infrared

Most tutorials I’ve found so far are about 3-pin photodiodes. These are meant to recieve digital IR signals from TV remotes or similar devices. The 2-pin diodes can be used to simply meassure the available IR light. So you could use this to build a distance sensor, if you add a IR LED emitter and then meassure the reflected light, or to meassure the IR light emitted by a natural or artificial light source.