Chess clock is based on :

https://www.instructables.com/How-to-Make-a-Chess-Clock-With-Arduino/ By simaopintocorreia

Instructable is well written and contains all information necessary for a successful project.

Clock is powered by rechargeable batteries held by my 2 battery holder.

I added a countdown clock to beginning of program and an alarm that sounds when a player looses. Busser is connected to pin 3.

Also added section to program that allow for play time to change: 1 min, 3 min, 5 min, and 10 min games.

To make wiring easier, I made two small boards - one for power and another for ground. That allows wire to be plugged into small boards rather than main arduino board. Switch does not work as planned - it does not completely shut off clock. Will design with proper switch. Plug power supply in to start clock.

Code follows:

#include