Found in a Popular Electronics from the 90s, this circuit uses components that are still current. The circuit triggers the vehicle's horn. The sensors can be increased in number.
We found this circuit in an old American documentation. SCRs can be modern equivalent types. The...
When the voltage exceeds the value given by the zener, this circuit from a 1990 documentation...
This circuit was found in a 1970s documentation. The components are from that time, and...