On Fri, 20 Jan 2006, Danny Sauer wrote:

> I'd imagine there are examples somewhere of how to use a hall-effect
> switch to control power to an inductor through a transistor. :)  Maybe
> look around the DIY-EFI - http://www.diy-efi.org/ - and megasquirt -
> http://www.megasquirt.info/ - sites.

Most low cost magneto style electronic ignitions do not use a hall 
switch they use dI/dt sign change to cut the current circuit at the 
right moment. This can be achieved with something as simple as one 
transistor and two coils but usually there is more to it. Take a look at 
the simple circuits required to make a battery powered 'pendulum' toy. 
The ignition electronics work almost the same. Here is a circuit that 
may provide some ideas:

http://www.geocities.com/~uwezi/electronics/projects/pendulum.html

To use as a magneto replace the battery with the primary of an ignition 
coil and use a hefty magnet. The polarity of L1 may have to be reversed 
and something better used for Q (MOSFET should work).

Peter
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