Take this advice.
Because i think you dont know enough about "electricity"
A rev counter is a tachometer.
It's not that I don't know, it's I don't know what you guys call it I've guess that you guys meant the tachometer but don't want to play mister wise guy cause I'm from a other country and my english is not that well here were i'm from everything that I learned from electricity is in dutch totally different name . Now you guys understand why i'm asking so much .