Subject:
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Re: Question about Sharp IR demodulators
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Thu, 11 Jun 1998 01:41:44 GMT
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Original-From:
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Bill Richman <(bill_r@inetnebr.)AntiSpam(com)>
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Viewed:
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3642 times
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I had a similar experience, except that all my IR demodulators were
from Radio Shack; two were some I'd gotten in a "grab bag" quite a few
years ago, and the others were brand new. The original one reacted to
40KHz the way you describe yours doing - whenever it "sees" 40KHz, the
output goes active. On the new ones that I had, though, the behavior
was more like what you describe for the ISU160; they go active when
they first see 40KHz, but then they quickly go inactive again, until
you pulse the 40KHz. I ended up modulating the transmitter at 200Hz
and putting a 567 tone-decoder set up to look for 200Hz on the output.
Perhaps you could do something similar? The 40KHz is just a carrier,
and is modulated by the 200Hz signal. The IR demodulator strips out
the 40KHz, leaving just the original 200Hz modulation at its output.
At least one person tried to convice me I was crazy, but I swear that
Radio Shack's detectors have changed over the years, even though they
sell them under the same RS part number. The case style, as well as
the markings of the devices themselves, have changed slightly; I have
ot believe the characteristics have as well...
On Wed, 10 Jun 1998 14:13:13 -0500 (CDT), "Paul E. Rybski"
<rybski@cs.umn.edu> wrote:
> I'm working on a project where I've got robots hunting targets
> equipped with a 40 kHz oscillator circuit which is continuously pulsing
> an IR LED. I was using the Sharp GP1U52 IR demodulator, which is the one
> that you can get from Radio Shack (the alumimum box version). We were
> able to get a very strong signal from this component. However, when we
> switched to the IS1U60 IR demodulator (the one that you get with the
> Handyboard from Gleason--the little green one), we found that we could
> only get a signal when we first turned on the 40 kHz transmitter. If the
> transmitter continuously bathed the IS1U60 in 40 kHz light, the receiver
> returned nothing. If we switched the transmitter on and off, we got a
> single pulse from the receiver whenever power was applied.
>
> So... it seems that the IS1U60 is designed to receive IR pulses
> in a communications mode like from a VCR remote or another handyboard.
> It does not seem to respond to continuous transmission. Has anybody else
> had this problem? It's a whole lot easier to obtain the IS1U60s instead
> of the GP1U52s (Radio Shacks only stock 2 or 3 at a time!) and it seems
> that the GP1U52 is the only way to go.
-Bill Richman
bill_r@inetnebr.com
http://incolor.inetnebr.com/bill_r
(Home of the COSMAC Elf Simulator!)
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Message is in Reply To:
 | | Question about Sharp IR demodulators
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| Hi everyone, First, sorry for the blank message just now -- hit the send button instead of the cancel. I'm working on a project where I've got robots hunting targets equipped with a 40 kHz oscillator circuit which is continuously pulsing an IR LED. (...) (28 years ago, 10-Jun-98, to lugnet.robotics.handyboard)
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