Upon pressing the switch, the circuit generates a pulse whose duration depends on C. The transistors can be BC548 and the power can be between 1 and 6 V. The circuit is from a 1975 publication.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...