From: Kevin McMurtrie
Subject: Re: Ignition Coil High Voltage Power Supply
User-Agent: MT-NewsWatcher/3.2 (PPC Mac OS X)
Date: Sun, 12 Jan 2003 09:47:53 GMT
NNTP-Posting-Date: Sun, 12 Jan 2003 01:47:53 PST
In article ,
Thoremail@example.com (P!erCer) wrote:
>John Larkin wrote in message
>> >> A) Is the output of my coil AC or DC? How do I check? I want pure or
>> >> pulsed DC.
>> >If You use an automotive ignition-coild and pulse the current on the
>> >primary, I'd say is is DC. you shut off the current, and the coild makes a
>> >flyback-voltage, which is in one direction only. For it to be AC would
>> >require some kind of capacitor it could swing/oscillate with (sp?)
>> 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, the average DC voltage output from a transformer is always zero.
The primary voltage is hardly 12V too. It's -12V while it's charging,
about +300V during flyback, some bouncing, and then eventually 0V. It's
at -12V a lot longer than +300V so it all averages out to zero, not
counting some wire resistance that can throw the average off a bit.