Garmin v1.0b Clock User Manual
Contents
1. adapter a 12V battery or other true 12V source The 12V power adapter included with the GPS upgrade kit is a switch mode power supply which will work without problems Nixie Display ULA t 20885 Reier Jens Optional PPS Active Indicator 5 Optionally although recommended you may wish to run a jumper wire from the AUX_A pad to the decimal point indicator on the seconds nixie This will light up the decimal point on the right hand nixie as long as PPS signal has been received from the GPS within the last second Remember that the GPS takes about five minutes to get synchronization on power up before the PPS signal will be received The decimal point pins on the nixies are directly to the left and right of the bottom most pin approximately in the 5 o clock and 7 o clock positions You can use any decimal point you wish as the indicator The AUX_B pad can also be used except this pad will toggle on or off each time a new pulse is recetved on the PPS line The effect of connecting to the AUX_B pad is the indicator will turn on for a second then off for a second and then repeat so long as the PPS signal is active If the PPS signal stops the AUX_B connected indicator will maintain it s last state Conclusion A conclusion is the place where yon got tired of thinking Harold Fricklestein When you power up the GPS modified clock with the GPS plugged into it it will at first appear and function as it did without the GPS Set2. the time to within 15 minutes and let the clock run When the GPS acquires the satellite signal the time displayed will correct itself and stay locked onto the GPS PPS output from then on Additionally every morning at 2 45am local time the clock will recheck that it has the correct time according to the GPS unit If you connected the jumper wire to one of the nixie decimal places it will light up to indicate that the GPS has synchronization and is sending PPS signals If the GPS does not acquire synchronization within five minutes you may need to move the GPS antenna to a location closer to a window or away from obstructions I hope you enjoy your GPS upgrade If you have trouble with the unit please contact me Peter Jensen at jensen peterjjensen com Update The new revision of the the PCB has a place to put a header to mate with the connector which is already on the GPS unit The surface mount header is shown in the picture below and is now included with the GPS upgrade kit Connecting to the thru hole connection points as described in this manual still works but using the header is a cleaner and easier method This manual will be updated soon to reflect this change GLEDER a oO In this picture the header shown is oriented with the pins facing the bottom of the image while it needs to be soldered into place with the pins facing the top of the image Make sure the six pins on the header line up with the six pads
3. GPS Upgrade Kit for IN 14 Nixie Clock General Instructions v1 0b Instructions for Adding a Garmin GPS 18 LVC to a IN 14 Nixie Clock 2007 Peter J Jensen LLC Ann Arbor MI Scary Warning DANGER BUILDING OR MODIFYING THIS KIT INVOLVES WORKING WITH DANGEROUS POTENTIALLY LETHAL VOLTAGES POWER LINE VOLTAGES ARE DANGEROUS IF YOU ARE NOT EXPERIENCED WORKING WITH DANGEROUS POTENTIALLY LETHAL VOLTAGES RETURN THE KIT FOR A REFUND IF YOU DO NOT ACCEPT FULL RESPONSIBILITY FOR WORKING WITH THESE POTENTIALLY LETHAL VOLTAGES RETURN THE KIT FOR A REFUND BY BUILDING OR MODIFYING THIS KIT YOU ACKNOWLEDGE AND AGREE THAT PETER J JENSEN LLC AND ITS MEMBERS BEAR NO RESPONSIBILITY OR AS LITTLE AS IS PERMISSIBLE BY LAW FOR ANY HARM TO PERSON PROPERTY OR ANYTHING ELSE ANYBODY CAN THINK OF DUE TO YOU WORKING WITH THESE DANGEROUS POTENTIALLY LETHAL VOLTAGES OR BUILDING THIS KIT Overview A man with a watch knows what time it is A man with bvo watches is never sure Segal s Law This document describes how to connect a Garmin GPS 18 LVC to the IN 14 Nixie Tube Clock from tubeclock com The GPS unit will allow the clock to set and maintain time display to sub millisecond accuracy Timing accuracy comes from the GPS receiver in the Garmin GPS 18 hardware The GPS 18 receives signals from the network of satellites which orbit the Earth and transmit accurate time codes via radio waves These time codes are typically use
4. and the two support pins on the front of the header line up with the two support pads on the PCB closest to the edge of the PCB The boatd header which mates directly with the connector on the GPS 18 is Digikey com part number 455 1806 1 ND
5. d for calculating position for navigational purposes but they also provide a highly reliable time source GPS Advantages and Disadvantages The advantages of GPS time synchronization include a high degree of accuracy over long periods of time it is referenced to atomic clocks and it s ubiquitous availability anywhere on the Earth The disadvantage is that the signal is very weak so the GPS 18 hardware should be placed in a position where it has a line of site view of the sky The unit will work indoors but at least placing it on a window sill is a good idea Even thin material like paper will effect the receiver s performance The Garmin GPS 18 LVC has a magnetic base and also a screw to help with mounting Seatch on amazon com or the web for part numbers 010 10541 00 suction cup mount or 010 10453 00 flange mount if you would like mounting hardware for the GPS 18 LVC Operation The Nixie Clock will communicate to the GPS 18 via two mechanisms first is an RS 232 serial port for communicating the time and setup information and second is a Pulse Per Second PPS signal which will keep the clock in syne when the serial communications ate not in use A copy of the complete GPS 18 manual can be found on the Garmin website http www garmin com manuals 425 TechnicalSpecification pdf When the clock is turned on the GPS will take from a few seconds to five minutes to acquire the satellites signal During this time the clock w
6. ill run using it s on board oscillator and you will need to set it to within 15 minutes of the correct time This is necessary because the GPS system does not provide time zone information When the signal is acquired the GPS will send a signal to the clock by beginning strobing of the PPS line and the clock will then read the next serial port message and adjust the time Once the PPS signal has begun the GPS unit will continue sending one pulse per second until power is turned off regardless of the satellite tracking state The clock will synchronize its second counter to this PPS signal In addition to setting the time on the first PPS signal every morning at 2 45am the clock will query the GPS unit over the serial line It will adjust the clock to the nearest half hour offset of the UTC time provided from the GPS The GPS provides the Universal Coordinated Time same as Greenwich Mean Time The clock assumes the user has set the time to within half an hour of the correct local time 1 e plus or minus 15 minutes and uses the the UTC time from the GPS calculate the exact time Parts The first rule to tinkering is 10 save all the parts Paul Erlich Part Name Description PIC16F688 Microcontroller Updated microcontroller with support for GPS 1 Watt 1000hm Resistor Replaces Y Watt 1k Ohm Resistor R1 This will allow more 5V power supply current to power the GPS 18 Wire Optional to connect nixie decimal point disp
7. lay to AUX_A or AUX_B driver output This will cause the nixie decimal point to light up a Pulse Per Second PPS signal is being received Garmin GPS 18 LVC The GPS antenna and receiver on a 5 meter cable Make sure the GPS 18 has a view of the sky as unobstructed as possible It will work indoors but at least placing the unit on a window sill is a good idea 12V DC Power Adapter The 12V power adapter included with the GPS upgrade kit is a switch mode power supply WARNING Please make sure to use the GPS modified clock ONLY with a switch mode 12V power adapter a 12V battery or other true 12V source The 12V power adapter which shipped with the non GPS kit is transformer based and provides too high a Voltage for the GPS modified clock The transformer based power adapter can actually output up to about 18V which will burn out the 1000hm dropping resistor If you would like mounting hardware for the GPS 18 LVC search on amazon com or the web for part numbers 010 10541 00 suction cup mount or 010 10453 00 flange mount How To Connect The GPS Famous actaty is no substitute for understanding H H Williams These instructions assume that you are adding the GPS upgrade to a completed IN 14 nixie clock kit purchased through tubeclock com If you are adding the upgrade at the same time as building the kit you will not need to remove the standard parts Simply substitute the parts that came with the GPS upgrade kit i
8. nstead If you purchased a completed IN 14 nixie clock you may use these instructions to upgrade the clock yourself 1 To provide sufficient current for the GPS unit resistor R1 will need to be replaced This resistor was a 2 Watt 1k Ohm part located on the right hand side of the PCB Remove R1 and replace it with the 1 Watt 100 Ohm part provided 2 There are six wires which lead to the GPS 18 Each of these wires connects to a solder pad on the Nixie Clock circuit board Snip off the connector provided on the GPS 18 strip the wire ends and solder them to the pads on the clock PCB as listed in the table below Color Signal Name Wire Connection Point on Gauge Clock 1 Yellow Pulse Per Second Output 28 RAO 2 Red Vin 5V Power In 26 5V_A 3 Black Ground 28 GND_A 4 White GPS Serial Transmit 28 RC1 5 Black Ground 26 GND_A 6 Green GPS Serial Receive 28 RCO In 14 Nixie Display 2086 Beweise 3 Gently pry the old microcontroller from the socket and insert the new PIC16F688 4 Finally the 12V DC power adapter will need to be replaced WARNING the 12V power adapter which shipped with the non GPS kit is transformer based and provides too high a Voltage for the GPS modified clock The transformer based power adapter can actually output up to about 18V which will burn out the 100Ohm dropping resistor Please make sure to use the GPS modified clock ONLY with a switch mode 12V power
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