This circuit, which can be built with several CMOS gates, was found in the March 1996 issue of Electronics Now magazine. The circuit has the base frequency determined by R1 and C1.
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...