This circuit takes advantage of the hysteresis of a relay to provide a latching effect. The circuit acts as a trigger and the components must be according to the used relay.
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....