Found in a 70s RCA manual, this circuit uses transistors from the era. Equivalent types can be used such as TIP31 for Q1 and BD135 for Q2.
This circuit is from Radio Electronics from the 90s. It supplies a voltage between 800 V and 2 000...
Found in an old Popular Electronics, this circuit warns when a remote lighting system is not...
Using an analog microamperimeter this circuit has a phototransistor adapted to the wheel as a...