This latched alarm uses a double relay for this purpose and can control higher power external loads like a siren. The circuit is from 1974 documentation and has a very low consumption.
This is a Japanese commercial circuit found in a 1967 documentation. The transistors are from the...
This circuit was obtained in the publication 101 Electronics Projects of 1979. The circuit can be...
This control of DC motors for currents up to about 200 mA was obtained in an American publication of...