Can a Led be used to measure ambiant light?

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TimB
Posts: 262
Joined: Wed Oct 04, 2006 7:25 am
Location: London UK

Can a Led be used to measure ambiant light?

Post by TimB » Sun Mar 16, 2008 1:02 pm

I have an app that flashs a led, trouble is in day time its to dim and at night to bright.

Now I have seen people use Leds as buttons so obviously there is some feed back in them, but can I use them as a crude ambient light sensor, so I can use it to set the brightness level?

Ta

Tim

TimB
Posts: 262
Joined: Wed Oct 04, 2006 7:25 am
Location: London UK

Post by TimB » Sun Mar 16, 2008 1:06 pm


TimB
Posts: 262
Joined: Wed Oct 04, 2006 7:25 am
Location: London UK

Post by TimB » Sun Mar 16, 2008 5:15 pm

Its really quite simple

I put a v meter across a LED and in the dark got a low voltage and under a table lamp got 0.2v well within the range of the A/D

So when my led is off or every x mins I will to an a/d on it to determine the voltage and adjust my pwm accordingly

Cheers

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