From: Ian Stirling
Subject: Re: cheap IR camera?
Date: Fri, 20 Sep 2002 15:44:44 +0000 (UTC)
References: <54ji9.145941$Jo.45144@rwcrnsc53> <firstname.lastname@example.org>
NNTP-Posting-Date: Fri, 20 Sep 2002 15:44:44 +0000 (UTC)
User-Agent: tin/1.5.6-20000803 ("Dust") (UNIX) (Linux/2.4.18 (i686))
In sci.electronics.design fred bartoli wrote:
> Ian Stirling a ?crit dans le message :
>> In sci.electronics.design Leon Heller wrote:
>> > "George Gonzalez" wrote in message
>> > news:54ji9.145941$Jo.45144@rwcrnsc53...
>> >> Lately I've been resuscitating a pallet-load of Tek 465 and 475 scopes.
>> >> Some have easy-to-find problems with the power supply-- dried up
>> >> electrolitics,
>> >> bad bridge rectifiers.
>> >> Most of the rest have shorted tantalum capacitors from one of the power
>> >> supplies (-8, -15, +5, +15) to ground. These are a bit difficult to
>> > find,
>> >> as there are many caps sprinkled around the boards. The method I'm
>> >> now is to push a few amps into the shorted power bus with an external
>> > power
>> >> supply, then feel around for warm or hot capacitors.
>> >> This isnt a very good method, as it's hard on the series decoupling
>> > chokes,
>> >> wound with like #30 wire, they get a lot warmer than optimum. Also
>> >> depending on the severity of the short, the capacitor can get anything
>> > from
>> >> just barely warm, to finger-burning HOT.
>> >> Are there any reasonably priced IR sensors, like a small CCD TV camera?
>> >> Last one I saw was 1000's of $, but that was a couple decades ago.
>> > CCDs tend to be quite sensitive to IR. You could try putting an ambient
>> > light filter in front of an ordinary camera and see if it will detect
> the IR
>> > emitted by the hot components.
>> Umm, no.
>> CCDs are sensitive to at most about 1000nm, and that at very low levels.
>> If it's hot enough to be emitting that sort of light, it'll be at
>> around 500C or so.
> A friend of mine have one camcorder (Sony IIRC) that has an IR mode. We
> tested it and could clearly see ourselves in the dark.
> Worth a try if you have an ordinary one.
> I also could ask him the ref if you're interested.
It's long-wave IR only that's usefull for sensing heat.
The Sony one was only sensing near IR (it can be a couple of times more
sensitive in this mode, as well as being able to use IR lights) not thermal
CCDs can't pick up thermal IR from things at 200C at all.
http://inquisitor.i.am/ | mailto:email@example.com | Ian Stirling.
"Give a man a fire, and he's warm for a day. Set him on fire, and he's warm
for the rest of his life" -- Terry Pratchett-Jingo