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Snowmobile Tach/Pulse Adapter

Discussion in 'Automotive Electronics' started by drew.hinds10, Oct 20, 2016.

  1. drew.hinds10

    drew.hinds10 New Member

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    I'm trying to add a tach to my 2000 Arctic Cat. It has a 370 2 stroke 2 cylinder. It requires a 4 pulse tach (which is extremely expensive). I have a 6 pulse and need to convert it with a universal pulse adaptor. What in : out ratio would I need to use? I'm not super familiar with pulses or tachs in general (I know the basics but that's it) so I'm not too great at deciphering this sheet.
     
  2. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi,
    Are you saying that the Cat has 4 pulse Tacho output pulse rate and you want to convert the 4 pulses to 6, in order to drive a 6 pulse Tacho display.?

    E
     
  3. drew.hinds10

    drew.hinds10 New Member

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  4. dave

    Dave New Member

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  5. Ian Rogers

    Ian Rogers Super Moderator Most Helpful Member

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    Is it just an electrical pulse.... If so a simple pic will do the job... What's the maximum RPM?
     
  6. drew.hinds10

    drew.hinds10 New Member

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    I believe it's an electrical pulse, Max rpm is 10,000. Can't get a picture of the tach right now. It hooks up off of the coil I believe.
     
  7. drew.hinds10

    drew.hinds10 New Member

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    Forgot to mention I have it hooked up right now without the adaptor in, it reads 500rpm when it should read about 3,000 (guessing off of sound)
     
  8. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi,
    If you don't have the facilities to program a PIC, this is one option using logic IC's.

    It is a very basic circuit as you have not specified the required voltage levels or drive capability required for the pulses in and out.

    One image shows the operation at 1000 pps and the other at 10,000 pps.

    E

    EDIT:

    That's a difference of 6 times.?
    Which does not match up with your original post.??
     

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    Last edited: Oct 22, 2016
  9. drew.hinds10

    drew.hinds10 New Member

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    That was just an estimate, I may be off a thousand rpm or so, hard to tell. I think on paper I need a 2:3 ratio right?
     
  10. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi 10,
    If you decide that you want to build the device, let me know and I will post a more detailed/optimised circuit.
    The circuit posted above gives a 2:3 ratio ie: 4 pulses in with 6 pulses out.
    The method is the 4 pulses are doubled to produce 8 pulses, then the divider blocks 2 of these pulses, so the output is 6 pulses.

    But I must know from you the input signal specification. ie: voltage levels from the 4 Tacho source
    Also the output drive voltage/current required to drive the 6 Tacho.

    E
     
  11. Ian Rogers

    Ian Rogers Super Moderator Most Helpful Member

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    If you decide to put a simple micro in series... I've set up a CCP module to capture 4 input pulses and send out 6 in the same time frame..

    I too need to know the voltage and current required to drive the Tacho..
     

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