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Ignition Coil and Capacitor oscillations

  1. Dec 21, 2013 #1
    BOB S had posted this in a now closed thread:

    https://www.physicsforums.com/showthread.php?t=360072

    Regarding this analysis ...
    https://www.physicsforums.com/attachment.php?attachmentid=20126&d=1250393723

    My questions ...

    Q1) Does this oscillation from the L-C circuit actually cause several (+/-/+/-) sparks on the spark plug each time the peak voltage on the secondary exceeds the break-over voltage?

    Q2) How quickly does the loading from the spark plug via the secondary dampen out that oscillation in the real world?

    Q3) So, how many "sparks" are there in one compression cycle?
     
  2. jcsd
  3. Dec 21, 2013 #2

    dlgoff

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    The attachment was a simulation. The capacitor is there to reduce arcs across the points from the inductive back-voltage, thus increasing the point's lifetime. His simulation has the output on the capacitor which is not how auto ignition systems are designed.

    [​IMG]

    Faraday's Law and Auto Ignition
     
  4. Dec 21, 2013 #3

    sophiecentaur

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    Once the arc has struck, the LC resonance is very heavily damped (shorted right out) so you will get one main spike and a small 'ring' at DC. The spark itself will have a wide band of RF oscillation, during the current spike.
     
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