The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Bob_Roller on March 09, 2013, 08:58:31 AM
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Went online this morning, looking for Hall Effect sensors .
Found a source in the US .
Purchase 25 units and the price is $13US each .
http://www.bbautomacao.com/home_hall_effect_sensor_cyhme56.html
One question I have, is the note about adding a 1-10K resistor between the input voltage and sensor output signal .
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Hello Bob,
I hope it is a suitable replacement.
I've been told that Chinese replacement lack the magnetic shield to protect from the magnetic field produced by the alternator. And so misfire or do not work at all in airheads but are fine in K or more recent BMW bikes..
If I'm true, and I hope not, I hope you did not buy the 25 units ....
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No, I just saw this today .
I have 4 of the Honeywell sensors .
Just curious about the shielding, the sensor is enclosed in an aluminum canister and the three wires coming out of the 'beancan' are not sheilded on the Honeywell part .
Nor, does the wiring diagram show the wires to be sheilded from the 'beancan', or the wiring going to the ignition control module .
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As far as I know, there is an iron shield around the effective part in the Honeywell unit.
This circuit is very sensitive to magnetic fields ans as such must be shielded to react only to the changes induced by the aluminium vane passing in front of it.
The Chinese sensors seems to lack the iron shield, if I'm not mistaken.
Edit :
As far as I can tell, someone in Advrider seems to had luck using this sensor to ignite his airhead... I'm gald to be wrong ! That means there IS an alternative to the discontinued Honeywell sensor !
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It might be a dumb question but...
Could you explain the Hall effect please?
I´ve heard of it, searched in the internet, but it seems there are more info about the sensor itself than the effect... I thought it was more related to newer bikes and no airheads!!
Thanks!!
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A Hall Effect sensor, is an electronic switch, no moving parts .
On the '81 and newer bikes, they are used in place of contact breaker points type ignition .
There is a steel cup with a rectangular hole or window in it, when the window passes by the sensor, it is exposed to a small magnet , the sensor becomes conductive and passes an electric signal to the ignition control unit, which amplifies it and sends power to the ignition coil .
That's kind of a quick simple explanation .
http://en.wikipedia.org/wiki/Hall_effect_sensor
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Basically, one runs a current (usuallly constant, and small) across a conductor (often this is really more of a semiconductor material). There is very little voltage drop across it until a magnetic field oriented perpendicular to the current flow is applied, which causes a voltage rise across the width of the conductor, which is used as the signal to generate ignition timing in this particular application. Actually, in this switch, the magnets cause a voltage to appear across the conductive material until a magnetic/ferrous vane passes through the air gap and basically "short circuits" the magnetic flux between the 2 sides of the sensor. This is what causes the "pulse" that is fed to the ICU.
All open collector output devices need a pullup resistor of some sort - it is possible that there is one integrated into the ICU on the bike, but I don't have a schematic for it. It shouldn't be too hard to test one to see if it needs an external resistor or not. The thing that I noticed when I was looking into these awhile ago is that the sensitivity and responsiveness of the device is a bit different from the original Honeywell. I think that it would probably still work, but it might have to be tweaked a little in comparison to the Honeywell device so that the firing angle is exactly the same - I think by my initial estimates the difference would only amount to a few arc-seconds..
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Which would be taken care off by the ignition set up with the strobe. if I'm not mistaken.
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Correct.