This circuit activates a relay after a time given by C1 and R1. The circuit is from a Radio Electronics from December 1974. The relay voltage is the same as that used in the power supply.
This circuit was obtained from a 1966 documentation. The transistors are of the time. The circuit...
This circuit is a source that allows antenna boosters to be powered by the signal cable itself, as shown...
In this very simple circuit, the LED flashes at a frequency of 60 Hz. It is convenient to check the...