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 circuit was found in an American publication from the 1980s. In the original version it...
This circuit is from an American documentation of the 1980s. The circuit can be implemented with more...
This is a diagram of a 1958 commercial receiver. The circuit was found in documentation at the...