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From: Ian Malcolm
Subject: Re: IR LED test .
Date: Fri, 20 Dec 2002 11:44:25 +0000
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NNTP-Posting-Date: 20 Dec 2002 22:31:05 GMT
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Hasan Alikhany wrote:
> By h.Alikany
> Simple !
> You can see IR light by a VHS camera or handycam.
> Bye !
Bit of a overkill to dedicate a video camera to remote testing.
We only use that effect when a customer has to see it working as there
is a security camera/monitor near the counter.
For workshop use, we use an IR photodiode connected directly to the
scope input. The photodiode was stripped out of an old *OLD* tv (cant
remember which one, but you are in the right pile of junk when you find
chassis with the RC receiver on a separate PCB in a metal can with 3
wires back to the main board). For anyone else rummaging their junk
pile, you are looking for a black 2 lead IR receiver with a little domed
lens that measures as a diode.
Its easiest to solder it into a Phono plug and then use a phono - BNC
The 1M 30pF scope input low pass filters it so you only see the
envelope, not the 40KHz pulse train. Start with around a 10ms/div
sweep, and enough gain so you see ripple from the photodiode from the
workshop lights and a good remote 6" away should give pulses filling
most of your screen.
You can buy a made up unit from some suppliers but we wanted one *now*
and didn't really want to pay a x 5 mark-up on the parts.
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk [at]=@, [dash]=- &
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