I think this article will answer most of your questions:
http://www.micro-examples.com/public/microex-navig/doc/090-u
ltrasonic-ranger.html

You're right about that datasheet. I've never seen one that
doesn't even give a pinout or reference circuit.

Allen

> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-
> bounces@mit.edu] On Behalf Of Lindy Mayfield
> Sent: Monday, October 21, 2013 2:15 PM
> To: Microcontroller discussion list - Public.
> Subject: [EE] Help understanding how these ransducers
> work
>=20
> After a few year hiatus I want to restart my interest in
> hobby electronics.  One of the last projects that I never
had
> time to start was a range finder.  I wanted to build a
> sonar/radar.  I have a 400ST/400SR pair of,  for want of a
> better word, "round thingies with two wires attached."  :)
> Here is a datasheet I found on the net, out of many, but
> basically they all look the same (to me).
>=20
> http://www.robot-
> electronics.co.uk/datasheets/t400s16.pdf
>=20
> I can very easily find examples how to make this work in
> practice, and I'm quite sure that I could do it just
copying but
> not  understanding.  But I want to work backwards from the
> datasheet, and this particular one doesn't make sense to
> me.
>=20
> My EE knowledge is in the still-learning phase.  The
> datasheet is nothing like I've ever seen, but here are
some
> assumptions and questions that I am thinking of in order
to
> at least try to figure out how to connect them up.
>=20
> 1) It has two leads.  I cannot see in the DS where/how to
> connect them, but can I assume that one of them is ground?
> 2) In the case of the transmitter, can I assume that one
is
> ground the other is some sort of waveform that causes it
to
> make a sonar like sound?  Like a speaker?
> 3) If so, what sort of signal?  I guess PWM, and I would
> definitely try that first.  I see 40Khz in the DS and that
seems
> to point there.
> 4) Then, for the transmitter, I connect one to ground,
> another to a PIC pin generating a 40Khz PWM signal.
>=20
> The transmitter logically seems like a speaker of sorts,
but
> how to connect it up with pieces parts like resistors,
> transistors, capacitors, etc still alludes me.  But I'm
willing to
> do the work to figure that part out if I have a hint where
to
> look.
>=20
> The receiver seems more difficult.
>=20
> 1) I assume one of the 2 pins goes to ground, the other
> connected to a PIC pin.
> 2) I know that speakers also can generate an electrical
pulse
> when connected in a certain way.  I think this may be
> something like that.
> 3)  Would I also be reading a PWM signal as input?  But
> "what" tells me the distance?
> 4) And like the transmitter, what other pieces parts do I
> need, capacitors, op amps, resistors, etc.
>=20
> I'm not asking for the fish, just how to go about building
a
> fish catching machine.  :)
>=20
> Thanks as always,
> Lindy
>=20
>=20
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