He hooked up a microphone and a photodiode to the Arduino, allowing him to use both sound and light to trigger his camera, depending on which mode he selects.

Users will need to provide their own Arduino Pro Mini and the hardware features a 1.4 W, 8 Ohms, Texas Instruments TPA2005D1, 14 bit ganged PWM, PWM 8 kHz low pass smoothing filter all powered by ...