Instructables

does anyone know of a good ultrasonic sound emitter i can make?

working something that found in some old text to test a theory but need a nice small hand held design for a ultrasonic sound emitter where the frequencies can be altered by the turn of a knob can anyone help please direct me to a good link either here or to some other sight.

Have you tried searching for an ultrasonic frequency generator schematic yet? A quick search through google will give you a mice list of schematics for building your own frequency generator.
.....a mice list of schematics.... And mice emit ultrasonics ! You could always build the mouseorgan.....