The use of a diac improves the performance of the two dimmers in the previous circuits. The circuit is from the same Radio Electronics magazine in an article that teaches how to use triacs.
Found in American documentation from the 90s, this circuit can use a BC548 instead of the original...
This circuit acts on the dynamic range of an audio signal, which can be useful for recording,...
This circuit doubles the frequency of a signal using a varicap. In this case, the input is 28 MHz,...