MAKE contributor Jonathan Foote turned an motion-activated candy dispenser into a cat feeder with the addition of an Evil Mad Science Art Controller coupled with an ordinary vacation timer. The Art Controller is a board with an ATtiny2313 and a relay, and is designed to be a simple solution for laypeople to safely trigger high voltage. Jonathan has the controller set to automatically trigger the relay when it powers up, so it immediately dispenses when the timer kicks in.
I hooked up the motor to the timed switch, and set it to run for seven seconds when it gets power, as it does when triggered by a timer. Since I had a 5V power supply I removed the voltage regulator from the art controller and used the holes for pin headers to connect the existing power supply and motor wires. The resulting hack will reliably and elegantly deliver meals to my favorite pet.
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