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Old Oct 21, 2009, 05:53 PM
the speed of gravity.
U.K.
Joined Jul 2009
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Discussion
Brushless RPM Sensor-Cable length?

Hi, I'm doing an "electric tail" conversion on a Maxi-Joker 2 and I'm going to use two rpm sensors. I've no problem with the modification to the secondary connection.
My question is that the conversion is putting the motor out at the end of the tail boom...it's a long way from the v3 logger. I'm going to run the sensor wire to the ESC inside the tail boom out the end where the ESC is.
Is the sensor going to work with a long cable run like this?
Thanks.
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Old Oct 21, 2009, 08:14 PM
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Victoria, Canada
Joined Feb 2009
158 Posts
Jumping in ahead of Bill...

I'd recommend keeping the "live" connections between the brushless motor and sensor short and extending the "data" cable between the sensor and eLogger. i.e. place the sensor with the motor (and run the interface cable all the way back to the eLogger), rather than keeping the sensor with the eLogger and extending the "To Motor 1" and "To Motor 2" wires.

My logic here is that the motor-to-sensor connection is far more sensitive to stray EMI noise (that would show up as erroneous spikes or dips in your recorded RPM data) than the sensor-to-eLogger connection, which I bet is probably pretty robust and resistant to interference.
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Old Oct 22, 2009, 06:48 AM
the speed of gravity.
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Joined Jul 2009
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adding chokes?

Thanks for your reply.
Since these are naturally sensitive to emi I question why we do not put chokes on them? I mean, it can't hurt to have them.
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Old Oct 22, 2009, 07:14 AM
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Son, Norway
Joined Sep 2004
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Quote:
Originally Posted by nooobolocity
Thanks for your reply.
Since these are naturally sensitive to emi I question why we do not put chokes on them? I mean, it can't hurt to have them.
I would choke the signal itself (kind of emi).
(Which leads me to think that it might be better to cut the wire instead of coiling it up as I do now ).

Fred
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Old Oct 22, 2009, 02:34 PM
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Victoria, Canada
Joined Feb 2009
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excellent question about the chokes: I guess some testing is in order. good luck! :-)
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Old Oct 22, 2009, 02:38 PM
the speed of gravity.
U.K.
Joined Jul 2009
10 Posts
Quote:
Originally Posted by flarssen
I would choke the signal itself (kind of emi).
(Which leads me to think that it might be better to cut the wire instead of coiling it up as I do now ).

Fred
Where do you find the information that it would choke the signal? I would not even worry about this as the advantage of stopping noise is the greater benefit.
If you use a round circle choke, the each time you pass the wire around the choke and through the hole your doubling the effect of it's power. So it is a good way to shorten a long wire.
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