All of the lawnmower and chainsaw engines I have ever seen have a
magneto with points.  Though I can believe new ones may have some
electronic circuit instead of points.  But you still need something to
suddenly change the current path in the coil.  Doing this machanically
may be possible, by hinging the core laminations or such, I doubt it
would be practical.

Sherpa Doug

P.S. Actually I do remember a Kohler engine that used a Piezo stack to
generate the spark, no coils or magnets involved!  I think you shut it
off by shorting the spark plug with a spring steel strap.

> -----Original Message-----
> From: Olin Lathrop [mailto:olin_piclist@EMBEDINC.COM]
> Sent: Thursday, August 09, 2001 6:24 PM
> To: PICLIST@MITVMA.MIT.EDU
> Subject: Re: [PIC]: Building a Servo
>
>
> > The spark coil has three terminals.  One is ground, one is
> for the spark
> > plug, and the third goes to the breaker points.
>
> But he's got one of those ignitions where mechanical action
> slowly builds up
> then quickly breaks the magnetic circuit.  These don't have
> points or a
> primary circuit.  The electrical part is only the high voltage coil.
>
>
> ********************************************************************
> Olin Lathrop, embedded systems consultant in Littleton Massachusetts
> (978) 742-9014, olin@embedinc.com, http://www.embedinc.com
>
> --
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>
>
>

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