RunRyder RC
 10  Topic Subscribe
WATCH
 2 pages [ <<    <     1     ( 2 )    >    >> ] 3216 views
Helicopter
e-
Align
Other › Ferrite Rings
01-24-2007 08:11 PM  10 years agoPost 21
CHARGE

rrApprentice

FUTURE PLANET EARTH

My Posts: All  Forum  Topic

How many times should you wrap the lead? is 2 times ok? so i don't have to add an extension to reach the rec.

A positive outlook is all that is required

PM  EMAIL  Attn:RR  Quote
01-24-2007 08:32 PM  10 years agoPost 22
BikeNBoatN

rrVeteran

Santa Ana, CA USA

My Posts: All  Forum  Topic

The more turns, the better they work. 5 is considered good. I can get 5-6 wraps on mine. I don't think only two turns would help very much. Better than nothing, but probably not a whole lot better.

Get a servo extension harness. That way you can put lots of turns around the ferrite ring, without affecting the overall length. And you can easily add it or remove it to see if it helps or not.

Brent
Slow and Smooth 2-D Scale Flyer
AMA #35431

PM  EMAIL  GALLERY  Attn:RR  Quote
01-24-2007 11:19 PM  10 years agoPost 23
# 1 VIBE USA

rrApprentice

North East,VT

My Posts: All  Forum  Topic

does the ring only go on speed controller?

can u make it go faster

PM  EMAIL  GALLERY  Attn:RR  Quote
01-25-2007 02:27 AM  10 years agoPost 24
lovetofly

rrApprentice

Dallas, TX - USA

My Posts: All  Forum  Topic

The rings can go on any lead (except the antenna, of course) but the ESC is a prime candidate because of the nature of its operation. It usually generates more RF noise than any other component since it is switching the power on and off to the motor.

PM  EMAIL  Attn:RR  Quote
01-25-2007 03:07 AM  10 years agoPost 25
# 1 VIBE USA

rrApprentice

North East,VT

My Posts: All  Forum  Topic

thanks lovetofly that helps to confirm i have it in the right spot.

can u make it go faster

PM  EMAIL  GALLERY  Attn:RR  Quote
01-25-2007 03:30 AM  10 years agoPost 26
dkshema

rrMaster

Cedar Rapids, IA

My Posts: All  Forum  Topic

The ferrite ring isn't there to attenuate radiated RF noise from the ESC -- you would do that by wrapping the whole ESC in conductive material and tying that shield to ground. It's there to attenuate conducted RF noise in the cable. In the case of the ESC, the conducted noise ends up being on the power supply leads that feed power to the RX, as well as the digital PWM signal used to control the speed (throttle pulse).

It doesn't take a lot of noise on the power leads to upset the digital circuits inside a receiver. In PPM receivers, all the noise has to do is to reset or cause an extra shift or load pulse in a shift register. In a PCM or spread spectrum receiver, that noise needs to upset the processor that's running everything.

FYI -- a spectrum analyzer was used a couple years back to sniff out a Phoenix 35 ESC. The noise generated rolled off into the noise floor around 15 MHz. Up to 15 MHz, it was a noise monster. Above 15 MHz it was pretty benign.

Your receiver's front end band-pass filters coupled with the mixer in the front-end ought to be able to keep that kind of crap (low-level, out-of-band RF) from getting in through the antenna. That's true with our current PPM/PCM receivers, and your 2.4 GHz system ought to be even better at keeping out that noise.

But if you let garbage in through the power supply leads or pump it into a signal lead, that's not good. Digital systems like clean power. One thing most receiver designs lack is a good, effective noise trap on their power leads. That function is generally relegated to a moderate value tantalum capacitor, and maybe a ceramic capacitor in parallel with it. Not that effective for killing large, fast spikes. A ferrite ring in the ESC to RX lead won't hurt, will help, but not for the reason most people think it will, as it isn't doing squat to attenuate radiated RF noise.

The more turns you can get on the toroid, the better it will be, keep the winds tight and neat.

That's six and a half turns above.

DigiKey (http://www.digikey.com) part number P12721-ND. 49 cents each, plus shipping. Buy 20 or 30 to make the shipping worthwhile. Amaze your friends by passing out some of the remainder and curing what ails.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

PM  EMAIL  GALLERY  Attn:RR  Quote
01-25-2007 10:55 AM  10 years agoPost 27
# 1 VIBE USA

rrApprentice

North East,VT

My Posts: All  Forum  Topic

Thanks Dave for the great post I hope this helps answer some questions about glitches i know it enlightend me.

can u make it go faster

PM  EMAIL  GALLERY  Attn:RR  Quote
01-25-2007 02:56 PM  10 years agoPost 28
Darren Lee

rrElite Veteran

Woodstock, GA

My Posts: All  Forum  Topic

According to the "FAQ'S" video on Spektrum's website, ferrite rings are not needed and they recommend NOT to use them.

http://www.spektrumrc.com/Products/...M2710#dx7videos

PM  EMAIL  GALLERY  Attn:RR  Quote
01-23-2012 02:19 AM  5 years agoPost 29
cjcj1949

rrNovice

uk

My Posts: All  Forum  Topic

Is this the right way to make an inductor

By wrapping the positive wire and the negative wire in the same direction we achieve two magnetic fields in the opposite direction which cancel. It is not an inductor, just a bit of bling.

Just think of the positive wire to begin with. That will do the job perfectly and will produce a force on a North pole in a given direction. It will magnetize the ferrite and it will have an Inductance that can be measured and an impedance at the frequency it is required to reject of 2PifL.

However because they can't be bothered to remove the negative wire that gets wound in exactly the same direction. Un fortunately the current in the negative wire is in the opposite direction to the positive wire. It will now produce a field in the opposite direction which will cancel out the field of the positive wire.

No field, no inductance, no impedance. No Use.

If we do need this, just wrap the positive lead around the torroid, or use a ferrite bead or two.

PM  EMAIL  Attn:RR  Quote
01-23-2012 03:47 AM  5 years agoPost 30
dkshema

rrMaster

Cedar Rapids, IA

My Posts: All  Forum  Topic

Must be a slow night over in the UK, dredging up a 5-year old post to pick nits, and lose in the process...

cjcj -- half right. You are describing what could be called "normal mode" noise.

The toroid and its operation suppresses COMMON MODE noise and is highly effective. Perhaps that is why these useless bits of ferrite materials are found on just about every consumer appliance in use these days.

The problem with using ferrite beads on each of the conductors as you suggest is that at the currents we see in our equipment, the ferrite material easily saturates and no longer is an effective noise suppressor.

Wrapping just the positive lead around the toroid does not do anything for common mode noise and since you're going to be saturating the magnetic material, it won't suppress the normal mode noise, either.

For the toroid, the fact that the incoming and return current cancel each other is exactly the reason the toroid does its job so well. The material is NOT magnetized by the current flowing in the two wires -- even at very large currents, therefore it does NOT saturate, and it remains an effective material. The common mode choke presents a low impedance to the input/output current you need to power your equipment, however it makes for a high-impedance path to the common mode noise present on that pair of wires, keeping it out of the equipment, or keeping it from radiating FROM the equipment.

-----

As for your statement that the ferrite toroid doesn't work to suppress noise that can render a receiver inoperable, you simply are dead wrong.

It is a statement that can be clearly demonstrated to be dead wrong by the simple process of inserting the choke between a receiver and the ESC, and removing it. Day and night difference, especially in the pre-2.4 GHz radio systems that are prevalent today. Many a 72 MHz receiver that was useless in a typical electric-power installation became highly reliable and usable with the simple installation of that useless toroid.

-----

The Spektrum FAQ video does mention toroids on the ESC, but only in passing. The primary focus of his comment is the use of amplified y-harnesses and chokes on the servo harnesses. This was becoming a common practice as electric flight was taking hold in the pre-2.4 GHz world.

The comments were directed at the fact that 2.4 GHz systems aren't going to be affected by the traditional RF noise found in RC systems, since that noise is generally outside the and below the 2.4 GHz part of the spectrum and would be filtered out by the radio's front end and RF processing circuitry. I will agree with that. What isn't mentioned, is that noise (from noisy sources such as ESCs) can be conducted on the power lines into the receiver. Noisy power can kill digital electronics. If the spikes aren't large enough to damage the digital stuff, they CAN be large enough to upset the digital nature of the receivers. It really doesn't take much in the way of noise on power lines to play havoc with digital devices. A random spike here and there can upset counters, latches, reset lines, and other stuff that makes your radio do its thing.

A 49 cent passive toroid (if you have to actually buy one because most ESCs and switching regulators COME with them these days) that adds a couple of grams to your flying weight is really cheap insurance.

-----

The text in the above article is here, in case it's not clear in the posted picture:
In a common mode (CMN) filter each winding of the inductor is connected in series with one of the input power lines. The connections and phasing of the inductor windings are such that the flux created by each winding appears to cancel (actually sums to zero within the core material) the flux generated by its opposing winding. The insertion impedance of the inductor to the input power line is therefore negligible.

The two figures below illustrate both the flux generated by the power lines and that induced by any common mode noise present on the lines. While ‘power line’ flux sums to zero (often thought of as ‘canceling’) because of its opposing nature, the common mode flux is left unopposed and therefore encounters the high reactive impedance of the core material. This high impedance offers filtering action against the common mode noise.

[Two pictures inserted here]

Toroidal cores are most popular for CMN filters as they are inexpensive and have very low leakage flux. Toroids are typically wound by hand (or individually on winding machines), and so can have higher manufacturing costs than bobbin wound shapes such as EE and pot cores. However, the higher inductance allowed by having no inherent air gap at a mating surface can add as much as 30% more impedance at lower frequencies. Normally a non-metallic divider is placed between the two windings, and the wound unit is epoxied to a printed circuit header for attaching to a PC board.

-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz

PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 2 pages [ <<    <     1     ( 2 )    >    >> ] 3216 views
Helicopter
e-
Align
Other › Ferrite Rings
 Print TOPIC  Make Suggestion 

 10  Topic Subscribe

Wednesday, December 13 - 12:54 pm - Copyright © 2000-2017 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online