I installed a new Head Unit in my car, it's a pioneer 7800MP. Anyhow there's a visual effect that comes with it and it shows my engine's RPM and battery Voltage. FOr the battery voltage I would understand how it works...But the RPM...pioneer doesn't show how it's working. It just works and accurately... Can somebody explain howcome it works? I'm astonished!

 

I just found out just how it works, it works with mathematical induction. From the voltage differentials , the HU can calculate the engine's RPM. Thank guys

 

Thats a cool function and ay I can see how it works off the varying voltage due to output

Garett