This circuit divides the grid 60 Hz frequency to obtain 20 Hz to drive mechanical watches used at the time. The circuit is from a 1970 CQ magazine.
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...