After dealing with excessively long showers for too long, I set up a system to manage the amount of time our kids could effectively use the shower.
Parts (not a complete list, mostly the electronics side):
- Brass Liquid Solenoid Valve (adafruit.com)
- Rugged Metal Pushbutton with LED Ring (adafruit.com)
- Arduino Pro 328 – 5V/16MHz (sparkfun.com)
- MOSFET (digikey.com)
- Schottky diode (digikey.com)