Coils for ION ...use regular coils?

[garfield at pilgrimhouse.com]

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