Signal conversion

Discussion in 'General Electronics Chat' started by mikefr24, Nov 4, 2007.

  1. mikefr24

    Thread Starter New Member

    Nov 4, 2007
    2
    0
    My brother installed a 8 cylinder engine into a car that used to have a 4 cylinder. Now of course the tachometer is reading 2x the correct RPM. The original car tach reads pulses from the distributor and he would like to use the original tach with is new engine. Is there a way to do this with logic chips or a analog circuit to divide the signal by 2?

    Thanks,

    Mike
     
  2. recca02

    Senior Member

    Apr 2, 2007
    1,211
    0
    if it uses a counter u would need a flipflop that will divide the pulses applied to its clock input by 2.
    (edit: maybe someone can provide a more elegant solution)
     
  3. John Luciani

    Active Member

    Apr 3, 2007
    477
    0
    A single chip sounds like an elegant solution to me ;)

    (* jcl *)
     
  4. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    I concur. Any old flip-flop chip capable of running on 12V and sourcing enough current for the meter circuit would work just fine.
     
  5. chesart1

    Senior Member

    Jan 23, 2006
    269
    1
    Should Mike be concerned about noise due to the steep rising and falling edges of the flip flop output?
     
  6. Nomad

    Active Member

    Oct 21, 2007
    43
    0
    that shouldn't be a problem. i've not had any of my speed sensor or tach circuits cause a problem with a square wave output. i actually needed to isolate one project and used an audio transformer driven with the square wave, talk about a nasty output. but it worked fine.
     
  7. Dragon

    Active Member

    Sep 25, 2007
    42
    0
    An innocent D-Flip Flop sould complete the puzzle without any glictches.:p
     
  8. recca02

    Senior Member

    Apr 2, 2007
    1,211
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    i was thinking of T or jk in toggle mode.
    what wud be the inputs for a D FF?
     
  9. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    You tie the ^Q output to the D input. The clock will toggle so the Q output changes at half the rate of the clock.
     
  10. recca02

    Senior Member

    Apr 2, 2007
    1,211
    0
    got it.
    thanks a lot.
     
  11. mikefr24

    Thread Starter New Member

    Nov 4, 2007
    2
    0
    Thank you gentlemen. I happen to have a drawer full of Flip Flops. I will try one out and let you know how it worked.

    Thanks,
     
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