I have been searching, but can find a solution.
I made a nixie clock that is powered by an arduino board. It keeps time by tracking milliseconds, but as you know milliseconds on arduino are not that accurate. I am pretty close to correct (only off a couple seconds per day) at 998.3 milliseconds per second. I would try to get more accurate to keep better time but it overflows in like 6 days anyway. I'm sure there is a way to program around all this, but I have no idea how to program.
I have an old laptop with windows 7 that stays right next to the clock (I use it as a print server). Does anyone know how I could make it so once per day the laptop would automatically upload the sketch? I can choose the time the sketch starts at, so at say 02:59:53 it would upload the sketch with the 03:00:00 time (takes a few seconds to upload and power back on. The clock would never be off by very much since it would update every day, and would reset itself automatically after power outages.