Found in Philips' 1967 documentation, this circuit makes use of period components. The SCR can be of any type, depending on the power of the controlled load.
This circuit was found in a 90’s 303 Circuits. The components are from the period and the heating...
Found on Popular Electronics this circuit has variations found throughout this site and section....
The transistors in this circuit from a 1994 technical publication may be BC548 and the 12 V supply...