Subject:
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Re: sonar
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Mon, 18 Nov 1996 01:16:55 GMT
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Original-From:
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Fred G. Martin <fredm@media.mit+NoMoreSpam+.edu>
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Viewed:
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1253 times
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> I have a Polaroid unit. This is what it looks like. There is ONE
> transducer a nd a ranging module(driving circuit). The transducer acts
> as both a "speaker" a nd a "microphone" as opposed to separate units
> in the Panasonic case.
>
> So...someone correct me if I'm wrong...the Digikey things are
> missing the dri ving circuitry. As an analogy to the Polariods, you
> only get the "speaker" and "microphone" part. Thus you have to build
> this yourself which will cost some $.
yes. the polaroid board is pretty sophisticated, really, in that it
ramps up the input gain the longer it waits for the ultrasonic
reflection pulse. this compensates for the exponential falloff in
"volume" as sound disperses on the way out and again on the way back.
it's possible to build a simple ckt with an oscillator for output, a
fixed gain input, and a 567-style tone decoder, but this doesn't work
as well.
if you did do this, the HB's IR output could serve as the oscillator,
since it's a 40kHz ckt with a power transistor output.
-Fred
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Message is in Reply To:
 | | Re: sonar
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| (...) I think I found your treasure. It's under "Audio, Buzzers, Microphones, Speakers..." right? ...Panasonic ceramic devices? This is my input: I have a Polaroid unit. This is what it looks like. There is ONE transducer and a ranging (...) (28 years ago, 18-Nov-96, to lugnet.robotics.handyboard)
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