This UPS circuit was published in the March 1985 issue of Radio Electronics magazine. The components used are still common, although some may be difficult to obtain.
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...