This circuit is intended for underwater communications. Of course, the critical point is the shielding to avoid water. The circuit is from an Electronic Hobbysts Handbook from the 90s.
For experiments with ionization chambers and Geiger valves this circuit generates high voltage from...
This control allows to start or stop a motor up to 3 or 4 A with a low intensity signal. The...
The battery is charged by the photocell that keeps the low consumption beacon in the dark. The...