Re: Electronic Ignition Install - No Spark from Coils

Brad Walker

I've been a member of this group for a long time and never really post until now.. But, I use these Hall-effect sensors in my professional life and there is no way to know about the "alignment tolerance" with the document. These sensors are measured using the strength of the magnetic field. The Hall-effect sensor vendor will provide you with details about the spacing and how it effects the
magnetic field.

Here is a chart from a vendor that shows how the sensor operates in the presence of a mag field. Notice if the magnetic flux is not strong enough, the sensor will never turn on.

So if the vendor hasn't properly characterized the sensor, then it really could be a problem.

-brad w.

On Sun, Nov 15, 2020 at 8:04 AM Anthony P <solarant@...> wrote:
This is all very good information/findings for public distribution.

Seems like the free magnet passing over the sensor should be a recommended early trouble shooting procedure.  Maybe even a bench procedure for proving system function before an aircraft is involved.

"The alignment is within the tolerance of the manual but not enough to get the spark."
This is a problem. If the sensor is within the stated alignment tolerance radially and axially, but the system does not function, then the tolerance spec is wrong. Not good. 
Due to many factors, the stated alignment tolerance needs to be well within the actual alignment tolerance for system functionality. 
Otherwise someone could be on the cusp of functionality without knowing it and vibration, thermal expansion, sensor performance thermal effects, magnetic strength thermal effects,... could push it into the non-functioning region.
Added to this list are magnetic field shape and strength variation from the manufacturer.  This, of course, should be baked into the system level alignment tolerance.
What are the radial and axial alignment tolerance specs?  ,_

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