This circuit was found in the July 1995 issue of Electronics Now magazine. The integrated circuit is an RCA-era type. The triac must be equipped with a heat sink.
The circuit in the figure is based on two integrated LM108 and its gain is basically determined by the...
Found in a 1968 Ferranti documentation, this circuit can be implemented with modern equivalent...
This amplifier stage was equipped with a Motorola radio from the 70s. The transistors were from...