4 Jun
2013
4 Jun
'13
1:53 p.m.
This is pretty similar to the once-common Polaroid
ranging systems
built into some "instant" cameras; many of these were repurposed for
non-photographically-related ranging applications, and Polaroid sold
eventually started selling them in development kits for all sorts of stuff.
I have that development kut wsomewhere. I was amused by the other
Polaroid products included, the power uspply was a Polapulse flat battery
(you got 2 in the kit), for all any 6V supply would do. And you even got
a little square of polarising filter to put over the LED display on the
test board.
I pulled one out of a defunct instant camera and turned it into an
"electronic tape measure" many years ago:
The boards from the cameras and indeed the transceiver board from the
development kit used a pair of ICs made by TI. There were publisehd data
sheets for them (they appear in one of the data books, I forget which
one, but I cna try to find it if anyone is interested).
http://www.neurotica.com/misc/polaroid_sonar.jpg
The principles behind sonar depth sounders are mostly identical.
Be cafeful. The Polaroid transducer is electrostatic. There's a thin
diaphragm and a back electorde, it woks like an electrostatic
speaker/condenser microphone (as we called them). Most, if not all,
marine depth sounders are piezoelectrice (work like a crystal
speaker/microphone). The drive chracteristics are rather diffierent.
-tony
