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.
The transistor can be a BC548 and the coil has the following characteristics for 1 MHz. L1 has 80...
This inverter is critical for transformers and can use modern equivalent transistors like MJ2955 on...
This simple circuit, which requires a low current (50mA) relay for 5 to 12V power supplies, was...