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 is one of the many approaches we have on the site for this low power 0.5 W amp using the...
Figure bellow shows how the 4510 can be cascaded for counts higher than 10. The circuit shows the...
This circuit is from an English magazine of 1977. The circuit is still current, just using BC547...