We found this circuit in a 1957 Raytheon transistor publication. The circuit can be assembled with more modern transistors with minor changes. The handset must be high impedance magnetic.
With the circuit shown in the figure we have a frequency modulation which is produced by a...
This is a circuit found in a 1970's Radio Electronics. The circuit works with virtually any triac...
This circuit was found in a 1970s RCA publication. Transistors support modern equivalent types....