This circuit operates from 25 to 65 kHz depending on the transducer used and the settings. We found it in the Radio Electronics magazine of July 1985. The 9V to 12V power supply is not given.
This switching power supply was found in an Electronic Design from the 90s. The components are...
This burglar alarm is highly efficient, depending of course on the care with which it is...
This circuit is from a 1969 Electronics World. The transistors may be modern general-purpose...