I made this device for a sculptor who specialises in water sculptures. He wanted to be able to record a sequence of on and off commands (from the push button) for a mains powered pump in one of his installations, looping from the last stored command to the beginning.
I used an Arduino Mini with external I2C EEPROM to store the sequence of commands for a duration of up to 1h 50m. It switched a mains relay through a transistor. The large round black object in the photo below is a high quality toroid transformer for the power supply for the Arduino.
The system needed to be robust and water resistant. Hence, the large cable glands and the fact that I potted the whole system in polyurethane.
