This circuit was found in a Popular Electronics from the 90's. The transistors are general-purpose types and the loaded load depends on the voltage and must have a maximum current of 100 mA.
Found in General Electric and 1967 documentation, this circuit automatically turns off the...
This amplifier stage without an output transformer was found in Radio Electronics magazine from...
Found in an Electronics World of 1968 this circuit can use current SCRs and the diodes are...