This circuit is from American documentation from 1970. It can be designed with a BC558 and for the operational, we can use equivalents. The FET can be the BF245.
This circuit consists of a speed regulator for direct current motors. The integrated circuit used...
When the sensor of this circuit is cut for a moment, the second 555 produces a tone for a time...
This circuit for generating precise reference signals was found in the April 1973 issue of Radio...