This circuit is from Philips' 60s documentation. The circuit can be applied to modern operational amplifiers. The power supply must be symmetrical.
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...