This circuit was found in the September 1992 issue of Radio Electronics magazine. The circuit does not use a transistor to drive the relay and has no adjustments.
This class B push-pull amplifier circuit with a few hundred milliwatts of power was found in an...
In the figure we have a window detector that uses only a voltage comparator. The circuit can use...
This circuit was found in an old American documentation. The operational used is of the...