Primary ignition voltage

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lbarron
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Joined: Tue Jun 09, 2009 8:21 pm

Primary ignition voltage

Post by lbarron » Tue Jun 09, 2009 8:31 pm

Hello, I have been thinking about the relationship betveen the primary and secondary ignition voltage patterns given by conventional spark ignition systems.
What do you think causes the primary to mirror the secondary pattern?
Is it the effect of the secondary slowing the collapse of the magnetic field, the capacitance between the 2 coils or anything else?
I have mentioned this before on the Autonerdz forum but since then i have been looking a bit more into this.
I'm not trying to answer my own questions, I just want to understand this.
Thanks for any responses.
L. Barron.

PeterF
OneWave
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Location: Cambridgeshire

Post by PeterF » Fri Jun 12, 2009 12:24 pm

Hi,
The main reason the primary mirrors the secondary is that the coil is really just a step-up transformer of about 100:1 ratio. The primary voltage causes a current which is converted into magnetic flux which is then converted back into a voltage in the secondary. With a perfect transformer, no losses and no spark, the input and output voltages would be in the exact ratio of the transformer turns ratio.
PeterF.

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Autonerdz
TwoWaves
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Pri and Sec

Post by Autonerdz » Fri Jun 12, 2009 4:33 pm

Good explanation from Peter. The dynamics of coupled inductors are complex though.

Only parts of the primary mirror secondary. For example, the spark line.

Had a question about whether the primary kick is affected by secondary conditions and decided made this little silent movie. Answers the question and shows off the PicoScope really well too :shock:

http://www.autonerdz.com/flash/prisec.html

_________________
Tom Roberts
(The Picotologist)
http://www.autonerdz.com
skype: autonerdz
THE PicoScope Automotive Authority
In North America

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