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.
Found in American documentation from the 1970s, this circuit is intended for amplifying analog TV...
Photoelectric cells can be used as sensitive light sensors. However, the low voltage they generate...
This circuit was found in a 90s American documentation. The circuit uses still common components...