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› Location of Ferrite core on UBEC
08-07-2009 08:29 PM  8 years agoPost 1
Melnic

rrElite Veteran

Columbia, MD,USA

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Any of you folks experts on electrical noise?
I was curious why the ferrite cores on my external switching BEC's or ESC's with switching BEC's have the ferrite core near the servo connector that plugs into the RX.
I always though that you wanted to filter the noise AT the point of the sourse? that means the ferrite core should go at the BEC.
Or are is it the case that the servo wire going from the BEC could be picking up additional noise and they then filter just before it goes INTO the Rx.

I have one BEC in particular that the ferrite is so close to the Rx point that it was hard to tie it down. I want the ferrite not to bounce and pull the connector loose. Having it close to the connector does not help me to mount it, it makes it harder.

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08-08-2009 05:14 AM  8 years agoPost 2
helicraze

rrElite Veteran

Victoria - Australia

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From what i read the position is not critical, just the fact that it is there.

I read it in hyperion or kontronik manual i think. Can't remember.

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08-09-2009 09:23 PM  8 years agoPost 3
Dan A.

rrApprentice

Rancho Santa Margarita, CA

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helicraze is correct. No matter where the core is positioned along the wire, it will impede a rapid change in electrical current flow (unwanted spikes), keeping the signal stable in the presence of electrical noise.

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08-10-2009 03:44 AM  8 years agoPost 4
BrunoBL

rrKey Veteran

Pomerode, SC, Brazil -26.71, -49.17

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It should in principle be possible to pick up noise from other sources along the wire after the ferrite toroid, before its connection to the Rx. Following that rationale, the closer the toroid is to the Rx, the better. But most if not all of noise the Rx is going to see comes from the ESC, so in practical terms... as long as the toroid is somewhere along the wire, you will be OK.


...Bruno.
Spectra G on Avgas 100LL, Jewel generator
T-Rex450SE V2
DX7

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08-11-2009 04:38 AM  8 years agoPost 5
Dan A.

rrApprentice

Rancho Santa Margarita, CA

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Sorry Bruno, but I must correct your misconception. Regardless of the location of the electrical noise along the wire, and regardless of the position of the ferrite core along the wire, a sudden change in electrical current is induced into the wire (due to a moving electro mechanical field relative to the wire) and is conducted through the entire wire equally. The current change is basically equal at all points along the wire. The inductive reactance of the ferrite core presents an impedance to any change in current. The more rapid the change in magnetic flux density (and resultant induced current change), the greater the inductive reactance.
XL = 2 x pi x FL

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