Ron,
Is this some kind of a special project you are working on, or do you
just want to get your lawnmower running? If it's a case of just
getting a mower running - provide some specifics like engine name,
numbers, etc., and either I or someone else can probably help you out.
Ken.
I was working on my father-in-law's lawnmower. I replaced the points
and didn't want to do it every year.
I recalled this simple little circuit and got obsessed with finding it
again. Still no luck.
The zener and SCR sounds like it may be the ticket.
Thanks everyone for your responses.

Ron Thompson
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA

http://www.plansandprojects.com

The ultimate result of shielding men from the effects of folly is
to fill the world with fools.
--Herbert Spencer, English Philosopher (1820-1903)