Question about a tach

[Night Wolf]

This has nothing to do with my car,,,, but just wondering how a tach in general is set up...... one the back of it, I see a connection for - (neg. ?) and G (ground?) I know that one has to be the ground, and the other connects to the spark plug wire...... but can someone go in more detail? isn't - usually ground? so in this case would - or G actually be the ground? and where do I go about hooking the wire up to the spark plug? hmmm.... what I am trying to say is, where would I pick the "signal" going to the spark plug up to banch it off to the tach? and finally, being that the wire going to the spark plug obviously has electrcal current going through it, what type of wire should I use? (insalated?) and what gauge?

Thanks for the help

[Wallflower]

Take off a spark plug wire, stick your finger in the end of it, and have someone start your car .... You will quickly learn that you do not get the tach signal from the spark plug wire. You will blow the damn tach up. Tach signal comes off the distributor wire harness, or from the DIS coil harness wires. There should be instructions with the tach as to it's connection.

[Night Wolf]

I got the tach used, with no instructions...... itwill be going on a simple machine (tractor) single cyl. etc... so I was wondering how I would go about hooking it up. I just thought that the tach would measure the speed of the impulse from the spark plug wire, and turn that into a signal that can be read (from the tach)

[Themeneea]

i think your thinking of a timing gun. i think the signal comes from the coil