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 circuit maintains on a flashing LED at a frequency determined by the capacitor. The...
This circuit controls loads powered by the power grid, remembering that it is a half wave...
This two competitor version of the game is shown below and uses lamps as indicators. You can...