I have an old and simple car (Renault Express gasoline engine 1990). I bought it because it has almost no electronics and is simple to repair. I discovered one of the drawbacks with the simple technology which is that it will not warn me if I have left the headlights on when parking the car. I sometimes drive with headlights on as I live in a forested area where the light is often poor. I intend to get LED running lights but until then I need to detect:
- Are the headlights switched on
- The engine is not running.
- If 1 and 2 are true then I want to sound a warning. I would like to do this using passive components such as diodes and relays and possibly a Hall effect sensor but avoid using microprocessor. The car has 12volt electrics with negative earth. I had thought to power the sensor circuit from the courtesy light circuit which switches on interior light when the door is opened.
Question 1. Can I wrap a few turns of wire round the headlight supply line and use a Hall effect sensor? What kind of output will the sensor produce? Can I connect the output to a relay to sound the buzzer?
All suggestions gratefully received. Today I had to call the breakdown service for the fourth time to start the car. I know I can do better!
I have the usual boxes of various components just waiting to be put to good use.
Best wishes to any reader.