Tach signal waveform shape???
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Tach signal waveform shape???

  1. #1
    Distinguished Member David 519's Avatar
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    Default Tach signal waveform shape???

    Our playback tach quit working before Phoenix and I'd like to confirm if its the tach or the interface module between the mag/tach. Obviously, the easiest thing would be to plug the tach directly into a car with a standard ignition. Unfortunately, I don't know anybody that has one.
    I have a function generator that can simulate various wave forms and am familiar with trigger thresholds. I'm guessing the signal is some type of TTL or similar square wave. So anybody give me an idea what the tach signal waveform shape looks like from a MSD or similar ignition? Hope its the interface module and not the tach....
    thx
    Quote Originally Posted by gn7 View Post
    ....... David 519 is 100% correct........

    Quote Originally Posted by fuelinmyveins82 View Post
    .....I think people forget that racing is supposed to fun. Losing shouldn't be discouraging it should motivate you work on your pile to make it faster.....

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    Hondo Jet blown540's Avatar
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    For testing purposes I would use a square wave, it's the ideal waveform for triggering digital electronics

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    gn7
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    Distinguished Member David 519's Avatar
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    Quote Originally Posted by gn7 View Post
    the MSD tach out is a 50% duty cycle 5-18v square wave
    Thanks!!
    Quote Originally Posted by gn7 View Post
    ....... David 519 is 100% correct........

    Quote Originally Posted by fuelinmyveins82 View Post
    .....I think people forget that racing is supposed to fun. Losing shouldn't be discouraging it should motivate you work on your pile to make it faster.....

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    gn7
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    If it's an Autometer or similar, 12v square wave ideally.
    Keith-


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    Cantard 71hallett's Avatar
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    Quote Originally Posted by gn7 View Post
    gunna hook that bad boy up to your TIG to check it
    Never heard of this...how do you do it?
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    It would be a balmy 85* in Steel's shop if he would move a little faster

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    Distinguished Member David 519's Avatar
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    Quote Originally Posted by gn7 View Post
    the MSD tach out is a 50% duty cycle 5-18v square wave
    Quote Originally Posted by gn7 View Post
    gunna hook that bad boy up to your TIG to check it
    Dammit, GN you had me for a bit there. I was out running errands and the "duty cycle" part of your post was rattling around in my head.... I know tach pulses don't have a duty cycle and it finally occured to me you actually did get that off a tig welder...
    Now see if it was a mag, you actually could weld with it......
    Quote Originally Posted by gn7 View Post
    ....... David 519 is 100% correct........

    Quote Originally Posted by fuelinmyveins82 View Post
    .....I think people forget that racing is supposed to fun. Losing shouldn't be discouraging it should motivate you work on your pile to make it faster.....

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    Cantard 71hallett's Avatar
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    Quote Originally Posted by David 519 View Post
    Now see if it was a mag, you actually could weld with it......
    lmfao.......now if only the piston would hold still.
    Quote Originally Posted by gn7 View Post
    It would be a balmy 85* in Steel's shop if he would move a little faster

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    Distinguished Member David 519's Avatar
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    Quote Originally Posted by 71hallett View Post
    lmfao.......now if only the piston would hold still.
    Kinda askin a lot here, don't you think
    Quote Originally Posted by gn7 View Post
    ....... David 519 is 100% correct........

    Quote Originally Posted by fuelinmyveins82 View Post
    .....I think people forget that racing is supposed to fun. Losing shouldn't be discouraging it should motivate you work on your pile to make it faster.....

  13. #11
    steelcomp was here
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    Quote Originally Posted by 71hallett View Post
    lmfao.......now if only the piston would hold still.
    LOL...self repairing...that's an idea...!
    Man, you guys are harsh...
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.

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    gn7
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    Quote Originally Posted by David 519 View Post
    Dammit, GN you had me for a bit there. I was out running errands and the "duty cycle" part of your post was rattling around in my head.... I know tach pulses don't have a duty cycle and it finally occured to me you actually did get that off a tig welder...
    Now see if it was a mag, you actually could weld with it......
    No, actually, I got that off MSD's web site for the "input" for the RPM/tach on a race pak data logger. It said it can accept that signal, and that is the signal delievered by most aftermarket ignitions. I just figured if you had a Miller Sycwave, you might be able to drive it with that. Really wasn't trying to screw with you.



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  15. #13
    gn7
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    Quote Originally Posted by 71hallett View Post
    lmfao.......now if only the piston would hold still.
    Quote Originally Posted by David 519 View Post
    Kinda askin a lot here, don't you think
    Quote Originally Posted by steelcomp View Post
    LOL...self repairing...that's an idea...!
    Man, you guys are harsh...
    That's it! I am never posting another blowed piece again. Iam taking a worse beating for a torched piston than Hotbo did for putting 2 bend rods in a brand new rebuild. This is a tough crowd



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