KW-Konverter (2-35 MHz auf Mittelwelle umsetzen, mit 2x 3N211)

This simple ultrasonic (US) transmitter uses only one CMOS IC and a few discrete com- ponents, and will generate a short pulse of ultrasound. This can be used to tngger an ultrasonic receiver (such as the one described elsewhere in this issue) to activate a relay or other circuit.