We found this circuit in the July 1971 Radio Electronics magazine. The circuit activates a Sonalert or a relay for a higher power warning system.
We found this circuit in a Poptronics from 1998. The circuit can be extended to more competitors...
May 2017 - Mouser Electronics already has Microchip's new MCP14A0451 and MCP14A0452 integrated...
This step of good gain was obtained in an American publication of the 1980s. The circuit can be...