Ira
It certainly solves a problem for us as we approach running the
engine for the first time with our BMA E1. We have a 720-12R but
haven't fitted it yet. Very interested in how you have it configured
- channel etc. Where exactly across the radius of the contact plate
is the embedded magnet - if you had a photo of your set up? Did you
get your probe from Westach direct or via ACS?
Regards
Paul
G-GIDY
(running out of jobs to do!!!!!)
On 6 Dec 2007, at 17:29, rampil wrote:
>
> Greetings All,
>
> A tech tidbit for the group.
>
> I have been investigating why my prop tach sensor doesn't work and
> finally discovered the solution, which I put forth for other who may
> wind up in this boat.
>
> I have an AirMaster prop and a Blue Mountain EFIS. So far there is no
> way for the BMA to read the engine RPM signal (although that may
> change soon). The AirMaster hub has a magnet embedded in it's contact
> plate for its own internal RPM sensing. Since I could not expose the
> electric RPM signal, I put my own Hall effect sensor on a bracket
> mounted
> to the Rotax gear box of my 912uls. The sensor I used is a Westach
> 720-12R.
>
> This sensor never produced a pulse train signal for the Blue Mountain
> to analyze.
>
> I finally put a scope on the probe and discovered that indeed not
> pulses
> were generated by a spinning prop. (I really did not want my scope
> that close to the spinning prop ;-) )
>
> It turns out that the Hall Effect sensor uses a neat integrated sensor
> chip which it turns out is sensitive only to a SINGLE magnetic
> polarity.
> By random chance, AirMaster uses the wrong one. (North vs South, etc).
> The Westach pulses just fine when I swish a different magnet past it.
>
> It turns out that Westach can build the probe with sensitivity to the
> opposite magnet face. The part number is you need this new probe
> is 720-12RAM. Same price as the original 720-12R probe.
>
> Hope this solves someone else's mystery too!
>
> Ira N224XS
>
> --------
> Ira N224XS
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=150815#150815
>
>
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