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[DPRG] Using an IR LED as IR photodiode
Subject: [DPRG] Using an IR LED as IR photodiode
From: Subhobroto Sinha
subhobroto at gmail.com
Date: Mon Oct 23 20:59:39 CDT 2006
Hi
Crazy as I am, I want to use an IR LED as IR photodiode, because I
noticed that the response of an IR LED to IR is very good.
Just take a normal IR LED, connect it across a DVMM and shine some IR
on it.... for me, I registered 0.4 volts @ 2uA....
I think that's quite good ! Is it not ?
Just wired it to LM358 thinking of boosting the 0.4v to 3.5 volts, and
guess what...
I see very nominal amplification at the output.
For example, adjusting the pot, so that output read 1v when no IR was
shining on the diode, I only got 1.1v when I shone some IR on it...
Yes, just hooking up the IR LED to the DVMM (Digital Volt Meter) gave
me ~ 0.01 volt when no IR was shining on it vs 0.4v when I shone the
same IR Light on the LED....
I am a digital guy and analog is not my strong point I admit, but this....
Help me out guys !
Schematic at :
http://subhobroto.googlepages.com/IR.Tacho.png
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