In this circuit R1 is 56 ohm and R2 is 220 ohm for the 110 V network. SCRs are according to the load. We found it in Philips 1968 documentation.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...