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.
The frequency of this Pierce oscillator, found in 1969 documentation, depends on the crystal. The...
This simple timer with unijunction transistor was found in an old American technical...
Found in documentation from the 1960s, this power supply employs germanium diodes from the time....