This car alarm was obtained in a Signetics documentation from the 1980s. The circuit uses the 555 and has a pulsed output to activate a relay that controls the horn. The sensors are parallel connected.
This circuit includes a high voltage inverter to power a Geiger tube. We found it in an American...
This circuit generates a signal up to a few megahertz depending only on the LC resonant circuit...
With the CMOS circuit shown, rectangular signals up to a few megahertz can have their frequency divided...