This alarm siren circuit has a latch. We found it in an article in the January 1975 Radio Electronics magazine. Note the power given by Rx and the speaker. It can be increased by changing Q1.
July 2017 - Microchip's new MCP39F511 demonstration and development boards, which consist of...
This circuit, which controls both the temperature and the level of a liquid in a reservoir, was...
This circuit provides a constant current of 1 mA, stabilized by an LED, which can be equivalent to that...