This simple 12 V power supply with current up to 2 A was found in a Popular Electronics from the 90s. The zener diode is 14 V and transistor Q2 can be a TIP42.
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...