From: Spehro Pefhany
Subject: Re: Infrared led tester
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Date: Thu, 19 Dec 2002 23:04:37 GMT
NNTP-Posting-Date: Thu, 19 Dec 2002 18:04:37 EST
On Thu, 19 Dec 2002 20:50:06 +0000, the renowned John Woodgate
>I read in sci.electronics.design that Spehro Pefhany
> wrote (in om>) about 'Infrared led tester', on Thu, 19 Dec 2002:
>>On Thu, 19 Dec 2002 18:40:55 +0000, the renowned John Woodgate
>>>I read in sci.electronics.design that Gregory Calvert
>>>wrote (in ) about 'Infrared led
>>>tester', on Thu, 19 Dec 2002:
>>>>Anybody know of an easy way to test ir leds? Be gentle, I'm a beginner.
>>>What do you want to test? If they draw current, and only when connected
>>>the right way round to the supply, they almost certainly work.
>>Mmm, well, I'd add if they drop about the right voltage (around
>>1.2-1.5V) at the right current they are almost certainly working.
>>There are a few ways for these things to fail shorted.
>Shorted but still diodes? I wrote:
>>and only when connected
>>>the right way round to the supply,
>A small grovel is in order, I think. (;-)
I'll go along with that suggestion. In fact, checking reverse
leakage might be a measure of damage due to overheating, similarly
to using leakage of MOS transistors to measure radiation damage.
Seems I didn't read your response thoroughly.
>>>If you need to 'see' the IR output, many video cameras are sensitive to
>>FWIW, I just tried it quickly with a digital still camera and it
>>didn't work very well, if at all.
>Many of those now have IR filters because solar IR degrades the visual
This isn't a new one (1998) but it was fairly high end at the time.
That sounds reasonable. I suppose similar considerations would apply
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