0 Multiplexer U708 selects whether the gate is a single period of the reference period measurement or a gate of known duration frequency measurement Counter 1 is a programmable divide by N co
3. X6 X6 no adjust V Vofst The EXPAND and OFFSET conditions for each display are retained when the DISPLAY is changed Thus when the DISPLAY is changed from Y to B the EXPAND and OFFSET turn off If the DISPLAY is changed back to Y the EXPAND and OFFSET return to conditions set for Y Output The phase is given by the equation tanl Y Yofst X Xofst Note that the X and Y offsets affect the value of while the X and Y expands do not The Phase Output voltage is 50 mV per degree with a resolution of 2 5 mV or 1 20 of a degree The output range is from 180 to 180 degrees The phase output is updated every 3 5 mS To achieve maximum accuracy the magnitude R should be as large a fraction of full scale as possible If R is less than 0 5 of full scale the phase output defaults to zero degrees The Phase Output may not be expanded and the OFFSET keys do not offset the Phase Output However the Phase Output can be offset using the Reference Phase shift The Reference Phase shift which may be adjusted via the phase controls in the reference section rotates the lock in s internal coordinate axes relative to the reference input The Phase Output is the phase difference between the signal and the lock in s coordinate system For example if a signal exactly in phase with the reference input is being measured and the Reference Phase shift is zero the Phase Output will be zero also This is because the lock in c
4. command is used by both interfaces to set the remote local status J n1 n2 n3 n4 The J command sets the RS232 end of record characters sent by the SR530 to those specified by the decimal ASCII codes n1 n4 If no argument is included the end of record sequence returns to the default a carriage return otherwise up to four characters may be specified The end of record required by the SR530 when receiving commands is not affected Kn The K command simulates a front panel key press The effect is exactly the same as pressing the selected key once The parameter n is required Key Post Time Constant Up Post Time Constant Down Pre Time Constant Up Pre Time Constant Down Select Display f phase 01 O ND I5 22 6 90 Up 7 90 Down 8 Zero Phase Simultaneous 90 Up and Down 9 Reference Trigger Mode 10 Reference Mode f 2f 11 Degrees Up 12 Degrees Down 13 Channel 2 Rel 14 Channel 2 Offset On Off 15 Channel 2 Offset Up 16 Channel 2 Offset Down 17 Channel 2 Expand 18 Output Display Up 19 Output Display Down 20 Channel 1 Expand 21 Channel 1 Rel 22 Channel 1 Offset On Off 23 Channel 1 Offset Up 24 Channel 1 Offset Down 25 Dyn Res Up 26 Dyn Res Down 27 Sensitivity Up 28 Sensitivity Down 29 Local 30 Line X 2 Notch Filter 31 Line Notch Filter 32 Bandpass Filter Lm n The L command sets and reads the status of the line notch filters If m is 1 then the 1X line notch is se
5. 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 62 R 307 R 308 R 309 R310 R 311 R 312 R 313 R 314 R 315 R 316 R 317 R 318 R 319 R 320 R 321 R 322 R 323 R 324 R 325 R 326 R 327 R 328 R 329 R 330 R 332 R 333 R 334 R 335 R 336 R 337 R 338 R 339 R 340 R 341 R 342 R 343 R 344 R 345 R 346 R 347 R 348 R 349 R 350 R 351 R 352 R 353 R 354 R 355 R 356 R 357 R 358 SR530 COMPONENT PARTS LIST SRS part VALUE 4 00040 401 13K 4 00193 407 499 4 00073 401 330K 4 00021 401 1 0K 4 00021 401 1 0K 4 00021 401 1 0K 4 00034 401 10K 4 00069 401 300K 4 00099 401 680K 4 00099 401 680K 4 00093 401 6 2K 4 00138 407 10 0K 4 00034 401 10K 4 00034 401 10K 4 00032 401 100K 4 00170 407 249K 4 00199 407 6 81K 4 00199 407 6 81K 4 00163 407 2 80K 4 00150 407 13 0K 4 00159 407 2 10K 4 00029 401 1 8K 4 00088 401 51K 4 00021 401 1 0K 4 00161 407 2 49K 4 00029 4
6. 1 8W 0 1 25ppm Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 64 R 433 R 501 R 502 R 503 R 504 R 505 R 506 R 507 R 508 R 509 R 510 R 511 R 512 R 513 R 514 R 515 R 516 R 518 R 519 R 520 R 521 R 522 R 523 R 524 R 525 R 526 R 527 R 528 R 529 R 530 R 531 R 532 R 533 R 534 R 535 R 536 R 537 R 538 R 539 R 540 R 541 R 542 R 543 R 544 R 545 R 546 R 547 R 548 R 549 R 701 R 702 SR530 COMPONENT PARTS LIST SRS part VALUE 4 00021 401 1 0K 4 00022 401 1 0M 4 00022 401 1 0M 4 00022 401 1 0M 4 00022 401 1
7. 5 00103 524 1 0U 5 00036 522 6800U 5 00056 512 1U 5 00056 512 1U 5 00100 517 2 2U 5 00100 517 2 2U 1 00014 160 9 PIN D 1 00016 160 RS232 25 PIN D 1 00238 161 GPIB SHIELDED 5 00010 501 270P 5 00014 501 390P 5 00014 501 390P SR530 COMPONENT PARTS LIST DESCRIPTION Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Electrolytic 25V 20 Rad Capacitor Electrolytic 25V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Electrolytic 25V 20 Rad Capacitor Electrolytic 25V 20 Rad Cap Mini Electrolytic 50V 20 Radial Capacitor Tantalum 35V 20 Rad Capacitor Electrolytic 50V 20 Ax Capacitor Electrolytic 50V 20 Ax Cap Mini Electroly
8. Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 63 R 359 R 360 R 361 R 362 R 363 R 364 R 365 R 366 R 367 R 368 R 369 R 370 R 371 R 372 R 373 R 374 R 375 R 376 R 377 R 378 R 401 R 402 R 403 R 404 R 405 R 406 R 407 R 408 R 409 R 410 R 411 R 412 R 413 R 414 R 415 R 417 R 418 R 419 R 420 R 421 R 422 R 423 R 424 R 425 R 426 R 427 R 428 R 429 R 430 R 431 R 432 SR530 COMPONENT PARTS LIST SRS part VALUE 4 00045 401 2 0K 4 00032 401 100K 4 00084 401 5 1K 4 00181 407 32 4K 4 00132 407 1 10K 4 00032 401 100K 4 00045 401 2 0K 4 00021 401 1 0K 4 00151 407 130K 4 00156 407 16 2K 4 00130 407 1 00K 4 00130 407 1 00K 4 00030 401 10 4 00023 401 1 1M 4 00033 404 100M 4 00033 404 100M 4 00033 404 100M 4 00033 404 100M 4 00187
9. Quite often one component of 32 ZxLINE FREQUENCY NOTCH FILTER BANDPASS FILTER LOw PASS FILTERS INPUT DISCRIMINATOR DIGITAL INPUTS PUL RANGE PU FREQUENCY PHASE SHIFT CONTROL OVERLOAD INDICATOR 1 21 SELECTION UNLOCK INDICATOR u PROCESSOR SYSTEM AUTO TRACKING BANDPASS FILTER HICH CAIN A C AMPLIFIER SIGNAL MONITOR gt 2 OUTPUT LOW PASS FILTER LOW PASS FILTER CHOPPER STABILIZED 1m X05 asos D C AMPLIFIER iai RPD gt Teeth OUTPUT ly fy LOW PASS FILTER LOW PASS FILTER CHOPPER STABILIZED 1m 10S asos D C AMPLIFIER ANALOG CONTROLS PHASE SHIFT SIGNAL OFFSET REAR PANEL D A TRACKING BANDPASS AND PANEL METERS RATIO OUTPUTS FRONT PANEL this picket fence of frequencies would land on some noise source giving a spurious result To overcome this difficulty designers employed tuned amplifiers or heterodyning techniques All of these fix ups had drawbacks including phase and amplitude errors susceptibility to drift and card swapping to change frequencies In contrast the SR530 detects the signal by mixing a reference sine wave in a precision analog multiplier Because of the low harmonic content of this sine wave the instrument is insensitive to harmonics This approach has eliminated the difficulty performance compromises and cost of the older techniques The Signal Channel The instrument has both current and voltage inputs The current input is a virt
10. R Offset X Noise X5 external D A Y Pain Y Offset phase shift of signal Y Noise X6 external D A 2 Precision mirrored analog meter Four digit auto ranging LCD display shows same values as the analog meters 10 V output corresponds to full scale input lt 1Q output impedance X RcosQ 10 V full scale lt 12 output impedance Y em 10 V full scale lt 10 output impedance Four digit LCD display for reference phase shift or frequency Interface controls all functions Baud rates from 300 to 19 2 K Interface controls all functions IEEE 488 Std 4 BNC inputs with 13 bit resolution 10 24 V 2 BNC outputs with 13 bit resolution 10 24 V Ratio output equals 10X Channel 1 output divided by the Denominator input Range 1 Hz to 100 kHz 196 accuracy Stability 150 ppm C Distortion 2 THD Amplitude 1 accuracy 500 ppm C stability Front Panel Summarv Signal Inputs Signal Filters Sensitivitv Dvnamic Reserve Status Indicators Displav Select Analog Meters Output LCD s Output BNC s Expand REL Offset X BNC Y BNC Reference Input Reference Trigger f 2f Mode Single Ended A True Differential A B or Current I Bandpass Q of 5 Auto tracking filter In or Out Line Notch Q of 10 Notch Filter at line frequency In or Out 2XLine Notch Q of 10 Notch Filter at twice line frequency In or Out Full scale sensitivity from 100 nV to 500 mV RMS for voltage inputs or f
11. U 709 U 710 U 711 U 712 U 713 U 714 U 715 U 716 U 717 U 718 U 719 U 720 U 721 U 722 U 801 U 802 U 803 U 804 U 805 U 806 SRS parti VALUE 3 00126 335 51A05 3 00084 340 ICL7650 3 00126 335 51A05 3 00076 340 DG211 3 00090 340 LF411 3 00064 340 CA3081 3 00035 340 74074 3 00087 340 LF347 3 00058 340 AD7524 3 00046 340 74HC374 3 00077 340 DG528 3 00059 340 AD7542JN 3 00058 340 AD7524 3 00077 340 DG528 3 00087 340 LF347 3 00076 340 DG211 3 00076 340 DG211 3 00087 340 LF347 3 00087 340 LF347 3 00087 340 LF347 3 00094 340 LM311 3 00087 340 LF347 3 00076 340 DG211 3 00092 340 LHOO71 3 00132 340 Z80A CPU 3 00081 341 2KX8 100 3 00491 340 UPD71054C 3 00037 340 74HC138 3 00037 340 74HC138 3 00037 340 74HC138 3 00040 340 74HC157 3 00049 340 74HC74 3 00045 340 74HC32 3 00051 340 74HCU04 3 00047 340 74HC4040 3 00049 340 74HC74 3 00042 340 74HC175 3 00042 340 74HC175 3 00044 340 74HC244 3 00046 340 74HC374 3 00039 340 74HC14 3 00046 340 74HC374 3 00046 340 74HC374 3 00046 340 74HC374 3 00045 340 74HC32 3 00493 340 UPD71051C 3 001 11 340 MC68488 3 00044 340 74HC244 3 00044 340 74HC244 3 00049 340 74HC74 3 00109 340 MC1488 SR530 COMPONENT PARTS LIST DESCRIPTION Relay Integrated Circuit Thru hole Pkg Relay Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integr
12. and Harmonics AM Biraadcast Stations T amp FRA Broadcasts Noise RADAR 14 Background GO Hz iMHz i100 MHz Frequency 1 GHz Noise Spectrum Some of the non essential noise sources appear in this spectrum as spikes on the intrinsic background There are several ways which these noise sources work their way into an experiment Capacitive Coupling A voltage on a nearbv piece of apparatus or operator can couple to a detector via a stray capacitance Although Cstray May be very small the coupled in noise may still be larger than a weak experimental signal Stray Capacitance Detector Experimant 60 Hz Power Circuit Capacitive Noise Coupling into To estimate the noise current through C lay the detector we have dV dt i stray jWCstravVnoise where a reasonable approximation to Cetrav can be made by treating it as parallel plate capacitor Here w is the radian frequency of the noise source perhaps 2 x 60Hz Vigise is the noise voltage source amplitude perhaps 120 VAC For an area of A 01 m 2 and a distance of d 0 1m the capacitor will have a value of 0 009 pF and the resulting noise current will be 400pA This meager current is about 4000 times larger than the most sensitive current scale that is available on the SR510 lock in Cures for capacitive coupling of noise signals include 1 removing or turning off the interfering noise Source 2 measuring v
13. constant is not large enough or the ENBW is too large The OVLD LED blinks four times a second when an output is overloaded This occurs if an output exceeds full scale For example during a quadrature measurement where X exceeds full scale while Y is near zero a blinking OVLD indicates that it is safe to take data from the Y output since only the X output is overloaded The signal path to the Y output is not overloaded OVLD also blinks if a noise measurement is attempted on an output which exceeds full scale If the OVLD LED is on continuously or flashes randomly then an overload has occurred before 10 the output i e in the ac amplifier or output time constant In this case the dynamic reserve sensitivity time constant or ENBW needs to be adjusted UNLK indicates that the reference oscillator is not phase locked to the external reference input This can occur if the reference amplitude is too low the frequency is out of range or the trigger mode is incorrect for the reference signal waveform ERR flashes when an error occurs on one of the computer interfaces such as an incorrect command invalid parameter etc ACT indicates activity on the computer interfaces This LED blinks every time a character is received or transmitted by the SR530 REM indicates that the unit is in the remote state and that the front panel controls are not operative There are two remote states The Remote With Lockout will not allow a
14. lost When this happens the over run flag will be set in your computer s UART and it may be recognized by the operating system generating an error message such as I O Device Error See the W command in the SR530 Command List for another way to slow data transmission Baud Rate The RS232 baud rate of the SR530 is switch selectable from 300 to 19 2K baud see configuration switch setting in the front of this manual 19 2K baud means that data is transmitted at 19 200 bits second With one start bit 2 stop bits 8 data bits and no parity bits each ASCII character requires 573 usec to be transmitted 1 1bits 19 2K sv AEN baud The typical data string 5 1270 lt cr gt has 7 characters requiring 4 msec to be sent Stop Bits Generally selection of 2 stop bits will result in fewer data transmission errors Parity The Parity bit provides a check against faulty data transfer It is not commonly used in local data transmission environments If the parity option is selected the SR530 will transmit 8 data bits and a parity bit however no parity check of incoming data is done Voltage Levels The RS232 uses bipolar voltage levels 15V Space Binary O or Start Bit it Data Line Assented or On State if Contro Line 49V DN DC 3V Mark Binary 1 or Stop Bit if Data Line N Inhibit or Off if Control Line 15V The control lines use positive logic For example the DCE tells the
15. 00096 401 62K 4 00039 401 120K 4 00094 401 6 8K 4 00063 401 3 0K 4 00094 401 6 8K 4 00063 401 3 0K 4 00021 401 1 0K 4 00021 401 1 0K 4 00034 401 10K 4 00138 407 10 0K 4 00138 407 10 0K 4 00045 401 2 0K 4 00032 401 100K 4 00021 401 1 0K DESCRIPTION Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Comp 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Comp 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film
16. 1 2 Vg cos w wg t Vpsd2 Vs sin w t cos wst 1 2 Vs sin wp Wg t O 1 2 Vs sin Wy wg t The sum frequency component of each PSD is attenuated by a low pass filter and only those difference frequency components within the low pass filter s narrow bandwidth will pass through to the dc amplifiers Since the low pass filter can have time constants up to 100 seconds the lock in can reject noise which is more than 0025 Hz away from the reference frequency input For signals which are in phase with the reference 0j the output of PSD1 will be a maximum and the output of PSD2 will be zero If the phase is non zero Vpsd1 cos and Vpsd2 sin The magnitude output is given by 211 2 V R Vpsd1 2 Vpsd2 s and is independent of the phase The phase output is defined as gt tan Vpsa2 Vpsd1 Thus a dual phase lock in can measure the amplitude of the signal independent of the phase as well as measure an unknown phase shift between the signal and the reference Understanding the Specifications The table below lists some specifications for the SR530 lock in amplifier Also listed are the error contributions due to each of these items The specifications will allow a measurement with a 2 accuracy to be made in one minute We have chosen a reference frequency of 5 kHz so as to be in a relatively quiet part of the noise spectrum This frequency is high enough to avoid low frequen
17. 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Switch Toggle Right Angle PCB Mount Switch Toggle Right Angle PCB Mount Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Transistor TO 92 Package Transistor TO 92 Package Washer Flat Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 24 UL1007 Strip 1 4x1 4 Tin 55 REF BR1 BR2 BT1 C 101 C 102 C 103 C 104 C 105 C 106 C 107 C 108 C 110 C 111 C 116 C 117 C 118 C 120 C 121 C 122 C 123 C 124 C 125 C 126 C 127 C 128 C 129 C 131 C 132 C 133 C 134 C 136 C 137 C 145 C 146 C 147 C 148 C 201 C 202 C 203 C 204 C 205 C 206 C 207 C 208 C 209 C 210 C 211 C 212 C 213 SRS parti VALUE 3 00062 340 KBP201G BR 81D 3 00062 340 KBP201G BR 81D 6 00001 612 BR 2 3A 2PIN PC 5 00069 513 AU 5 00069 513 AU 5 00038 509 10U 5 00008 501 22P 5 00002 501 100P 5 00008 501 22P 5 00030 520 2200U 5 00030 520 2200U 5 00038 509 10
18. 32 4K 4 00132 407 1 10K 4 00151 407 130K 4 00156 407 16 2K 4 00130 407 1 00K 4 00130 407 1 00K 4 00034 401 10K 4 00032 401 100K 4 00045 401 2 0K 4 00088 401 51K 4 00030 401 10 4 00030 401 10 4 00030 401 10 4 00033 404 100M 4 00033 404 100M 4 00187 407 4 53K A 00045 401 2 0K 4 00217 408 1 000K 4 00217 408 1 000K 4 00085 401 5 1M 4 00217 408 1 000K 4 00217 408 1 000K 4 00193 407 499 4 00130 407 1 00K 4 00131 407 1 00M DESCRIPTION Pot Multi Turn Side Adjust Pot Multi Turn Side Adjust Pot Multi Turn Side Adjust Pot Multi Turn Side Adjust Printed Circuit Board Transistor TO 92 Package Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal
19. 408 C 409 SR530 COMPONENT PARTS LIST SRS parti VALUE 5 00059 512 47U 5 00060 512 1 0U 5 00056 512 AU 5 00038 509 10U 5 00038 509 10U 5 00055 512 15U 5 00060 512 1 0U 5 00003 501 10P 5 00009 501 24P 5 00110 525 560P 5 00038 509 10U 5 00060 512 1 0U 5 00049 566 001U 5 00058 512 33U 5 00008 501 22P 5 00008 501 22P 5 00017 501 47P 5 00017 501 47P 5 00056 512 1U 5 00038 509 10U 5 00060 512 1 0U 5 00049 566 001U 5 00058 512 33U 5 00049 566 001U 5 00003 501 10P 5 00003 501 10P 5 00035 521 47U 5 00035 521 47U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00033 520 47U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00016 501 470P 5 00016 501 470P 5 00100 517 2 2U 5 00100 517 2 2U 5 00060 512 1 0U 5 00052 512 01U 5 00052 512 01U 5 00060 512 1 0U 5 00060 512 1 0U 5 00052 512 01U 5 00052 512 01U 5 00003 501 10P 5 00056 512 AU DESCRIPTION Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Capacitor Electrolytic 50V 20 Rad Capacitor Electrolytic 50V 20 Rad Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Polystyrene 50V 5 Ax Capacitor Electrolytic 50V 20 Rad Cap Stacked Metal Film 50V 5 40 85c Cap Polyester Film 50V 5 40 85c Ra
20. 410 C 411 C 412 C 413 C 414 C 415 C 416 C 417 C 418 C 419 C 420 C 421 C 422 C 501 C 502 C 503 C 504 C 505 C 506 C 507 C 508 C 509 C 510 C 511 C 512 C 513 C 514 C 515 C 516 C 517 C 518 C 519 C 520 C 521 C 523 C 525 C 526 C 527 C 701 C 702 C 703 C 704 C 705 C 706 C 707 C 708 C 709 C 710 C 711 C 712 C 801 SR530 COMPONENT PARTS LIST SRS parti VALUE 5 00056 512 AU 5 00056 512 AU 5 00056 512 AU 5 00049 566 001U 5 00053 512 033U 5 00072 513 10U 5 00056 512 AU 5 00060 512 1 0U 5 00052 512 01U 5 00052 512 01U 5 00049 566 001U 5 00013 501 33P 5 00013 501 33P 5 00012 501 330P 5 00136 519 01U 5 00007 501 220P 5 00002 501 100P 5 00008 501 22P 5 00054 512 047U 5 00054 512 047U 5 00054 512 047U 5 00054 512 047U 5 00054 512 047U 5 00054 512 047U 5 00054 512 047U 5 00054 512 047U 5 00049 566 001U 5 00049 566 001U 5 00049 566 001U 5 00002 501 100P 5 00056 512 1U 5 00049 566 001U 5 00052 512 01U 5 00052 512 01U 5 00052 512 01U 5 00052 512 01U 5 00023 529 1U 5 00023 529 AU 5 00007 501 220P 5 00007 501 220P 5 00040 509 1 0U 5 00040 509 1 0U 5 00052 512 01U 5 00052 512 01U 5 00052 512 01U 5 00052 512 01U 5 00052 512 01U 5 00052 512 01U 5 00052 512 01U 5 00052 512 01U 5 00012 501 330P DESCRIPTION Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Polyester Film 50V 5 40 85c
21. 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 0 1 25ppm Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 65 R 703 R 705 R 706 R 707 R 708 R 709 R710 R711 R712 R 801 R 802 R 803 R 901 R 902 R 903 R 904 R 905 R 906 R 907 R 908 R 909 R 910 R 911 R 912 R 913 R 914 RN401 RN801 RN802 S0702 SW1 SW2 SW601 SW602 T 1 U 101 U 102 U 103 U 104 U 105 U 106 U 107 U 108 U 109 U 110 U 111 U 112 U 113 U 114 U 115 U 117 SRS parti VALUE 4 00027 401 1 5K 4 00021 401 1
22. 50V 5 40 85c Capacitor Electrolytic 16V 20 Rad Capacitor Electrolytic 16V 20 Rad Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Polystyrene 50V 5 Ax Cap Polyester Film 50V 5 40 85c Rad Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Capacitor Ceramic Disc 50V 10 SL Capacitor Polystyrene 50V 5 Ax Cap Polyester Film 50V 5 40 85c Rad Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c 56 REF C 214 C 215 C 216 C 217 C 218 C 230 C 301 C 302 C 303 C 304 C 305 C 306 C 307 C 308 C 310 C 311 C 312 C 313 C 314 C 315 C 317 C 318 C 319 C 320 C 321 C 322 C 323 C 324 C 325 C 326 C 327 C 328 C 329 C 330 C 331 C 332 C 333 C 334 C 335 C 336 C 337 C 338 C 401 C 402 C 403 C 404 C 405 C 406 C 407 C
23. C v3 0 large model and the COMI port Set all switches in SW2 to UP on SR530 for 19 2 kbaud The ramp on x6 can be watched by setting the SR530 display to D A main char str1 20 str2 20 STR3 20 float v1 V2 x init init COM1 port to 19 2 kbaud txstr woS set character interval to 0 x 0 while 1 txstr q1 read channel 1 output rxstr strij into strl sscanf strl SE amp vl scan strl for a float variable 49 txstr q2 read channel 2 output rxstr str2 into str2 sscanf str2 Sf amp v2 scan str2 for a float variable x 0 0025 increment x6 output by 2 5 mv if x gt 10 x 0 sprintf str3 X6 fS x make x6 command string txstr str3 send x6 command print results to screen printf Channel 1 10 36 Channel 2 10 36 n vl v2 ACKCkCk kk ck k ck ck k ck k k k k k k k k k k k k k k k k k k k kX k k k k k k k k k x k k x nocom error handling routine goes here printf RS232 Timeout Error n putch 7 exit 50 Program Example 4 IBM PC Microsoft Basic via GPIB This program requires the Capital Equipment In this program the CEC card s ROM starts at Corporation GPIB card for the IBM PC or XT It OCOOOOH the system controller s address is 21 has firmware in ROM to interface high level and the SR530 has been assign
24. Not Ready For Data line is held low by any designated listener who is not ready to accept data When every listener is ready the line goes high and the talker may release data to the bus After data is on the bus the talker pulls the DAV Data Valid line down At this point each listener retrieves the data Before and during the retrieval of the data the listener holds the NDAC No Data Accepted line down When every listener has received the data the NDAC line goes high allowing the talker to release the DAV line high Finally the listener pulls down the NDAC line until another transfer is initiated 45 Data Bus There are eight data lines which use negative logic and pass the bits of each byte in parallel General Interface Lines These five lines operate independently of the handshake lines and use negative logic 1 The EOI End or Identify line is used by the talker to designate the end of message 2 The SRQ Service Request line is used by any device to ask for service The controller can serial poll each device each device returns an 8 bit status byte to determine who needs attention It can also do a parallel poll using the EOI and ATN lines where each device is assigned a single data line 3 The ATN Attention line makes both talkers and listeners accept information and passes control of the DAV line to the controller This line is used by the controller to identify talkers and listeners through their add
25. dynamic reserves are available at all sensitivities If the sensitivity is changed to a setting for which the dynamic reserve is not allowed the dynamic reserve will change to the next setting which is allowed Sensitivity takes precedence over the dynamic reserve The sensitivity range of each dynamic reserve is shown below Dvnamic Reserve Sensitivitv Range LOW 1 uV through 500 mV NORM 100 nV through 50 mV HIGH 100 nV through 5 mV Dynamic Reserve The dynamic reserve DR is set using the keys in the DYNAMIC RESERVE section The reserve is displayed by the three indicator LED s HIGH NORM LOW Only those dynamic reserve settings available for the sensitivity are allowed see above table For example when the sensitivity is 500 mV the DR will always be LOW The dynamic reserve and output stability of each setting are shown below Setting Dynamic Reserve Output Stability ppm C LOW 20 dB 5 NORM 40 dB 50 HIGH 60 dB 500 Since a higher DR results in degraded output stability you should use the lowest DR setting for which there is no overload indication Note that using the Bandpass Filter provides about 20dB of additional DR and so allows you to operate with a lower DR setting Status There are five STATUS LED s OVLD indicates a signal overload This condition can occur when the signal is too large the sensitivity is too high the dynamic reserve is too low the offset is on the expand is on the time
26. input port X1 X4 in volts If n is 5 or 6 then v may also be sent If v is included the designated analog output port X5 or X6 will be set to v volts where v has the range 10 238V to 10 238V If v is absent the output value of the selected port is returned On power up port X5 is the ratio output An X 5 command will read the ratio output An X 5 command with the parameter v will set port X5 to v volts overriding the ratio output Port X5 will return to the ratio output on power up or reset Y n The Y command reads the status byte See the following section for a definition of the Status Byte n designates one bit 0 7 of the status byte If n is included the designated bit of the status byte is returned The bit which is read is then reset If n is absent the value of the entire byte is returned and all status bits are then reset This status byte may also be read over the GPIB using the serial poll command Z The Z command causes an internal reset All settings return to the default values shown on page 15 The ERR LED will be on for about three seconds to indicate that the stored instrument settings are being ignored If the RS232 echo mode is on the sign on message is sent over the RS232 interface Status Byte The SR530 maintains an 8 bit status register which the user may read to obtain information on the unit s status The status byte may be read in two ways by sending the Y command which returns the
27. is turned on the CHANNEL 1 OUTPUT DIGITAL DISPLAY will show the SERIAL NUMBER of the instrument and the CHANNEL 2 OUTPUT DIGITAL DISPLAY will show the firmware VERSION The REFERENCE DIGITIAL DISPLAY shows the model number of 16 the instrument All displays return to normal after 3 seconds Local and Remote When the instrument is programmed via the computer interface to be in the REMOTE state WITHOUT LOCK OUT the LOCAL key will return the instrument to LOCAL front panel control If the instrument is in the REMOTE WITH LOCK OUT state no front panel key will return the status to LOCAL In this case a RETURN TO LOCAL command must be sent over the computer interface or the power must be turned off and back on Defaults If the LOCAL key is held down when the POWER is turned on the instrument settings will be set to the defaults shown below instead of the settings in effect when the power was turned off Parameter Setting BANDPASS OUT LINE OUT LINE X 2 OUT SENSITIVITY 500 mV DYN RES LOW DISPLAYS XY EXPANDS OFF OFFSETS OFF value 0 PRE TIME CONSTANT 100 mS POST TIME CONSTANT 0 1 S ENBW 1Hz REFERENCE MODE f TRIGGER MODE SYMMETRIC REFERENCE DISPLAY FREQUENCY PHASE SHIFT 0 Whenever default values are used at power up the red ERR LED will turn on for about 3 seconds If the ERR LED is on when the instrument is powered on without the LOCAL key down then the instrument is ignoring the retained settings This c
28. of terminating characters sent by the SR530 is determined by which interface is being used and whether the echo feature is in use The terminating sequence for the GPIB interface is always lt cr gt lt lf gt with EOI The default sequence for RS232 is cr when the echo mode is off and lt cr gt lt lf gt when the echo mode is on The terminating sequence for the RS232 interface may be changed using the J command Note that the terminating characters are sent with each value returned by the SR530 Thus the response to the command string G T1 P cr while using the RS232 non echo mode would be 5 lt cr gt 4 lt cr gt 45 10 lt cr gt Front Panel Status LED s The ACT LED flashes whenever the SR530 is sending or receiving characters over the computer interfaces The ERR LED flashes whenever an error has occurred such as an illegal command has been received a parameter is out of range or a communication buffer has exceeded 240 characters This LED flashes for about three seconds on power up if the battery voltage is insufficient to retain previous instrument settings The REM LED is on whenever the SR530 is programmed to be in the remote state RS232 Echo and No Echo Operation In order to allow the SR530 to be operated from a terminal an echo feature has been included which causes the unit to echo back commands received over the RS232 port This feature is enabled bv setting switch 6 on SW2 to the DOWN position In t
29. present Phase Output After auto phase is performed the J output will be 0 deg R will be unchanged X will be maximized and Y will be minimized Offset Channel 2 The OFFSET section controls the manual offset The offset is turned ON and OFF using the upper key in the OFFSET section When the offset is ON the lower two keys are used to set the amount of offset A single key press will advance the offset by 0 025 of full scale If the key is held down the offset advances in larger and larger increments the largest increment being 10 of full scale When the offset is turned OFF the applied offset returns to zero but the offset value is not lost The next press of the upper offset kev return to ON sets the offset to the previously entered value If an attempt is made to advance the offset value bevond full scale the ON LED will blink An offset up to 1 024 times the full scale sensitivitv mav be entered When the EXPAND is on this is 10X the full scale output Note that the offsets either manual offset or those generated by the REL function represent a fraction of the full scale reading and so their absolute value will change when the sensitivity scale is changed A signal which has been nulled by an offset will not be nulled when the sensitivity scale is changed The analog meter and the output BNC indicate the same value given by the equation where Ae 1 or 10 per the Expand Ay 1 Sensitivity Vi magnitude o
30. signal at the reference frequency or at twice the reference frequency to allow for convenient measurement of the harmonic of the signal Output Filters can have one pole 6 dB per octave or two poles 12 dB octave A two pole filter provides a signal to noise improvement over a single pole filter due to its steeper roll off and reduced noise bandwidth Single pole filters are preferred when the lock in is used in a servo system to avoid oscillation 31 In many servo applications no output filtering is needed In this case the SR530 may be modified to reduce the output time constant to about 20 uS Contact the factory for details Noise measurement is a feature which allows direct measurement of the noise density of the signal at the reference frequency This is a useful feature to assess at what frequency you should run your experiment Ratio Capability allows the lock in s output to be divided by an external voltage input This feature is important in servo applications to maintain a constant loop gain and in experiments to normalize a signal to the excitation level Computer Interface allows a computer to control and to record data from the instrument This is the single most important feature for extending the lock in s capabilities and it s useful lifetime Measurements which are impractical without a computer become simple when a computer is used to coordinate various parts of the experiment The Internal Oscillator p
31. simple ASCII commands A key feature of the instrument is its four A D inputs and two D A outputs These analog I O ports may be used to read and supply analog voltages to an experiment or measurement All of the input and output ports have a full scale range of 10 24VDC with 2 5 mV resolution and 0 05 accuracy Computer control can eliminate set up errors reduce tedium allow more complete data recording and post measurement analysis Also the computer can play an active role in the data acquisition by adjusting gains etc in response to changing measurement conditions The microprocessor based design eliminates many analog components to improve performance reliability and reduce cost For example the magnitude and phase outputs are calculated by the microprocessor instead of using an analog vector summer This eliminates the temperature drifts and inaccuracies associated with nonlinear analog circuits and greatly reduces the number of parts Each unit is computer calibrated at the factory and calibration constants are placed in the instrument s read only memory The SR530 has only one fifth of the analog trimming components that are found in older designs Circuit Description Introduction The SR530 Lock in amplifier is an integrated instrument combining state of the art analog design with advanced microprocessor based control and interfaces This discussion is intended to aid the advanced user in gaining a better unde
32. the offset by 0 025 of full scale If the key is held down the offset advances in larger and larger increments the largest increment being 1096 of full scale When the offset is turned OFF the applied offset returns to zero but the offset value is not lost The next press of the upper offset key return to ON sets the offset to the previously entered value If an attempt is made to advance the offset value beyond full scale the ON LED will blink An offset up to 1 024 times the full scale sensitivity may be entered When the EXPAND is on this is 10X the full scale output Note that the offsets either manual offset or those generated by the REL function represent a fraction of the full scale reading and so their absolute value will change when the sensitivity scale is changed A signal which has been nulled by an offset will not be nulled when the sensitivity scale is changed The analog meter and the output BNC indicate the same value given by the equation Vout 10Ag AyVjcos V og if the output is X where Ae 1or 10 per the Expand Ay 1 Sensitivity Vi magnitude of the signal phase between signal amp reference Vos offset fraction of FS 1 024 When the DISPLAY is X X OFST or X NOISE the OFFSET keys adjust the X OFFSET which affects the X RCOSQ output When the DISPLAY is R or R OFST the OFFSET keys adjust the R OFFSET When the DISPLAY is X5 the OFFSET up and down keys set the output volt
33. the square wave by eight and 2 2 U327 selects the frequency of the square wave chopper The square wave output of U322 serves as the reference to the quadrature oscillator PLL This PLL is identical to the triangle oscillator sine wave shaper described above U1004 detects the zero crossings of the triangle wave to feed back to the phase comparator U1002 This ensures that the quadrature triangle wave is 90 deg out of phase from the first sine wave The quadrature triangle is shaped into a sine wave by 2 2 U1009 and amplified by 2 2 U1014 U1012 is a comparator which generates a square wave in phase with the quadrature sine wave U1013 divides the frequency of the square wave by eight and 1 2 U1011 selects the frequency of the square wave chopper Demodulator and Low Pass Amplifier Amplifier U402 and switch U401 select the polarity of the reference sine wave This allows phase shifts up to 360 degrees from the reference input The sine wave is ac coupled by U403 and inverted by U404 U405 selects alternating polarities of the sine wave at the chopper frequency f 2 or f 16 This chopped sine wave is then multiplied by the output of the signal amplifiers by the analog multiplier U406 The synchronous output of the multiplier that corresponds to the in phase signal is a square wave at the chopper frequency The output is ac coupled by U407 to remove the dc offset of the multiplier U408 inverts the signal and U405 chops the square wave
34. the two ENBW indicators will be on showing the Equivalent Noise Bandwidth of the rms noise calculation The ENBW is set using the keys below the ENBW indicator LED s same keys as used to set the POST filter The PRE filter keys do nothing in this case Pressing the upper key when the bandwidth is already 1 Hz will reset the rms noise average output to zero restarting the calculation Likewise with pressing the lower key when 10 Hz is already selected The noise is the rms deviation of the output within a 1 or 10 Hz equivalent noise bandwidth about the reference frequency A dc output does not contribute to the noise the noise is determined only by the ac wiggles at the output By measuring the noise at different frequencies the frequency dependence of the noise density can be found This usually has the form of V gjse 1 f The noise computation assumes that the noise has a Gaussian distribution such as Johnson noise Since the computation takes many time constants reciprocal ENBW the noise output should be allowed to approach a steadv value before a reading is taken Forthe 1 Hz ENBW this time is on the order of 15 to 30 seconds for the 10 Hz ENBW the output stabilizes much faster The noise output will varv slightiv since there will alwavs be noise variations that are slow compared to the bandwidth Anv DC component in the output will not contribute to the noise However a large DC output will cause the noise computa
35. to recover a dc output U409 buffers the chopper output before the first low pass time constant Op amps U416 and 2 2 U402 make up the first low pass amplifier with relays U411 U415 and U417 selecting the time constant The second low pass amplifier is U419 Analog switch U418 selects the time constant and gain The full scale output of U418 is 5 volts The quadrature demodulator and low pass amplifiers are identical to that described above The quadrature detector output is provided bv U1119 Analog Output and Control The dc output of the demodulator low pass amplifiers is passed to the reference input of multiplying DAC U502 The DAC is programmed with the appropriate attenuation to calibrate the overall gain of the lock in Every gain setting in each dynamic reserve is calibrated independently and the proper attenuations are stored in the unit s ROM The quadrature output is calibrated by DAC U1201 Amplifiers U1204 and U1205 buffer the two demodulator outputs to drive the X and Y BNC s A D s Analog multiplexer U504 selects the signal to be digitized by the microprocessor This signal can be either the lock in s in phase or quadrature output or one of the four independent analog inputs buffered by U501 These general purpose inputs are located on the rear panel of the instrument The selected signal is sampled and held on capacitor C502 and buffered by 4 4 U508 The A D conversion is done by successive approximation using comp
36. 0 3 00126 335 51A05 3 00126 335 51A05 3 00126 335 51A05 3 00126 335 51A05 3 00126 335 51A05 3 00084 340 ICL7650 3 00126 335 51A05 3 00076 340 DG211 3 00090 340 LF411 3 00088 340 LF353 3 00035 340 74074 3 00058 340 AD7524 3 00087 340 LF347 3 00076 340 DG211 3 00090 340 LF411 3 00090 340 LF411 Miscellaneous Parts List REF U 702 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Zo Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 Z0 SRS part VALUE 3 00161 342 27128 150 0 00045 013 4 40 MINI 0 00078 031 4 40X1 M F 0 00167 023 6 32X1 2RP 0 00179 000 RIGHT FOOT 0 00180 000 LEFT FOOT 0 00185 021 6 32X3 8PP 0 00187 021 4 40X1 4PP 0 00204 000 REAR FOOT 0 00209 021 4 40X3 8PP 0 00247 026 6 32X1 4 TRUSSP 0 00248 026 10 32X3 8T RUSSP 0 00371 026 4 40X3 16PF 6 00054 611 375A 3AG 7 00147 720 BAIL 7 00203 720 SR500 34 7 00204 720 SR500 35 7 00211 720 SR530 25 7 00215 720 SR530 29 7 00216 720 SR530 30 SR530 COMPONENT PARTS LIST DESCRIPTION Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Relay Relay Relay Relay Relay Integrated Circuit Thru hole Pkg Relay Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circu
37. 00KHz 200 ppm C 60 Hz notch 50 dB Q 10 adjustable from 45 to 65 Hz 120 Hz notch 50 dB Q 10 adjustable from 100 to 130 Hz Tracking bandpass set to within 196 of ref freq Q 5 20dB LOW 1 uV to 500 mV sensitivity 40dB NORM 100 nV to 50 mV sensitivity 60dB HIGH 100 nV to 5 mV sensitivity Bandpass filter adds 20 dB to dynamic reserve Line Notch filters increase dynamic reserve to 100 dB 0 5 Hz to 100 kHz 1 MO ac coupled SINE 100 mV minimum 1Vrms nominal PULSE 1 Volt 1 usec minimum width Fundamental f or 2nd Harmonic 2f Acquisition Time Slew Rate Phase Control Phase Noise Phase Drift Phase Error Orthogonalitv Demodulator Stabilitv Time Constants Offset Harmonic Rej Outputs amp Interfaces Channel 1 Outputs Channel 2 Outputs Output Meters Output LCD s Output BNC s X Output Y Output Reference LCD RS232 GPIB A D D A Ratio Internal Oscillator 25 Sec at 1 Hz 6 Sec at 10 Hz 2 Sec at 10 kHz 1 decade per 10 S at 1 kHz 90 shifts Fine shifts in 0 025 steps 0 01 rms at 1 kHz 100 msec 12 dB TC 0 17 Less than 1 above 10Hz 90 1 5 ppm C on LOW dynamic reserve 50 ppm C on NORM dynamic reserve 500 ppm C on HIGH dynamic reserve Pre 1msec to 100 sec 6 dB Octave Post 1sec 0 1 sec none 6 dB Octave or none Up to 1X full scale 10X on expand Both channels may be offset 55 dB bandpass filter in X RcosQ X Offset R magnitude
38. 01 1 8K 4 00197 407 6 49K 4 00088 401 51K 4 00021 401 1 0K 4 00035 401 10M 4 00030 401 10 4 00032 401 100K 4 00032 401 100K 4 00025 401 1 2M 4 00073 401 330K 4 00046 401 2 0M 4 00069 401 300K 4 00022 401 1 0M 4 00021 401 1 0K 4 00021 401 1 0K 4 00021 401 1 0K 4 00069 401 300K 4 00093 401 6 2K 4 00138 407 10 0K 4 00032 401 100K 4 00034 401 10K 4 00203 407 75 0K 4 00187 407 4 53K A 00160 407 2 26K A 00163 407 2 80K A 00034 401 10K DESCRIPTION Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor
39. 0K 4 00034 401 10K 4 00034 401 10K 4 00069 401 300K 4 00034 401 10K 4 00032 401 100K 4 00034 401 10K 4 00032 401 100K 4 00034 401 10K 4 00034 401 10K 4 00065 401 3 3K 4 00107 402 10 4 00107 402 10 4 00060 401 240 4 00024 401 1 2K 4 00024 401 1 2K 4 00060 401 240 4 00107 402 10 4 00107 402 10 4 00053 401 200 4 00063 401 3 0K 4 00063 401 3 0K 4 00053 401 200 4 00107 402 10 4 00107 402 10 4 00220 420 10KX8 4 00225 425 100KX9 4 00225 425 100KX9 1 00026 150 28 PIN 600 MIL 2 00014 207 SPSTX8 2 00014 207 SPSTX8 2 00017 216 APDT 2 00004 213 DPDT 6 00007 610 SR510 530 8 00085 860 SR513 ASSY 8 00085 860 SR513 ASSY 3 00076 340 DG211 3 001 18 325 78L15 3 00124 325 79L15 3 00076 340 DG211 3 00130 340 5532A 3 00076 340 DG211 3 00088 340 LF353 3 00076 340 DG211 3 00089 340 LF357 3 00076 340 DG211 3 00089 340 LF357 3 00076 340 DG211 3 00089 340 LF357 3 00088 340 LF353 SR530 COMPONENT PARTS LIST DESCRIPTION Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Comp 1 2W 5 Resistor Carbon Comp 1 2W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor C
40. 0M 4 00034 401 10K 4 00034 401 10K 4 00034 401 10K 4 00034 401 10K 4 00218 408 10 00K 4 00219 408 20 00K 4 00218 408 10 00K 4 00219 408 20 00K 4 00166 407 200K 4 00207 407 806K 4 00021 401 1 0K 4 00021 401 1 0K 4 00034 401 10K 4 00021 401 1 0K 4 00086 401 51 A 00086 401 51 A 00218 408 10 00K A 00218 408 10 00K 4 00078 401 39K 4 00059 401 22K 4 00032 401 100K 4 00021 401 1 0K 4 00034 401 10K 4 00057 401 220 4 00210 407 9 09K 4 00130 407 1 00K 4 00032 401 100K 4 00032 401 100K 4 00034 401 10K 4 00057 401 220 4 00034 401 10K 4 00057 401 220 4 00034 401 10K 4 00057 401 220 4 00034 401 10K 4 00057 401 220 4 00034 401 10K 4 00034 401 10K 4 00042 401 15K 4 00034 401 10K 4 00034 401 10K 4 00042 401 15K 4 00054 401 200K 4 00032 401 100K 4 00031 401 100 4 00079 401 4 7K DESCRIPTION Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W
41. 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg ON ON ON MS a ee ee ASN lee ND 76 REF U 1102 U 1103 U 1104 U 1105 U 1106 U 1107 U 1108 U 1109 U 1110 U 1111 U 1112 U 1113 U 1114 U 1115 U 1116 U 1117 U 1118 U 1119 U 1120 U 1121 U 1201 U 1202 U 1203 U 1204 U 1205 SRS part VALUE 3 00091 340 LF412 3 00090 340 LF411 3 00106 340 LT1007 3 00074 340 CD4066 3 00057 340 AD534 3 00090 340 LF411 3 00106 340 LT1007 3 00090 340 LF411 3 00084 340 ICL765
42. 1 10 0 10S 8 00003 801 10 0 10S 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 2 00001 201 D6 01 01 7 00039 701 SR521 4 00034 401 10K 4 00034 401 10K 4 00227 425 22KX9 4 00226 425 150X9 DESCRIPTION LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LCD Display LCD Display LCD Display Analog Meter Analog Meter Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Mo
43. 1 2 24 0 00128 053 4 24 0 00129 053 5 24 0 00136 053 8 1 2 24 0 00139 054 9 26 X20 0 00203 032 323914 1 00011 130 20 PIN IDP 1 00073 120 INSL 1 00145 131 20 PIN DIF POL 7 00305 710 SR530 31 7 00306 709 SR530 32 36 9 00815 924 DBL SIDED 1 2 SRS part VALUE 5 00016 501 470P 5 00038 509 10U 5 00060 512 1 0U 5 00049 566 001U DESCRIPTION Resistor Network SIP 1 4W 2 Common Resistor Network SIP 1 4W 2 Common Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Nut Hex Spacer Washer lock Washer nylon Window Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 26 UL1061 Termi
44. 10K 7 00037 701 SR501 4 00079 401 4 7K 4 00083 401 47K 4 00202 407 698 4 00189 407 41 2K 4 00186 407 4 22K 4 00190 407 42 2K 4 00186 407 4 22K 4 00202 407 698 4 00078 401 39K 4 00186 407 4 22K 4 00022 401 1 0M 4 00042 401 15K 4 00070 401 30K 4 00034 401 10K 4 00022 401 1 0M 4 00079 401 4 7K 4 00104 401 82K 4 00034 401 10K 4 00034 401 10K 4 00188 407 4 99K 4 00188 407 4 99K 4 00022 401 1 0M 4 00022 401 1 0M 4 00031 401 100 4 00031 401 100 2 00013 215 DPDT 2 00013 215 DPDT 3 00087 340 LF347 3 00085 340 ICL8038 3 001 18 325 78L15 3 00124 325 79L15 0 00100 040 1 4X1 16 0 00122 053 2 1 4 24 0 00136 053 8 1 2 24 DESCRIPTION Cap Monolythic Ceramic 50V 20 Z5U Cap Monolythic Ceramic 50V 20 Z5U Capacitor Tantalum 35V 20 Rad Cap Stacked Metal Film 50V 5 40 85c Capacitor Silver Mica 500V 5 DM15 Capacitor Tantalum 35V 20 Rad Capacitor Ceramic Disc 50V 10 SL Capacitor Electrolytic 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Electrolytic 35V 20 Rad Capacitor Tantalum 35V 20 Rad Pot Multi Turn Side Adjust Trim Pot Single Turn In Line Leads Pot Multi Turn Side Adjust Printed Circuit Board Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film
45. 148 3 00004 301 1N4148 3 00007 301 1N747A 3 00203 301 1N5711 3 00203 301 1N5711 3 00004 301 1N4148 3 00003 301 1N4007 3 00003 301 1N4007 3 00003 301 1N4007 3 00003 301 1N4007 6 00004 61 1 1A 3AG 4 00006 440 20 4 00012 441 20K 4 00012 441 20K 4 00013 441 50K 4 00014 441 5K 4 00011 441 10K 4 00011 441 10K 4 00011 441 10K 4 00011 441 10K 4 00002 440 100 4 00002 440 100 7 00036 701 SR500 3 00016 323 2N6485 3 00016 323 2N6485 3 00031 325 MPSA18 3 00887 325 MPS2907A 3 00026 325 2N5210 3 00026 325 2N5210 3 00026 325 2N5210 3 00026 325 2N5210 3 00026 325 2N5210 4 00033 404 100M SR530 COMPONENT PARTS LIST DESCRIPTION Crystal Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Diode Fuse Trim Pot Single Turn In Line Leads Pot Multi Turn Trim 3 8 Square Top Ad Pot Multi Turn Trim 3 8 Square Top Ad Pot Multi Turn Trim 3 8 Square Top Ad Pot Multi Turn Trim 3 8 Square Top Ad Pot Multi Turn Trim 3 8 Square Top Ad Pot Multi Turn Trim 3 8 Square Top Ad Pot Multi Turn Trim 3 8 Square Top Ad Pot Multi Turn Trim 3 8 Square Top Ad Trim Pot Single Turn In Line Leads Trim Pot Single Turn In Line Leads Printed Circuit Board Transistor TO 71 Package Transistor TO 71 Package Transistor TO 92 Package Transistor TO 92 Package Transistor TO 92 Packag
46. 23 529 AU 5 00023 529 AU 5 00023 529 AU 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 4 00016 445 10K 4 00016 445 10K DESCRIPTION Cap Stacked Metal Film 50V 5 40 85c Cap Polyester Film 50V 5 40 85c Rad Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Electrolytic 25V 20 Rad Capacitor Electrolytic 25V 20 Rad Capacitor Electrolytic 25V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Ceramic Disc 50V 10 SL Cap Stacked Metal Film 50V 5 40 85c Cap Monolythic Ceramic 50V 20 Z5U Cap Monolythic Ceramic 50V 20 Z5U Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Monolythic Ceramic 50V 20 Z5U Cap Monolythic Ceramic 50V 20 Z5U Capacitor Ceramic Disc 50V 10 SL Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Polyester Film 50V 5 40 85c Rad Cap Stacked Metal Film 50V 5 40 85c Capacitor Mylar Poly 50V 5 Rad Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Polyester Film 50V 5 40 85c Rad Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Cap Stacked Metal Fi
47. 407 4 53K A 00045 401 2 0K 4 00217 408 1 000K 4 00217 408 1 000K 4 00085 401 5 1M 4 00217 408 1 000K 4 00217 408 1 000K 4 00193 407 499 4 00130 407 1 00K 4 00131 407 1 00M 4 00022 401 1 0M 4 00217 408 1 000K 4 00193 407 499 4 00217 408 1 000K 4 00203 407 75 0K 4 00080 401 47 4 00142 407 100K 4 00034 401 10K 4 00132 407 1 10K 4 00179 407 30 1K 4 00183 407 348K 4 00155 407 150K 4 00184 407 37 4K 4 00212 407 9 76K 4 00161 407 2 49K 4 00021 401 1 0K 4 00045 401 2 0K 4 00131 407 1 00M 4 00131 407 1 00M 4 00146 407 110K 4 00140 407 10 2K 4 00032 401 100K 4 00021 401 1 0K DESCRIPTION Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Comp 1 4W 5 Resistor Carbon Comp 1 4W 5 Resistor Carbon Comp 1 4W 5 Resistor Carbon Comp 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 0 1 25ppm Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film
48. 9K 4 00021 401 1 0K 4 00045 401 2 0K 4 00131 407 1 00M 4 00131 407 1 00M 4 00146 407 110K 4 00140 407 10 2K 4 00021 401 1 0K 4 00021 401 1 0K 4 00218 408 10 00K 4 00219 408 20 00K 4 00218 408 10 00K 4 00219 408 20 00K 4 00210 407 9 09K 4 00130 407 1 00K 4 00032 401 100K 4 00032 401 100K 4 00034 401 10K 4 00057 401 220 4 00034 401 10K 4 00057 401 220 3 00094 340 LM311 3 00072 340 CD4046 3 00076 340 DG211 3 00094 340 LM311 3 00093 340 LM13600 3 00066 340 CA3140E 3 00076 340 DG211 3 00066 340 CA3140E 3 00093 340 LM13600 3 00093 340 LM13600 3 00076 340 DG211 3 00094 340 LM311 3 00068 340 CD4018 3 00091 340 LF412 3 00076 340 DG211 DESCRIPTION Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W
49. CHANNEL 2 LCD display provides a read out of the displayed parameter in real units The scale of the displayed quantity is indicated by the four scale LED s to the right of the display This read out auto ranges and will reflect the sensitivity added when the EXPAND function is on When displaying X6 the scale LED s are off and the units are volts Rel Channel 2 Every time the REL key is pressed the displayed parameter is offset to zero This is done by loading the displayed parameter s offset with minus one times the present output If the output is greater than 1 024 times full scale the REL function will not be able to zero the output In this case the OFFSET ON LED will blink and the offset value will be set to its maximum value The REL function and the manual OFFSET are both ways to enter the offset value After using the REL key the offset may be adjusted using the manual OFFSET When the DISPLAY is Y Y OFST or Y NOISE the REL key sets the Y OFFSET which affects the Y RSINQ output If Y NOISE is being displayed the REL function zeroes Y and the noise output will require a few seconds to settle again The REL key zeroes the X6 output when the DISPLAY is D A Auto Phase When the DISPLAY is phase the REL key sets the Reference Phase Shift to the absolute phase difference between the signal and the reference This is done by setting the Reference Phase Shift to the sum of the Reference Phase Shift and the
50. Calibration should be done oniv bv a qualified electronics technician kkkkkkkkk WAR N I NG kkkkkkkkk The calibration procedure requires adjusting the instrument with power applied and so there is a risk of personal injury or death by electric shock Please be careful Most of the calibration parameters are determined by a computer aided calibration procedure after burn in at the factory These calibration parameters are quite stable and so will not need to be adjusted Calibration parameters which may need field adjustment are detailed below Multiplier Adjustments On the HIGH dynamic reserve setting there can be some reference frequency feedthrough This section describes how to null this unwanted output This adjustment requires an oscilloscope and a signal generator which can provide a 500Hz reference signal Allow the unit to warm up for about 1 hour Reset the unit by turning it off and back on while holding the LOCAL key down Select voltage input A and connect a 50 1 2 terminator or shorting plug to the A input BNC connector Connect the 500 Hz reference signal to the reference input Set the SENSITIVITY to 1mV and the DYN RES to HIGH The PRE TIME CONSTANT should be set to 1mS and the POST TIME CONSTANT to NONE Connect the scope to the CHANNEL 1 OUTPUT on the front panel Set the scope to 2V div and 5mS div Externally trigger the scope using the reference input signal After about 90 seconds the scope displa
51. Common Hardware Problems Common Software Problems RS232 Interface Introduction to the RS232 Data Communications Equipment Wait Command Termination Sequence GPIB IEEE 488 Interface Introduction to the GPIB GPIB Capabilities Response to Special GPIB commands Serial Polls and SRQ s Echo Mode using the RS232 Using Both the RS232 amp GPIB Lock in Technique Introduction to Lock in Amplifiers Measurement Example Understanding the Specifications Shielding and Ground Loops Dynamic Reserve Current Inputs Bandpass Filter Notch Filters Frequency Range Output Time Constants Noise Measurements Ratio Capability Computer Interfaces Internal Oscillator SR530 Block Diagram Block Diagram Signal Channel Reference Channel Phase Sensitive Detector DC Amplifier and System Gain Microprocessor System Circuit Description Introduction Signal Amplifier Current Amplifier Notch Filters Bandpass Filter Reference Oscillator PSD LP Filters and DC Amplifier Analog Output A D s D A s Expand Front Panel Microprocessor Control RS232 Interface GPIB Interface Power Supplies Internal Oscillator Calibration and Repair Introduction Multiplier Adjustments Amplifier and Filter Adjustments CMRR Adjustment Line Notch Filter Adjustment 2xLine Notch Filter Adjustment Repairing Damaged Front End Appendix A Noise Sources and Cures Johnson Noise 1 f Noise Noise Spectrum Capacitive Coupling Inductive Coupling Gro
52. DTE that it is clear to send CTS by placing gt 3 VDC on pin 5 of the interface Similarly the DTE can tell the DCE that it is not ready by placing 3 VDC on pin 20 DTR of the interface The data lines pins 2 and 3 use negative logic A zero bit is represented by a positive voltage and a one bit is represented bv a negative voltage A start bit is a positive voltage and a stop bit is a negative voltage Data is transmitted with the least significant bit first The a 1 14 ms 9600 Baud 104 uS HL paui LSB I m ASC Code Eege Two Stop Be 44 letter A which has the ASCII code 41H 0100 0001 would appear as follows If a parity option was selected the parity bit would be sent after the 8th data bit but before the first stop bit Final Tip When vou are trving to get the RS232 to work with your computer it is helpful to be able to eavesdrop on the RS232 data lines going between the SR530 and the computer This can be done with an ASCII RS232 terminal and the following connector to pin 2 or 3 on RS232 to isten to Computer or SR510 To test the connector place the hook clip on pin 2 of the same connector shorting pin 2 to pin 3 Now when vou tvpe at the terminal kevboard data transmitted from pin 2 is received at pin 3 and displayed on the terminal screen To use asa debugging tool attach the hook clip to either pin 2 or pin 3 of the RS232 cable on the SR530 to show
53. Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Comp 1 4W 5 Resistor Carbon Comp 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 0 1 25ppm Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 0 1 25ppm Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM 75 R 1109 R1110 R 1111 R1112 R 1113 R 1114 R 1115 R 1116 R 1117 R 1118 R 1119 R 1120 R 1121 R 1122 R 1123 R 1124 R1125 R 1126 R 1127 R 1128 R 1129 R 1130 R 1132 R 1133 R 1201 R 1202 R 1203 R 1204 R 1205 R 1206 R 1207 R 1208 R 1209 R 1210 R 1211 R 1212 U 1001 U 1002 U 1003 U 1004 U 1005 U 1006 U 1007 U 1008 U 1009 U 1010 U 1011 U 1012 U 1013 U 1014 U 1101 SR530 COMPONENT PARTS LIST SRS part VALUE 4 00022 401 1 0M 4 00217 408 1 000K 4 00193 407 499 4 00217 408 1 000K 4 00203 407 75 0K 4 00080 401 47 4 00142 407 100K 4 00032 401 100K 4 00034 401 10K 4 00132 407 1 10K 4 00179 407 30 1K 4 00183 407 348K 4 00155 407 150K 4 00184 407 37 4K 4 00212 407 9 76K 4 00161 407 2 4
54. Internal Oscillator The INTERNAL OSCILLATOR is a voltage controlled oscillator with a sine wave output To use the oscillator as the reference source connect the REF OUTPUT on the rear panel to the REF INPUT on the front panel The REF OUTPUT is a 1 Vrms sine wave The SINE OUTPUT mav be used as the stimulus to the experiment The SINE OUTPUT can be set to three amplitudes 1 V 100 mV and 10 mV rms using the amplitude switch The output impedance is 6000 The AMP CAL screw adjusts the amplitude The oscillator frequency is controlled by the VCO INPUT voltage A voltage from OV to 10V will adjust the frequency according to the VCO RANGE selected Three ranges are available 1 Hz V 100 Hz V and 10 KHz V The input impedance is 10 kQ The FREQUENCY CAL screw adjusts the frequency There are four ways to set the frequency 1 Connect X5 or X6 D A outputs to the VCO INPUT The frequency can now be set from the front panel by setting the DISPLAY to D A and adjusting X5 or X6 The frequency is also controllable via the computer interfaces by programming X5 or X6 18 2 If the VCO INPUT is left open then the oscillator will run at the top of its range i e 10 Hz 1 KHz or 100 KHz 3 A 10 KQ potentiometer may be connected from the VCO INPUT to ground This pot will then set the frequency 4 Connect the VCO INPUT to an external voltage source which can provide 0 to 10V In all four cases if the REF OUTPUT is connect
55. MODEL SR530 LOCK IN AMPLIFIER A RS Stanford Research Svstems 1290 D Reamwood Avenue Sunnvvale CA 94089 U S A Phone 408 744 9040 Fax 408 744 9049 Email info thinkSRS com e www thinkSRS com Copyright 1997 2001 2005 2013 Stanford Research Systems Inc All Rights Reserved Rev 2 4 11 2013 Condensed Information SAFETV and Preparation for use Svmbols Specifications Front Panel Summarv Abridged Command List Status Bvte Definition Configuration Switches Guide to Operation Front Panel Signal Inputs Signal Filters Sensitivitv Dvnamic Reserve Status Indicators Displav Select Channel 1 Displav R Output Output Channel 1 Rel Channel 1 Offset Channel 1 Expand Channel 1 X RCOSO Output Channel 2 Display Output Output Channel 2 Rel Channel 2 Auto Phase Offset Channel 2 Expand Channel 2 Y RSINO Output Reference Input Trigger Level Reference Mode Reference Display Phase Controls Time Constants Noise Measurements Power Switch Local Remote Operation Default Settings Rear Panel AC Power GPIB IEEE 488 Connector RS232 Connector Signal Monitor Output Pre Amp Connector A D Inputs and D A Outputs Ratio Feature Internal Oscillator Table of Contents JO QO ND Guide to Programming Communications Command Syntax Status LED s RS232 Echo Feature Try out with an ASCII Terminal Command List Status Byte Errors Reset Command Trouble Shooting Interface Problems
56. NE NOTCH to IN the SENSITIVITY to 10mV and the DYN RES to LOW Connect the scope to the SIGNAL MONITOR output on the rear panel Set the scope to AC coupled 0 2V div 10mS div Trigger the scope externally using the reference input signal The LINE NOTCH frequency and depth are adjusted by the pair of 20 turn potentiometers located under the middle two holes in the signal shield row 4 on the circuit board Using a small screwdriver carefully adjust one pot until the line output on the scope is minimized Then adjust the other pot until the output is minimized Iterate between the two pots until there is no further improvement Set the SENSITIVITY to 5mV 2mV and 1mV repeating the adjustments at each sensitivity Repeat this procedure using a reference frequency of 120 0 Hz 100 0 Hz and the LINEX2 NOTCH filter The LINEX2 NOTCH is adjusted by the pair of 20 turn potentiometers located under the back two holes in the signal shield row 5 on the circuit board Replace the top panel 39 Replacing the Front End Transistors Both the voltage and current front end transistors Q101 and Q102 are 2N6485 IMF6485 dual JFETS These transistors are selected at the factory to meet the noise specifications This section outlines their replacement procedure in the event that they become damaged during use Remove the AC power cord from the unit Remove top and bottom panels Release the signal shields by removing the four screw
57. Q of 5 and follows the reference frequency The passband is therefore 1 5 of the reference frequency The bandpass filter can provide an additional 20 dB of dynamic reserve for noise signals at frequencies outside the passband The filter also improves the harmonic rejection of the lock in The second harmonic is attenuated an additional 13dB and higher harmonics are attenuated by 6 dB octave more You may wish to use the bandpass filter and select a low dynamic reserve setting in order to achieve a better output stability Since the processor can only set the bandpass filter s center frequency to within 1 of the reference frequency this filter can contribute up to 5 of phase shift error and up to 5 of amplitude error when it is used In addition the bandpass filter adds a few nanovolts of noise to the front end of the instrument when it is in use Line Notch Filters should be used in most measurement situations The filters will reject about 50 dB of line frequency noise about a factor of 300 If your reference frequency is one octave away then these filters will introduce a 5 phase shift error and a few percent amplitude error Their effect on your signal is negligible if your reference frequency is more than two octaves away The frequency range of the SR530 lock in amplifier extends from 0 5Hz to 100KHz No additional cards are required for the instrument to cover its full frequency range The SR530 can be used to detect a
58. Q on the GPIB interface This bit is reset after the SR530 has been serial polled This bit is set only for status reads via a serial poll ie Bit 6 always zero for the RS232 Bit 7 Command Error This bit is set when an illegal command string is received Errors Whenever a parameter out of range or an unrecognized command error occurs the appropriate status bits are set and the ERR LED flashes In addition any commands remaining on the current command line up to the next lt cr gt are lost The ERR LED will also light if any of the internal communication buffers overflows This occurs when 240 characters are pending on the command queue or output queue The ERR LED will go off as soon as all buffers drop below 200 characters again Reset The Z command resets the unit to its default state The default front panel settings are listed in the DEFAULTS section of the Guide to Operations In addition the interface status returns to LOCAL the SRQ mask is cleared the RS232 character WAIT interval is set to 6 and the terminating sequence is reset to the proper defaults The command and output buffers are cleared by the Z command Therefore it is bad practice to use the Z command before all previous commands have been processed and all responses have been received Trouble Shooting Interface Problems If you are having difficulty getting your computer to communicate with the SR530 look to the sections on the RS232 a
59. RFACE H DEF SEG amp HC000 BASE ADDRESS OF CEC CARD INIT 0 TRANSMIT 3 RECV 6 ADDRESSES OF CEC FIRM WARE ROUTINES ADDR 21 SYS 0 CONTROLLER ADDRESS INZ IFC UNT UNL MTA LISTEN 23 DATA Z 13 r Q1 IFC MTA LISTEN 23 DATA Qi 13 Q2 IFC MTA LISTEN 23 DATA Q2 13 X6 IFC MTA LISTEN 23 DATA X6 LISN IFC UNT UNL MLA TALK 23 U r CALL INIT ADDR SYS INIT X6 OUTPUT TO ZERO CALL TRANSMIT INZ STATUS RESET SR530 GOSUB 600 CHECK TRANSMIT STATUS E X 0 INIT X6 OUTPUT TO ZI T CALL TRANSMIT Q1 STATUS GOSUB 600 GOSUB 510 VI VAL ANSS CALL TRANSMIT Q2 STATUSS GOSUB 600 GOSUB 510 VI VAL ANS ERO READ CHANNEL 1 OUTPUT GET RESULT INTO VI READ CHANNEL 2 OUTPUT GET RESULT INTO V2 51 390 400 PRINT CH1 V1 CH2 V2 410 420X X 0025 INCREMENT X6 OUTPUT BY 2 5 MV 430 IF X210 THEN X 0 RESET RAMP 440 X X6 STRS X 13 MAKE X6 COMMAND STRING 450 CALL TRANSMIT X STATUS SET NEW X6 VOLTAGE 460 GOSUB 600 470 480 GOTO 300 LOOP FOREVER 490 500 GET AN ANSWER STRING FROM THE SR530 510 CALL TRANSMIT LISN STATUS MAKE SR530 A TALKER 520 GOSUB 600 530 ANSS SPACES 10 INIT ANSWER STRING 540 CALL RECV ANSS LENGTHS STATU
60. RS232 ASCII computer terminal to the SR530 using a 2 wire link The terminal is a DTE and the SR530 is aDCE To operate correctly the SR530 and the terminal must have the same settings for baud rate parity and number of stop bits The control lines in the RS232 Standard which are used to indicate that a device is ready to accept 43 data must also be connected correctly at the terminal end If the terminal responds to a control line it will believe that the SR530 is not ready to accept data because the line is not passed in this example and will therefore not send any data CASE 2 RS232 with Control Lines DEVICE A DEVICE B The data lines are the same as in Case 1 In addition to the data lines there are two control lines used CTS Pin 5 Clear to send is a signal asserted by the DCE to tell the DTE that the DCE is ready to receive data DTR Pin 20 Data Terminal Ready is a signal asserted by the DTE to tell the DCE that the DTE is ready to receive data The SR530 responds to the control lines as follows 1 Ifthe lines are not connected the SR530 assumes that you are ready to receive data 2 Data will not be transmitted from the SR530 if the DTR line pin 20 is low This is useful in the case when your program is not yet ready to receive data If data transmission is not suspended then data may be overwritten in your computer s UART as it is not being retrieved by the program and so will be
61. RTS LIST SRS part VALUE 3 00130 340 5532A 3 00087 340 LF347 3 00093 340 LM13600 3 00073 340 CD4052 3 00073 340 CD4052 3 00076 340 DG211 3 00038 340 74HC139 3 00038 340 74HC139 3 00087 340 LF347 3 00088 340 LF353 3 00076 340 DG211 3 00094 340 LM311 3 00075 340 CD4538 3 00072 340 CD4046 3 00093 340 LM13600 3 00066 340 CA3140E 3 00093 340 LM13600 3 00076 340 DG211 3 00076 340 DG211 3 00076 340 DG211 3 00049 340 74HC74 3 00094 340 LM311 3 00094 340 LM311 3 00072 340 CD4046 3 00093 340 LM13600 3 00076 340 DG211 3 00066 340 CA3140E 3 00076 340 DG211 3 00066 340 CA3140E 3 00093 340 LM13600 3 00093 340 LM13600 3 00094 340 LM311 3 00091 340 LF412 3 00068 340 CD4018 3 00076 340 DG211 3 00094 340 LM311 3 00094 340 LM311 3 00076 340 DG211 3 00091 340 LF412 3 00090 340 LF411 3 00106 340 LT1007 3 00074 340 CD4066 3 00057 340 AD534 3 00090 340 LF411 3 00106 340 LT1007 3 00090 340 LF411 3 00084 340 ICL7650 3 00126 335 51A05 3 00126 335 51A05 3 00126 335 51A05 3 00126 335 51A05 DESCRIPTION Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circui
62. Rad Cap Stacked Metal Film 50V 5 40 85c Capacitor Mylar Poly 50V 5 Rad Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Polyester Film 50V 5 40 85c Rad Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Polystyrene 50V 5 Rad Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Polyester Film 50V 5 40 85c Rad Cap Polyester Film 50V 5 40 85c Rad Cap Polyester Film 50V 5 40 85c Rad Capacitor Ceramic Disc 50V 10 SL Cap Stacked Metal Film 50V 5 40 85c Cap Polyester Film 50V 5 40 85c Rad Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Monolythic Ceramic 50V 20 Z5U Cap Monolythic Ceramic 50V 20 Z5U Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Electrolytic 50V 20 Rad Capac
63. S READ RESULT INTO ANS 550 GOSUB 600 560 RETURN 570 580 590 CHECK STATUS OF LAST TRANSMISSION FOR ERRORS 600 IF STATUS 0 THEN RETURN STATUS OKAY 610 PRINT STATUS CODE STATUS ON GPIB ERROR 620 STOP 52 Program Example 5 HP85 via GPIB This program provides an example of an HP85 program using the GPIB interface which could be used to control the lockin amplifier In this example the SR530 should be addressed as device 16 by setting the switch bank SW1 per the instructions Page 7 10 x 0 20 OUTPUT 716 Q 30 ENTER 716 V1 40 DISP CH1 VI 50 OUTPUT 716 Q2 60 ENTER 716 V2 70 DISP CH2 V2 80 X X 0025 90 IF X gt 10 THEN X 0 100 OUTPUT 716 X6 X 110 GOTO 20 53 Documentation This section contains the parts lists and schematics for the SR530 lock in amplifier The first digit of any part number can be used to locate the schematic diagram for the part For example R415 is located on sheet 4 of the schematic diagrams 54 REF C 1 R 21 R22 R 23 R 24 R 25 SW1 SW2 U 1 U2 U3 U4 Z0 Z0 Z0 SR530 COMPONENT PARTS LIST Oscillator Board Parts List SRS part VALUE 5 00023 529 AU 5 00023 529 AU 5 00102 517 4 7U 5 00054 512 047U 5 00087 516 390P 5 00102 517 4 7U 5 00014 501 390P 5 00034 526 100U 5 00100 517 2 2U 5 00034 526 100U 5 00100 517 2 2U 4 00016 445 10K 4 00003 440 100K 4 00016 445
64. SR530 26 7 00213 720 SR530 27 7 00214 720 SR530 28 9 00144 907 3 32 BLACK 9 00188 917 SR510 530 SER 9 00216 907 1 8 BLACK 9 00217 907 3 16 BLACK Front Panel Board Parts List REF C 607 C 608 C 609 C 610 C 6100 C 6101 C 6102 C 6103 C 6105 C 6106 D 601 D 602 D 603 D 604 DS601 DS602 DS603 DS604 DS605 DS606 DS607 DS608 DS609 DS610 SRS parti VALUE 5 00023 529 1U 5 00023 529 1U 5 00023 529 1U 5 00023 529 1U 5 00019 501 68P 5 00019 501 68P 5 00052 512 01U 5 00052 512 01U 5 00023 529 1U 5 00023 529 1U 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN SR530 COMPONENT PARTS LIST DESCRIPTION Hardware Misc Screw Black All Types Hardware Misc Wire 18 UL1015 Strip 3 8 x 3 8 No Tin Wire 18 UL1015 Strip 3 8 x 3 8 No Tin Screw Black All Types Connector BNC Connector Male Connector Card Edge Connector Card Edge Socket THRU HOLE Line Cord Fabricated Part Fabricated Part Fabricated Part Fabricated Part Fabricated Part Fabricated Part Shrink Tubing Product Labels Shrink Tubing Shrink Tubing DESCRIPTION Cap Monolythic Ceramic 50V 2096 Z5U Cap Monolythic Ceramic 50V 2096 Z5U Cap Monolythic Ceramic 50V 2096 Z5U Cap Monolythic Ceramic 50V 2096 Z5U C
65. SWITCH 1 OF SW2 DOWN SW2 UP 9600 BAUD NO PARITY OPEN COM1 9600 N 8 2 CS DS CD AS 1 SET UP COM1 PORT TO 9600 BAUD NO PARITY 8 DATA BITS 2 STOP BITS r IGNORE CTS CLEAR TO SEND DSR DATA SET READY AND CD CARRIER DETECT r PRINT 41 CLEAR UART BY SENDING SPACES PRINT 41 Z RESET SR530 FOR I 1 TO 200 NEXT I WAIT FOR RESET TO FINISH r xX 0 INIT X6 OUTPUT TO ZERO r PRINT 41 Qi READ OUTPUT INPUT 1 V1 INTO VI PRINT 41 Q2 READ OUTPUT INPUT 1 V2 INTO V2 r PRINT CH1 V1 CH2 V2 r X X 0025 INCREMENT X6 OUTPUT BY 2 5 MV IF X gt 10 THEN X 0 RESET X6 RAMP PRINT 1 USING X6 X SET X6 OUTPUT VOLTAGE r GOTO 200 LOOP FOREVER 46 Program Example 2 IBM PC Microsoft Fortran V3 3 via RS232 Machine language routines to interface to the To use these routines the file for232 inc also on COM 1 RS232 port are provided in the file the SR575 disk must be included in the RS232 OBJ found on the SR575 disk These FORTRAN source routines allow for simple interfacing to the SR530 at 19 2 kbaud from FORTRAN programs Oniv two wires between the IBM PC s ASVNC port and the SR530 are needed pins 2 amp 3 of the RS232 but pins 5 6 8 and 20 should be connected to
66. U 5 00081 516 1P 5 00100 517 2 2U 5 00035 521 47U 5 00100 517 2 2U 5 00100 517 2 2U 5 00035 521 47U 5 00100 517 2 2U 5 00060 512 1 0U 5 00060 512 1 0U 5 00030 520 2200U 5 00030 520 2200U 5 00057 512 22U 5 00057 512 22U 5 00060 512 1 0U 5 00060 512 1 0U 5 00060 512 1 0U 5 00052 512 01U 5 00052 512 01U 5 00003 501 10P 5 00003 501 10P 5 00009 501 24P 5 00009 501 24P 5 00003 501 10P 5 00017 501 47P 5 00020 501 7 5P 5 00109 525 150P 5 00048 566 0015U 5 00051 512 015U 5 00055 512 15U 5 00060 512 1 0U 5 00059 512 47U 5 00003 501 10P 5 00109 525 150P 5 00048 566 0015U 5 00051 512 015U 5 00055 512 15U 5 00060 512 1 0U SR530 COMPONENT PARTS LIST Main Board Parts List DESCRIPTION Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Batterv Capacitor Mvlar Polv 50V 5 Rad Capacitor Mylar Poly 50V 5 Rad Capacitor Electrolytic 50V 20 Rad Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Electrolytic 16V 20 Rad Capacitor Electrolytic 16V 20 Rad Capacitor Electrolytic 50V 20 Rad Capacitor Silver Mica 500V 5 DM15 Capacitor Tantalum 35V 20 Rad Capacitor Electrolytic 25V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Electrolytic 25V 20 Rad Capacitor Tantalum 35V 20 Rad Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film
67. add 90 degrees and the lower key will subtract 90 degrees Holding both keys down at once sets the phase shift back to zero The REFERENCE DIGITAL DISPLAY automatically displays the phase whenever any of the PHASE keys are pressed The phase ranges from 180 degrees to 180 degrees and is the phase delay from the reference input signal Time Constant There are two post demodulator low pass filters labeled PRE and POST The PRE filter precedes the POST filter in the output amplifier Each filter provides 6 dB oct attenuation The PRE filter time constant ranges from 1 mS to 100 S and is selected by the two keys below the PRE filter indicator LED s Holding down either key will advance the time constant four times a second in the desired direction In many servo applications no time constant is needed The SR530 may be modified to reduce the output time constant to about 20 uS Contact the factory for details The POST filter time constant can be set to 1 S or 0 1 S or can be removed altogether NONE using the two keys below the ENBW indicators When set to NONE the total attenuation is that of the PRE filter or 6 dB oct When the POST filter is 1 S or 0 1S the total attenuation is 12 dB oct for frequency components beyond the larger of the POST and PRE filter bandwidths reciprocal time constant Noise Measurements When the DISPLAY is set to X NOISE Y NOISE none of the PRE and POST indicator LED s are on Instead one of
68. age of D A output X5 also on the rear panel up to 10 24 V Adjusting X5 will cancel the RATIO output Expand Channel 1 The output EXPAND is toggled by pressing the key in the Channel 1 EXPAND section The expand status is indicated by the X10 expand on and the X1 expand off LED s Only the Channel 1 OUTPUT is affected the X RCOS Q output is not expanded The X5 D A output may not be expanded X RCOSQ Output The analog output X Xofst is available at the X RCOSO BNC connector An input signal equal 12 in magnitude to the selected sensitivity which is in phase with the reference oscillator will generate a 10V output The output impedance is lt 1Q and the output current is limited to 20 mA The X RCOS output is affected by the X offset but may not be expanded The X RCOSQ is not affected by the DISPLAY setting except for two cases When the DISPLAY is set to X OFST the X RCOSQ output is the X offset When the DISPLAY is set to X NOISE the X RCOSO output has a bandwidth equal to the ENBW 1 or 10 Hz instead of the time constant Channel 2 Display The channel 2 outputs are summarized below Y is equal to RsinO where J is the phase shift of the signal relative to the reference oscillator of the lock in display CH2 Y setting output expand offset RSINQ Y Y Yofst yes yes Y Yofst YOFST Vofst yes yes Yofst Phase no no Y Yofst Phase no no Y Yofst YNOISE Y noise yes yes V Vofetlenbw
69. al Purpose A D and D A There are four analog input ports labeled X1 through X4 These inputs may be digitized and read via the computer interfaces The range is 10 24 V to 10 24 V and the resolution is 2 5 mV The input impedance is 1 MQ A digitization can be performed in about 3 mS but the result may take longer to transmit over the interface being used There are two analog output ports labeled X5 and X6 The voltages at these ports may be programmed via the computer interfaces The range is 10 24 V to 10 24 V and the resolution is 2 5 mV The output impedance is lt 1Q and the output current is limited to 20 mA Ratio Output X5 is the ratio output when not programmed by the computer interface or set via the front panel X5 becomes the ratio output whenever the unit is turned on The voltage at X5 is the ratio of the Channel 1 Output to the analog voltage at port X1 An output of 10 V corresponds to a ratio of 1 The ratio is computed by digitizing the Channel 1 Output and the voltage at port X1 and then taking the ratio The resolution is 2 5 mV For best accuracy the sensitivity should be set to provide at least a 50 full scale signal and the analog denominator X1 should be 5V or greater The ratio is updated approximately every 3 mS For the Ratio feature to work the voltage at the denominator input must exceed 40 mV When the DISPLAY is set to D A the ratio output is 10 times the magnitude R divided by X1
70. an be due to a low battery SR530 Guide to Operation Rear Panel AC Power The ac line voltage selector card line fuse and line cord receptacle are located in the fuse holder at the left side of the rear panel See the section Preparation for Use at the front of this manual for instructions on setting the ac voltage selector and choosing the correct fuse GPIB Connector The SR530 has an IEEE 488 GPIB interface built in The GPIB address is set using SW1 located to the right of the interface connectors Refer to page 7 for switch setting details RS232 Connector The SR530 has an RS232 interface The connector is configured as a DCE The baud rate paritv stop bits and echo mode are selected using SW2 located to the right of the interface connectors Refer to Page 7 for switch setting details Signal Monitor Output This BNC provides the buffered output of the signal amplifiers and filters This is the signal just before the demodulator The output impedance is lt 1Q When a full scale input is applied the peak to peak amplitude at this output is 20 mV 200 mV or 2 V for dynamic reserve settings of high norm and low respectively Preamp Connector This 9 pin D connector provides power and control signals to external peripherals such as pre amplifiers The available power is described below Pin Voltage Current Available 1 20 100 mA 2 5 10 mA 6 20 100 mA 7 Signal ground 8 Digital ground Gener
71. apacitor Ceramic Disc 50V 1096 SL Capacitor Ceramic Disc 50V 1096 SL Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Monolythic Ceramic 50V 20 Z5U Cap Monolythic Ceramic 50V 20 Z5U Diode Diode Diode Diode LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular LED Rectangular 70 SR530 COMPONENT PARTS LIST REF SRS part VALUE DESCRIPTION DS61 1 3 00012 306 GREEN LED Rectangular DS612 3 0001 2 306 GREEN LED Rectangular DS613 3 00012 306 GREEN LED Rectangular DS614 3 00012 306 GREEN LED Rectangular DS615 3 00012 306 GREEN LED Rectangular DS616 3 00012 306 GREEN LED Rectangular DS617 3 00012 306 GREEN LED Rectangular DS618 3 00012 306 GREEN LED Rectangular DS619 3 00012 306 GREEN LED Rectangular DS620 3 00012 306 GREEN LED Rectangular DS621 3 00012 306 GREEN LED Rectangular DS622 3 00012 306 GREEN LED Rectangular DS623 3 00012 306 GREEN LED Rectangular DS624 3 00012 306 GREEN LED Rectangular DS625 3 00012 306 GREEN LED Rectangular DS626 3 00012 306 GREEN LED Rectangular DS627 3 00012 306 GREEN LED Rectangular DS628 3 00012 306 GREEN LED Rectangular DS629 3 00012 306 GREEN LED Rectangular DS630 3 00012 306 GREEN LED Rectangular DS631 3 00012 306 GREEN LED Rectangular DS632 3 00012 306 GREEN LED Rectangular DS633 3 00012 306 GREEN LED Rectang
72. arator U514 to compare the sampled and held signal with known outputs of U505 a 12 bit DAC witha precision reference Note that the output of U506 an 8 bit DAC is summed with the output of U505 This 8 bit DAC corrects for offset errors which can accumulate as analog voltages pass through buffers S H amps and comparators These offsets are measured after each unit is manufactured and values to compensate for these offsets are placed in the unit s ROM The polarity of the offset corrected 12 bit DAC is set by 2 4 U511 and the SIGN bit yielding 13 bits of resolution from 10 24 to 10 24 volts D A s In addition to providing reference voltages for A D conversion the DAC output voltage mav be multiplexed bv U507 to one of eight sample and hold amplifiers which provide analog output and control voltages The microprocessor refreshes each S H amplifier everv few milliseconds to prevent droop Two of these outputs are available as general programmable outputs on the rear panel Two are 36 used to program the band pass filter and the reference oscillator phase shift One output is subtracted from the lock in output in U508 to provide a variable offset and another is the rms noise output The remaining two outputs generate the magnitude and phase output voltages Expand 3 4 U511 and 4 4 U1202 are the expand amplifiers They provide a selectable gain of 10 to the channel 1 and 2 outputs just before the output buffers Front Panel
73. arbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Comp 1 2W 5 Resistor Carbon Comp 1 2W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Comp 1 2W 5 Resistor Carbon Comp 1 2W 5 Resistor Network DIP 1 4W 2 8 Ind Resistor Network SIP 1 4W 2 Common Resistor Network SIP 1 4W 2 Common Socket THRU HOLE Switch DIP Switch DIP Switch Rocker PCB Mount LHS of 510 Switch Rocker PCB Mount RHS of 510 Transformer SRS sub assemblies SRS sub assemblies Integrated Circuit Thru hole Pkg Transistor TO 92 Package Transistor TO 92 Package Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg 66 REF U 118 U 201 U 202 U 203 U 204 U 205 U 206 U 207 U 208 U 301 U 303 U 304 U 305 U 306 U 307 U 308 U 309 U 310 U 311 U 312 U 313 U 314 U 315 U 316 U 317 U 318 U 319 U 320 U 321 U 322 U 323 U 324 U 325 U 326 U 327 U 328 U 329 U 401 U 402 U 403 U 404 U 405 U 406 U 407 U 408 U 409 U 410 U411 U 412 U 413 U 414 SR530 COMPONENT PA
74. asure verv small ac signals A Lock in amplifier can make accurate measurements of small signals even when the signals are obscured bv noise sources which mav be a thousand times larger Essentially a lock in is a filter with an arbitrarily narrow bandwidth which is tuned to the frequency of the signal Such a filter will reject most unwanted noise to allow the signal to be measured A typical lock in application may require a center frequency of 10 KHz anda bandwidth of 0 01 Hz This filter has a Q of 10 well beyond the capabilities of passive electronic filters In addition to filtering a lock in also provides gain For example a 10 nanovolt signal can be amplified to produce a 10 V output a gain of one billion All lock in measurements share a few basic principles The technique requires that the experiment be excited at a fixed frequency in a relatively quiet part of the noise spectrum The lock in then detects the response from the experiment in a very narrow bandwidth at the excitation frequency Applications include low level light detection Hall probe and strain gauge measurement micro ohm meters C V testing in semiconductor research electron spin and nuclear magnetic resonance studies as well as a host of other situations which require the detection of small ac signals Experiment i Differential AC Amplifier 1 VRMS Phase Lock Loop 28 A Measurement Example Suppose we wish to measure the
75. ated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit Integrated Circuit STATIC RAM I C Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Thru hole Pkg Z SN MSN MSN MS MSN MSN MSN MSN MSN MSN ASN MSN MSN ASN S ASN AS AS A S ASN S Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Int
76. ating voltage by orienting the printed circuit board to position the desired voltage to be visible when pushed firmly into its slot Rotate the fuse pull lever back into its normal position and insert the correct fuse into the fuse holder LINE FUSE Verify that the correct line fuse is installed before connecting the line cord For 100V and 120V use a 1 Amp fuse and for 220V and 240V use a 1 2 Amp fuse LINE CORD This instrument has a detachable three wire power cord with a three contact plug for connection to both the power source and protective ground The protective ground contact connects to the accessible metal parts of the instrument To prevent electrical shock always use a power source outlet that has a properly grounded protective ground contact FURNISHED ACCESSORIES Power Cord Operating Manual ENVIRONMENTAL CONDITIONS OPERATING Temperature 4 10 C to 40 C Specifications apply over 418 C to 28 C Relative Humidity 9096 Non condensing NON OPERATING Temperature 25 C to 65 C Humidity 9596 Non condensig OPERATE WITH COVERS IN PLACE To avoid personal injury do not remove the product covers or panels Do not operate the product without all covers and panels in place WARNING REGARDING USE WITH PHOTOMULTIPLIERS It is relatively easy to damage the signal inputs if a photomultiplier is used improperly with the lock in amplifier When left completely unterminated a PMT will charg
77. ce LCD Time Constants ENBW Power Switch Adjust phase in smoothly accelerating 0 025 steps or by 90 steps Press both 90 buttons to zero the phase Display reference phase setting or reference frequency Pre filter has time constants from 1 mS to 100 S 6 dB Octave Post filter has time constants of 0 0 1 or 1 0 S 6 dB Octave Equivalent Noise Bandwidth Specifies the bandwidth when making Noise measurements 1Hz or 10 Hz ENBW Instrument settings from the last use are recalled on power up Abridged Command List En O En 1 K32 L1 0 L1 1 L2 L2 0 L2 1 MO M1 N1 Auto offset X Auto offset Y Auto offset R Auto phase Return Bandpass Filter Status Take out the Bandpass Filter Put in the Bandpass Filter Return the Reference LCD Status Display the Reference Frequency Display the Reference Phase Shift Return Dynamic Reserve Setting Set DR to LOW range Set DR to NORM range Set DR to HIGH range Return Channel n 1 or 2 Expand Status Turn Channel n Expand off Turn Channel n Expand on Return the Reference Frequency Return the Sensitivity Setting Select 10 nV Full Scale G1 G3 with SRS preamp only Select 500 mV Full Scale Return Preamp Status 1 installed Return the Remote Local Status Select Local Front panel active Select Remote Front panel inactive Select Remote with full lock out Set RS232 End of Record to lt cr gt Set End of record to n m o p Simulates Key press of b
78. ct the R output but AR will not affect X and Y The AP command will execute the auto phase routine This is done by setting the reference phase shift with the present phase difference between the signal and the reference input The output then reads zero and the reference displav reads the signal phase shift AP maximizes X and minimizes V but R is unaffected The A commands may be issued at any time regardless of the DISPLAY setting B n If n is 1 the B command sets the bandpass filter in If n is O the bandpass filter is taken out If n is absent then the bandpass filter status is returned C fn If n is 1 the C command sets the reference LCD display to show the phase setting If n is O the LCD will display the reference frequency If n is absent the parameter being displayed frequency or phase is returned Note that the P and F commands are used to read the actual values of the phase and frequency D n If n is included the D command sets the dynamic reserve If n is absent the dynamic reserve setting is returned 21 n Dyn Res 0 LOW 1 NORM 2 HIGH Note that not all dynamic reserve settings are allowed at every sensitivity E m n The E command sets and reads the status of the output expands If m is 1 then Channel 1 is selected if m is 2 Channel 2 is selected The parameter m is required If n is 1 the E command expands the selected output channel n is 0 the expand is t
79. cy 1 f noise as well as line noise The frequency is low enough to avoid phase shifts and amplitude errors due to the RC time constant of the source impedance and the cable capacitance 29 The full scale sensitivity of 100 nV matches the expected signal from our sample The sensitivity is calibrated to 1 The instrument s output stability also affects the measurement accuracy For the required dynamic reserve the output stability is 0 1 C For a 10 C temperature change we can expect a 1 error A front end noise of 7 nV VHz will manifest itself as a 1 2 nVrms noise after a 10 second low pass filter since the equivalent noise bandwidth of a single pole filter is 1 4RC The output will converge exponentially to the final value with a 10 second time constant If we wait 50 seconds the output will have come to within 0 7 of its final value The dynamic reserve of 60 dB is required by our expectation that the noise will be a thousand times larger than the signal Additional dynamic reserve is available by using the bandpass and notch filters A phase shift error of the PLL tracking circuits will cause a measurement error equal to the cosine of the phase shift error The SR530 s 1 phase accuracy will not make a significant contribution to the measurement error Specifications for the Example Measurement Specification Value Error Full Scale Sensitivity 100 nV Dynamic Reserve 60 dB Reference Frequency 5 kHz Gain Acc
80. d Cap Stacked Metal Film 50V 5 40 85c Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Cap Stacked Metal Film 50V 5 40 85c Capacitor Electrolytic 50V 20 Rad Cap Stacked Metal Film 50V 5 40 85c Cap Polyester Film 50V 5 40 85c Rad Cap Stacked Metal Film 50V 5 40 85c Cap Polyester Film 50V 5 40 85c Rad Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Electrolytic 25V 20 Rad Capacitor Electrolytic 25V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Electrolytic 16V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Capacitor Ceramic Disc 50V 10 SL Cap Stacked Metal Film 50V 5 40 85c 57 REF C
81. d if m is 2 the post time constant is selected The parameter m is required If n is included the T command sets the selected time constant If n is absent the setting of the selected time constant is returned n Pre Time Constant m 1 1 1 mS 2 3 mS 3 10 ms 4 30 mS 5 100 mS 6 300 mS 7 1 S 8 3 S 9 10 S 10 30 S 11 100 S n Post Time Constant m 2 0 none 1 0 1 S 2 1 S Um n The U command sets and reads the unit s calibration bytes m is the address offset of the byte 0 511 If n is absent the value of the addressed calibration byte is returned If n is included the addressed calibration byte is set to the value of n 0 255 The new value will be in effect until the power is turned off or a reset command is issued Use of this command is not recommended V n If n is included the V command sets the GPIB SRQ service request mask to the value n 0 255 If n is absent the value of the SRQ mask is returned W fn The W command sets and reads the RS232 character wait interval If n is included the SR530 will wait nx4 mS between characters sent over the RS232 interface This allows slow computer interfaces to keep up n can range from 0 to 255 If n is absent the wait value is returned The wait interval is set to 6 on power up Xn v n designates one of the 6 general purpose analog ports located on the rear panel If n is 1 2 3 or 4 the X command will return the voltage on the designated analog
82. dB roll off in either direction Thus the pass band between 7096 pass points is always equal to 1 5th of the center frequency The center frequency is continually adjusted to be equal to the internal demodulator frequency When the reference mode is f the filter tracks the reference When the mode is 2f the filter frequency is twice the reference input frequency The center frequency tracks as fast as the reference oscillator can slew and may be used during frequency scans The bandpass filter adds up to 20 dB of dynamic reserve for noise signals outside the pass band and increases the harmonic rejection by at least 13dB 2nd harmonic attenuated by 13 dB higher harmonics attenuated 6dB octave more If not needed to improve the dynamic reserve or the harmonic rejection then the filter should be left OUT Sensitivity The sensitivity is displayed as a value 1 500 and a scale nV uV mV When using the current input which has a gain of 106 V A these scales read fA pA and nA The two keys in the SENSITIVITY section move the sensitivity up and down If either key is held down the sensitivity will continue to change in the desired direction four times a second The full scale sensitivity can range from 100 nV to 500 mV The sensitivity indication is not changed by the EXPAND function The EXPAND function increases the output sensitivity Volts out volts in as well as the resolution of the digital output display Not all
83. dwidth of Af in Hz For a 1MQ resistor V2 1 2 0 13 uVNHz To obtain the rms noise voltage that you would see across this 1M resistor we multiply 0 130 V NHz by the square root of the detector bandwidth If for example we were looking at all frequencies between dc and 1 MHz we would expect to see an rms Johnson noise of V2 1 2 0 13 uV VHz 106 Hz 1 2 130 uV 1 f Noise Arising from resistance fluctuations in a current carrying resistor the mean squared noise voltage due to 1 f noise is given by V2 AR I2 Af f where A is a dimensionless constant 10711 for carbon R is the resistance the current Af the bandwidth of our detector and f is the frequency to which the detector is tuned For a carbon resistor carrying 10 mA with R 1k Af f 1Hz we have Vnoise Vrms 40 And Others Other noise sources include flicker noise found in vacuum tubes and generation and recombination noise found in semiconductors All of these noise sources are incoherent Thus the total noise is the square root of the sum of the squares of all the incoherent noise sources Non Essential Noise Sources In addition to the intrinsic noise sources listed above there are a variety of non essential noise Sources i e those noise sources which can be minimized with good laboratory practice It is worthwhile to look at what might be a typical noise spectrum encountered in the laboratory environment Power Lina
84. e Transistor TO 92 Package Transistor TO 92 Package Transistor TO 92 Package Transistor TO 92 Package Resistor Carbon Comp 1 4W 5 60 R102 R 103 R 104 R 105 R 108 R 109 R110 R111 R112 R113 R114 R115 R116 R117 R118 R119 R 120 R 121 R 122 R 126 R 127 R 128 R 130 R 132 R 133 R 134 R 135 R 138 R 139 R 140 R 141 R 142 R 143 R 144 R 145 R 146 R 147 R 148 R 149 R 150 R 151 R 152 R 153 R 154 R 155 R 156 R 157 R 158 R 159 R 160 R 161 SR530 COMPONENT PARTS LIST SRS part VALUE 4 00033 404 100M 4 00030 401 10 4 00031 401 100 4 00031 401 100 4 00130 407 1 00K 4 00199 407 6 81K 4 00199 407 6 81K 4 00130 407 1 00K 4 00130 407 1 00K 4 00145 407 110 4 00145 407 110 4 00047 401 2 2 4 00196 407 6 04K 4 00210 407 9 09K 4 00130 407 1 00K 4 00193 407 499 4 00180 407 301 4 00141 407 100 4 00141 407 100 4 00210 407 9 09K 4 00130 407 1 00K 4 00021 401 1 0K 4 00082 401 470K 4 00082 401 470K 4 00179 407 30 1K 4 00179 407 30 1K 4 00131 407 1 00M 4 00052 401 20 4 00052 401 20 4 00150 407 13 0K 4 00174 407 280 4 00168 407 22 6K 4 00150 407 13 0K 4 00157 407 16 9K 4 00157 407 16 9K 4 00193 407 499 4 00180 407 301 4 00141 407 100 4 00141 407 100 4 00179 407 30 1K 4 00201 407 634 4 00195 407 54 9K 4 00176 407 3 01K 4 00178 407 3 83K 4 00211 407 9 53K A 00193 407 499 A 00180 407 301 4 00141 407 100 4 00141 407 100 4 00033 404 100M 4 00204 407 750 DESCRIPTION Resistor Carb
85. e 7 GPIB Capabilities The GPIB capabilities of the SR530 consistent with IEEE standard 488 1978 are shown in the table below Also shown are the responses of the SR530 to some standard commands Code Function SH1 Source handshake capability AH1 Acceptor handshake capability T5 Basic Talker Serial Poll Unaddressed to talk if addressed to listen L4 Basic Listener Unaddressed to listen if addressed to talk Service request capability No parallel poll capability SR1 PPO DC1 RLO Device Clear capability REN LLO GTL not implemented l command sets Remote Local SR530 Response to GPIB Commands Mnemonic Command Response DCL Device Clear Same as Z command SDC Selected Same as Z command Device Clear SPE Serial Poll Send Status Byte Enable amp clear status byte Because the SR530 can be controlled by an RS232 interface as well as the GPIB the remote local functions are not standard There is no local with lock out state When in the local state remote commands are processed even without the REN command being issued This is because the RS232 interface has no provision for bus commands and remote commands over the RS232 interface would never be enabled Serial Polls and Service Requests The status byte sent by the SR530 when it is serial polled is the same status byte which is read using the Y command except for bit 6 SRQ Ofcourse when the SR530 is serial polled it does not encode the s
86. e a cable to a few hundred volts in a very short time If this cable is connected to the lockin the stored charge may damage the front end transistors To avoid this problem provide a leakage path of about 100 KO to ground inside the base of the PMT to prevent charge accumulation Symbols you may find on SRS products Description Alternating current Caution risk of electric shock Frame or chassis terminal Caution refer to accompanying documents Earth ground terminal On supply Off supply SR530 Specification Summarv General Power Mechanical Warrantv Signal Channel Inputs Impedance Full Scale Sensitivitv Maximum Inputs Noise Common Mode Gain Accuracv Gain Stabilitv Signal Filters Dvnamic Reserve Reference Channel Frequency Input Impedance Trigger Mode 100 120 220 240 VAC 50 60 Hz 35 Watts Max 17 x 17 x 5 25 Rack Mount Included 16 Ibs Two years parts and labor Voltage Single ended or True Differential Current 10 Volts Amp Voltage 100 MO 4 25 pF ac coupled Current 1 kQ to virtual ground Voltage 100 nV 10 nV on expand to 500 mV Current 100 fA to 0 5 uA Voltage 100 VDC 10 VAC damage threshold 2 VAC peak to peak saturation Current 10 mA damage threshold 1 uA ac peak to peak saturation Voltage 7 nV NHz at 1 kHz Current 0 13 pAW Hz at 1 kHz Range 1 Volt peak Rejection 100 dB dc to 1KHz Above 1KHz the CMRR degrades by 6 dB Octave 1 2 Hz to 1
87. e tracking rate of the VCO is proportional to the VCO frequency The triangle output is compared to a constant voltage by U314 1 2 U313 and 1 2 U312 select f or 2f operation This signal is fed back to the phase detector U306 to be compared with the reference output of U304 U315 compares the triangle output with a variable voltage to generate a square wave signal phase shifted from the reference The range of this fine phase shift control is 5 to 95 degrees The output of U315 serves as the reference to a second phase locked loop This second PLL uses a similar proportional tracking triangle VCO Comparator U329 looks at the square wave output of the VCO while comparator U328 detects the zero crossings of the triangle output 1 2 U327 selects one these comparators to feed back to the phase detector U316 Since the square and triangle outputs are in quadrature U327 selects either an in 35 phase or quadrature relationship between the two VCO s Thus the output of the second VCO can be shifted from 5 to 185 deg from the reference The triangle output is divided by R363 and R362 before reaching transconductance amplifier 2 2 U322 The amplitude of the triangle input to this amplifier is enough to just saturate the input and provide a sine wave output 2 2 U325 then amplifies the sine wave before it goes to the demodulator U324 is a comparator which generates a square wave in phase with the sine output U326 divides the frequency of
88. ed to the REFERENCE INPUT on the front panel the frequency may be read on the front panel REFERENCE DIGITAL DISPLAY or via the computer interfaces SR530 Guide to Programming The SR530 Lock in Amplifier is remotely programmable via both RS232 and GPIB interfaces It may be used with laboratory computers or simply with a terminal All front panel features except signal input selection and power may be controlled and read via the computer interfaces The SR530 can also read the analog outputs of other laboratory instruments using its four general purpose analog input ports There are also two programmable analog output ports available to provide general purpose control voltages Communicating with the SR530 Before using either the RS232 or GPIB interface the appropriate configuration switches need to be set There are two banks of 8 switches SW1 and SW2 located on the rear panel SW1 sets the GPIB address and SW2 sets the RS232 parameters The configuration switches are read continuously and any changes will be effective immediately For details on switch settings see page 7 at the front of this manual Command Syntax Communications with the SR530 use ASCII characters Commands to the SR530 may be in either UPPER or lower case A command to the SR530 consists of one or two command letters arguments or parameters if necessary and an ASCII carriage return cr or line feed lt lf gt or both The different parts of
89. ed as GPIB languages to the GPIB address 23 Subroutine calls in Microsoft BASIC are done to To monitor the GPIB activity with an RS232 memory locations specified by the name of the terminal SW1 6 should be down and the ASCII subroutine The address is relative to the segment terminal should be attached to the rear panel address specified by the DEF SEG statement RS232 connector preceding CALL 10 20 30 40 50 60 70 80 90 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 320 330 340 350 360 370 380 EXAMPLE PROGRAM TO READ TH E SR530 OUTPUT AND RAMP THE X6 ANALOG OUTPUT USING IBM PC BASICA AND D E CAPITAL EQUIPMENT CORP GPIB INTERFACE CARD THE RAMP ON X6 CAN BE MATCHED BY SETTING THE SR530 DISPLAY TO D A ON THE SR530 REAR PANEL SET SWITCHES 4 AND 6 ON SWI TO DOWN DEVICE ADDRESS 23 RS232 ECHO ON AND SWITCH 4 1 ON SW2 TO DOWN RS232 BAUD RATE 9600 ALL OTHER SWITCHES SHOULD BE UP NOTE THAT THE RS232 ECHO IS FOR DEBUGGING AND DEMOSTRATION PURPOSES UNDER NORMAL CONDITIONING SWITCH 6 OF SW1 SHOULD BE UP SINCE THE RS232 ECHO SLOWS DOWN THE GPIB INTE
90. ed voltage Once a value of v is sent the offsets may be turned off and on without losing the offset values by using the O commands without the v parameter Note that the X and Y offsets will affect the R output but the R offset does not affect the X or Y output P v If v is absent the P command returns the reference phase shift setting from 180 to 180 degrees When v is included the phase is set to the value of v up to 999 degrees Q1 Q2 QX QY The Q commands return the output values in units of volts or degrees For an input signal of 50 uV on a full scale sensitivity of 100 uv a Q command will return the string 50 00E 6 Q1 and Q2 read the parameters being shown on the Channel 1 and Channel 2 output displays as selected with the S command QX and QY read the X RCOS and Y RSIN J BNC outputs R n If n is included the R command sets the reference input trigger mode If n is absent the trigger mode is returned n Mode O ositive 1 Symmetric 2 Negative S n If n is included the S command selects the parameters shown on the Channel 1 and 2 analog meters output digital displays and output BNC s If n is absent the displayed parameter is returned n Channeli Channel2 0 X Y 1 X Offset Y Offset 23 2 R 3 ROffst J 4 5 X Noise V Noise X5 D A X6 D A T m n The T command sets and reads the status of the time constants If m is 1 the pre time constant is selecte
91. egrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg 68 SR530 COMPONENT PARTS LIST SRS part VALUE 3 001 10 340 MC1489 3 00078 340 DS75160A 3 001 17 325 78L12 3 00123 325 79L12 3 00079 340 DS75161A 3 00095 331 LM317K 3 00099 331 LM337K 3 001 14 329 7815 3 001 14 329 7815 3 001 14 329 7815 3 00120 329 7915 3 00120 329 7915 3 00120 329 7915 3 001 13 340 7805CK 3 001 16 325 78L05 3 00096 340 LM317L 3 00100 340 LM337L 0 00005 007 SR530 0 00014 002 6J4 0 00016 000 TIE ANCHOR 0 0001 7 002 TRANSCOVER 0 00019 003 MICA 0 00025 005 3 8 0 00043 01 1 4 40 KEP 0 00048 01 1 6 32 KEP 0 00064 027 6 20X5 8P 0 00079 031 4 40X3 16 M F 0 00084 032 36154 0 00089 033 4 0 00095 040 4 FLAT 0 00096 041 4 SPLIT 0 00113 053 10 424 0 00117 053 12 424 0 00119 053 15 424 0 00128 053 4 24 0 00130 050 5 5 8 18 0 00132 053 6 1 2 24 0 00136 053 8 1 2 24 0 00153 057 GROMMET2 0 00185 021 6 32X3 8PP 0 00187 021 4 40X1 4PP 0 00207 003 TO 5 0 00222 021 6 32X1 4PP 0 00225 052 17 22 BLACK 0 00226 052 17 22 WHITE 0 00227 052 17 22 RED 0 00228 052 17 22 GREEN 0 00231 043 4 SHOULDER 0 00241 021 4 40X3 16PP 0 00249 021 6 32X1 1 2PP 0 00256 043 6 SHOULDER DESCRIPTION Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Transistor TO 92 Package Transistor TO 92 Package Integrated Circuit Thru hole Pkg Voltage Regula
92. either data sent from the Computer or the SR530 The baud rate paritv and stop bits of the terminal must match those of the SR530 and the computer If vour terminal has a mode which will displav control characters such as carriage returns and line feeds itis helpful to operate in that mode A variant of the eavesdropping approach is diagrammed below With this cable arrangement the ASCII terminal can listen to the data passing in both directions The only drawback is that the terminal will display garbled data if both devices transmit data at the same time Appendix C Introduction to the GPIB The IEEE 488 Standard specifies the voltage levels handshake requirements timing hardware details pinout and connector dimensions for a 16 line bit parallel bus Manv instruments mav be connected in series to communicate over the same cable Because the bits are passed in parallel the GPIB is faster than the RS232 The controller generally your computer coordinates data transfer on the bus by designating all participating instruments including itself as either a talker or a listener Listeners can receive data placed on the bus by the Talker Devices can have the capacity to operate in either mode The address of each device is set by switches in the device and must be between 0 and 30 Bus Description Byte Transfer Control Group This consists of 3 negative logic lines that implement the GPIB handshaking The NRFD
93. en applied differentially to the gates of Q101 Q101 is a low noise dual JFET The drain current through R109 is kept constant by 2 2 U101 The other half of U101 maintains a virtual null between the drains of the two transistors and thus an identical current flows through R110 Any input that would cause a differential between the two drains is amplified by 1 2 U101 and fed back via R112 in such a way as to reduce that differential Since the two transistors are at equal and constant currents their gate source potentials are constant Thus the fed back signal which appears at the source of the right hand transistor exactly matches the input Likewise this signal will match the input 34 to the left hand transistor but with the opposite sign Resistors R112 and R110 attenuate the fed back signal from the output of U101 resulting in a differential input single ended output fixed gain of 10 amplifier P101 adjusts the current balance between the two transistors and therefore their gain match and common mode rejection The output of the pre amp is scaled by resistors R119 R122 and analog switch U103 which make up a 1 2 5 10 attenuator The signal is then amplified by 2 2 U102 Input overload is sensed through diodes D101 D104 Current Amplifier When the input selector is set to current the input to the pre amp comes from the output of the current to voltage converter 1 2 U102 U102 is a low voltage noise bipolar op amp Q102 serv
94. er the MODE key is pressed When the MODE is f the lock in will detect signals at the reference input frequency When the MODE is 2f the lock in detects signals at twice the reference input frequency In either case the reference oscillator has a maximum frequency of 100 KHz thus when in the 2f mode the reference input frequency may not exceed 50 KHz Reference Display The REFERENCE DIGITAL DISPLAY shows either the reference oscillator frequency or phase shift The displayed parameter toggles between the two whenever the SELECT key is pressed The appropriate scale indicator below the display will be on It is useful to check the frequency display to verify that the lock in has correctly locked to your reference The reference frequency is measured to 1 part in 256 resolution at all frequencies The display reads 000 if there is no reference input and 199 9 kHz if the input frequency exceeds 105 kHz Phase Controls The phase shift between the reference oscillator of the lock in and the reference input signal is set using the four keys in the PHASE section The two keys below the FINE label increment the phase setting in small amounts A single key press will change the phase by 0 025 degrees in the desired direction Holding the key down will continue to change the phase with larger and larger steps with the largest step being 10 degrees The two 90 keys are used to change the phase by 90 degree increments The upper key will
95. es as an input buffer to provide low current noise to the input The op amp always maintains a null at the gates of Q102 thus providing an input impedance of 1KQ R128 The input current is converted to a voltage by R135 and the op amp Q103 bootstraps out the summing junction capacitance of Q102 Notch Filters U107 is a high Q line frequency notch filter which can be switched in and out by analog switch 1 4 U106 The frequency and depth of the filter can be adjusted with P102 and P103 Resistors R146 R149 and switch U108 make up a selectable attenuator U118 is a line frequency 2nd harmonic notch filter selected by 2 4 U106 P104 and P105 agjust the frequency and depth The second notch filter has a gain of 3 and its output is scaled by U110 and resistors R156 R159 The signal then takes two paths to inverting amplifier U111 and to the input of the tracking bandpass filter U111 has the same gain as the bandpass filter The output of either U111 or the bandpass filter is selected by 3 4 U112 and 4 4 U106 and amplified by U113 U114 and U115 provide a last stage of gain and scaling and the final output is ac coupled and buffered by 4 4 U208 Bandpass Filter The bandpass filter is a three op amp state variable active filter 3 4 of U201 make up the three op amps of the standard filter U203 U204 and U205 are analog switches which select the feedback capacitors for the 5 decades of operation The two halves of U202 are matched
96. f the signal phase between signal amp reference Vos Offset fraction of FS lt 1 024 When the DISPLAY is Y V OFST or Y NOISE the OFFSET keys adjust the V OFFSET which affects the Y RSINQ output When the DISPLAY is Q the OFFSET keys do nothing When the DISPLAY is X6 the OFFSET up and down keys set the output voltage of D A output X6 also on the rear panel up to 10 24V Expand Channel 2 The output EXPAND is toggled by pressing the key in the Channel 2 EXPAND section The expand status is indicated by the X10 expand on and the X1 expand off LED s Only the Channel 2 OUTPUT is affected the V RSINQ output is not expanded and X6 may not be expanded 14 V RSINQ Output The analog output Vi Vote is available at the Y RSINO BNC connector An input signal equal in magnitude to the selected sensitivity which is 90 out of phase with the reference oscillator will generate a 10V output The output impedance is 410 and the output current is limited to 20 mA The Y RSIN output is affected by the Y offset but may not be expanded The Y RSINQ is not affected by the DISPLAY setting except for two cases When the DISPLAY is set to Y OFST the Y RSINQ output is the Y offset When the DISPLAY is set to Y NOISE the Y RSINO output has a bandwidth equal to the ENBW 1 or 10 Hz instead of the time constant Reference Input The REFERENCE INPUT BNC is located in REFERENCE INPUT section The input i
97. filtered signal with the reference sine waves The difference frequency component of the multipliers outputs are dc signals that are proportional to the amplitude of the signal The low pass filters which follow each multiplier can reject any frequency components which are more than a fraction of a Hertz away from the signal frequency DC Amplifiers and System Gain Dc amplifiers amplify and offset the outputs of the two low pass filters The total system gain is the product of the ac and dc amplifier gains The partitioning of the system gain between these ac 33 and dc amplifiers will affect the stability and dynamic reserve of the instrument The output is most stable when most of the gain is in the ac amplifier however high ac gain reduces the dynamic reserve For the most demanding applications the user may specify how the system gain is partitioned However with prefilters that are able to provide up to 100 dB of dynamic reserve and with chopper stabilized dc amplifiers most users will not be concerned with just how the system gain is allocated A Microprocessor Based Design The instrument was designed to take full advantage of its microprocessor controller This approach provides several key advantages The instrument may be interfaced to a laboratory computer over the RS232 and IEEE 488 interfaces In addition to simply reading data from the lock in the computer can control all of the instrument settings with
98. gether on the connector at the IBM end Sstorage 2 Sinclude for232 inc 20 for 232 inc must be included to call subroutines in RS232 0BJ link with RS232 0BJ on SR565 disk RS232 0BJ defines init initializes COM1 to 19 2 kbaud txstr str str is a string terminated with transmits str to COMI rxstr str str must be declared with length of 15 or greater fills str with string received from COMI if and error occurs nocom is called Nocom should be a FORTRAN subroutine in your program program ex2 character 20 stri str2 str3 Example program to read the SR530 outputs and ramp the X6 analog output using Microsoft FORTRAN v3 3 and the COM1 port Set all switches in SW2 to UP on SR530 for 19 2 kbaud The ramp on X6 can be watched by setting the SR530 display to D A initialize COM1 port to 19 2 kbaud call init set character wait interval to zero call txstr w0 reset X6 to zero x6 0 0 read channel 1 output into string variable stri call txstr q1 call rxstr strl read channel 2 output into string variable str2 call txstr q2 47 1000 2000 3000 call rxstr str2 convert string variable into real variable vl and v2 read str1 1000 v1 read str2 1000 v2 format bn f10 0 print results to screen write 2000 v1 v2 format Channel 1 G10 3 3x Channel 2 G10 3 ramp x6 by 2 5 mV x6 x6 0025 if x6 gt 10 x6 0 0 make
99. gnal that the lock in can tolerate before overload to the full scale input Dynamic reserve is usually expressed in dB Thus a DR of 60 dB means that a noise source 1000 times larger than a full scale input can be present at the input without affecting the measurement of the signal A higher DR results in a degraded output stability since most of the gain is DC gain after the phase sensitive detector In general the lowest DR which does not cause an overload should be used The Current Input has a 1 kQ input impedance and a current gain of 10 Volts Amp Currents from 500 nA down to 100 fA full scale can be measured The impedance of the signal source is the most important factor to consider in deciding between voltage and current measurements For high source impedances gt 1 MQ and small currents use the current input Its relatively low impedance greatly reduces the amplitude and phase errors caused by the cable capacitance source impedance time constant The cable capacitance should still be kept small to minimize the high frequency noise gain of the current preamplifier For moderate source impedances or larger currents the voltage input is preferred A small value resistor may be used to shunt the source The lock in then measures the voltage across this resistor Select the resistor value to keep the source bias voltage small while providing enough signal for the lock in to measure The Auto Tracking Bandpass Filter has a
100. he DISPLAY is changed from X to R the EXPAND and OFFSET assume the conditions set the last time the DISPLAY was R If the DISPLAY is changed back to X the EXPAND and OFFSET return to conditions set for X R Output The magnitude R is given by the equation R X Xofgt T ed Ze 1 2 Rofst Note that the X and Y offsets affect the value of R while the X and Y expands do not The magnitude output has a resolution of 12 bits plus sign and is updated every 3 5 mS To achieve maximum accuracy the magnitude should be as large a fraction of full scale as possible R is expanded after the calculation Thus when R is expanded the full scale resolution drops by a factor of 10 to about 9 bits Output Channel 1 The CHANNEL 1 output is available at the left hand OUTPUT BNC connector The output parameter is selected by the DISPLAY setting and can be X X OFST R magnitude R OFST X NOISE or X5 external D A Note that X5 is the ratio output at power up When displaying X5 the ratio output is 10R X1 All outputs are 10V full scale when the EXPAND is off With the EXPAND on the output is multipled by 10 effectively increasing the full scale sensitivity by 10 X5 may not be expanded The output impedance is lt 10 and the output current is limited to 20 mA The left hand analog meter always displays the CHANNEL 1 OUTPUT voltage Accuracy is 2 of full scale The CHANNEL 1 LCD display provides a read out of the displayed pa
101. he SRQ Mask to the value n See the Status Byte definition Return the RS232 wait interval Set RS232 wait interval to nX4mS Return the voltage at the rear panel analog port n n from 1 to 6 Set analog port 5 to voltage v Set analog port 6 to voltage v Return the Status Byte value Test bit n of the Status Byte Reset to default settings and cancel all pending commands Status Bvte Definition Bit Meaning 0 Magnitude too small to calculate phase Command Parameter is out of range No detectable reference input PLL is not locked to the reference Signal Overload Auto offset failed signal too large SRQ generated Unrecognized or illegal command NOOR WD Configuration Switches There are two banks of 8 switches SW1 and SW2 located on the rear panel SW1 sets the GPIB address and SW2 sets the RS232 parameters The configuration switches are read continuously and any changes will be effective immediately SW1 GPIB Mode Switches Bit Example Function 1 up GPIB Address Switches 2 up Address 0 to 30 allowed 3 up up for bit 1 4 down down for bit 0 5 up Most Significant Bit 6 down down to echo on RS232 normally up 7 up Not Used 8 up Not Used If the GPIB mode switches are set as shown in the example column above then the lockin will be addressed as GPIB device 23 and all GPIB commands and data will be echoed over the RS232 for de bugging purposes SW2 RS232 Mode Switches Bi
102. his indicates that the SR530 is ready to accept commands Type the letter P followed by a carriage return P lt cr gt The SR530 responds by sending to the terminal the characters 0 00 indicating that the phase is set to O degrees In general a command with no arguments or parameters reads a setting of the unit To set the phase to 45 degrees type the command P45 lt cr gt To see that the phase did change use the SELECT key on the front panel to display the phase on the REFERENCE 20 DIGITAL DISPLAY Typing the phase read command P lt cr gt will now return the string 45 00 to the terminal Now read the gain using the sensitivity read command G cr The response should be 24 meaning that the sensitivity is at the 24th setting or 500 mV Change the sensitivity by typing G19 lt cr gt The sensitivity should now be 10 mV Check the front panel to make sure this is so The Channel 1 Output of the lock in is read by typing the command Q1 cr The response is a signed floating point number with up to 5 significant digits plus a signed exponent Change the gain to 10 uV using the G10 command The response to the Q1 command will now be similar to the previous one except that the exponent is different Attach a DC voltmeter to the X6 output on the rear panel The range should allow for 10V readings The voltage at the X6 output can be set using the X6 command Type X6 5 0 lt cr gt and the X6 output will change to 5 0V To
103. his mode the SR530 will send line feeds in addition to carriage returns with each value returned and will also send the prompts OK gt and to indicate that the previous command line was either processed or contained an error Operating the SR530 from a terminal is an ideal way to learn the commands and responses before attempting to program a computer to control the SR530 When the unit is controlled by a computer the echo feature should be turned off to prevent the sending of spurious characters which the computer is not expecting Try Out with an ASCII Terminal Before attempting any detailed programming with the SR530 it is best to try out the commands using a terminal Connect a terminal with an RS232 port to the RS232 connector on the rear panel of the SR530 A straight RS232 cable is required since the SR530 is a DCE and the terminal is a DTE Set the baud rate parity and stop bits to match the terminal by setting SW2 per the switch setting table given on page 7 The echo mode should be enabled switch 6 DOWN After setting SW2 and connecting the terminal hold down the LOCAL key while turning the unit on This causes the SR530 to assume its default settings so that the following discussion will agree with the actual responses of the SR530 The ACT and ERR LED s on the front panel will flash for a second and the sign on message will appear on the terminal Following the message the prompt OK gt will be displayed T
104. input is a current input with an input impedance of 1 KO to a virtual ground The largest allowable dc current before overload is 1 HA No current larger than 10 mA should ever be applied to this input The conversion ratio is 106 V A thus the full scale current sensitivities range from 100 fA to 500 nA with a max ac input before overload of 1 uA peak You should use short cables when using the current input Signal Filters There are three user selectable signal filters available a line frequency notch a 2X line frequency notch and an auto tracking bandpass Each of the filters has a pair of indicator LED s and a function key located in the SIGNAL FILTERS section of the front panel Pressing a key will toggle the status of the appropriate filter The status of each filter is displayed as IN filter active or OUT filter inactive The notch filters have a Q of 10 and a depth of at least 50 dB Thus the line frequency notch is 6 Hz wide and the 2X line notch has a width of 12 Hz Both of these filters can increase the dynamic reserve up to 50 dB at the notch frequencies The achievable reserve is limited by the maximum allowable signals at the inputs The notch frequencies are set at the factory to either 50 Hz or 60 Hz The user can adjust these frequencies See the Maintenance and Repair section for alignment details These filters precede the bandpass filter in the signal amplifier The bandpass filter has a Q of 5 and a 6
105. ission from the SR530 This can cause problems for the GPIB interface if the echo mode is on switch 6 of SW1 The SR530 with the RS232 Interface The RS232 is a popular serial interface standard for bit serial communication Despite the existence of the standard there are manv permutations of control lines baud rates and data formats If you do not have a lot of experience interfacing RS232 equipment vou should read Appendix B for a description of the RS232 and interfacing tips Data Communications Equipment DCE The SR530 is configured as DCE so that it may be connected directly to a terminal If the SR530 is to be interfaced with another DCE device a special cable sometimes referred to as a modem cable is required To use the RS232 interface you must set the switches in SW2 to match your computer s baud rate parity and number of stop bits Refer to Page 7 for details Wait Command The SR530 normally waits until the RS232 Clear to Send control line CTS is asserted before sending characters However some computers do not set and reset the CTS line possibly causing the SR530 to send data when the computer is not ready to read it The SR530 may be slowed down using the W command Sending Wn causes the unit to wait nx4 mS before sending each character over the RS232 bus The command WO sets the wait interval to zero and results in the fastest transmission The wait interval is set to 6 24 mS on power up Te
106. it Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg DESCRIPTION EPROM PROM I C Nut Mini Standoff Screw Roundhead Phillips Hardware Misc Hardware Misc Screw Panhead Phillips Screw Panhead Phillips Hardware Misc Screw Panhead Phillips Screw Black All Types Screw Black All Types Screw Black All Types Fuse Fabricated Part Fabricated Part Fabricated Part Fabricated Part Fabricated Part Fabricated Part 77 SR530 COMPONENT PARTS LIST
107. itor Electrolytic 50V 20 Rad Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Capacitor Ceramic Disc 50V 10 SL 58 REF C 802 C 803 C 804 C 805 C 806 C 807 C 808 C 809 C 901 C 902 C 903 C 904 C 905 C 906 C 907 C 908 C 909 C 910 C 911 C 912 C 913 C 914 C 915 C 916 C 917 C 918 C 919 C 920 C 923 C 924 C 925 C 926 C 927 C 928 C 929 C 930 C 931 C 932 C 933 C 934 C 935 C 936 C 937 C 938 C 939 CN801 CN802 CN803 CX1 CX713 CX714 SRS part VALUE 5 00012 501 330P 5 00012 501 330P 5 00052 512 01U 5 00052 512 01U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00035 521 47U 5 00035 521 47U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00035 521 47U 5 00035 521 47U 5 00192 542 22U MIN 5 00100 517 2 2U 5 00046 510 2200U 5 00046 510 2200U 5 00192 542 22U MIN 5 00192 542 22U MIN 5 00034 526 100U 5 00034 526 100U 5 00034 526 100U 5 00034 526 100U 5 00103 524 1 0U
108. l Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Comp 1 4W 5 Resistor Metal Film 1 8W 1 50PPM 61 R 162 R 163 R 165 R 166 R 167 R 168 R 169 R 170 R 171 R 172 R 173 R 174 R 175 R 176 R 177 R 178 R 201 R 202 R 203 R 204 R 205 R 206 R 207 R 208 R 209 R 210 R 211 R 212 R 213 R 214 R 215 R 216 R 217 R 218 R 219 R 220 R 221 R 222 R 223 R 224 R 225 R 226 R 227 R 228 R 229 R 301 R 302 R 303 R 304 R 305 R 306 SR530 COMPONENT PARTS LIST SRS parti VALUE 4 00188 407 4 99K 4 00035 401 10M 4 00215 407 909 4 00141 407 100 4 00215 407 909 4 00141 407 100 4 00134 407 1 24K 4 00144 407 107 4 00182 407 33 2 4 00035 401 10M 4 00193 407 499 4 00180 407 301 4 00165 407 200 4 0021 1 407 9 53K 4 00130 407 1 00K 4 00035 401 10M 4 00135 407 1 50K 4 00194 407 5 11K 4 00138 407 10 0K 4 00138 407 10 0K 4 00153 407 15 0K 4 00138 407 10 0K 4 00135 407 1 50K 4 00130 407 1 00K 4 00150 407 13 0K 4 00033 404 100M 4 00138 407 10 0K 4 00135 407 1 50K 4 00130 407 1 00K 4 00150 407 13 0K 4 00033 404 100M 4 00032 401 100K 4 00032 401 100K 4 00035 401 10M 4 00032 401 100K 4 00177 407 3 48K 4 00039 401 120K 4
109. lected if m is 2 the 2X line notch is selected The parameter m is required If n is 1 the L command sets the selected filter in If n is 0 the selected filter is taken out If n is absent the status of the selected filter is returned M fn If n is 1 the M command sets the reference mode to 2f If n is O the reference mode is set to f If n is absent the reference mode is returned N m If m is 1 the N command sets the ENBW to 10 Hz If m is 0 the ENBW is set to 1 Hz If m is absent the ENBW setting is returned OX n v OY n v OR fn v The OX OY and OR commands set the offsets for the X Y and R outputs respectively If nis 1 the offset is turned on If n is 0 the Offset is turned off If n and v are absent the offset status on or off is returned The value of the offset is read using the S and Q commands If n is included then v may be sent also v is the offset value up to plus or minus full scale in units of volts For example to offset half of full scale on the 100 uV sensitivity v should be 50 0E 6 or an equivalent value However if the sensitivity is then changed to 200 uV the offset is now half of the new full scale or 100 uV When the sensitivity is changed the offset is preserved as a constant fraction of full scale rather than as a voltage referred to the input The expand function will on the other hand preserve the value of the offset as an input referr
110. lm 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Cap Monolythic Ceramic 50V 20 Z5U Cap Monolythic Ceramic 50V 20 Z5U Capacitor Ceramic Disc 50V 10 SL Capacitor Polystyrene 50V 5 Rad Cap Polyester Film 50V 5 40 85c Rad Cap Polyester Film 50V 5 40 85c Rad Cap Monolythic Ceramic 50V 20 Z5U Cap Monolythic Ceramic 50V 20 Z5U Cap Monolythic Ceramic 50V 20 Z5U Cap Monolythic Ceramic 50V 20 Z5U Diode Diode Diode Diode Pot Multi Turn Side Adjust Pot Multi Turn Side Adjust 74 P 1103 P 1104 P 1201 P 1202 PC1 Q 1201 R 1001 R 1002 R 1003 R 1004 R 1005 R 1006 R 1007 R 1008 R 1009 R 1010 R 1011 R 1012 R 1013 R 1014 R 1015 R 1016 R 1017 R 1018 R 1019 R 1020 R 1021 R 1022 R 1023 R 1024 R 1025 R 1026 R 1027 R 1028 R 1029 R 1030 R 1031 R 1032 R 1033 R 1034 R 1035 R 1036 R 1037 R1101 R 1102 R 1103 R 1104 R 1105 R 1106 R 1107 R 1108 SR530 COMPONENT PARTS LIST SRS part VALUE 4 00016 445 10K 4 00016 445 10K 4 00016 445 10K 4 00016 445 10K 7 00040 701 SR522 3 00026 325 2N5210 4 00045 401 2 0K 4 00021 401 1 0K 4 00021 401 1 0K 4 00021 401 1 0K 4 00069 401 300K 4 00093 401 6 2K 4 00022 401 1 0M 4 00069 401 300K 4 00046 401 2 0M 4 00073 401 330K 4 00032 401 100K 4 00138 407 10 0K 4 00203 407 75 0K 4 00032 401 100K 4 00034 401 10K 4 00187 407 4 53K A 00160 407 2 26K A 00163 407 2 80K 4 00084 401 5 1K 4 00032 401 100K 4 00181 407
111. mentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Switch Momentary Push Button Printed Circuit Board Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Network SIP 1 4W 2 Common Resistor Network SIP 1 4W 2 Common 72 Quad Board Parts List REF C 1001 C 1002 C 1004 C 1005 SR530 COMPONENT PARTS LIST SRS parti VALUE 4 00226 425 150X9 4 00222 425 150X7 3 00086 340 ICM7211AM 3 00086 340 ICM7211AM 3 00086 340 ICM7211AM 3 00071 340 CD4030 3 00071 340 CD4030 3 00071 340 CD4030 3 00046 340 74HC374 3 00042 340 74HC175 3 00044 340 74HC244 3 00053 340 74LS164 3 00053 340 74LS164 3 00053 340 74LS164 3 00053 340 74LS164 3 00053 340 74LS164 3 00053 340 74LS164 3 00053 340 74LS164 3 00053 340 74LS164 3 00053 340 74LS164 0 00042 010 4 40 HEX 0 00077 030 3 16 X5 16 NYLN 0 00102 042 10 LOCK 0 00104 043 4 NYLON 0 00106 044 CLEAR 0 00111 053 1 3 4 24B 0 00112 053 1 3 4 24R 0 00117 053 12 24 0 00118 053 14 24 0 00119 053 15 24 0 00126 053 3
112. nation Connector Male Connector BNC Connector Female Front Panel Lexan Overlay Tape All types DESCRIPTION Capacitor Ceramic Disc 50V 10 SL Capacitor Electrolytic 50V 20 Rad Cap Stacked Metal Film 50V 5 40 85c Cap Polyester Film 50V 5 40 85c Rad 73 REF C 1006 C 1007 C 1008 C 1009 C 1010 C 1011 C 1012 C 1013 C 1014 C 1015 C 1016 C 1017 C 1018 C 1101 C 1102 C 1103 C 1104 C 1105 C 1106 C 1107 C 1108 C 1109 C 1110 C 1111 C 1112 C 1113 C 1114 C 1115 C 1116 C 1117 C 1120 C 1121 C 1122 C 1123 C 1124 C 1125 C 1126 C 1201 C 1202 C 1203 C 1204 C 1205 C 1206 C 1207 C 1208 D 1001 D 1002 D 1103 D 1104 P 1101 P 1102 SR530 COMPONENT PARTS LIST SRS parti VALUE 5 00058 512 33U 5 00049 566 001U 5 00003 501 10P 5 00003 501 10P 5 00035 521 47U 5 00035 521 47U 5 00035 521 47U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00100 517 2 2U 5 00008 501 22P 5 00060 512 1 0U 5 00023 529 1U 5 00023 529 1U 5 00060 512 1 0U 5 00060 512 1 0U 5 00023 529 AU 5 00023 529 AU 5 00003 501 10P 5 00056 512 AU 5 00056 512 AU 5 00056 512 AU 5 00056 512 AU 5 00049 566 001U 5 00053 512 033U 5 00072 513 10U 5 00056 512 AU 5 00060 512 1 0U 5 00049 566 001U 5 00013 501 33P 5 00013 501 33P 5 00054 512 047U 5 00054 512 047U 5 00023 529 AU 5 00023 529 AU 5 00012 501 330P 5 00136 519 01U 5 00049 566 001U 5 00049 566 001U 5 00023 529 AU 5 000
113. nd GPIB interfaces for some tips specific to your particular interface An ASCII terminal is a valuable aid for debugging interface problems You can use it to 1 become familiar with the SR530 s command structure 2 see GPIB bus transactions by using the GPIB echo mode 3 eavesdrop on transactions when using the RS232 interface 4 substitute a human for the SR530 bv using a null modem cable to make the DTE a DCE and attaching the terminal to the port to which you would normally have connected the SR530 This allows you to test your program s responses to inputs which you provide from the terminal Common Hardware Problems include 1 The RS232 or GPIB cables are not properly attached 2 The configuration switches for the RS232 characteristics or GPIB address are not set correctly Make sure the RS232 echo is off when using the RS232 interface with a computer The GPIB with RS232 echo 25 mode should be off when not debugging the GPIB interface 3 Your computer requires an RS232 control line to be asserted but your cable does not pass it between the SR530 and the computer or your computer is not asserting the DTR line on the RS232 Common Software Problems include 1 You have sent the wrong command to ask for data from the SR530 Your program will wait forever for a response which is not going to come This may not be your fault we have seen Microsoft s Interpreted Basic on the IBM PC occasionally
114. noise current passing through the finite resistance of the ground bus This problem arises because we have used two different grounding points which are not at exactly the same potential Some cures for ground loop problems include 1 grounding everything to the same physical point 2 using a heavier ground bus to reduce the potential drop along the ground bus 3 removing sources of large currents from ground wires used for small signals 42 Microphonics provides a path for mechanical noise to appear as electrical noise in a circuit or experiment Consider the simple circuit below Lock In Amplifier Coaxial Cable The capacitance of a coaxial cable is a function of its geometry so mechanical vibrations will cause the cable capacitance to vary with time Since C Q V we have CdV VdC dQ i dt dt dt so mechanical vibrations will cause a dC dt which in turn gives rise to a current i which will affect the detector Ways to eliminate microphonic signals include 1 eliminate mechanical vibrations 2 tie down experimental cables so they will not sway to and fro 3 use a low noise cable that is designed to reduce microphonic effects Thermocouple Effect The emf created by dissimilar metal junctions can give rise to many microvolts of dc potential and can be a source of ac noise if the temperature of the junction is not held constant This effect is large on the scale of many low level measurements Ap
115. ny inputs from the front panel The Remote Without Lockout command allows you to return the front panel to operation by pressing the LOCAL key Display Select The keys in the DISPLAY section select the parameters to be displayed on the OUTPUT METERS and the output of the two OUTPUT BNC connectors The displayed parameters are indicated by one of the six DISPLAY LED s and can be either the two demodulator outputs X Y the demodulator output offsets X OFST Y OFST the magnitude and phase R Q the magnitude offset and phase R OFST the rms noise on X and Y X NOISE Y NOISE or the D A outputs X5 D A X6 When displaying NOISE the equivalent noise bandwidth is selected in the TIME CONSTANT section When displaying D A the 2 outputs are the X5 and X6 rear panel D A outputs allowing the D A outputs to be set from the front panel This feature can be used to set the reference frequency when using the internal oscillator Channel 1 Display The channel 1 outputs are summarized below X is equal to Rcos where is the phase shift of the signal relative to the reference oscillator of the lock in display CH1 X setting output expand offset RCOSQ X X Xofst yes yes X Xofst XOFST Xofst yes yes Xofst R R Rofst yes yes X Xofst ROFST Rofst yes yes X Xofst XNOISE Xnoise yes yes X Xofstienbw X5 X5 no adjust X Xofst The EXPAND and OFFSET conditions for each display are retained when the DISPLAY is changed Thus when t
116. oltages with low impedance sources and measuring currents with high impedance sources to reduce the effect of istray 3 installing capacitive shielding by placing both the experiment and the detector in a metal box 41 Inductive Coupling Here noise couples to the experiment via a magnetic field 60 Hz Power Circuit Detector Experiment Inductive Noise Coupling A changing current in a nearby circuit gives rise to a changing magnetic field which induces an emf in the loop connecting the detector to the experiment emf d dt This is like a transformer with the experiment detector loop as the secondary winding Cures for inductively coupled noise include 1 removing or turning off the interfering noise source difficult to do if the noise is a broadcast station 2 reduce the area of the pick up loop by using twisted pairs or coaxial cables or even twisting the 2 coaxial cables used in differential hook ups 3 using magnetic shielding to prevent the magnetic field from inducing an emf at high frequencies a simple metal enclosure is adequate 4 measuring currents not voltages from high impedance experiments Resistive Coupling or Ground Loops Currents through common connections can give rise to noise voltages Experiment Detector Ground Bus Power Circuit Resistive Coupling Here the detector is measuring the voltage across the experiment plus the voltage due to the
117. on Comp 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Carbon Film 1 4W 5 Resistor Carbon Film 1 4W 5 Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Metal Film 1 8W 1 50PPM Resistor Meta
118. oordinate system is in phase with the reference input and signal If the Reference Phase shift is set to 45 degrees then the lock in coordinate system rotates to 45 degrees from the reference input Thus the reference input is now at 45 degrees from the lock in coordinate axes Since the reference and signal are in phase the signal is now at 45 degrees with respect to the lock in coordinates and the Phase Output will be 45 degrees The sum of the Reference Phase shift and the Phase Output is the absolute phase difference between the signal and the reference input Therefore the Phase Output may be offset to zero by adjusting the Reference Phase shift This is sometimes necessary when the Phase Output is near 180 degrees and varies between 180 and 180 degrees Output Channel 2 The CHANNEL 2 output is available at the right hand OUTPUT BNC connector The output parameter is selected by the DISPLAY setting and can be Y Y OFST phase phase Y NOISE or X6 ext D A All outputs are 10V full scale when the EXPAND is off With the EXPAND on the output is multipled by 10 effectively increasing the full scale sensitivity by 10 O and X6 may not be expanded The phase output is 50 mV deg 20 deg per Volt up to 9 V 180 deg The output impedance is 140 and the output current is limited to 20 mA The right hand analog meter always displays the CHANNEL 2 OUTPUT voltage Accuracy is 296 of full scale The
119. pendix B Introduction to the RS232 The RS232 is a standard for bit serial asvnchronous data communication The standard defines the format for data transmission the electrical specifications for the signal levels and the mechanical dimensions of connectors Despite the definition of a standard there are so manv permutations of control lines data formats and transmission speeds that getting two RS232 devices to communicate usuallv requires some work In this section we will provide some basic information to aid vou in connecting vour RS232 device to the SR530 Computer Interface CASE 1 The Simplest Configuration DEVICE A DEVICE B In this case one wire is used to send data from device A to device B and another wire is used to send data from device B to device A Notice that pin 2 is an output on device A and an input on device B It is good practice to run the ground pin 7 between the devices as well The RS232 defines two tvpes of devices DTE Data Terminal Equipment and DCE Data Communications Equipment An RS232 port on a computer mav be either a DTE or DCE but nearly every terminal with an RS232 portis a DTE RS232 ports on a computer which are intended to connect to a modem such as the COM1 port on the IBM PC are DTE The SR530 is configured as DCE and so it may be directly connected to ASCII terminals and to the COM ports on IBM PC s and compatibles As an example consider connecting an
120. rameter in real units The scale of the displayed quantity is indicated by the three scale LED s to the left of the display This read out auto ranges and will reflect the sensitivity added when the EXPAND function is on When displaying X5 the scale LED s are off and the units are volts Rel Channel 1 Every time the REL key is pressed the displayed parameter is offset to zero This is done by loading the displayed parameter s offset with minus one times the present output If the output is greater than 1 024 times full scale the REL function will not be able to zero the output In this case the OFFSET ON LED will blink and the offset value will be set to its maximum value The REL function and the manual OFFSET are both ways to enter the offset value After using the REL key the offset may be adjusted using the manual OFFSET When the DISPLAY is X X OFST or X NOISE the REL key sets the X OFFSET which affects the X RCOSO output If X NOISE is being displayed the REL function zeroes X and the noise output will require a few seconds to settle again When the DISPLAY is R or R OFST the REL key sets the R OFFSET The REL key zeroes the X5 output when the DISPLAY is D A Offset Channel 1 The OFFSET buttons control the manual offset The offset is turned ON and OFF using the upper key in the OFFSET section When the offset is ON the lower two keys are used to set the amount of offset A single key press will advance
121. read this back to the terminal just type X6 lt cr gt When setting the X6 voltage the voltage may be sent as an integer 5 real 5 000 or floating point 0 500E1 number Now connect the X6 output to the X1 input also on the rear panel X1 through X4 are analog input ports To read the voltage on X1 simply type X1 lt cr gt The response 5 000 should appear on the terminal The analog ports X1 through X6 can be used by your computer to read outputs of other instruments as well as to control other laboratory parameters At this point the user should experiment with a few of the commands A detailed command list follows SR530 Command List The leading letters in each command sequence specify the command The rest of the sequence consists of parameters Multiple parameters are separated by acomma Those parameters shown in are optional while those without are required The variables m and n represent integers while v represents a real number Parameters m and n must be expressed in integer format while v may be in integer real or floating point format The A command causes the auto offset rel function to execute Auto offset is performed by reading the output and using that value as the appropriate offset Every time an AX command is received the auto offset function is executed on the X output The AY command auto offsets the Y output The AR command auto offsets the R output Note that AX and AY will affe
122. reference applied to the input from continually interrupting the controller When such an SRQ occurs the controller should change some parameter so as to solve the problem and then re enable the SRQ mask bit again using the V command GPIB with RS232 Echo Mode It is sometimes useful when debugging a GPIB system to have some way of monitoring exactly what is going back and forth over the bus The SR530 has the capability to echo all characters sent and received over the GPIB to its RS232 port This mode of operation is enabled by setting switch 6 of SW1 to the DOWN position The baud rate stop bits and parity of the RS232 port are still set by SW2 Of course the RS232 port operates at much lower speeds than the GPIB and will slow down the GPIB data rate in this mode Use the WO command to allow the RS232 interface to run at full speed otherwise the GPIB transactions may take so long that the controller can hang During actual use this mode should be disabled The SR530 with BOTH Interfaces If both interfaces are connected commands may be received from either interface Responses are always sent to the source of the request except in GPIB echo mode It is unwise to send commands from the two interfaces at the same time since the characters from different sources can become interleaved on the command queue and result in unrecognized command errors The Lock in Technique The Lock in technique is used to detect and me
123. resistance of a material and we have the restriction that we must not dissipate very much power in the sample If the resistance is about 0 1Q and the current is restricted to 1 uA then we would expect a 100 nV signal from the resistor There are many noise signals which would obscure this small signal 60Hz noise could easily be 1000 times larger and dc potentials from dissimilar metal junctions could be larger still In the block diagram shown below we use a 1Vrms sine wave generator at a frequency w as our reference source This source is current limited by the 1 MQ resistor to provide a 1 uA ac excitation to our 0 10 sample Two signals are provided to the lock in The 1VAC reference is used to tell the lock in the exact frequency of the signal of interest The lock in s Phase Lock Loop PLL circuits will track this input signal frequency without any adjustment by the user The PLL has two outputs cos w t and sin wt The signal Vs cos wet 2 from the sample under test is amplified by a high gain ac coupled differential amplifier The output of this amplifier is multiplied by the PLL outputs in two Phase Sensitive Detectors PSD1 and PSD2 This multiplication shifts each frequency component of the input signal ws by the reference frequency Wy SO that the output of the PSD s are given by Lock In Amplifier DC Amplifier Output Low Pass Filter Vpsd1 Vg cos wyt cos wet 2 1 2 Va cos W Ws t
124. resses 4 The REN Remote Enable line changes the status of an instrument from local to remote 5 The IFC Interface Clear line clears the bus of all data and activity Though GPIB is a very powerful interface strict protocol must be observed for it to operate successfully Appendix D Program Examples All of the program examples which follow do the same thing only the computer language or interface is changed The programs read the Channel 1 and 2 Outputs and write the results to the computer screen In addition the X6 analog output port is ramped from 0 to 10V Program Example 1 IBM PC Basic via RS232 In this example the IBM PC s ASYNC port known as COM1 or AUX to DOS users will be used to communicate with the SR530 Only two wires between the IBM PC s ASYNC port and the SR530 are needed pins 2 amp 3 of the RS232 but pins 5 6 8 and 20 should be connected together on the connector at the IBM end 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250 260 270 280 290 300 310 EXAMPLE PROGRAM TO READ USING IBM PC BASICA AND THE RAMP ON X6 HE SR510 OUTPUT AND RAMP THE X6 ANALOG OUTPUT HE COM1 RS232 PORT CAN BE WA ON THE REAR PANEL OF TH AND ALL OTHER SWITCHES b IN CHED BV SETTING THE SR530 DISPLAV TO A D SR530 SET
125. ries which may be selected by the voltage selector card in the fuse holder The 15VAC is rectified by diode bridge BR2 and passed to 5V regulator U909 The output of U909 powers the microprocessor and its related circuitry The 40VAC output is half wave rectified by BR1 and regulated by U901 and U902 to provide 20V and 20V These two dc voltages are then regulated again by 15V regulators U903 U908 Each 15V regulator powers a separate section of the lock in to reduce coherent pick up between sections U911 and U912 provide plus and minus 7 5V and U910 generates 5V for the analog circuits 37 Internal Oscillator The internal oscillator is on a small circuit board attached to the rear panel of the instrument Local regulators Q1 and Q2 provide power to the board The VCO input is internally pulled up by R12 This pulls the VCO input to 10V when the VCO input is left open 2 4 U1 translates the VCO input voltage to provide a negative control voltage to U2 the function generator P3 adjusts the VCO calibration U2 is a sine wave generator whose frequency range is selected by the VCO Range switch and capacitors C4 C6 P2 adjusts the sine wave symmetry at low frequencies 4 4 U1 buffers the output of U2 P1 adjusts the amplitude of the output sine wave The output amplitude on the SIne Out is selected by the amplitude switch The output impedance is 600 Q Calibration and Repair This section details calibration of the instrument
126. rmination Sequences The default RS232 termination characters are sufficient to interface with most computers however it will occasionally be necessary to send special terminating sequences to fit the requirements of some computers This can be done with the J command The format for the 26 command is J n1 n2 n3 n4 where n1 n2 n3 and n4 are decimal values between 0 and 255 corresponding to the ASCII codes of the desired termination characters For instance if the desired termination sequence is an asterisk ASCII 42 two carriage returns ASCII 13 and a line feed ASCII 10 the appropriate command is J 42 13 13 10 If a G command is sent requiring an answer of 24 sensitivity 500 mV the SR530 would respond with the string 24 lt cr gt lt cr gt lt lf gt Up to four terminating characters may be specified by the J command If no arguments are sent with the J command the terminating sequence returns to the default echo on lt cr gt lt lf gt echo off lt cr gt The J command does not affect the terminating character lt cr gt required at the end of commands received by the SR530 It also does not affect the terminating sequence sent with data over the GPIB interface The SR530 with the GPIB Interface For a brief introduction to the GPIB standard please read Appendix C at the back of this manual Before using the GPIB interface you must set the switches in SW1 per the instructions on pag
127. rom 100 fA to 500 nA RMS for current inputs Select Dynamic Reserve Stability Sensitivity Ranges LOW 20 dB 5 ppm 1 uV to 500 mV NORM 40 dB 50 ppm 100 nV to 50 mV HIGH 60 dB 500 ppm 100nV to5mV OVLD Signal Overload UNLK PLL is not locked to the reference input ERR _ Illegal or Unrecognized command ACT RS232 or GPIB interface Activity REM Remote mode front panel has been locked out Channel 1 Channel 2 X RcosQ Y Pain X Offset Y Offset R Magnitude Q Phase R Offset B no offset X Noise Y Noise X5 D A X6 D A Displays Channel 1 and 2 Outputs as a fraction of full scale Displays the Channel 1 and 2 Outputs in absolute units Channel 1 and 2 Outputs follow Analog Meters 10 V for full scale Multiplies the Channel 1 or 2 Analog Meter and Output voltage by a factor X1 or X10 Set the Channel 1 or 2 Offset to null the output subsequent readings are relative readings REL with phase display performs auto phasing REL with X5 X6 display zeroes the D A outputs Enables or Disables Offset and allows any offset up to full scale to be entered X Y and R may be offset and X5 X6 may be adjusted Phase is offset using the reference phase shift X Rcosg output 10V full scale Y Pain output 10V full scale 1 MQ Input 0 5 Hz to 100 KHz 100 mV minimum Trigger on rising edge zero crossing or falling edge PLL can lock to either X1 or X2 of the reference input frequency Phase Controls Referen
128. rovides a reference source for the lock in This allows the lock in s frequency to be set without an additional signal generator It also provides a sine wave to be used as the signal stimulus in an experiment The frequency may be set via the computer interface as well as manually LOCK IN AMPLIFIER DIAGRAM LOW NOISE DIFFERENTIAL AMPLIFIER LINE FREQUENCY NOTCH FILTER DIFFERENTIAL VOLTAGE INPUTS CURRENT INPUT o CURRENT TO VOLTAGE CONVERTER REFERENCE INPUT c INI DISCRIMINATOR PHASE LOCK LOOP PRECISION SINE CONVERTER LINEAR PHASE SENSITIVE DETECTOR QUADRATURE PRECISION PHASELOCK SINE CONVERTER REAR PANEL A D INPUTS Loop AND RATIO INPUT ANALOG MULTIPLEXER DIGITAL CONTROLS AND S H AMPLIFIER A C AND D C GAINS NOTCH FILTERS RS 232 IEEL 488 COMPUTER INTERFACE SR530 Block Diagram Several new concepts are used to simplifv the design of SR530 lock in amplifier In addition to implementing recent advances in linear integrated circuit technologv the instrument was designed to take full advantage of its microprocessor controller to improve performance and to reduce cost As an example of the new techniques used in the SR530 consider the harmonic rejection problem Previously lock in amplifiers used a PLL with a square wave output The Fourier components of the square wave created a serious problem the lock in would respond to signal and noise at f 3f 5f ad infinitum
129. rstanding of the instrument The SR530 has eight main circuit areas the signal amplifier the reference oscillator the demodulator the analog output and controls the front panel the microprocessor the computer interfaces and the power supplies With the exception of the front panel the quadrature oscillator and demodulator and a few pieces of hardware the entire lock in is built on a single printed circuit board Each section is isolated from the others as much as possible to prevent spurious signal pickup To aid in the location of individual components the first digit or first two digits of a four digit part number of each part number generally refers to the schematic sheet number on which it occurs To help find the part on the circuit board the parts list includes a location on the circuit board for each component Parts with a four digit part number beginning with 10 11 or 12 are found on the quadrature detector plug in board located in the center of the main circuit board Part numbers beginning with 6 refer to parts on the front panel Signal Amplifier Assuming the input selector switch is set to a voltage input the signal is coupled in through capacitors C101 and C102 The input impedance is set by the 100 MQ resistors R101 and R102 over the operating frequency range Note that R103 isolates the signal shields from the instrument ground forcing the return signal current back along the cable shields The signal is th
130. s ac coupled and the impedance is 1 MO The dc voltage at this input should not exceed 100 V and the largest ac signal should be less than 10 V peak Trigger Level The TRIGGER MODE indicator toggles from POSITIVE to SYMMETRIC to NEGATIVE when the TRIGGER MODE key is pressed If the center TRIGGER MODE LED is on the mode is SYMMETRIC and the reference oscillator will lock to the positive zero crossings of the ac reference input The ac signal must be symmetric e g sine wave square wave etc and have a peak to peak amplitude greater than 100 mV A signal with 1 Vrms amplitude is recommended The phase accuracy of the reference channel is specified for a 1Vrms sinewave in the symmetric trigger mode If the upper TRIGGER MODE LED is on the mode is POSITIVE The trigger threshold is 1V and the reference oscillator will lock to the positive going transitions of the reference input This mode triggers on the rising edges of a TTL type pulse train The pulse width must be greater than 1 uS If the lower TRIGGER MODE LED is on the mode is NEGATIVE The trigger threshold is 1V and the reference oscillator will lock to the negative going transitions of the reference input This mode triggers on a negative pulse train or on the falling edges of a TTL tvpe pulse train remembering that the input is ac coupled The pulse width must be greater than 1 uS Reference Mode The REFERENCE MODE indicator toggles between f and 2f whenev
131. s which hold it onto the circuit board Be careful not to lose the nuts Carefully slide the shields back and then lift them out The input transistors are located on the main board just behind the input selector switch Q101 is the voltage A A B front end and Q102 is the current I front end Desolder and replace the appropriate transistor Replace the signal shields Be careful to check that the shields do not touch anv circuit board traces around their edges Replace the top and bottom panels If Q101 the voltage front end has just been replaced the Common Mode Rejection needs to be readjusted using the procedure described in the Amplifier Adjustments section Appendix A Noise Sources and Cures Noise random and uncorrelated fluctuations of electronic signals finds its wav into experiments in a varietv of wavs Good laboratorv practice can reduce noise sources to a manageable level and the lock in technique can be used to recover signals which may still be buried in noise Intrinsic Noise Sources Johnson Noise Arising from fluctuations of electron density in a resistor at finite temperature these fluctuations give rise to a mean square noise voltage V2 kr Re Z f df 4kTR Af where k Boltzman s constant 1 38x10 23J K T is the absolute temperature in Kelvin the real part of the impedance Re z f is the resistance R and we are looking at the noise source with a detector or ac voltmeter with a ban
132. send a curly bracket ASCII 253 when it was supposed to have sent a carriage return ASCII 13 2 Your computer s baud rate has been changed and no longer matches the SR530 s baud rate 3 The initial command sent to the SR530 was invalid due to a garbage character left in the command queue from power up or the first character in you computer s UART is garbage also due to power up It is good practice to send a few carriage returns to the SR530 when your program begins and have your program clear out its UART at the start of your program 4 The SR530 is not sending the correct end of record marker for your computer For example it appears that Microsoft s Rev 3 2 FORTRAN on the IBM PC under DOS 2 1 requires two carriage returns for an end of record marker The J command can be used to set the SR530 end of record marker to 2 carriage returns The end of record marker is that sequence which indicates that the response is complete From the keyboard a single carriage return is the end of record marker 5 Answers are coming back from the SR530 too fast overwriting the end of record markers and causing the computer to hang waiting for a complete response In this case the W command can be used to slow down the response time of the SR530 preventing overwriting 6 Answers are coming back from the SR530 too slowly due to the W6 default setting for the character interval time Use the W command to speed up the transm
133. t Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Relay Relay Relay Relay 67 REF U 415 U 416 U 417 U 418 U 419 U 420 U 421 U 501 U 502 U 503 U 504 U 505 U 506 U 507 U 508 U 509 U 510 U 511 U 512 U 513 U 514 U 515 U 516 U 517 U 701 U 703 U 704 U 705 U 706 U 707 U 708
134. t 1 Bit2 Bit3 Baud Rate up up up 19200 down up up 9600 up down up 4800 down down up 2400 up up down 1200 down up down 600 up down down 300 Bit Setting Explanation 4 up Odd parity down Even parity 5 up No parity down Parity enabled 6 up No echo for computer down Echo mode for terminal 7 up Two stop bits down One stop bit 8 unused Eight data bits are always sent regardless of the parity setting The most significant bit is always Zero Example Bit 1 down and all others up for RS232 communication at 9600 baud no parity two stop bits and no echo or prompts by the SR530 SR510 Guide to Operation Front Panel The front panel has been designed to be almost self explanatorv The effect of each kevpress is usuallv reflected in the change of a nearbv LED indicator or bv a change in the quantitv shown on a digital displav This discussion explains each section of the front panel proceeding left to right Signal Inputs There are three input connectors located in the SIGNAL INPUT section of the front panel The rocker switch located above the B input selects the input mode either single ended A differential A B or current I The A and B inputs are voltage inputs with 100 MQ 25 pF input impedance Their connector shields are isolated from the chassis ground by 10Q These inputs are protected to 100V dc but the ac input should never exceed 10V peak The maximum ac input before overload is 1V peak The l
135. t of this common mode noise However not all of the noise can be rejected especially the high frequency noise and so the lock in may overload on the high sensitivity ranges Experiment Lock In Amplifier Grounds may be at Different Potantials Quasi Differential Connection The second method of connecting the experiment to the lock in is called the true differential mode Here the lock in uses the difference between the center conductors of the A amp B inputs as the input signal Both of the signal sources are shielded from spurious pick up Experiment Lock in Amplifier Dt Are Grounds may ba al Different Potentials True Differential Connection With either method it is important to minimize both the common mode noise and the common mode signal Notice that the signal source is held near ground potential in both cases A signal which 30 appears on both the A amp B inputs will not be perfectly cancelled the common mode rejection ratio CMRR specifies the degree of cancellation For low frequencies the CMRR of 100 dB indicates that the common mode signal is canceled to 1 part in 10 but the CMRR decreases by about 6 dB octave 20 dB Decade starting at 1KHz Even with a CMRR of 10 a 10 mV common mode signal behaves like 100nV differential signal There are some additional considerations in deciding how to operate the lock in amplifier Dynamic Reserve DR is the ratio of the largest noise si
136. tatus byte as a decimal number The SR530 can be programmed to generate a service request SRQ to the GPIB controller every time a given status condition occurs This is done using the V n command The mask byte n 0 255 is the SRQ mask byte The mask byte is always logically ANDED with the status byte If the result is non zero the SR530 generates an SRQ and leaves the status byte unchanged until the controller performs a serial poll to determine the cause of the service request When the unit has been serial polled the status byte is reset to reflect all of the status conditions which have occurred since the SRQ was generated For example if we want to generate an SRQ whenever there is an overload or unlock condition we need an SRQ mask byte equal to 00011000 binary or 24 decimal V24 command The byte 00011000 binary corresponds to the status byte with the no reference and unlock status bits set If an overload occurs then an SRQ will be generated The serial poll will return a status byte showing SRQ and overload If an unlock condition occurs before the serial poll is concluded another SRQ will be generated as soon as the serial poll is finished A second serial poll will reflect the unlock condition 27 Any SRQ generated by the no reference unlock overload and auto over range conditions will also reset the corresponding bit in the SRQ mask byte This is to prevent a constant error condition such as no
137. the command do not need to be separated by spaces If spaces are included they will be ignored If more than one parameter is required by a command the parameters must be separated by a comma Examples of commands are G 5 lt cr gt setthe sensitivity to 200 nV T 1 4 lt cr gt set the pre filter to 30 mS F cr read the reference frequency P 45 10 cr set phase shift to 45 10j X 5 1 23E 1 cr set port X5 to 0 123 V Multiple commands may be sent on a single line The commands must be separated by a semicolon character The commands will not be executed until the terminating carriage return is sent An example of a multiple command is G 5 T 1 4 P 45 10 cr It is not necessary to wait between commands The SR530 has a command input buffer of 256 characters and processes the commands in the order received Likewise the SR530 has an output buffer for each interface of 256 characters In general if a command is sent without parameters it is interpreted as a request to read the status of the associated function or setting Values returned by the SR530 are sent as a string of ASCII characters terminated usually by carriage return line feed For example after the above command is sent the following read commands would generate the responses shown below Command Response from the SR530 G cr 5 lt cr gt lt lf gt T 1 cr 4 lt cr gt lt lf gt P lt cr gt 45 10 lt cr gt lt lf gt The choice
138. tic 50V 20 Radial Cap Mini Electrolytic 50V 20 Radial Capacitor Electrolytic 35V 20 Rad Capacitor Electrolytic 35V 20 Rad Capacitor Electrolytic 35V 20 Rad Capacitor Electrolytic 35V 20 Rad Capacitor Tantalum 50V 20 Rad Capacitor Tantalum 50V 20 Rad Cap Electro 25V 10 Ax Mallory TCX Cap Stacked Metal Film 50V 5 40 85c Cap Stacked Metal Film 50V 5 40 85c Capacitor Tantalum 35V 20 Rad Capacitor Tantalum 35V 20 Rad Connector D Sub Right Angle PC Female Connector D Sub Right Angle PC Female Connector IEEE488 Reverse R A Female Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL Capacitor Ceramic Disc 50V 10 SL 59 REF CY1 D 101 D 102 D 103 D 104 D 105 D 106 D 201 D 202 D 203 D 204 D 301 D 302 D 303 D 401 D 402 D 403 D 404 D 501 D 502 D 701 D 702 D 703 D 704 D 901 D 902 D 903 D 904 FU1 P 101 P 102 P 103 P 104 P 105 P 401 P 402 P 403 P 404 P 501 P 502 PC1 Q 101 Q 102 Q 103 Q 201 Q 202 Q 502 Q 701 Q 702 Q 703 R 101 SRS parti VALUE 6 00010 620 4 000 MHZ 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4148 3 00004 301 1N4
139. tion to initiallv rise to a large value before approaching the final answer As a result the computation will take longer to settle If the OVLD indicator is blinking four times a second then either the X or Y output is overloaded and the corresponding noise calculation should be ignored If the OVLD LED is on continuously then the input signal is overloading the ac amplifier or time constant filters In this case both noise outputs will be wrong To obtain a value for the noise density the noise reading should be divided by the square root of the ENBW Thus when the ENBW is 1 Hz the noise output is the noise density and when the ENBW is 10 Hz the noise density is the noise output divided by V10 For example if the input noise is measured to be 7 nV with the ENBW set to 1 Hz the noise density is 7 nV VHz Switching the ENBW to 10 Hz results in a faster measurement and a reading of 22 nV on the output The noise density is 22 nV V10 Hz or 7 nV VHz At frequencies 10 Hz the noise density should be independent of the ENBW Power This is the instrument s POWER switch When the power is turned off the front panel settings are retained so that the instrument will return to the same settings when the power is next turned on The SR530 always powers up in the LOCAL mode The D A outputs X5 and X6 are not retained during power off X5 always becomes the RATIO output at power on and X6 is always reset to zero When the power
140. tor TO 3 Metal Can Voltage Regulator TO 3 Metal Can Voltage Reg TO 220 TAB Package Voltage Reg TO 220 TAB Package Voltage Reg TO 220 TAB Package Voltage Reg TO 220 TAB Package Voltage Reg TO 220 TAB Package Voltage Reg TO 220 TAB Package Integrated Circuit Thru hole Pkg Transistor TO 92 Package Integrated Circuit Thru hole Pkg Integrated Circuit Thru hole Pkg Heat Sinks Power_Entry Hardware Hardware Misc Power_Entry Hardware Insulators Lugs Nut Kep Nut Kep Screw Sheet Metal Standoff Termination Tie Washer Flat Washer Split Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 18 UL1007 Stripped 3 8x3 8 No Tin Wire 24 UL1007 Strip 1 4x1 4 Tin Wire 24 UL1007 Strip 1 4x1 4 Tin Grommet Screw Panhead Phillips Screw Panhead Phillips Insulators Screw Panhead Phillips Wire 22 UL1007 Wire 22 UL1007 Wire 22 UL1007 Wire 22 UL1007 Washer nylon Screw Panhead Phillips Screw Panhead Phillips Washer nylon IL I wre a 69 SRS part VALUE 0 00257 000 HANDLES 0 00371 026 4 40X3 16PF 0 00500 000 554808 1 0 00521 048 3 18 0 00526 048 10 1 2 18 0 00893 026 8 32X3 8PF 1 00003 120 BNC 1 00010 130 20 PIN ELH 1 00012 135 20 PIN CARD 1 00013 135 40 PIN CARD 1 00029 150 TO 3 1 00053 172 USA 7 00201 720 SR500 32 7 00202 720 SR500 33 7 00210 720 SR530 22 7 00212 720
141. transconductance amplifiers operating as programmable voltage controlled current sources which take the place of the normal frequencv setting resistors A voltage proportional to the reference frequencv is converted into a current bv 1 4 U208 and Q201 This current programs the effective resistance of the two transconductance amplifiers and thus tunes the center frequency of the filter to follow the reference The output of the filter is buffered by 4 4 U201 The two remaining op amps in U208 are used to detect signal overloads throughout the amplifier chain Reference Oscillator The reference input signal is ac coupled and buffered by U301 R378 isolates the reference shield from the lock in ground to prevent ground loop currents 1 2 U303 switches the polarity of the reference reaching comparator U304 U305 is a retriggerable one shot whose output indicates a no reference condition if no comparator pulses are generated for three seconds U309 is a dual transconductance amplifier in a triangle VCO configuration U310 selects the integrating capacitor depending on the frequency range The VCO frequency is determined by the programming current through R318 and therefore by the output voltage of U308 C306 is the phase locked loop low pass filter which is buffered by U308 U307 is a programmable current source used to charge and discharge C306 The amount of current available to U307 is determined by the VCO control voltage thus th
142. ual ground and the 100 MQ voltage inputs can be used as single ended or true differential inputs There are three signal filters Each of these filters may be switched in or out by the user The first filter is a line notch filter Set to either 50 or 60 Hz this filter provides 50 dB of rejection at the line frequency The second filter provides 50 dB of rejection at the first harmonic of the line frequency The third filter is an auto tracking bandpass filter with a center frequency tuned by the micro processor to the frequency of the signal These three filters eliminate most of the noise from the signal input before the signal is amplified A high gain ac amplifier is used to amplify the signal before entering the phase sensitive detector The high gain which is available from this programmable amplifier allows the lock in to operate with a lower gain in its dc amplifier This arrangement allows high stability operation even when used on the most sensitive ranges Reference Channel The processor controlled reference input discriminator can lock the instrument s PLL to a variety of reference signals The PLL can lock to sine waves or to logic pulses with virtually no phase error The PLL outputs are phase shifted and shaped to provide two precision sine waves The two sine waves have 90 of phase shift between them Phase Sensitive Detectors The Phase Sensitive Detectors are linear multipliers which mix the amplified and
143. ular DS634 3 0001 2 306 GREEN LED Rectangular DS635 3 0001 2 306 GREEN LED Rectangular DS636 3 00012 306 GREEN LED Rectangular DS637 3 00012 306 GREEN LED Rectangular DS638 3 00013 306 RED LED Rectangular DS639 3 00013 306 RED LED Rectangular DS640 3 00013 306 RED LED Rectangular DS641 3 00012 306 GREEN LED Rectangular DS642 3 00012 306 GREEN LED Rectangular DS643 3 00012 306 GREEN LED Rectangular DS644 3 00012 306 GREEN LED Rectangular DS645 3 00012 306 GREEN LED Rectangular DS646 3 00012 306 GREEN LED Rectangular DS647 3 00012 306 GREEN LED Rectangular DS648 3 00012 306 GREEN LED Rectangular DS649 3 0001 2 306 GREEN LED Rectangular DS650 3 00012 306 GREEN LED Rectangular DS651 3 00012 306 GREEN LED Rectangular DS652 3 00012 306 GREEN LED Rectangular DS653 3 00012 306 GREEN LED Rectangular DS654 3 0001 2 306 GREEN LED Rectangular DS655 3 0001 2 306 GREEN LED Rectangular DS656 3 0001 2 306 GREEN LED Rectangular DS657 3 00012 306 GREEN LED Rectangular DS658 3 00012 306 GREEN LED Rectangular DS659 3 00012 306 GREEN LED Rectangular DS660 3 00012 306 GREEN LED Rectangular DS661 3 00012 306 GREEN LED Rectangular 71 SR530 COMPONENT PARTS LIST SRS part VALUE 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 3 00012 306 GREEN 8 00001 820 FE0206 8 00001 820 FE0206 8 00001 820 FE0206 8 00003 80
144. und Loops Microphonics Thermocouple Effect Appendix B RS232 Simplest Case Using the RS232 Using Control Lines Baud Rates Stop Bits Parity Voltage Levels Eavesdropping Appendix C GPIB Introduction to the GPIB Bus Description Appendix D Program Examples Program Description IBM PC Microsoft Basic via RS232 IBM PC Microsoft Fortran via RS232 IBM PC Microsoft C via RS232 ji IBM PC Microsoft Basic via GPIB HP 85 HP Basic via HPIB Documentation Parts List Oscillator Board Parts List Main Board Parts List Front Panel Board Parts List Quad Board Parts List Miscellaneous Schematic Diagrams Safetv and Preparation for Use CAUTION This instrument may be damaged if operated with the LINE VOLTAGE SELECTOR set for the wrong applied ac input source voltage or if the wrong fuse is installed LINE VOLTAGE SELECTION The SR530 operates from a 100V 120V 220V or 240V nominal ac power source having a line frequency of 50 or 60 Hz Before connecting the power cord to a power source verify that the LINE VOLTAGE SELECTOR card located in the rear panel fuse holder is set so that the correct ac input voltage value is visible Conversion to other ac input voltages requires a change in the fuse holder voltage card position and fuse value Disconnect the power cord open the fuse holder cover door and rotate the fuse pull lever to remove the fuse Remove the small printed circuit board and select the oper
145. unter whose output is either counted for one period of the reference or generates the gate pulse during which reference pulses are counted I O addresses are decoded by U705 U 706 and U707 The microprocessor controls the lock in functions through I O ports U714 U721 U713 generates an interrupt to the CPU every 4 msec to keep the microprocessor executing in real time RS232 Interface The RS232 interface uses an 8251A UART U801 to send and receive bytes in a bit serial fashion Any standard baud rate from 300 to 19 2K baud may be selected with the configuration switches The X16 transmit and receive clock comes from counter 2 of U704 The RS232 interface is configured as DCE so that a terminal may be connected with a standard cable When a data byte is received by the UART the RxRDY output interrupts the CPU to prevent the data from being overwritten GPIB Interface The interface to the GPIB is provided by U802 an MC68488 General Purpose Interface Adapter GPIA The GPIB data and control lines are buffered by drivers U808 and U811 Because the GPIA uses a 1 MHz clock wait states are provided by U805 to synchronize I O transactions with the 4 MHz CPU The GPIA interrupts the CPU whenever a GPIB transaction occurs which requires the CPU s response The GPIB address is set by switch bank SW1 Power Supplies The line transformer provides two outputs 40VAC and 15VAC both center tapped The transformer has dual prima
146. uracy 1 1 Output Stability 0 1 C 1 Front End Noise lt 7 nV VHz 1 2 Output Time Constant gt 10S 0 7 Total RMS Error 2 Shielding and Ground Loops In order to achieve the 2 accuracy given in this measurement example we will have to be careful to minimize the various noise sources which can be found in the laboratory See Appendix A for a brief discussion on noise sources and shielding While intrinsic noise Johnson noise 1 f noise and alike is not a problem in this measurement other noise sources could be a problem These noise sources can be reduced by proper shielding There are two methods for connecting the lock in to the experiment the first method is more convenient but the second eliminates spurious pick up more effectively In the first method the lock in uses the A input in a quasi differential mode Here the lock in detects the signal as the voltage between the center and outer conductors of the A input The lock in does not force A s shield to ground rather it is connected to the lock in s ground via a 100 resistor Because the lock in must sense the shield voltage in order to avoid the large ground loop noise between the experiment and the lock in anv noise pickup on the shield will appear as noise to the lock in For a low impedance source as is the case here the noise picked up by the shield will also appear on the center conductor This is good because the lock in s 100 dB CMRR will reject mos
147. urned off for the selected channel If n is absent the expand status of the selected channel is returned Note that the expands do not affect the X and Y BNC outputs only the Channel 1 and 2 outputs f F The F command reads the reference frequency For example if the reference frequency is 100 Hz the F command returns the string 100 0 If the reference frequency is 100 0 kHz the string 100 0E 3 is returned The F command is a read only command G n If n is included the G command sets the gain sensitivity If n is absent the gain setting is returned Sensitivity 10 nV 20 nV 50 nV 100nV 200nV 500nV 2 uv O O 01 O N I5 23 200mV 24 500mV Note that sensitivity settings below 100 nV are allowed only when a pre amplifier is connected H The H command reads the pre amplifier status If a pre amplifier is connected a 1 is returned otherwise a 0 is returned The H command is a read only command I n If n is included the command sets the remote local status If n is absent the remote local status is returned n Status O Local all front panel keys are operative 1 Remote front panel keys are not operative The LOCAL key returns the status to local 2 Lock out front panel keys are not operative No key returns the status to local Another command is needed to return to local When using the GPIB interface the REN LLO and GTL commands are not implemented The
148. utton 1 see un abridged command list Simulates Key press of button 32 Return Status of Line Notch Filter Remove Line Notch Filter Insert Line Notch Filter Return Status of 2XLine Filter Remove 2XLine Notch Filter Insert 2XLine Notch Filter Return the f 2f Status Set reference mode to f Set reference mode to 2f Return the ENBW setting Select 1 Hz ENBW Select 10 Hz ENBW OX OX 0 OX 1 v OY OY 0 OY 1 v OR ORO OR 1 v Q1 Q2 QX QY RO R2 S0 S1 S2 S3 S4 S5 T1 T1 1 T1 11 X5 v X6 v Yn Return X Offset Status Turn off X Offset Turn on X Offset v offset Return Y Offset Status Turn off Y Offset Turn on Y Offset v offset Return R Offset Status Turn off R Offset Turn on R Offset v offset Return the Phase Setting Set the Phase to v Abs v lt 999 deg Return the Channel 1 output Return the Channel 2 output Return the X Output Return the Y Output Return the trigger mode Set the trigger for rising edge Set the trigger for zero crossing Set the trigger for falling edge Return the display status Display X and Y Display X and Y Offsets Display R and J Display R Offset and J Display X and Y noise Display X5 and X6 ext D A Return pre filter setting Set the pre filter TC to 1 mS Set the pre filler TC to 100 S Return the post filter setting Remove post filter Set the post filter TC to 0 1 S Set the post filter TC to 1 0 S Return the value of the SRQ mask Set t
149. value of the byte in ASCII coded decimal or when using the GPIB by performing a serial poll The returned status byte reflects all of the status conditions which have occurred since the last time the byte was read After the status byte has been read it is cleared Thus the status byte should be read initially to clear all previous conditions especially after a power up or after settings have been changed The definitions for each bit of the status byte are given below 24 Bit 0 Not Used Bit 1 Command Parameter Out of Range This bit is set if a parameter associated with a command is not in the allowed range Bit 2 No Reference This bit is set when no reference input is detected either because the amplitude is too low or the frequency is out of range Bit 3 Unlock This bit is set when the reference oscillator is not locked to the reference input If there is no reference input bit 2 no reference will be set but bit 3 unlock may not be Bit 4 Overload This bit is set if there is a signal overload This can happen when the sensitivity is too high the dynamic reserve is too low the offset is on or the expand is on Overloads on the general purpose A D inputs or the ratio output are not detected Bit 5 Auto Offset Out of Range This bit is set if the auto offset function cannot zero the output because the output exceeded 1 024X full scale Bit 6 SRQ This bit is set if the SR530 has generated an SR
150. x6 command string write str3 3000 x6 format Cx6 74378 call txstr str3 and loop forever goto 20 stop end KKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKKK subroutine nocom in case of a timeout error this routine runs put your error handler here write char 7 write RS232 Timeout Error stop end 48 Program Example 3 IBM PC Microsoft C v3 0 via RS232 Machine language routines to interface to the COM1 RS232 port are provided in the file RS232 OBJ found on the SR575 disk These routines allow for simple interfacing to the SR530 at 19 2 kbaud from C programs To use these routines the large model must be used Compile with the AL switch and link with RS232 OBJ Only two wires between the IBM PC s ASYNC port and the SR530 are needed pins 2 8 3 of the RS232 but pins 5 6 8 and 20 should be connected together on the connector at the IBM end include lt stdio h gt pe Compile with gt MSC program name AL link with RS232 0BJ on SR565 disk RS232 0BJ defines init Initializes COM1 to 19 2 kbaud txstr str Char str str must terminate with char Sends string str to COMI rxstr str str must be declared with 15 characters or more length Fills str with string received from COMI If an error occurs your procedure nocom is called Nocom must be a C procedure in your program Example program to read the SR510 outputs and ramp the x6 analog Output using Microsoft
151. y should show a 500 Hz sine wave on a 30 Hz 500 16 Hz square wave Remove the four screws holding the top panel on Slide the top panel back about half way Using a small screwdriver adjust P402 at location D2 to 38 minimize the 500 Hz output Adjust P403 at location C2 to minimize the 30 Hz output Now set the both time constants to 1S Adjust P404 at location F4 to zero the output This adjustment has a range of 20 of full scale on the HIGH dynamic reserve setting 2 on NORM and 0 2 on LOW This zeroes the DC output of Channel 1 on all dynamic reserve ranges Now connect the scope to the CHANNEL 2 OUTPUT Set the PRE TIME CONSTANT to 1mS and the POST TIME CONSTANT to NONE Adjust P1102 to minimize the 500 Hz output Adjust P1103 to minimize the 30 Hz output Set both time constants to 1S Adjust P1104 to zero the output All three potentiometers are located on the plug in board in the center of the main circuit board Replace the top panel Amplifier and Filter Adjustments This section describes how to adjust the Common Mode Rejection and Line notch filter frequencies An oscilloscope and a signal generator which can provide an accurate line frequency and twice line frequency sine wave are required Allow the unit to warm up for about 1 hour Reset the unit by turning it off and back on while holding the LOCAL key down Remove the four screws holding down the top panel Slide the panel back about halfway CMRR

SR530 User`s Manual - Stanford Research Systems

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