From: John Larkin
Subject: Re: Ignition Coil High Voltage Power Supply
Date: Sun, 12 Jan 2003 11:06:49 -0800
Organization: Posted via Supernews, http://www.supernews.com
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On 11 Jan 2003 23:08:49 -0800, Thorfirstname.lastname@example.org (P!erCer)
>> A regular points-and-coil ignition system (or even a fancy CD type)
>> produces a damped sinusoid every shot. The DC component is nil. The
>> output of any transformer averages 0 volts, ie, has no DC component.
>Hmm...I don't really see why.
>The transformer is driven by current oscillating from 0 to 12 volts.
>From what I understand, the transformer's function is to amplify this
>voltage by a certain number. No matter what the voltage is, I will
>never get below 0. The output may indeed be sinusoidal, but the
>offset will place the "average" point into a strong DC range.
No, really, you can't get a non-zero average voltage out of a
transformer. The secondary of the transformer is excited by the
rate-of-change of the magnetic field generated by the primary, not by
the static field. A transformer is not a simple amplifier.
OK, a perfect transformer, with no copper resistance and a
non-saturable core, will transform DC; but the primary current will
increase linearly with time, without limit, and the mag field strength
will track, until *something* breaks; then the field will collapse and
all the nice DC you got will be repaid, in spades, by an equal-area
negative swing. So the average is zero.
If you could get DC from a real transformer, you could replace the
primary with a permanent magnet, and then you'd have free DC forever,
which violates conservation of energy and attracts black helicopters.