This circuit is the receiver for the previous transmitter modulated by an audio signal. The transducer is a ceramic capsule, in which case the circuit becomes ideal for telegraphic transmissions.
This basic configuration aof a touch switch controls a relay. Power supply can be 5, 6 or 12 V...
This circuit is from an April 2000 Poptronics. The magazine no longer exists, but the circuit can...
This circuit that uses potentiometer tuning, was found in a documentation from the 80's. The...