Bidirectional led

Thread Starter

DancinNancy

Joined Oct 1, 2008
24
Trying to wire up several leds to be used to emit light as well as be a sensor. I know very little on the subject except that when you reverse bias the led you can use it as a sensor. Any pointers or websites where i could learn about this?
 

Thread Starter

DancinNancy

Joined Oct 1, 2008
24
I'm trying to use it for a senior project in college. It will be used to show different patterns also used to read which leds are being pressed. I found a video online that showed LED's being used as sensors while they were all lit and didn't know how to do it
 

Externet

Joined Nov 29, 2005
2,668
Perhaps by turning the leds on and off repeatedly and fast enough to make them appear as constantly on; while sampling the voltage they generate during the off intervals.
Green leds are better for photodetection.
Miguel
 

beenthere

Joined Apr 20, 2004
15,819
An LED that is biased almost into conduction might make a good light detector. The closer the wavelength to the one emitted should increase sensitivity. The effect would be like a photodiode. You should see some current with light present, and none or much less in the dark.
 
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