This circuit is used in magnetic tape recorders, having been found in documentation in the 1960s. The circuit uses Japanese transistors, and the critical components are transformers.
This 1987 circuit has a very interesting concept. It powers a second set of rhythmic lights from...
This circuit with reed sensors is very simple, feeding a 12 V siren when triggered. The circuit has a...
The signal from this transmitter is injected into a cable that you want to follow along a...