Coils for ION ...use regular coils?

[Shannen Durphey]

garfield at pilgrimhouse.com wrote:
> 
> On Fri, 29 May 1998 15:47:16 -0500, Walter Petermann
> <corsaro at brokersys.com> wrote:
> 
> >I read on a previous answer that the coil secondary and coil
> >primary have one end connected together to the minus
> >terminal. If this is true,
> >the firing current must also pass through the primary (when
> >the minus terminal is 'let go' to fire). Wouldn't you be
> >able to monitor the current through a resistor connected to
> >the positive terminal? Then just ignore the current reading
> >during dwell.
> >
> >...disregard if I misunderstood the bits of conversation
> 
> Nope, you understood right. It's just that this common point we're
> talking about is tied to either gnd or +BAT already, during the time we
> need to measure the current in the secondary (that's essentially, as you
> observe, what we need to do, since that's the same current as what's
> passing throught the plug and the ionized gases).
> 
> So OK, mental picture time; you have the common point tied to +BAT, and
> the other side of the primary is of course floating (you've OPENED the
> primary to collapse the field and fire the plug). So here we have a
> secondary winding, one end of which is tied to a low impedence source,
> and we need to impress 80-400V on top of that, and measure the current!
> which is on the order of a microamp!! You don't wanna be doing that in a
> low impedance circuit that has to supply 8-10A during the rest of it's
> workday.
> 
> Lemme just appeal to my betters, and say you won't find any of the
> patent authors trying to do THAT! Heh. Instead, for these kinds of
> autotransformer setups, they just isolate the measurement circuit from
> the secondary with HV diodes and cut to the chase.
> 
> Hope this helps explain the vagaries a tad better. Always need to
> consider the scales of things, like the primary current levels compared
> to the ionization current levels. That's why you need SOME form of
> isolation, at least from the primary, and if not, then from BOTH primary
> and secondary circuits. Hence, either an independent secondary, or the
> HV diodes. Those are the ONLY two alternatives I've seen in ALL the
> patents so far, and also the only ones I can see would work, also.
> 
> Gar
Hey Gar,
why does the independent secondary have to be in the IGN
coil?  What if there were another, smaller transformer in
series in the primary side?  Couldn't you use that to create
a representative voltage for measuring?  I assume I'll need
my hat for this one.

Shannen