[chbot] Anyone tried LEDs as light sensors

[Andrew Errington]

Yes, I have!

I built a solar tracker, using a pair of LEDs connected to a comparator. 
It was kind of cool.

I believe green LEDs produce the greatest voltage.

A

On Mon, November 10, 2008 13:00, Charles Manning wrote:
> 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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