This circuit was found in an Electronics World of 1968, making use of components of the time, not common today. The power supply is not provided.
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...