Pl help me if you have any information. This will be a gratefull help to the students for their studings.
Mail from PBG Sri Lanka
See an earlier post - Ultrasonic distance measurement if i find more it will be added here Ultrasound Have a look at all links below, that might help
Ultrasonic Sound
"Sounds in the range 20-100kHz are commonly used for communication and navigation by bats, dolphins, and some other species. Much higher frequencies, in the range 1-20 MHz, are used for medical ultrasound."

4QD-TEC: Ultrasonics: remote control and Intruder detector - These ultrasonic circuits are all quite old: my notes date them at mid-70s so ... The last circuit is an ultrasonic preamp with a twin T feedback to make it ...
Schematics Depot (tm) - ultrasonic switch circuit - The ultrasonic receiver circuit uses an ultrasonic receiver transducer to sense ultrasonic signals. It also uses a two-stage amplifier, a rectifier stage, ...
Silicon Chip Online - Circuit Notebook - Besides being used as a Bat Detector, the circuit could also be used as a simple tool to indicate frequency, to find tyre punctures (which emit ultrasound), ...
Ultrasonic (Ultrasound) Electronic Circuits - Ultrasonic (Ultrasound) Circuits
delabs