Hi Lindy:

These are raw transducers which are much harder to use than range finder mo=
dules.
for example:
https://solarbotics.com/product/40300/
or
https://solarbotics.com/product/40310/

Search eBay for ultrasonic range finder.

To roll your own you need to (1) drive the transducer with a short pulse of=
 40 kHz drive and then use a second=20
transducer as a receiver with a narrow band amplifier centered at 40 kHz th=
en envelope detect that.  The two different=20
model numbers you mention have different bandwidths which determines the ri=
se and fall time of the pulse they can=20
generate.  The range finder modules have done all that for you and probably=
 for less money.

--=20
Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html

--=20
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