The signal from this transmitter is injected into a cable that you want to follow along a pipeline. Monitoring is done using an ordinary AM receiver out of season.
The purpose of this circuit is to adapt a common speaker to function as a microphone. The circuit is...
This preamp with a transistor for turntables with crystal capsules was found in a Japanese...
This circuit was obtained in a 1999 English magazine. We can easily assemble it because all the...