https://github.com/davedarko/FixieTubes

I wanted to use the "square wave out" from the DS3231 module for a blink-every-second LED, but the control register for the DS1307 and DS3231 were different, so I had to switch libraries a bit.

I used an old cell phone charger and soldered it directly to the arduino, since I had no plug for the connector I wanted to use.