This circuit was found in 1980s American documentation. The transducer is a piezoelectric capsule and the power supply voltage can be between 3 and 18 V.
Found in the December 1974 issue of Radio Electronics, this circuit is similar to the previous one,...
This circuit uses an ignition coil to generate the high voltage that electrifies a fence. However, in...
This astable with active cycle adjustment was found in a Popular Electronics from the 90's. The...