Recently I did some work on my car electric circuits. I see many relays are used in car circuits. These relays are used for simple switching, and I wonder why these circuits are based on relays and not on transistors or other electronic components usable for switching purposes. I thought that transistors were cheaper, smaller and more reliable than classic el-mech relays for switching.
Note: In car applications a 12 V car battery is used to power the coil of a relay and the same 12 V power is what's switched by the relay. Sometimes a relay switches just another signal line, i.e. without any high power load on it. And still, I can see no transistors in there. So I believe there is a solid reason why it is done this way, and I must be missing something here. 🙂