I am tinkering with this when I have time exactly now!

You cannot have decent results if you do not take the RPM into account.

The normal setup for simple cases is a movable sensor on a lever that
allows -5 to +5 degrees of advance. Provide a lever or a hole for a lever
so you can actuate it without touching the cylinder or the prop. You can
also have an electronic delay.

To account for RPM there are several dozen ways. With only one sensor you
can measure the 'width' of the pulse from the Hall.

Arrange such that the falling edge from the Hall pulse triggers the firing
(not the rising edge). Build an ignition circuit that won't issue a last
deadly spark when you turn it off (since it is on the trailing edge).

good luck,

Peter

PS: BTW did you calculate the ignition power at 20,000 rpm and 20mJ/spark
assuming single spark ;-). Because I did and I will try to run the engine
very slowly ...

----

Hi=20
I know that quite a few people on the list fly R/C planes, so I was =
wondering if anyone has some advice:

I have a 2-stroke glowplug engine that I'm intending to convert to spark =
ignition. I've built an electronic ignition
unit using a magnet in the prop driver and a Hall sensor that will mount =
on the crankcase.

My question is how do I determine the position of the Hall sensor with =
respect to TDC of the engine?

I am only interested in single-speed (full throttle) running at the =
moment.

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