Optocsatoló

The general purpose optocouplers consist of a gallium arsenide infrared emitting diode driving a silicon pho- totransistor in a 6-pin dual in-line package.

http://tronixstuff.com/2010/09/21/education-introduction-to-the-optocoupler/

http://fritzing.org/projects/optocoupler

http://www.hestore.hu/prod_10001323.html