This power control for powers up to about 10 W uses wire potentiometers in an arrangement that allows to maintain the impedance. The circuit is from old European documentation.
With this circuit it is possible to use a common hair dryer as a hand dryer. The circuit is timed...
This circuit was obtained from an English magazine from 1979, but can be easily assembled today...
This circuit was obtained in a 1975 magazine, but it can be easily assembled using BC548...