Found in American documentation, this circuit can be used as a shield. The technology is CMOS and the input is BDC. Next to the diagram formulas for calculating the components.
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...