Found in a 1969 documentation, this circuit for the 20 MHz band does not use a transformer. The circuit is a phase detector that makes use of the transistor of the time.
This control stage or shield can be used with motors from 3 to 12 V and currents up to 3 A....
By connecting several photocells in series, we can directly activate a sensitive relay, as shown in...
The coils of this simple mid-wave radius are wound 28 or 26 on a 12 to 30 cm long ferrite rod and the...