Found in an American publication of 1968, this circuit makes use of a pilot light of the time. It can be replaced with LED with appropriate series resistor. Transistors may be modern equivalents.
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 American documentation from the 90's. Inductors are critical...
This configuration from the 1970s can be applied to modern equivalent operational amplifiers. The...