Ignition Coil and Capacitor oscillations

  1. BOB S had posted this in a now closed thread:


    Regarding this analysis ...

    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. dlgoff

    dlgoff 3,158
    Science Advisor
    Gold Member
    2014 Award

    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.


    Faraday's Law and Auto Ignition
  4. sophiecentaur

    sophiecentaur 14,705
    Science Advisor
    Gold Member

    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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