piclist 2000\12\16\115852a >
Thread: Ultrasonic Sensors
face BY : Dan Michaels email (remove spam text)

Matt Bennett wrote:
>I'd have to agree with Fred- the ringing of an ultrasonic sensor is a
>mechanical result of the excitation voltage.
>You can reduce the ringing by applying a load to the transmitting sensor
>immediately after you send the pulse out.  In my experiments I tried a
>bunch of different resistors, but then found it was most effective to
>just short it out.

Hi Matt,

I looked at your imaging sonar page. Pretty cool. It sounds like
you are the guy with the info on the U/S sensors that I haven't
been able to find. I bought some 40 khz transducers from Jameco but
there is no info about the best way to hook them up/etc. I want to
use them on the PIC minibot control board I am designing for range
sensing, and want the minimal circuitry [it's always that way].

In the bot literature, they use pretty simple ckts. An NPN inverter
with 22K pullup R, U/S xmtr from collector to gnd, and base driven
by 40khz oscillator thru 1K resistor. Receiver is simple high-gain
opamp circuit.

Could you comment on this simple lashup, vis-a-vis your experience?
This would be regarding ranging, and not imaging.

Also, looking at your sonar imaging stuff, I was wondering if you
couldn't improve the image quality somewhat by using simple
edge-enhancement techniques? Take 3 ranges a few degrees apart
in azimuth, and subtract a weighted version of the outer 2 from
the center.

thanks and best regards,
- Dan Michaels
Oricom Technologies

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