LEDs & Photodiodes

Discussion in 'General Electronics Chat' started by Mazaag, Apr 18, 2006.

  1. Mazaag

    Thread Starter Senior Member

    Oct 23, 2004
    Hey Guys,
    I was reading an article about using LEDs as touch-sensing devices. Is it true that a "switched off" LED acts as a Photodiode? What is the structural difference between a LED and a Photodiode?

  2. n9352527

    AAC Fanatic!

    Oct 14, 2005
    I have no idea about the physical or geometrical differences between them, but I do know that LEDs can be used as cheap replacements for photodiodes in some applications. Of course, not drop-in replacements because there are electrical and characteristic differences. As far as I know the characteristic differences are LEDs are much slower (in response) than photodiodes and LEDs would only detect light which has shorter wavelength than themselves. The elctrical differences would be the biasing and the VI response.