Magnets

[LIKES2CRAWL]

Ok, somewhere on here I saw a little green ring magnet that they were using to block noise on there servo I think. What's this all about, and what are they really for?

[EeePee]

http://en.wikipedia.org/wiki/Ferrite_bead

[jmizoguchi]

I wonder if you are running Specktrum 2.4 radio and Mamba Max (company say they have enough cap that noise issue is not problem) then when running brush motor, can you skip the cap on the motor and put magnets instead?

I say cap will be lighter and take less space but would work well?


been curious

[LIKES2CRAWL]

The ring I'm refering to I seen on here, it was a green ring and the wire was looped through it a couple times then went to the receiver.

[JohnRobHolmes]

It is to absorb excess electronic noise. It is useful on some BEC units, and some ESC rx wires.

AKA Toroid choke http://en.wikipedia.org/wiki/Toroid

[HndsWthtShdws]

Originally Posted by jmizoguchi

I wonder if you are running Specktrum 2.4 radio and Mamba Max (company say they have enough cap that noise issue is not problem) then when running brush motor, can you skip the cap on the motor and put magnets instead?

I say cap will be lighter and take less space but would work well?


been curious

If you mean to remove the 3 big black caps in the ESC, no you cant. ESC's work by pulsing power, which batteries don't like very much, the caps are in parallel with the battery so that the power drawn from the battery is smooth.


EDIT: You can get ferrite rings from RadioShack.

[jmizoguchi]

Originally Posted by HndsWthtShdws

If you mean to remove the 3 big black caps in the ESC, no you cant. ESC's work by pulsing power, which batteries don't like very much, the caps are in parallel with the battery so that the power drawn from the battery is smooth.


EDIT: You can get ferrite rings from RadioShack.

Sorry.. I ment was not to use 0.1.uf cap on motor itself to reduce the noise interference... can ferrite rings by itself can replace that?

I know Mamba Max has 3 caps that ESC is already doing their noise reduction.

[DKNguyen]

I would trust the caps more than the noise because of a few things:

-capacitors are less picky about the noise range being supressed than ferrite beads
-ferrite beads can saturate if the EMI is too strong limiting their effectiveness
-capacitors can be placed much closer to the motor terminals than the ferrite beads which makes them more effective
-to get "proper" performance out of ferrite beads, they need to be placed at a precise point along the wire (very technical and no one ever does this), while capacitors just have to be placed as close to the terminals as possible.

I'd use caps before ferrite beads.

BTW, the caps inside the mamba are not for noise reduction. THey are to supress the inductive flyback from the motor/wires whenever the transistors switch during the period where the flyback diodes cannot turn on fast enough to absorb that initial flyback. And like HndsWthtShdws mentioned, they also provide a low inductance "on-the-spot" power source for the transient demands of all the pulsed power going on inside the ESC that the battery cannot due to inductances in the batteries and wires.

The caps are much too far away from the motor, being separated by the inductance of the wire, and much too large to be effective at the motor's noise frequencies.