The New Nixie Clock

Managed to find six old nixies on a PCB (from an old counter of some kind) going for a song on ebay, so thought i'd do another nixie clock.

Some slightly different electronics this time, BCD TTL counters and 74141 high voltage drivers. As a departure from my normal practice, I did a switchmode PSU (using a TL494 chip - pinched the design from the application notes and veroboarded a prototype. 150V at 10ma or so. I used a fairly meaty mosfet on a decent heatsink) - another learning point, fingers can be burnt by very hot semiconductor devices with sub-prime heatsinking.

Divided down a watch crystal to get 1HZ with cmos - a 4060 and 4013.

Getting that tiny watch crystal to ocillate was interesting. As to 32.768 KHZ it was like the crystal was on a mission to be unstable. Experimentation with lots of very small capacitors and the patience of a sleeping Furcot and we were there.

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