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Prop input from spark plug lead — Parallax Forums

Prop input from spark plug lead

I am dabbling with automating and tuning small 4 stroke engines.
I would like to capture the spark plug firing as an input.
I have experimented with a timing light inductor clamp on an oscilloscope and found that it gives a very sharp pulse of 10volts or more.
Can anyone suggest a buffer or clipping circuit to allow this pulse to be input into a Prop?

The next step is to create my own high voltage pulse to fire the spark plug. Any ideas on the best way of achieving this?

Comments

  • @macrobeak said:
    I am dabbling with automating and tuning small 4 stroke engines.
    I would like to capture the spark plug firing as an input.
    I have experimented with a timing light inductor clamp on an oscilloscope and found that it gives a very sharp pulse of 10volts or more.
    Can anyone suggest a buffer or clipping circuit to allow this pulse to be input into a Prop?

    The next step is to create my own high voltage pulse to fire the spark plug. Any ideas on the best way of achieving this?

    One possible solution is to use an Opto-Isolator circuit that will give you isolation from the higher voltage of the Spark Plug and the lower voltage of the Prop.

    SparkFun makes a small breakout board that should allow you to both monitor and send pulses to/from the Spark Plug setup using a Prop. The breakout board is out-of-stock at SparkFun, but is available at DigiKey.

    SparkFun BOB-09118
    Digikey BOB-09118

  • 4x5n4x5n Posts: 744

    @macrobeak said:
    I am dabbling with automating and tuning small 4 stroke engines.
    I would like to capture the spark plug firing as an input.
    I have experimented with a timing light inductor clamp on an oscilloscope and found that it gives a very sharp pulse of 10volts or more.
    Can anyone suggest a buffer or clipping circuit to allow this pulse to be input into a Prop?

    The next step is to create my own high voltage pulse to fire the spark plug. Any ideas on the best way of achieving this?

    I would try and go with the low voltage end. Much safer to go that way take the low voltage before the transformer would keep you from getting a handful of high voltage shocks.

  • I mentored a high school student who built a digital tach for his car. We took a 12V signal from the ECU (engine control unit) to drive the tach. Even then, we used an optoisolator to interface to the Propeller FLiP module.

    -Phil

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