This is the circuit of an automotive voltage regulator from the 1970s. The circuit is entirely electromechanical based on the closing of a relay contacts according to the voltage.
The original frequency of the Pierce Oscillator with bipolar transistor is given by the crystal, which...
This circuit was found in an American magazine in 1978. It activates a relay when the speed of a...
An interesting and useful configuration for the control of power loads is shown in the figure. In this...