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Photoresistors, Phototransistors, Photodiodes which to use?

supak111

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Apr 29, 2012
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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?
 
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Harald Kapp

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Nov 17, 2011
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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.
 

supak111

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