Right. But on the original coils used on Big Healeys the primary coil circuit
is also wired in series with the
secondary. This is to add a little more voltage to the output of the
secondary, and why coils connected incorrectly
will have less secondary voltage. Because of this I believe it may be possible
to induce a back current in the primary
(but I'm not sure).
Bob
On 4/10/2011 3:27 PM, mike brooks wrote:
> Bob,
> You are correct that putting a diode across ignition points wouldn't
> work, but
> your reasoning about high voltage is incorrect - ignition points
> break the low
> tension 12v primary circuit not the high tension secondary
> circuit, whose
> voltage travels from the coil secondary, via the distributor
> centre core and the
> rotor to each spark plug in turn.
>
> Mike Brooks
> '56 BN2
> Scotland
>
>
>
>
> AFAIK, points are made of solid tungsten
> (although, with our 'cheap at all
> costs' society that may not be true any
> more). Theoretically, you can file them down to almost nothing (but I
> wouldn't). Filing of points is mostly to get you
>
> home, where you can
> install a fresh set.
>
> The condensor--it's a capacitor--is an integral part of
> the primary ignition
> system. It affects the way the coil is
>
> charged and
> discharged, though I don't have the knowledge to totally explain it
> (in
> electronics it's known as a 'TC
>
> circuit'). The points in the fuel pump are
> just used as an on-off switch;
> timing isn't critical. The diode is known as
> a 'flywheel diode' because it shunts the back-current induced when the
> electromagnetic field in the pump body
>
> collapses. Come to think of it, if
> you put a diode across the ignition points
> the 'back-current' from the coil
> would
>
> flow through them instead of providing a spark at the plugs (and the
> diode
> would burn out the very first time, since
>
> there isn't a diode made
> that can withstand 20K volts or more that I know of).
>
--
*******************************************************************
Bob Spidell San Jose, CA bspidell@comcast.net
*******************************************************************
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