Workings of a Tachometer

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I was wondering of someone had any input on how exactly a tachometer works. Everything I read leads me to the tach getting the reading from either the ingnition coil or the electronic ignition system. I guess what my main question is what type of signal is being sent to the tach gauge. Is the gauge just reading a change in voltage or current or something else. Any info would help. Thanks!

posted by  clank19

Yes, the tachometer does operate off of the ignition system. As we all should know, an rpm is the number of times a crankshaft rotates a minute.

Answer to your question:
Each rotation of the crankshaft is counted by an engine speed sensor. It works by having a "disc" that is securely mounted on the rotating crankshaft that constantly passes a stationary magnetic coil the emits a current. Every full rotation of the crankshaft, the disc must pass the coil once (common sense). The current emitted by the magnetic coil is disrupted everytime the disc passes the coil. Each disruption counts as a pulse. Every pulse is one rotation of the crankshaft. Get it?

The pulses are counted and calculated into rpm.

posted by  What

Twhat, you ingnorant decertified beginner bitch. Instead of doing a copy and paste from some worthless website, why not impress us with your total lack of knowledge and explain how a tachometer works. While your uninformed little paragragh explains something nicely, what it does not do is explain the workings of a tachometer. While you may be able to pass this off to unknowing individuals, anyone with a reasonable amount of intelligence (obviously not you) knows what you've just described, or stolen the description to, is a hall effect style crankshaft position sensor.

My suggestion to you is to not post in this forum again until you actually know something instead of pretending. You are the smallest and weakest of all decertified beginner bitches. You are only worthy of being slapped.

SuperJew, as the only official pimpslapper (or in this case decertified beginner bitch slapper) please do the honors.

posted by  vwhobo

Vwhobo, shut the fuck up.
I don't copy and paste my information. I answered the person's question correctly.

Like I said in my previous post, the gauge is reading the "pulse" given off when the current being emitted by the coil is disrupted by the disc on the crankshaft.

Don't let vwhobo confuse you. The information that I've given you is correct.

Go look up Engine Speed Sensor.

posted by  What

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