Found in a 90s Popular Electronics, this circuit excites a 40 kHz ultrasonic transducer. The transistor can be a BD135 or other medium power.
We found this circuit in the 1983 Radio Electronics Special projects magazine. The components are...
With the presented circuit it is possible to detect signals from transmitters in a frequency range...
This circuit was found in a British documentation from 1969. It can be implemented with modern...