This negative voltage source was found in a Popular Electronics from the 90's. The transformer has 120V secondary and 4-12V primary.
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...