This circuit for powers up to 240 W was found in a 1967 RCA SCR manual. The SCR must be in accordance with the controlled load.
The circuit shown is from the Texas Instruments optoelectronics manual, applying to low power...
This circuit was found in a 1968 General Electric documentation. It has an input impedance of 2 M ohms...
This filter that rejects a frequency range determined by the double-T was found in the August 1993...