This type of configuration can be seen elsewhere in this section. This is from a 1965 General Electric Hobby Manual. The circuit applies to most modern triacs.
This filter that rejects determines frequency (notch) was found in a Popular Electronics of 1993....
This circuit operates with frequencies from 0.5 to 400 MHz. We find it in a 90’s NASA...
This circuit for adjusting sources simulating a load was found in a publication from 1993. The...