Spaceclam

i am trying to decrease electric noise coming from my motors. they are brushless feigao motors, and am curious as to whetherit would make a difference if i were to cap them like i would a normal brushed motor? that would require 5 capacitors. will it work?

Matt Kirsch

My Feedback: (21)

My question is, how do you know it's noise from the motors?

Brushless motors have no brushes with which to generate noise. Everything's hard wired.

Flypaper 2

Wouldn't really work. The RF noise comes from the arcing of the brushes. No brushes, no noise. Try separating the antenna, speed controller, batt. as far from one another as possible, although it's hard to do in these little planes.

Spaceclam

it's seemingly the only real source for noise.

smokingcrater

forget about the brushless controller? some of those are VERY noisy... as others have mentioned brushless motors don't have much chance to make noise, as they have no brushes. the only possibility is a bad bearing generating electrical noise (metal on metal contact), but in that case a cap isn't going to do anything anyway...

Leety

motor to gearbox is really noisy.
that's why outrunners are so much quieter.. (no GB)

Matthew007

lol I was searching RC universe to see if the capacitors on brushless esc effect performance and found this funny thread.
Do people even know how brushless motors work? A capacitor stores electric charge to flatten out alternating waves. DON'T put them on a brushless motor.

cyclops2

Brushhless noise problems are from parts layout and loose connections.


Including the the antenna wire being broken anywhere in the length of it. A GENTILE pull on the end and holding the receiver JUST ENOUGH, will show if it is broken with the motor on low speed.

2 people are needed for safety reasons !!!!!!!!!!!

Rich

ron_van_sommeren

Capacitors for noise suppression suppress noise in/on the AC (or DC) voltage, they don't flatten the AC. All depends on capacitors capacity/size.

Vriendelijke groeten Ron van Sommeren
• int. electric fly-in, Nijmegen, the Netherlands
• brushless motor building tips & tricks
• diy brushless motor discussion group
• Drive Calculator download & discussion group

cyclops2

The correct answer issssssssss.

No capacitors across any brushless motor.. unless.. you REALLY know how to calculate the capacitive reactance of the capacitor at all RPM's.

Very few engineers know how to do it. Then they still need to know how much power the capacitor can take. Even fewer know that.

NO capacitors. Period.

Rich

ron_van_sommeren

Hear hear and ditto

Prettig weekend Ron

ChopperMike

My AXI 4120 supposedly has caps on it according to the instructions. There is an additional lead inside the insulation of each of the leadouts which the instructions say are capacitors.




Mike

cyclops2

Could be.
They would be to prevent excessive spikes right at the windings. Right place.

Stilllllllllll. We do not want to just start putting them in. Bad things can and WILL happen if we get it wrong.

Rich

ChopperMike

I totally agree. My AXI has them for whatever reason but most BL motors don't. And brushed motors need them more than BL do. A BL motor receives an AC waveform and capacitors have low impedance at higher frequencies so installing the wrong value will have detrimental effects. Plus I'd be really surprised if the problem is due to noise from the motor.


Mike

John C

If you are having range issues causing glitching as the reason for wanting to reduce electrical noise, try a different motor speed controller. I just had a new one really mess up my systems range. Changed controller, problem solved.

John C

-pkh-

My Feedback: (2)

Or just get a 2.4GHz spread spectrum system and kiss your glitches goodbye.

ChopperMike

That'll do it. I had nothing but glitch problems with my TREX heli. They all went away completely with the purchase of my DX6. I bought the DX7 the day they came out and have not had a single glitch since.



Mike