[chbot] Anyone tried LEDs as light sensors

[Charles Manning]

I've been playing around a bit with light sensors and found some threads on
using LEDs as light sensors.

Yes, not only can LEDs be used to **make** light, they can also be used to
**detect** light by reverse biasing the LED

ie. by the wonders of ASCII art...

     Ground ---|>|------- ADC pin

Testing with an arbitrary LED from my junk box this gave a voltage of very
close to zero when dark and almost 1V when pointed towards a bright light.

That's quite a useful property given how easy it is to get LEDs relative to
phototransistors etc.

Regards

Charles
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