oh boy, i guess its way harder than i was expecting.
Specially having no knowledge about frequencys and currently have no Oscilloscope.
They sell them without a pair, and specify that "Single unit only required", so im guessing this sensor has the receiver and transmitter inside.
Hmm - I guess I should've looked at the datasheet; I looked at it after what was noted in the other thread:http://arduino.cc/forum/index.php/topic,84001.0.html
(and this is walking a tight-rope on multiple-thread posting - but I guess it's ok)
Those transducers don't have a receiver and transmitter inside; instead they are designed to act, as a single unit, as both (whereas other transducers are sold in pairs - one a transmitter, the other a receiver). So - the circuit in the datasheet can possibly work for you, if you can get the parts - alternatively, the circuit I posted could work as well, since the transducers can be used both ways. You might also look at the hexamite website for other sample ultrasonic drive circuits for singular transducers (albeit, meant for their products, not Futurlec's - but they could probably be adapted - the nice thing about their designs is that they don't use that adjustable transformer).
...and yes, if you want to be successful at this, you will need an oscilloscope, preferably a DSO with at least two channels (so you can monitor both send and receive pings, waveshapes, and amplitudes as you adjust/tune things)...