We found this circuit in a 1957 Raytheon transistor publication. The circuit can be assembled with more modern transistors with minor changes. The handset must be high impedance magnetic.
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...