1 Jul
2010
1 Jul
'10
6:12 p.m.
Tony Duell wrote:
Yes, you can. Also, IR item presence detectors in the paper handling
equipment I sometimes work with. A small digital camera can be a very
handy diagnostic instrument at times. Of course one could build
I susptct it's actually more like what you said later... If you have a
digital camera around, you can use it for this, but it's not necessirily
the best tool for the job, and it's probably not worth getting one solely
to use as an IR dtector. Quite so! I've only used one for that because it was
immediately
available at the moment of need.
That's pretty much what
I had in mind, though I must admit I was
thinking of a cheap op-amp of some sort. Discrete transistors are good
too, though. :-) I happen to have several old "hermetically sealed"
0-1ma meters and though it would make the "display unit" unnecessarily
large I somehow find the idea of using one of those as the output
indicator appealing somehow. I'm probably just pipe-dreaming a way to
finally use one of those. Of course there's no real reason not to use
both if desired - might take 1 more transistor at most or maybe just a
couple of current divider resistors - pump say 0-10ma through the LED
and 1/10th of that through the meter. Something like that...
Although=2C
I've not tried this=2C it was mentioned that most digital came=
ras
have some sensitivity to IR ( even though they have filters to block most )=
Yes,
Most semiconductior sensors, such as CCDs, respond to near-IR. I am
told you can 'see' most remote cotnrol outputs using one, for examplke. something much simpler and smaller using not very
many components which
would serve as well or better. Actually probably quite a lot better as
When I was setting uphe CX scanner, I used a simple remote control tester
that I'd built from a Mpalin kit. A photodiode driving a 3 transisor (I
think -- it's certainly discrete transistors, no ICs) amplifier, driving
an LED. The amplifier is AC coupled, so it responds well to the
flickering IR output of the average TV remote control.
It also responds to the IR laser beam from the CX scanner being swept
across the ptoodikode by the spinning mirror. So by holding the
photodiode in various positions I could see where the sweeping beam was
going.
And I have to say that 3 transisotrs is a lot fewer than the number you
find in a digital camera :-)
-tony