This circuit for light modulated in frequency (FM) operating at 50 kHz was found in a 90’s Electronics Now. The circuit has an active filter. Modern equivalent transistors can be used.
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...