Nixie Sync

The Karlsson Nixie clock (by Peter van der Jagt 1997) is very stylish. One of the first of the kind and definitely setting the trend. Unfortunately it does not hold the time after a power outage. For quite some time I was thinking of adding a time synchronization module.

Initially the idea was to use the long wave radio receiving the DCF77 signal. DCF77 is increasingly more problematic as the 77kHz frequency is impacted by the totality of high frequency digital power supplies that generate lots of radio noise.

The alternative is of course fully digital, relying on an Internet time source, based on the NTP protocol. Surprisingly (or not) the NTP-based module has proven to be super easy to build these days (...with the help of AI).

Actually I wanted to kill two birds with one stone: have the bloody clock display the right time and also test Claude's capabilities as a junior embedded software / electronics coworker. Both goals have been achieved. I found it entertaining, educating, and fruitful to do this project with Claude. Fundamentally - it works as expected. And I learned quite a lot on the way: about electronic circuits and also something about low level software.

One surprising finding was how - trying to explain to Claude the design of the clock's power supply - I uploaded a photo of the clock internals and Claude discovered the MC33064 reset supervisor chip in the corner of the photo and drove the robust reset architecture from that:

Two useful confirmations from these photos. The crystal reads 3.579545 MHz, so the post-reset startup delay is 0.57 ms or 9.2 ms depending on the DELAY option bit. More importantly, the SO-8 beside the MCU reads 33064 — that's consistent with an MC33064-5 undervoltage sensing circuit, an open-collector reset generator with a ~4.6 V threshold.

The other surprise was how easy it was to add the WPA2-Enterprise WiFi authentication. I have many consumer products (some pretending to be premium ones!) that do not support WPA2-Enterprise. So I was quite cautious asking Claude to add this, but it turned out to be really simple.

See all the details on my GitHub here: https://github.com/SzymonSlupik/NixieSync.