Physics 331 Electronics Laboratory Manual
Contents
1. Fig 4 4 Lab 4 Physics 331 Laboratory Manual 13 5 Diode Clamper The circuit of Fig 4 5 is used to clamp the negative peak of a signal at about 4 V Try it with sine triangle and square waves Explain the operation 5 0 1 uF 1N914 in out Fig 4 5 6 Signal Rectifier optional The next circuit Fig 4 6 will pass one polarity only of a pulse train Apply a square wave generate pulses at point A by differentiating and observe the rectified output Note the forward drop of the diode 1N914 in R Ro Fig 4 6 7 Zener Diode optional Substitute a Zener diode 1N4733 for the ordinary diode in Fig 4 1 Display the l V characteristic of the Zener diode and explain Caution Incorporate the necessary current limiting resistor R Consult the specification in the data sheet 14 Physics 331 Laboratory Manual Lab 4 Diode Specifications Rectifier diode 1N4001 Silicon Vreverse max 50 V lforward max 30 A lforward cont 1A Signal Diode 1N914 Silicon Vreverse max 75 V lforward max 2000 mA lforward cont 200 mA Zener Diode 1N4733 Silicon lforward max 49 mA VZener 5 1 Problems 1 Sketch the output waveform expected when a 100 Hz square wave 10 Vp 20 Vpp is applied to each of the folllowing circuits a in ale T 6 3 V Zener b in out 5 Vdc 3 Lab 5 Physics 331 Laboratory Manual 15 LAB 5 Transi2. V out 680 Q Q1 Q2 680 Q 2N3904 1ktrim 1N5234 22k 6 2 V Fig 11 1 a Find the feedback resistors and calculate the values of feedback resistors which will give Vout 10 V Build the circuit and use the variable power supply set at 15 V Adjust the trim pot so that Vout s 10 V with no load Compare the voltages at the emitter and base of Q1 i e the Zener and feedback voltages Measure the value of both arms of the trim resistance and compare with the 42 Physics 331 Laboratory Manual Lab 11 calculated values Reconnect the trim pot and put a 1 kQ load on the output Measure how much the load voltage drops Calculate the percent load regulation LR 100 x AVout Vfull load Now decrease the supply voltage to 12 V measure the drop in the output voltage and express this drop as a percent supply regulation SR 100 x AVoyi Vnominal Find the drop out voltage i e the input voltage below which the regulator won t regulate b Find the current sensing resistor and calculate the expected maximum output current if the output is shorted Is Does the current through the voltage divider need to be considered this calculation Measure the short circuit output current by putting an ammeter across the output to ground Now make a table showing the output voltage Vout the base emitter voltage of the limiting transistor and the base voltage of the pass transistor VB pass Measure these volta
3. 3 R C Relaxation Oscillator The next circuit in Fig 10 4 shows how to build a square wave generator called a relaxation oscillator What you do here is remove the input to the Schmitt trigger and reconnect it to one end of a capacitor The other end of the capacitor is at ground and the capacitor is allowed to charge through a resistor coming from the output of the comparator After the capacitor charges to the upper trip point the comparator output goes low to ground Now the capacitor will Lab 10 Physics 331 Laboratory Manual 39 discharge until it reaches the lower trip point The comparator output goes high again and the charging cycle continues The output oscillates between high and low with a frequency determined by the RC time constant of the resistor and capacitor 100 k Fig 10 4 Predict the frequency of the circuit Build it and a measure the frequency b measure the peak to peak voltage of the output and the voltage of the low level a b c observe the inverting point x and explain its behaviour and d d try to change the frequency by changing the capacitor and resistor combination 4 The Wien Bridge Oscillator Generating a sine wave is more difficult than a generating a square wave The Wien bridge circuit uses the parallel series lead lag circuit to maximize positive feedback for its critical frequency 1 2nRC The tungsten lamp in the negative feedback loop limits oscillatio
4. amps Lab 8 Physics 331 Laboratory Manual 31 b Output Offset Voltage Connect the circuit of Fig 8 4 using a 741C op amp 100k Fig 8 4 The bypass capacitors are used on each supply voltage to prevent oscillations This is discussed in Ch 22 of Malvino 5th ed These capacitors should be connected as close to the IC as possible Measure the dc output voltage Vout off From the closed loop gain of the circuit as connected you can calculated the input offset voltage Vin off ACL Also measure Vout off and calculate Vin off for the LF411 op amp in the same circuit c Maximum Output Current Disconnect the right end of the 100 k feedback resistor and connect it to 15 V This will apply about 15 mV to the inverting input and saturate the op amp Replace the 10 k load resistor by an ammeter and measure the maximum output current Imax Do this for both the 741C and LF411 op amps d Slew Rate Connect the circuit of Fig 8 5 choosing between 100 and 1 MQ Measure the slew rate of the 741C and LF411 op amps Power Bandwidth Change Ro to 10 k Set the ac generator at 1 kHz Adjust the signal level to get 20 V p p output from the op amp Increase the frequency from 1 to 20 kHz and find 32 Physics 331 Laboratory Manual Lab 8 the approximate frequency where slew rate distortion starts Do for both 741C and LF411 op amps f Maximum Peak to Peak MPP Measure the MPP value
5. VE and Vc for both of your transistors 18 Physics 331 Laboratory Manual Lab 5 Vcc 12V R2 Ro Ye R Re Fig 5 4 Homework Problems 1 Calculate the resistor values for part 2 a 2 Design the voltage divider bias circuit of part 2 g 3 Write a computer program that calculates the resistor values for a voltage divider bias circuit Your input parameters are Vcc Vce Use any high level language such as Pascal Modula 2 Fortran APL or Basic Run the program and turn a listing and sample output 4 Do the algebra you will need for part 2 c to obtain the Norton equivalent circuit from the currents obtained using the two values of Rg i e derive the equations for Iy and Ry in terms of the quantities you will measure Lab 6 Physics 331 Laboratory Manual 19 LAB 6 Transistor Amplifiers Reading Malvino Ch 10 through Ch 12 Hayes and Horowitz Class 4 Lab 4 and worked examples pp 90 and 115ff In this lab we experiment with different types of transistor amplifiers using the voltage divider bias 1 The Common emitter Amplifier a Starting from the voltage divider bias of the last experiment add an input coupling capacitor and a bypass capacitor on the emitter resistor to make a common emitter amplifier Calculate the values of the capacitors so that the low frequency 3 dB point of the ampllifier will be between 100 and 200 Hz Measure the amplification using the channel 1 of the scope to displ
6. t tow 2 6 Physics 331 Laboratory Manual Lab 2 If the sweep mode is logarithmic then the frequency is proportional to the exponential of the time and the rate at which it sweeps is proportional to frequency where k tsw In logarithmic mode for example if the sweep is from 10 Hz to 1000 Hz it covers the range from 10 Hz to 100 Hz in the same amount of time that it covers the range from 100 Hz to 1000 Hz In linear mode it covers the range from 10 Hz to 100 Hz in the same time that it covers the range from 100 Hz to 190 Hz and it would take 111 times longer to go from 100 Hz to 1000 Hz To set the sweep mode on the function generator follow these steps Press SHIFT MENU to enter the function generator menus Using the gt key select B SWP MENU Pressing 4 gives 1 START F You can now specify the beginning of the frequency shift using the knob Use gt to select other submenus such as 2 STOP F 3 SWP TIME and 4 SWP MODE LINEAR OR LOG We suggest that START F should be near zero and STOP F should be high enough to conveniently capture the frequency range of interest After you have entered in all the numbers depress SHIFT SWEEP to enter sweep mode The output of the function generator should now be sweeping through the specified frequencies You can display a picture of the frequency response of a circuit on the oscilloscope in the following way Trigger on the SYNCH signal from the function generator
7. 5 2 Lab 5 Physics 331 Laboratory Manual 17 2 Transistor Biasing a If Vgg 10 V in the circuit of Fig 5 3 calculate what values of Rg to i put Vc at 7 5 V ii put within 10 of 12 V iii put within 10 of ground Note You can use the DC function of the signal generator to give 10V dc Vcc 12 A 1k Fig 5 3 b Find standard resistor values closest to those calculated in a build the circuit and measure Vc for each case Use the external power supply for 12V Do the actual voltages agree within the precision of component values and the measurement accuracy Now replace the transistor with the other one with a different Compare Vc with that of the first transistor leaving Rp the same in both cases Does the change match your predictions based on the measured values of c Investigate how well the transistor circuit acts as a current source Measure the current flowing through the collector resistor for 500 Q 2 Model the response with a Norton equivalent circuit d Connect to 12 V and find Rg which puts Vc at 5 V Put an LED in the circuit and choose Rg so it will light when Vgs 5V f Design and build an emitter biased LED driver to switch off and on with 0 and 5V g Design a voltage divider biased circuit Fig 5 4 with the following specifications Vcc 12 V Ic 2 mA 7 5 V and Ve 1 V Build your circuit Compare calculated and measured values
8. ellipse you can calculate the phase difference 9 asin p where is the y intercept of the ellipse and A is the maximum value Fig 2 2 One should be able to automate the phase shift measurement with a digital scope Can you figure out a way of doing this automatically and use it to determine the phase shift curve and the 3 db point for the filter 2 High pass Filter a Use the frequency sweep method to display the attenuation of the high pass filter in Fig 2 3 as a function of frequency and take a picture Carefully examine the response at very low frequencies by manually changing the frequency 0 01 uF Vin Vout 15k Fig 2 3 b Find the 3dB point by manually sweeping the frequency Use the most accurate method of the two used in the previous section 8 Physics 331 Laboratory Manual Lab 2 3 RC Differentiator Integrator a Apply a 100 kHz square wave signal to the low pass filter of Fig 2 1 and explain the output wave form Apply a 100 Hz square wave to the high pass filter of Fig 2 3 and explain the output b Repeat with a triangle wave 4 Cascaded Filters a Investigate the frequency response of a low pass filter made by cascading two identical RC filters b Build a band pass filter by cascading a high pass and a low pass filter according the following design criterion the output impedance of the first filter should be about 1 10 the input impedance of the second filter where only r
9. of R needed to safeguard the diode b Display vs time Explain the dependence of the observed waveform on the applied voltage c Now replace the 1N4001 diode with an LED and record its characteristic curve Keep this LED and its curve for future use 2 Full wave Rectifier Bridge a Construct the full wave bridge rectifier circuit of Flg 4 2 using four 1N4001 rectifier diodes Explain the output wave form Remove one of the diodes and look at the symptoms 12 Physics 331 Laboratory Manual Lab 4 120Vac RE 12 6Vac transformer Fig 4 2 b Replace the missing diode and connect a 15 uF electrolytic filter capacitor across the output Measure the peak to peak ripple voltage and compare with your calculations Caution Observe the polarity of the capacitor c Repeat with a 400 uF filter capacitor You now have a respectable voltage source How much current can the load draw without exceeding the diode specifications 3 Voltage Doubler Connect the voltage doubler circuit of Fig 4 3 using 1N4001 diodes and explain its action in 0 01 uF ou 0 01 uF Fig 4 3 4 Diode Clipper The circuit of Fig 4 4 limits the range of a signal Use the 1N914 signal diode when you build it Drive it with a sine wave maximum output amplitude and observe and measure the output voltage Explain the operation Suggest how you can clip a sine wave symmetrically around zero and draw the circuit diagram 5 Vdc ik 4 1N914
10. of its use as a variable voltage regulator This property can also be used to configure it as an adjustable current source Fig 11 3 shows the idea 220 resistor establishes just over 4 mA Most of this current goes through the load because the ADJ input passes very little current Connect this circuit and check if the current varies as the load resistance is changed What is the voltage compliance What limits its performance at high and low currents Fig 11 3 44 Physics 331 Laboratory Manual Lab 11 Homework 1 Calculate the values of the feedback resistors for the three transistor regulator of part 1 which gives a regulated output voltage of 10 V Find the expected value of the short circuit output current limit 2 Design the 5 V regulator of part 2 using the LM317 adjustable regulator Find reasonable values for all unlabelled capacitors and resistors and provide for a 20 adjustment Lab 12 Physics 331 Laboratory Manual 45 LAB 12 TTL and CMOS Logic Gates Reading Hayes and Horowitz Class 13 and Lab 13 Today you will be introduced to the circuits of digital electronics We will start with some circuits made with discrete electronics to perform logical AND OR and NOT functions Next properties of the most commonly used integrated circuit series the LS TTL and HC CMOS are studied Finally you will use these basic chips to construct more complex circuits 1 Mickey Mouse Logic and the Totem Pole Outpu
11. 11 2 Full wave Rectifier 11 3 Voltage Doubler 12 4 een rere cree 12 5 8 2261 9 13 6 Signal Rectifier 13 7 Zener Diode 13 5 Transistor Fundamentals 15 1 Using Transistor Curve Tracers to Measure Operating Characteristics 15 2 Transistor a el ee A ei 17 Lab 6 Transistor 7777 19 1 The Common emitter 19 2 Emitter follower Amplifier 444000 0 19 3 The Push pull Output 0 4 01000 20 4 The Darlington 20 Lab 7 Field Effect Transistors 44444400 23 1 Junction FET Characteristic 2 2 0 23 2 FET Current SOUPCC 24 3 deena 24 4 Using the JFET as a Variable 25 The World s Simplest
12. AM Radio 25 9 The Common Source 26 Lab 8 Differential and Operational 0 00 29 1 The Differential 29 2 The Operational 30 Physics 331 Lab 9 Operational Amplifiers es science ase aaaea oa eaaa 33 1 Non inverting Voltage 33 2 Inverting Voltage Feedback 33 3 Current to Voltage Converter 2 422 0 000 33 3 The Active 22424442 34 4 Integrators and 34 Lab 10 Positive Feedback and 37 1 2 tet ACA Ata eee iat ted tae any 37 2 The Schmitt 20 44 0 4 38 3 R C Relaxation nens 38 4 The Wien Bridge 2 2 004800 39 Lab 11 Voltage 442244 ARETES EIS EFI ANASA RAR REE 41 1 Discrete Transistor Voltage Regulator 41 2 Three termina
13. AY menu and switch to the XY display instead of the YT display If the HORIZONTAL SCALE setting is vastly inappropriate for the signal being displayed the Lissajous figure may be incomplete To see this try varying HORIZ SCALE when displaying a Lissajous figure to make sure at least one full cycle is being displayed g Invert a signal using the VERTICAL menu and add subtract multiply and divide two signals applied to the two channels using the MATH functions Use the function generator for one signal and the PROB COMP signal for another h Printing You can print the scope display on a printer using the HARDCOPY function This is useful for recording results to put in your lab book Before using HARDCOPY you must ensure that the output port and printing options are correctly configured Use the UTILITY I O menu to select the hardcopy port e g Centronics Layout e g portrait and Hard Copy format e g Epson printer Lab 2 Physics 331 Laboratory Manual 5 LAB 2 RC and LR Circuits Reading Malvino Ch 16 sections 9 10 11 16 17 18 19 20 Hayes and Horowitz Class 2 Worked Examples and Lab 2 Read A Note on Reading Capacitors values p51 H amp H In this experiment the concept of impedance is examined The impedances of capacitors and inductors are investigated as a function of frequency Special emphasis is given to the RC circuit as low pass and high pass filter differentiator and integrator 1 Low pass F
14. Oo Xo equivalent to Q R Show that for large Q the expression Q where is the impedance of the capacitor or inductor at resonance and Aq is the full width at the points a b Calculate the resonant frequency of the tank circuit including RL na Calculate the impedance of the LRC circuit of Fig 3 2 wa Calculate the output voltage as a function of frequency What is the total current in the circuit at resonance 2 a In practice real inductor has a finite resistance associated with it RL in series with L Lab 4 Physics 331 Laboratory Manual 11 LAB 4 Diode Circuits Reading Malvino Ch 3 and Ch 4 Hayes and Horowitz Class 3 Worked Example and Lab 3 This experiment will demonstrate the fundamentals of semiconductor diodes and some of their applications 1 Diode Characteristic and Half wave Rectifier a Construct the circuit of Fig 4 1 Display the I V characteristic of the diode on the oscilloscope Use coupling and set zero volts at the centre of the screen Explain the l V curve 1N4001 Function Generator with floating output R AC voltage at least 10 V pp L Fig 4 1 An ohmmeter VOM can be used to measure the polarity of a diode The band on the diode represents the cathode i e the negative terminal when connected for forward conduction Caution Use the diode specifications at the end of the lab script to calculate the value and power rating
15. Physics 331 Electronics Laboratory Manual Simon Fraser University Physics Department Electronics Laboratory Table of Contents sectocesis tice setae sees cake etek A Re etd oe Ras r a ie So ogi ili Lab 1 Introduction to Equipment and DC 1 Ohm s Law its 1 2 Voltage Divider and Th venin s Equivalent Circuit 1 3 Oscilloscope and Function 0 0 2 tab 2 RG and ER Circuits 5 1 E eave erat 5 2 7 3 RC Differentiator Integrator ceceeececececeeeeeeneeceaeeeeeaeesecaeeeeeaeeeeceeeeeaeeneaees 7 4 Cascaded Filters Optional 7 5 LR Filters 7 tab 3 ERC Resonant Circuits ee ee ce 9 1 Series LAG Circuit aane aa nae a A aE a R 9 2 Parallel LO CirGuit ES 10 3 FOUTOr AMALYSIS 10 Lab 4 Diode 24 0 1100 0 11 1 Diode Characteristic Half wave
16. Position the trigger point near the left hand side the of the display Adjust the function generator s sweep time and the scope s HORIZ SCALE settings so that the end of the sweep is at the right hand side of the display You should choose the sweep time to be slow enough to allow for at least one cycle to take place before the frequency changes significantly Adjust the channel s zero volts position to the bottom of the display Increase the amplitude of the function generator s output so that a frequency response graph fills the display You can fill in the trace by using the envelope mode Choose ENVELOPE from the ACQUIRE MODE menu so that the screen will display the accumulation of several sweeps The number of sweeps accumulated is controlled by the General Purpose Knob c Set the signal generator to a single square wave frequency and measure the risetime response of the low pass filter from 10 to 90 maximum Compare with the theoretical relation 0 35 Hint There is a special function on the MEASURE menu for measuring rise times trise d In previous courses you may have measured phase shift in the following ways Lab 2 Physics 331 Laboratory Manual 7 1 Display both signals simultaneously on the oscilloscope and determine the phase difference from the time difference between the traces 2 Produce a Lissajou figure by applying one signal to the vertical deflection plates of the scope From the resulting
17. Try this with the 741 500 too 5 Fig 12 6 b NAND is All You Need NAND gates are very useful because all other logical functions can be built up from them Because of DeMorgan s theorem we know that NAND is all you need As an exercise design and build the AND function from NAND gates so that you can light one of the LEDs on you breadboard when both of the inputs are high Next build the OR function that lights an LED when one or both of the inputs is low 1 OR with negative logic input and positive logic output this is easy Verify they give the results you hope for Design build and test an XOR circuit exclusive OR function using only NAND gates 2175 rumoured that the Beatles once wrote a song with this title Unfortunately the title was changed at the last moment before release for marketing reasons Lab 12 Physics 331 Laboratory Manual 49 4 The Latch Flip Flop The flip flop is an essential element in digital and computer circuits Its ability to store information entered on its input after the input has been changed is useful for memories registers and counters almost every component of digital and microprocessor devices The simplest flip flop is the NAND latch shown below There are three useful states set reset and no change Fig 12 7 shows the no change state with both inputs high This is its quiescent resting position and the output could be either high or low depending on whether the pre
18. VDS 5 15 and 20 V on graph paper Determine Ipss and gmo Compare with specifications 2 FET Current Source The circuit of Fig 7 2 allows you to explore the behaviour of a JFET current source 12V 100k VOM 2N5486 5 6k Fig 7 2 Vary the load resistance and watch Vps and Ip Note the value of Vps which marks the departure from current source behaviour Select your own criterion Repeat for different Vas i e different source resistors and explain your results in terms of the characteristics measured in Part 1 3 Source Follower Drive the source follower of Fig 7 3 with a small 1 kHz sine wave Measure how much the gain differs from unity Observe the phase shift and examine the onset of distortion Lab 7 Physics 331 Laboratory Manual 25 12V 0 01 2 5486 1 4 7 Fig 7 3 4 Using the JFET as a Variable Resistor In part 2 you found that the current source failed when Vps fell too low you will deliberately bias the FET into the linear Ohmic region a Build the circuit of Fig 7 4 without the shaded components Drive it with a small sine wave of about 0 2V amplitude at 1 kHz Notice what happens to the gain and the distortion when you adjust the potentiometer The distortion is clearer if you drive the circuit with a triangle wave Explain the distortion V lt 1V 0 01 10k 1M 1M out 2N5486 330k 12 Fig 7 4 b Now try the compensati
19. ay the input and the channel 2 for the output Measure the low frequency 3dB point Compare the measured values with what you expected from calculations Now investigate the input and output impedances b You should have noticed the barn roof distortion of the design of part a Find a method to reduce the distortion without changing the bias Measure the effectiveness of your improvement How is the amplification affected 2 The Emitter follower Amplifier a Construct the emitter follower circuit shown below in Fig 6 1 Vcc 12V 130k 1 uF 10 uF 150k 7 5k L 4 Fig 6 1 b Calculate the base voltage Vp the emitter voltage Ve Vce and the emitter current Ie Measure these quantities and compare 20 Physics 331 Laboratory Manual Lab 6 c Measure the small signal gain at 1 kHz Is there any variation in the gain between 100 Hz and 10 kHz Can you detect any phase shift between the input and output Try to find the critical frequencies in the high and low frequency ranges d Measure output and input impedances Calculate the power gain Increase the amplitude of the input signal and determine the onset of distortion Explain 3 The Push pull Output Stage a Build the push pull emitter follower shown in Fig 6 2 Try to match the NPN PNP transistor pairs Voc 12 2N3904 in out 2N3906 V pp 2 Fig 6 2 b Explore crossover distortion by driving it with a signal of at least a few volts amp
20. columns of holes are connected electrically in groups of five along a vertical line The top and bottom halves are independent Typically one inserts an ic chip straddling the centre trough There are then four empty holes for making connections to each pin When you plug ic s into the breadboard a common convention is to put pin 1 on the left For other components make sure the leads are not in the same column of five unless you want them connected together The oscilloscope has many knobs and buttons which may be confusing at first It helps if you read the introductory booklet and manual provided by Tektronix If nothing seems to be happening press AUTOSTART N Alberding November 1990 Revised March 1994 Revised July 1996 General Purpose knob Miscellaneous controls Acquisition controls Cursor control Tektromix TDS 340 osuo VERTICAL ME HORIZONTAL TRIGGER ION 41 Posmon gt LeveL A A OREF1 VERTICAL HORIZONTAL TRIGGER MENU MENU MENU Menu controls 4 gt FORCE TRIGGER 5 2 ExT TAK I Me 227 Vertical Horizontal Trigger controls controls control
21. d compare the measured tail and base currents with the calculated values 12 V 1 5k Q1 2N3904 Q2 2N3904 220 220 4 7k 4 7 k 12 V Fig 8 1 b In Fig 8 2 a if you ground the base of transistor Q4 the transistors are identical and the components have the values shown then the output voltage will be 6 35 V For this experiment any deviation from 6 35 V will be called Vout off Connect the circuit of Fig 8 2 a Jumper the base of Q4 to ground and measure Vout off Take off the jumper and connect the potentiometer voltage divider and adjust it until the output voltage is 6 35 V Record the base voltage of Q4 as Vin off 30 Physics 331 Laboratory Manual Lab 8 12 V 12 V Q2 2N3904 out 220 220 a Fig 8 2 b c Calculate the expected values of the differential and common mode gains and the Common Mode Rejection Ratio Measure the differential and common mode gains A and Acm using the connection of Fig 8 2 b Use a frequency of 1 kHz and a signal level of around 10 mV 2 Operational Amplifier a Input offset and Bias Currents The 741C has a typical lin bias of 80 nA Assuming that this is the current through each 220 k resistor in Fig 8 3 calculate the dc voltages at both inputs Now connect the circuit and measure the input voltages Repeat this mesurement for the FET input LF411 amp Calculate lin off and lin bias in both cases and compare the two
22. d output impedances Build the circuit and repeat the measurements specified in part 1 3 Current to Voltage Converter The simplest current to voltage converter is just a resistor An op amp in the circuit makes a much better device The MRD 300 phototransistor can be hooked up as either a photodiode connect base and emitter leaving the collector unconnected or as a phototransistor base unconnected emitter and collector connected In either case it acts like a current source whose current depends on the amount of light that hits it a Connect the MRD 300 as a photodiode and use a 10 MQ feedback resistor as in Fig 9 1 If the output voltage is too large reduce the resistor to 1 MQ If you see fuzz on the output try 0 001 uF capacitor across the feedback resistor How does this capacitor affect the feedback at high frequencies Connecting the output of the op amp to the scope you should see the modulations from the lab s fluorescent lights What is the photocurrent produced by the MRD 300 Cover the phototransistor with you hand to make sure it s the lights you are seeing Look at the summing junction X with the scope as Vout varies Why is it better to use this op amp rather than just a 10 MQ resistor 34 Physics 331 Laboratory Manual Lab 9 light Vout MRD 300 phototransistor MRD300 no collector Power connections and pin connection numbers are not shown Fig 9 1 b An analog oscilloscope must b
23. e used for this exercise to work Connect the MRD 300 as a phototransistor as shown in Fig 9 2 Now how much photocurrent is produced Put the photodiode on the end of a twisted pair wire so that you can put the diode up against the screen of the scope This puts the scope in the feedback loop Why is the diode so shy 12 V light 100 k or more MRD300 no base connection Power connections and pin numbers not shown Fig 9 2 4 The Active Rectifier Build the active rectifier circuit shown in Fig 9 3 Explain why it works better than the passive rectifier used in a previous lab out 10k in Fig 9 3 Lab 9 Physics 331 Laboratory Manual 35 5 Integrators and Differentiators The following circuit acts like a differentiator at some frequencies an integrator at others Determine values of the resistors and capacitors so that the circuit will integrate one frequency range and differentiate in another range both easily accessible by your function generator Try it out Verify its properties by finding what range of freqencies it differentiates and what range it integrates Check it with square and triangle waves Examine the phase relationship between Vout and vin for a sine wave as a function of frequency Rf Cj Hw 4 gt out Fig 9 4 Homework 1 Design the circuits and calculate the quantities needed for parts 1 and 2 of this lab 2 Find values of capacitors and resistors for the combi
24. el Otherwise the input logic level will be indeterminant In order to convince yourself of this connect the 74HCOO Pins 7 and 14 should be ground and 5 V respectively You are using only one NAND gate so ground the other six inputs of the unused NAND gates Tie one input of a NAND to HIGH and connect about 6 inches of wire to the other input Leave the other end of that long wire dangling in air 1You can remember this rule by recalling the famous movie entitled Destroy all Monsters 48 Physics 331 Laboratory Manual Lab 12 Watch the output of the NAND gate as you wave your hand around near the long wire Try touching your other to 5 V as you do this waving What you see should convince you that you can t rely on the unconnected inputs of CMOS gates Now replace the chip with 741500 chip and notice the difference Turn power off before changing chips Indeterminate inputs can also cause both transistors of the complementary pair to conduct and consequently draw a lot of power from the supply Intermittent surges of load to the power supply can make glitches You can test this excessive current consumption using the setup below First connect all the NAND inputs to ground and verify the low power consumption on the meter s most sensitive scale Then put the meter on the 150 mA scale As you drive the inputs with a voltage intermediate between the LOW and HIGH levels appropriate for CMOS the measured current should go up abnormally
25. eria What is the effect of leaving an input unconnected 5V out 2 CMOS Logic Gates Elementary logic gates are even more easily built from CMOS field effect transistors Matched complementary pairs of MOSFET transistors are packaged in the CD4007 chip Fig 12 3 shows its pin arrangement For the following experiments always tie pin 14 to 5 V and pin 7 to ground 14 2 11 13 1 6 8 3 10 12 7 4 9 CD4007 MOS Transistor Array Fig 12 3 Two inverters are shown in Fig 12 4 The first using a passive pullup resistor is like an open drain output Try it and measure its output voltage as a function of time with 1 kHz square wave input and a 100 kHz input Now crank up the frequency as high as you can to see what happens Lab 12 Physics 331 Laboratory Manual 47 If you have 1 kHz and 100 kHz outputs on you breadboard use them Otherwise use the F34 at 5 Vpp with a dc offset of 2 5 V to give 0 and 5 V logic levels 5V 5V 14 10k 13 z Out in out gt L_ Fig 12 4 Now connect the right hand inverter circuit It uses a complementary MOSFET as active pullup Also look at its output as high and low frequencies and compare with the passive pullup The NAND gate shown in Fig 12 5 is simple Make it Test it 3 CMOS Logic Chips a Connect all Inputs1 When you use CMOS chips like the 74 00 NAND gates it is important to tie all inputs of all the gates on the chip to a definite logic lev
26. esistive impedances are considered Measure its frequency response 5 LR Filters optional Construct high pass and low pass LR filters and measure their frequency responses Homework Problems 1 For a RC low pass filter calculate Vout b The phase shift between Voyt and Vin The frequency 2 Repeat for a LR low pass filter 3 Repeat for a RC high pass filter 4 For the circuit of Fig 2 1 plot graphs of vs frequency a with linear axes V b with axes of log ays log f a log log plot Ensure that the high frequency f gt gt 1 RC behaviour is displayed c What is the filter attenuation in dB octave at high frequencies An octave is a factor two in frequency Lab 3 Physics 331 Laboratory Manual 9 LAB 3 LRC Resonant Circuits Reading Hayes and Horowitz Class 2 p 44 Class 3 sections A and B Lab3 section 3 1 Horowitz and Hill section 1 22 In this experiment the resonance in LRC circuits will be investigated 1 Series LRC Circuit Connect the circuit of Fig 3 1 Choose an inductor and calculate C to give a resonant frequency between 1 kHz and 100 kHz The resistance R should be chosen so that Q gt 2 L Signal Generator Fig 3 1 a Measure the resonant frequency This can be done conveniently using the Lissajous figure obtained from the input voltage and Vp b Measure the frequency dependence of the phase diffe
27. ges for load resistances of 1 330 Q 1000 and 0 short circuit output Explain the voltages you measure in terms of the current limiting mechanism Tabulate the values of Vout for each of the following troubles and compare with expected values i R2 open ii Zener open Zener short iv Q1 open 2 Three terminal Voltage Regulator Prepackaged voltage regulators exist for many commonly used output voltages If you re a hacker though it is convenient to have one regulator that can be adjusted for many different voltages The LM317 is one such device Its pins are labelled out adjust and in Two external resistors form a feedback circuit that controls the output voltage a Design a 5 V regulated power supply using the 317 and the diode bridge of Lab 4 The 317 maintains 1 25 V between the ADJ and OUT pins and the current in the ADJ lead is about 50 uA Provide a 20 voltage adjustment range with a trim pot Figure 11 2 shows the skeleton design Allow about 20 ripple on the output of the filter capacitor with a 1 k load Test the regulator as in part 1 Measure the LR SR and dropout voltage Try to measure the ripple rejection Lab 11 Physics 331 Laboratory Manual 43 12 6Vac transformer dc voltage with ripple regulated output Variac 0 120 Fig 11 2 3 Three Terminal Regulator as Current Source The 317 maintains about 1 25 V between the ADJ and OUT pins That s the basis
28. ilter a Construct the filter of Fig 2 1 Drive it with a sine wave and measure the attenuation Vout Vin as a function of frequency Check to see if the filter attenuates 6dB octave for frequencies well above the point or simply the point Measure the resistor s value and use the attenuation curve to calculate the capacitance and compare with its nominal value 15k Fig 2 1 But be careful of grounding Both ground clips of the scope probes are connected together within the scope They both go to earth ground Make sure that they are not connected to different points of your circuit To speed up the measurement first find the 3dB point then the 90 and 10 points A few more frequencies should be enough to give you a good graph b Set up the frequency sweep of the signal generator to display the frequency response of the low pass filter and print it Instead of changing the frequency manually you can use the frequency sweep capability of the function generator In frequency sweep mode the function generator gradually changes the frequency output from f to fo passing through all intermediate frequencies The sweep time tsw determines how long it takes to pass through the frequency range from f to fo After it reaches it abruptly returns to and repeats the sweep If the sweep mode is linear then the frequency change from is proportional to the time that has passed from the start of the sweep f fy
29. l Voltage 42 3 Three Terminal Regulator as a Current Source 43 Lab 12 GMOS Logic Gates 3st ics 45 1 Mickey Mouse Logic and the Totem Pole 45 2 CMOS Logic Gates fii nics Mien eae ccd ate tet 46 3 GMOS LOGIC CHIPS Sah eal 47 4 The Late a E E 49 Electronics Laboratory Introduction The experiments in this lab manual are designed to introduce various aspects of analog electronics starting from the simplest concepts such as Ohm s law and leading to practical electronic circuits including amplifiers integrated circuits oscillators voltage regulators and logic gates Each lab script is intended for a four hour lab period Some students may need more time to complete the labs especially at the beginning when the equipment is still unfamiliar The time can be used more efficiently if the student prepares in advance by reading the script and planning the procedure before coming to the lab The homework problems at the end of each lab script are intended to be done before the lab in order to prepare Each workstation in the lab has the necessary equipment an oscilloscope a function signal generator a multimeter and a
30. l problems assume you have JFET with Ipss 9 mA and Vggvoff 5 V 1 Calculate the current through the load for the circuit of Fig 7 2 assuming the JFET is in the current source region What are the limits maximum or minimum for the load resistance that allow the JFET to operate as a current source 2 Calculate the gain of the source follower in part 3 3 Do the calculations indicated for the optional part 5 28 Physics 331 Laboratory Manual Lab 7 Blank page Lab 8 Physics 331 Laboratory Manual 29 LAB 8 Differential and Operational Amplifiers Reading Malvino Chapter 18 First we will construct a differential amplifier and measure its properties Many of the characteristics of the differential amplifier pertain to integrated circuit operational amplifiers Next you will measure characteristics of the common 741C op amp and the better performing LF411 amp which has an FET input circuit Note In this experiment you may use either 12 V or 15 V for the op amp power depending on your breadboard box Certain values will have to be adjusted accordingly 1 The Differential Amplifier a Calculate the tail current of the circuit in Fig 8 1 as well as the base currents in each transistor 22 swamping resistors are used to improve the match between the discrete transistors Use the hres of your transistors or assume a value of 200 if you haven t kept them Build the differential amplifier shown in Fig 8 1 an
31. litude c Try to eliminate crossover distortion by inserting diodes or resistors in the bias circuit 4 OPTIONAL The Darlington Pair a Design and build an emitter follower using the Darlington pair connection of Fig 6 3 Lab 6 Physics 331 Laboratory Manual 21 2N3904 2N3904 Fig 6 3 b Measure current gain and input and output impedance c Can you explain the function of the 1 kQ resistor Hint See Horowitz and Hill Homework 1 Determine the capacitor values for use in part 1 a 2 Calculate the voltages and currents asked for in the emitter follower of part 2 b Also calculate the small signal voltage gain and the input and output impedances of the emitter follower If the emitter follower is driving an external load what load impedance yields maximum power transfer to the load Calculate the ratio of the maximum power transferred to the load to the input power This is the power gain 3 optional Design an emitter follower using the Darlington Pair Try to make the input impedance as high as practicable Calculate current gain input impedance and the output impedance Hints The critical frequency is the frequency at which the effect of the capacitor is to reduce the voltage by a factor of V2 If you choose the two capacitors so that this frequency is the same e g 150 Hz for both the input stage and the bypass the output at this frequency will be reduced by a factor of 2 For the bypass capacitor i
32. mitt trigger in Fig 10 3 2 Find the oscillation frequencies of the relaxation oscillator and Wien bridge oscillator shown in Figs 10 4 and 10 5 Lab 11 Physics 331 Laboratory Manual 41 LAB 11 Voltage Regulators Reading Malvino Chapter 23 Hayes and Horowitz Class 12 and Lab 12 These experiments will introduce the basic ideas about voltage regulators The first circuit uses three discrete transistors to demonstrate the principles of voltage regulation and current limiting Usually one uses prepackaged three terminal voltage regulators instead of building a discrete circuit The second experiment introduces a very practical voltage regulator whose voltage can be varied and which can also be used as a current source 1 Discrete Transistor Voltage Regulator The circuit of Fig 11 1 shows a circuit which will regulate the output voltage and limit the current output It uses three transistors Q1 Q2 and Q3 and a Zener diode We use a Zener voltage of 6 2 V because Zener diodes around 5 V to 6 V are the most stable against temperature variations One of the transistors acts as a common emitter amplifier so that the output voltage can be more than the Zener voltage Another called the pass transistor is an emitter follower which delivers most of the current to the load The third transistor performs the current limiting task Identify the amplifier transistor the pass transistor and the current limiting transitor Q2 33
33. n experimental box The multimeter can measure voltage current resistance and capacitance The experimental box includes 12 V power supplies for operational amplifiers and a 5 V supply for logic chips The independent Anatek variable power supply includes a robust current limiting control For those circuits built from independent components not using ic chips it is better to use this power supply because it withstands abuse much better than the power supplies in the experimental box Insert jumpers to create a continuous bus from one side to the other Use the horizontal bus pins for the voltages shown here These five holes are together are connected too but not to the ones above gn 12 These 25 holes These 25 holes are connected connected lt q But not to those on the left hand side Fig 0 1 The Breadboard Area The breadboarding area on the experimental box has holes for component leads 22 solid wire and ic pins Don t try to force larger wire into these hole because it will spring them too far and ruin the board The horizontal rows of holes on the top and bottom of the breadboard are connected together horizontally The left and right halves are independent We suggest that you use these horizontal rows for power supply voltages and ground You may wish to put a jumper wire between the left and right halves so that the voltages are the same across the board The Physics 331 vertical
34. nation integrator differentiator circuit of part 4 36 Physics 331 Laboratory Manual Lab 9 Blank page Lab 10 Physics 331 Laboratory Manual 37 LAB 10 Positive Feedback and Oscillators Reading Malvino Sections 21 2 21 3 21 9 chapter 22 Hayes and Horowitz Class 10 Lab 10 and Ch 4 worked examples on pp 227ff 1 Comparators a Connect the LF411 op amp as a comparator Drive the input with a sine wave and observe the output You are just using the high open loop gain of the op amp and swinging between positive and negative saturation One disadvantage of using the LF411 is its slow response time caused by the internal compensating capacitor used to avoid high frequency oscillations See if you can measure this limited response time out 12V Fig 10 1 b The LM311 is an op amp that is designed to be used as a comparator Unlike most op amps it has a faster response and you can change the voltage levels of the output With this op amp you get 12 V if Vin lt Vref and 12 V otherwise The open collector output of the 311 allows you to change these output levels independently of the power supply that runs the op amp Pin 1 comes from the emitter of the i c s output transistor It is not connected inside the chip Whatever voltage level you connect this to becomes the output if Vin gt Vref Often this pin is connected to ground Similarly pin 7 goes to the output transistor s collector This collector is not c
35. ns when they grow past a certain limit As the current through the lamp increases at higher output voltages then its resistance increases and cuts down the gain of the amplifier Thus a stable frequency is maintained by the lead lag circuit in the positive feedback loop and a stable amplitude is established by the self regulating effect of the tungsten lamp in the negative feedback 40 Physics 331 Laboratory Manual Lab 10 Fig 10 5 Build the circuit in Fig 10 5 and check if its frequency is 1 2nRC When you first turn it on you ll see the amplitude grow large until the negative feedback increases after the lamp warms up When you poke the noninverting input with your finger the output will wobble If you sweep the scope slowly and poke the noninverting input you can see the envelope of the oscillation bob up and down Can you explain this You can use this oscillator for radio frequencies Using R 470 C 220 pF in the lead lag circuit will give 1 2tRC 1 5 MHz When tried it though got a frequency of about 500 kHz The shift is probably because of stray capacitances and inductances in the circuit You will probably have to experiment yourself to get a frequency in the AM radio band We also found that increasing the 560 Q feedback resistor to 1 improved the output amplitude This way you can use the oscillator for the carrier frequency of the AM transmitter of the FET experiment Homework 1 Find the trip points of the Sch
36. on indicated by the shaded components Check the improvement by driving this circuit with a triangle wave Explain why there is some improvement c The World s Simplest AM Radio Transmitter Amplitude modulation can be produced with a slight modification shown in Fig 7 5 Use two function generators One supplies the carrier frequency of around 1 MHz The other can be set to sweep through an audible frequency range e g 400 2000 Hz This provides the variable modulation voltage Attach a long wire antenna a meter or two to the output and you re on the air Try to pick up the signal on a radio some distance away For fun you might connect the earphone output from a tape player or a microphone to Vmod instead of the second signal generator 26 Physics 331 Laboratory Manual Lab 7 yw NY TBF y f in lt 1V 0 01uF 10k 100k 2N5486 330k L Ki 12V Fig 7 5 5 The Common Source JFET Amplifier OPTIONAL if there is time a Build the common source JFET amplifier of Fig 7 6 Fig 7 6 b Calculate the drain current and Vas Measure Ip Vas and V ps and compare with the calculation c Calculate and measure the small signal voltage gain of the amplifier d Check the gain as a function of frequency and observe the phase shift e Drive the amplifier into distortion and explain its origin f Measure the input and output impedances Lab 7 Physics 331 Laboratory Manual 27 Homework For al
37. onnected in the chip either that s why it s call an open collector You connect this pin to a voltage that you want when Vin lt Vref for example 5 V Open collector outputs are commonly used if logic voltage levels representing true or false are different in one part of the circuit from another part Connect the LM311 as a comparator and observe its improved performance Note that some of the pin numbers of the LM311 are different from the 411 or 741 op amps 38 Physics 331 Laboratory Manual Lab 10 2 The Schmitt Trigger a Because of its fast response the 311 comparator can chatter if Vin hovers indecisively near the comparison point In this case the output will swing erratically between the positive and negative output levels as the input drifts up and down by very small amounts The Schmitt trigger uses positive feedback to reinforce the comparitor s decision Immediately after the input voltage crosses the trip point the trip point threshold level changes so that the input must significantly retrace its path in order to reverse the decision This means that there are two trip points one for rising input signals and another lower one for falling input signals 10k Fig 10 3 Calculate the trip points of the circuit in Fig 10 3 Build it and see if it operates like it should Put a sine wave on the input and note the hysteresis Also note that the triggering stops for sine waves below certain amplitudes
38. rator output in any way AUTOSET will result in a different configuration Furthermore not all of the oscilloscope s function settings are reconfigured by AUTOSET It is possible to save all settings of particular configuration for later recall from the oscilloscope s internal memory See the User s Manual for how to do this c Investigate the difference between AC DC and GND input coupling Press VERTICAL MENU Observe the signals when you choose AC DC and GND on the menu Normally you use DC even when you are measuring AC signals The purpose of the AC coupled input is to subtract a DC offset from a signal so that you can magnify the alternating component Add a DC offset to the signal by pulling the OFFSET button on the function generator You should notice that AC coupling subtracts the offset from the displayed waveform Avoid AC coupling unless you need to subtract an offset at low frequencies AC coupling can distort the signal s display AC coupling puts a high pass filter on the input to remove the DC offset So see this put the coupling on AC and decrease the function generator s frequency until the signal starts to appear smaller in amplitude After you finish put the frequency back to its original value d Learn the operation of the sweep and trigger controls Press TRIGGER MENU Make sure trigger source is CH1 Vary the level control to observe the effect of changing the trigger level There is a floating T on
39. rence between Vin and VL or Measure the magnitude of the voltages VL Vc Vp at the resonance frequency d Determine the bandwidth and Q of the circuit Using the frequency sweep method photograph the frequency dependence of Vp and determine the bandwidth and Q from the photograph f Photograph the frequency dependence of Vc 10 Physics 331 Laboratory Manual Lab 3 Parallel LC Circuit Construct the parallel resonant tank circuit of Fig 3 2 R Fig 3 2 a Measure the resonant frequency b Print a display of the voltage frequency response and find the bandwidth and Q c Investigate what happens when you load the output with a load resistor Fourier Analysis Drive the circuit of Fig 3 2 with a square wave and carefully observe the frequency response of the output voltage You will get peaks in the output sine wave response at the circuit s resonant frequency and at certain lower frequencies that have harmonics at the resonant frequency This is a sort of backward Fourier analysis The first few terms of the Fourier expansion of a square wave should be roughly related to the peak frequencies and amplitudes Try using the sweep generator to display a series of peaks at once Homework Problems 1 a Calculate the impedance of the series LRC circuit in Fig 3 1 b Calculate the resonant frequency Show that the voltage across R is maximum when the impedance is purely resistive
40. s controls Fig 0 2 The Tektronix TDS 340 Oscilloscope Control Panel Lab 1 Physics 331 Laboratory Manual 1 LAB 1 Introduction to Equipment and DC Circuits If you have done the AC circuits labs in physics 234 Spring 1995 or later you may skip Labs 1 2 and 3 and add labs on additional topics after Lab 10 Make sure you are familiar with the equipment by doing section 3 of Lab 1 if necessary Reading Malvino Ch 1 Hayes and Horowitz Class 1 Worked Examples and Lab 1 Note especially A preliminary note on procedure 1 Ohm s Law and its Disobedience a Verify Ohm s law for a 22 kQ resistor Use an analog volt ohm meter VOM for the current measurement and measure the voltage with a digital multimeter DMM Use the circuit of Fig 1 1 When using the meters start from the least sensitive scale and increase sensitivity until you get to the most sensitive scale appropriate for your reading 22k D gt Fig 1 1 The DMM doesn t really measure the voltage you want Find an alternative hookup that does measure the correct voltage What happens to the current measurement How do the internal resistances for the VOM and DMM affect the accuracy of the resistance determination Which hookup is most accurate for a 20 k resistor For a 20 MQ resistor b Measure V vs for the 1869 incandescent lamp Don t exceed 50 V Get enough points to show how the lamp di
41. s for both op amps by increasing the signal level at 1 kHz until you start to see clipping on either peak Homework 1 Calculate the values for and the base currents of the differential amplifier Use the currents to calculate lin bias and lin off Predict the differential gain A the common mode gain and the CMRR of the differential amp Express the CMRR in dB 2 Calculate the input voltages of the op amp circuit in part 2 a Lab 9 Physics 331 Laboratory Manual 33 LAB 9 Operational Amplifiers 11 Reading Malvino Chapters 19 and 20 and section 21 1 Hayes and Horowitz Class 8 Lab 8 and Ch 4 Worked examples on pp175 176 This week s experiment will use the ideal properties of operational amplifiers to build some commonly used practical circuits The diagrams in this lab don t explicitly show the power connections for the op amps Refer to Lab 8 if you have forgotten the power pin numbers 1 Non inverting Voltage Feedback Design a non inverting voltage amplifier with a closed loop gain of 10 Use the LF411 op amp and choose components with values closest to those specified in your design Build the circuit and measure the gain Calculate the theoretical input and output impedances then measure the input and output impedances if they are within measurable ranges 2 Inverting Voltage Feedback Now design amp circuit with a closed loop gain of 10 using inverting voltage feedback Calculate input an
42. sobeys Ohm s law Try to use the same graph paper by putting another scale on one of the axes if necessary Why is the curve nonlinear What is the resistance of the lamp Does that question make any sense 2 Voltage Divider and Th venin s Equivalent Circuit a Construct the voltage divider of Fig 1 2 Use the 12 V dc power supply of the breadboard for Vin Measure the open circuit output voltage Now connect a 10 kQ resistor on the 2 Physics 331 Laboratory Manual Lab 1 output as a load and explain why the output voltage changes What is its Th venin equivalent resistance and voltage Build the Th venin equivalent circuit using the variable dc power supply and verify that it behaves the same as the original when the output is loaded with a 10 kQ resistor 10k 10 Fig 1 2 b Now build the circuit of Fig 1 3 Measure the open circuit voltage and the short circuit current and find the Th venin equivalent resistance and voltage 33 k 10k out 22 k Fig 1 3 Usually you don t want to short circuit the output terminals of an unknown device because it might damage something inside Find the load resistance which lowers the output voltage by one half How does this value compare with the Th venin resistance 3 Oscilloscope and function generator a Show two signals on the oscilloscope display Adjust the function generator to produce a sine wave set the AMPLITUDE to 2 Vpp Apply the sine wave signal from the f
43. stor Fundamentals Reading Malvino Ch 6 through Ch 9 You will study bipolar junction transistors BUTs in this lab Most of the exercises will be done with the 2N3904 NPN transistor The terminal connections are illustrated in Fig 5 1 below gt Fig 5 1 1 Using Transistor Curve Tracers to Measure Operating Characteristics There are several Tektronix 575 curve tracers in the lab We also a new model Tektronix 571 The procedures will be slightly different depending on which one you use Abreviated instructions are available on the bench near each curve tracer a Determine the collector characteristics vs with as a parameter 571 curve tracer has a printer interface to let you make a hard copy of your curves You must use the polaroid camera to get hard copy from the 575 curve tracer Save the curves in your lab book and keep the particular transistor belonging to those curves Suggested settings for the curve tracers are listed below Tektronix 575 Tektronix 571 Ic collector mA 5mA div Function Acquisition VcE collector volts 2V div Type NPN Ig base step 0 01 mA step Vce max 20 V polarity Ic max 20 mA peak Volts 20 V Ib step 10 uA Steps 10 R load 100 Ohm P max 2 Watt 16 Physics 331 Laboratory Manual Lab 5 The series resistor is to limit power dissipation The maximum ratings are 40 Vcg 60V 6 Ic 200 mA The slope of the collector c
44. t These are among the simplest logic devices They are useful in their own right from time to time Also they demonstrate the input circuitry to the most commonly used TTL chips the low power Schottky LS TTL family Here we use standard 1N914 signal diodes instead of the faster Schottky diodes used in LS TTL gates OR AND NOT 5V 5V in out 5 3 in in out in in out Fig 12 1 The AND circuit illustrated in Fig 12 1 is similar to the input of the 741500 NAND gates Build it and confirm the logic function experimentally and record your results in a truth table When you test this gate use 0 V and 5 V for logical false and true TTL expects at least 2 0 V input for a high true input and guarantees at least 2 4 V fora high output CMOS requires at least 3 5 V for a high input and delivers at least 4 9 V for high output In what ways do these circuits disobey these criteria Try driving an LED First connect an LED from the output to ground and observe what happens Next connect the LED from the output to 5 V through a 2 2 k resistor This will invert the output signal Does it work better this way Why or why not 46 Physics 331 Laboratory Manual Lab 12 Build the NAND gate shown in Fig 12 2 which is very similar to an LS TTL circuit Notice the totem pole output Make a truth table of its operation showing the voltages on the bases of the totem pole transistors as well as the output voltage Do the voltage levels conform to TTL crit
45. t is not that you need to use Draw the equivalent circuit and derive a formula for vg vg Without the capacitor this ratio will be about 1 at all frequencies Choose the capacitor so that the ratio is A at the critical frequency 2 Lab 7 Physics 331 Laboratory Manual 23 LAB 7 Field Effect Transistors Reading Malvino Ch 13 and 14 Hayes and Horowitz Class 7 worked example and Lab 7 This lab introduces Field Effect Transistors and their applications 1 Junction FET Characteristic Curves Use a transistor curve tracer to determine the drain characteristics and transfer characteristics The 2N5486 is an n channel JFET having the following maximum ratings 25V 25V Vas 25V ID 30 mA The terminal pins are illustrated in Fig 7 1 Fig 7 1 a Measure the drain characeristics Ip vs Vps Tektronix 575 Tektronix 571 Ip collector mA 0 5 mA div Function Acquisition Vps collector volts 2 Vidiv Type N FET Vas base step generator 0 2V step Vds max 20 V d max 20 mA Polarity Vg step 0 5 V Offset varies withVgs off try 5V Steps 10 R load 0 25 Ohm P max 2 Watt 24 Physics 331 Laboratory Manual Lab 7 b Measure the transfer characteristics Ip vs Vas Tektronix 575 Tektronix 571 Ip Collector mA 0 5 mA div Use the cursor to read for each Vas base source volts 0 2 V step of the drain curves of part a at polarity both and Vps 5 15 and 20 V Plot the values
46. the screen to show you 4 Physics 331 Laboratory Manual Lab 1 where the triggered position of the input signal is displayed There is also an arrow on the right hand side if the screen to indicate the trigger voltage level If either of these indicators are not visible they may have been turned off Consult the user s manual or an instructor to find out how to turn them on again Change the trigger source to CH 2 which displays the SYNCH signal What effect does changing the trigger level have now Change the trigger slope from positive to negative Note the difference There s a button labelled Set Level to 50 which is handy to quickly stabilize a signal on the screen when you don t know where the trigger level should be set Reconnect the SYNCH signal from the function generator to EXT TRIG Select EXT TRIG for the trigger source This frees CH 2 for observing another signal while still allowing the trigger signal to come from SYNCH of the function generator e Learn to measure frequency assuming that the horizontal time base is accurately calibrated Centre the displayed waveform about a horizontal line Measure the period from zero zero crossing to zero crossing and calculate the frequency Compare with the value obtained using the MEASURE menu and from the function generator readout f Generate Lissajous figures by applying two signals of different frequencies to CH 1 and CH 2 Use the transformer for one signal Choose the DISPL
47. unction generator to Channel 1 of the oscilloscope Simultaineously apply the SYNCH output signal of the function generator to Channel 2 Press in sequence the oscilloscope s AUTOSET CLEAR MENU and CH 1 buttons AUTOSET should Lab 1 Physics 331 Laboratory Manual 3 configure the scope to measure the signals coming into the inputs The CLEAR MENU and CH 1 buttons ensure that the display is clean and your next operations will affect the CH 1 display The green light next to CH 1 should be lit You should see a 2 Vpp signal displayed on the CH 1 trace and a square wave displayed on the CH 2 trace What is the peak to peak voltage of the square wave b Change the scale and position of the waveforms Turn the SCALE knob under VERTICAL Notice how the display changes The V DIV legend beneath the display reflects the scale changes Adjust the CH 1 scale to 1 V div Press CH 2 and investigate the VERTICAL SCALE adjustment as before and leave CH 2 1 V div Press CH 1 Play with the VERTICAL POSITION knob Turn the HORIZONTAL SCALE knob and note how the displayed waveform changes The legend beneath the display reflects the change in sweep rate Move the trance left and right with the HORIZONTAL POSITION control After you have changed a few settings you should be able to return to the origional configuration by pressing AUTOSET The result of AUTOSET depends on the signals which input to the oscilloscope so if you have changed the function gene
48. urves is a measure of how imperfectly the transistor acts as a dle current source The parameter hoe is called the output admittance In the h equivalent model of the transistor the collector emitter output is modelled by an ideal current source in parallel with a resistance Noe is the inverse of this resistance Measure Noe from your curves What is the accuracy and over what range of Vce is this result valid b Plot the transfer characteristics vs Ig Measure directly using the following settings Tektronix 575 Tektronix 571 peak volts 0 5and15V Use the cursor to read values of Ic for use multiple exposures the ten values at 0 5 15 Plot these values on a graph Ic collector mA 5 mA div Ig base step 0 01 mA step Polarity Calculate the current gain hFE i atlc 1 mA Vce 5 V Compare this value of with that measured by the multimeter At this point find another transistor with at least 20 different Note the values of hg measured by the multimeter for both transistors label them and keep for later use Measure Ic vs VBE Connect the base and collector of the first transistor together as shown in Fig 5 2 Measure its diode characteristic curve using the method of Lab 4 This will give you Ic vs The effective emitter resistance should be approximately 25 mV Ic How closely does the transistor obey this relationship Fig
49. vious state was set or reset The set state is when 5 is low and R high The reset state is when R is low and 5 high The fourth state both inputs low results in an indeterminant output when the inputs return to their quiescent state If both S R are brought low and then raised the output retained by depends on which input goes high first This condition is not very useful and should be avoided Build the NAND latch shown in Fig 12 7 and make its truth table See if you can verify the indeterminancy of the fourth state You can use either 74HCOO 741 500 5 5 5 V 1 R Fig 12 7 The little bars above S and R indicate that the set or reset condition occurs when the respective input is grounded instead of at 5 V Homework Using only NAND gates design the circuits for the logical operations 1 AND 2 OR with inverse logic inputs and 3 XOR for part 3 b Congratulations you made it to The End
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