Steve,
The transducer used in ranging devices is typically the ones
which used to be made by Polaroid , but this product line seems
to have been spun off to www.senscomp.com. For
knowledgeable tinkering, you can buy individual narrowband
ranging systems quite inexpensively on the surplus market
(http://www.halted.com/store/product104.html or search for
senscomp and polaroid if that offer is gone).
Raimund Specht, who participates here, has a nice comparison
(with a table of tradeoffs) on his web site of the range of
transducers one might use for recording biological ultrasound
(e.g., http://www.avisoft-saslab.com/usg/polaroid.htm).
There is a range of DIY bat detector circuit designs on the net ,
though most of these emphasize low cost, employ a Emkay
(=Knowles) hearing aid electret mike, and roll off pretty steeply
above 50KHz.
If you don't want to build something, many, if not most, mid range
to high end bat detectors, have a high frequency output jack
which will give you a signal -- bearing the characteristics of the
transducer type the unit employs. Output will likely be quite noisy
relative to audio microphones for nature recording.
HTH,
Bill Rainey
--- In Steve Pelikan
<> wrote:
> Yes, in typing my previous post I doubled 96 correctly in my
head and typed
> it wrong. Sorry!
>
> A related question is whether anyone has designed/built a
power supply and
> preamp that can be used with ultasonic transducers of the sort
sold for
> applications like rangefinding. Some of these have responses
across the
> 30-50 KHz range.
>
> Not as an add or endorsement, but the kind of item I'm thinking
about is
> described in the data sheets for air ultrasonic devices at
> http://www.massa.com/.
>
> I read somewhere that frequency range of some of these
devices can be
> broadened by adding an appropriate resistor at an appropriate
place, and
> this seems to be reflected in the plots on some of the
datasheets.
>
> Thanks for info/suggestions,
>
> Steve P
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