Ultrasonic 25kHz transducers. We've used them in all sorts of neat little projects including a wind-speed sensor, range finder, and even data transmission. You can excite the transducer with a 25kHz square wave from any microcontroller but the output power is increased by higher voltages. See some of the application notes and schematics for ideas. Each transducer can be used as a transmitter or receiver and naturally filters out signals outside the 24-26kHz band. Sold by individual units.
- Center Frecuency: 25.0+-1.0KHz
- Sound pressure level (0dB=0.0002ubar): >=112dB
- Bandwidth (KHz): 4.0/106dB
- Beam angle (-6dB): 70º
- Driving voltaje (RMS): 30V
- Working Temperature (ºC): -30 a 80