I was just laying here, pondering what to do to my car to make it unique, and was wondering if anyone has been able to use a tach wire as an input. I suppose the next question would be whether or not it can be used at all to read the RPMs of the engine.
My project that I’m thinking of involves using some leds behind the grill of my hood scoop and side vents that will vary in brightness according to the RPMs of the engine. Voltage peak would be max 14v (again, assumption). So at idle I would set the brightness, then have it increase as the engine rpms increase.
My problem isn’t wiring or programming the Arduino, what I’m wondering is how to connect it to the vehicle to read the RPMs.