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  1. #1
    c_Moore's Avatar
    c_Moore Guest

    Default auto advance

    Hi everyone,
    I am the process of designing a autoadvance for a CD ignition modual that I made.Im using a 12F675 ,and a single hall sensor to trigger the spark on the engine.I'm not real sure how to do this.any suggestions would be greatly appreciated. Thanks Charlie
    Last edited by c_Moore; - 30th October 2004 at 00:01.

  2. #2
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    Hi c_Moore, for sure i cam help but, i don't understand what your project is suppose to do. Tell me more about. What go in and what you want as output.

    regards
    Steve

    It's not a bug, it's a random feature.
    There's no problem, only learning opportunities.

  3. #3
    c_Moore's Avatar
    c_Moore Guest

    Default auto advance

    Hi Mister E thanks for the reply.What I want to so is I have a hall sensor to sense input pulses.I set the static timint at 30 dgrees.What I need the PIC to do is at start up and idle delay enough to make the sparkplug fire at 4 degrees. as the RPM increases reduce the delay in proportion to the RPM until 7500 and above.Then have no dalay .To make the plug fire at all It takes a low pulse. Thanks for the help.Have a great day


    BTW: the engine this setup is on is a converted weedwacker I converted it to a model airplane engine.
    Last edited by c_Moore; - 31st October 2004 at 13:09.

  4. #4
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    Hi c_moore,
    of course you can use Hall effect sensor for your task. Or, as i saw in the past, take a wire (18 AWG & less) and make few turns over the spark plug wire(like a coil). Connect your wire to an opamp or voltage comparator input via capacitor and read it. This solution was use in some old remote starter and few RPM.

    regards
    Steve

    It's not a bug, it's a random feature.
    There's no problem, only learning opportunities.

  5. #5
    c_Moore's Avatar
    c_Moore Guest

    Default autoadvance

    HI Steve,
    That a good idea.I would of never thought of that.Could I do something like this:read the voltage input and use a A/D converter on the chip .As the voltage increased decrease the delay and as the voltage dropes increase it.Does this sound Practical? Thanks Charlie

  6. #6
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    hum... as you'll see the output signal will be pulsed so should read frequency. But if you want, you can convert it to voltage... for sure. An addition RC circuit + opamp as buffer will do so. Now you need 1 double opamp(747,tlo72,tlo82,Ne5532....) to do the *preamp* + frequency to voltage conversion. or there's a often use frequency to voltage converter on the market called LM2917. see datasheet
    http://www.national.com/ds/LM/LM2907.pdf
    Steve

    It's not a bug, it's a random feature.
    There's no problem, only learning opportunities.

  7. #7
    c_Moore's Avatar
    c_Moore Guest

    Default

    HI Steve,
    Thanks for the fast reply.I will check into the part numbers and see what I can come up with. Reguards Charlie

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