Hi guys, This is my first post so apologies if im not very clear on what im after. This project is for a car, and I need a type of switch/circuit. Basically I want to earth the signal in one cable, when another separate cable is also earthed. The state of the "signal" earth constantly changes, so the switch needs to be fast if possible to be able to match the state. The voltages of the 2 cables are totally different and can not be mixed (if that makes sense) Sorry if thats really badly worded, and thanks for any help.