On 2011-01-30, Steve B wrote:

Thank you for the simple explanation. I have seen many hand held devices,
and they range from $10 to $40. They all seem to be rather wimpy in their
performance. The one I have stops some dogs, yet does not faze others. I
wanted to build a strong one, but don't want to have to carry it around on a
two wheel moving dolly. Will investigate the transducer, and if I can find
one cheap, may do an Iggy experiment on it. I have a 9.6 Makita battery
that should do the power.


Steve, an easy route to take would be to make an ultrasound whistle
that is compressed air powered or even the kind that you blow air
into. Most whistles are, of course, made to be heard by regular
people, and those can be VERY loud and unpleasant to hear. All you
need to do it build/make one that makes ultrasound. That is determined
by certain chamber dimensions. Based on nothing but gut feel, I would
expect that a whistle with two times smaller chamber should make two
times higher sound frequency.

i