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.
This 16-second voice recording circuit was featured in a telephone answering machine circuit in...
The intensity of an audio signal can be controlled by a remote potentiometer on a DC circuit,...
This circuit was obtained from an old Signalite documentation. Neon lamps are special types of the...