Hi All,
When I upgraded from the G3 to the G4 BMA EFIS for my 912ULS,
I took it upon myself to engineer working solutions for the new BMA
Engine Pod.
The Rotax electric tach output was designed to go to a electro-mechanical
panel gauge, like the new UMA Rotax-specific Tach meter. The UMA
works great (although the RPM>IDLE contact never worked in my unit).
The electrical output of the engine was never designed for talking to a
digital or analog-to-digital conversion box. The voltage out of the flywheel
coils exceeds 100v at normal engine speed and the typical high impedance input.
The GRT guys may have spent some time working out a conversion/
protection circuit for their engine monitor.
I have my EFIS read RPM off a hall-effect sensor mounted on the gearbox
next to my prop brushes. It detects the embedded magnet in the prop
backing plate used by the Airmaster. The Hall-effect sensor is a stock
item at Westach and it produces nice digital pulses for the BMA Engine
pod. It works like a champ. There is a small caveat - the Airmaster
guys are not picky about which polarity they embed face up in the prop
plate. The Westach probe is only sensitive to one polarity, so you need
to check the magnet first, before ordering the sensor.
--------
Ira N224XS
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=211007#211007
|