This elementary receiver with a crystal earphone was found in Japanese documentation from the 1960s. The coil has 60 + 40 turns of wire 28 to 32 in a ferrite rod.
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...