> -----Original Message-----
> From: Roman Black [SMTP:fastvid@EZY.NET.AU]
> Sent: Thursday, January 16, 2003 12:38 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      Re: [EE]:  zenner in parallel and coil current
>
> Michael Rigby-Jones wrote:
>
> > You cannot do this with an igntion coil, the whole system relies on the
> > current in the primary of the ignition coil collapsing as quickly as
> > possible in order in create the required voltage in the secondary.  By
> > clamping the primary voltage to the supply rail the rate of change of
> > current will be greatly slowed, along with a corresponding descrease in
> > secondary voltage.
>
> Better still to read up on CDI and make a CDI ignition
> coil driver. This also has performance advantages. :o)
> -Roman
>
There certainly used to be many claims about the advantages of CDI, and I
built myself a system for a two stroke bike I had many years ago.  However,
few if any manufacturers actualy use this system in favour of an inductive
setup.  I believe the CDI system give very high peak energy, but quite short
duration and spark duration seems to be very important.  Some aftermarket
units overcome this by providing multiple sparks (at low RPM) but I am
dubious of any advantage this would provide, certainly on a stock road
engine anyway.

Regards

Mike


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