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Photoresistors, Phototransistors, Photodiodes which to use?

Discussion in 'General Electronics Discussion' started by supak111, Feb 2, 2013.

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  1. supak111

    supak111 ★ƃuᴉɯǝɥɔs sʎɐʍlɐ★

    Apr 29, 2012
    Can't seem to understand which is best to use here.

    I need a super simple light switch for 24v DC. Will be used in a pitch black room, switch should be OFF with no light present, ON when there is light. Which of these can let, say 200 mA through it for 1 second when the light hits it?

    Photoresistor, Phototransistor, or Photodiode?

    I think i can use second 2 to drive a transistor and then the transistor can conduct enough mA but I'm hoping to keep it simple and not have to add resistors and transistors if possible of course.

    Thanks guys :)

    PS I was going to try just using a photoresistor in line with whatever I'm trying to switch ON / OFF?
    Last edited: Feb 2, 2013
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    Nov 17, 2011
    Neither of these alone will suffice for the job. You will need additional circuitry. Google light sensor circuit and find a bunch of suitable circuits from very simple to rather sophisticated.
  3. supak111

    supak111 ★ƃuᴉɯǝɥɔs sʎɐʍlɐ★

    Apr 29, 2012
    i was afraid of that but thank you for your answer bud
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