This two-tube circuit, one being a double, was found in Radio Electronics magazine from July 1958. The distance to the microphone depends on noise and losses. The cable must be shielded.
The figure shows how to use the 4 transistors of the IC 4007 as a current drain. The circuit was...
This circuit was obtained in the publication 101 Electronics Projects of 1979. The circuit can be...
This control allows to start or stop a motor up to 3 or 4 A with a low intensity signal. The...