This circuit is from a 1972 Motorola publication. The used transistor can still be found, but it can be used equivalent. The circuit is powered by the amplifier with which it must operate.
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...