Found in the 1991 Electronics Experimenter Handbook, this circuit detects voltage variations in the circuit when the engine starts.
This circuit was found in a 1967 EEE. The transistors are from the time and can be tested...
With this circuit it is possible to obtain a higher voltage from a zener diode. The circuit is from...
This circuit for the experimenter of the 60s allowed testing the most common transistors in the...