This static switch or electronic contactor was found in a 1968 Motorola publication. The triac depends on the current of the load it controls. The values shown are for the 120 V power grid.
This circuit, which in our times would be called a shield, can also be used with other loads. The...
This circuit is from an old American documentation from the 70s. Transistor 2N3904 can be replaced by...
This application of the 555 was found in the November 1992 Radio Electronics magazine. The...