This circuit was found in an Electronic Experimenter Handbook from the 90's. The coil can be formed by 4 turns of wire 28 with 0.5 cm diameter without core for the FM band.
This circuit is for collectors. It is the circuit of one of the most popular transistor radios of the...
This circuit, from a 1978 publication, emits a modulated signal when the fine sensor is...
This simple amplifier uses a microphone attached to the telephone. The 3-transistor circuit was...