This circuit can use almost any operating system and has a high input impedance. The power supply must be symmetrical. The circuit was obtained in documentation from the 1980s.
The circuit shown in the figure below is suggested by ON Semiconductor (www.onsemi.com), based on...
This control is intended for 110 VAC or 220 VAC Motors. Any TIC series triac can be used according the power...
This circuit was found in a 1999 English magazine, but can be easily assembled with BC548...