One of my Nixie tube clocks uses a radio controlled time source to sync to, the MSK clock in the UK. This has not been that reliable, thus I decided it needed to be changed for another time sync system. The clock also supported GPS as a time source. Hum, this would mean getting another GPS unit, etc etc.. shed loads of work.
However, searching around the internet I came across Martin Oldfield who was using the serial output of the Raspberry PI to drive his clock with a script written by Clayton Smith to send the GPRMC sentence sentence to the clock. After a look through my box of bits, and a few components later, the signal inverting circuit was built, and with the customary LED, to let me know it was working.
The next issue, was the lack of serial port, I had already used up the on board UART on the Stratum 1 server. Another look though my supplies, I found a spare USB to serial cable, problem solved.
Only one other opportunity! It did not work..... after checking that I had cabled it correctly, and head scratching, I found that the GPS inverter circuit on the clock was missing, so back to the bits box... a transistor, and a couple of resistors later, and 'bingo' working :-)
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