Opto-isolator - ILD213T Breakout

This is a board designed for opto-isolation. This board is helpful for connecting digital systems (like a 5V microcontroller) to a high-voltage or noisy system. This board electrically isolates a controller from the high-power system by use of an opto-isolator IC. This IC has two LEDs and two photodiodes built-in. This allows the low-voltage side to control a high voltage side.

More information is available on the website of Sparkfun.