We found this circuit in an 80's Electronic Design. It makes use of couplers of the time that can be replaced with equivalents.
This 200-mW amplifier uses one of the first commercial power transistors. The circuit is from a...
Decade counters, such as the 4017, can be cascaded as sourcing signals with the frequency divided...
We found this circuit in an American 1980s documentation. The circuit uses a piezoelectric transducer...