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 is from a 1976 Motorola CMOS manual. It can be implemented with modern Darlingtons like...
In the figure we have the way of modulating or controlling the frequency of a relaxation...
The purpose of this circuit is to monitor the operation of an alternator in cars with a 12 V...