This circuit uses an optocoupler with a phototriac or optotriac to drive an external triac. The circuit is from a Radio Electronics magazine from December 1989.
This circuit for cars with mechanical ignition systems was found in the Electronics Experimenter handbook...
This code practice circuit was found in a 1990s issue of Radio Amaterur Today magazine. It...
The circuit presented was found in the Linear Applications Handbook of the National Semiconductoir of 1994....