The circuit is from a Radio Electronics magazine from October 1987. The Triac must be equipped with a heatsink and the transistors are general purpose.
This is the power supply for the amplifier in the previous circuit. We found it in the same Radio...
This circuit was found in an American publication from the 1980s. It can be made with most current...
This nonlinear gain circuit was found in a 1965 Electronic Design. The configuration can be used...