Coiled ESC wire ?

[SamS]

Why is it that my ESC has a metal ring and the ESC wire coils around it ?

is it there to take up slack or does it serve a purpose ?

thanks

[David Drew]

If it's what I think it is it's a choke to reduce RF interference. Absorbs unwanted radio frequency 'noise' that could interfere with your other electronics

[milly0812]

It's called a ferrite ring and is supposed to suppress interference ;-)

[SamS]

Ahh thank you !

[Vikki]

Spot on, guys

[Jamin_00]

AKA the Toroidal core.

I have no idea why they call it that but thats what they do in the Kontronik manual.

[cjcj1949]

It's a torroid shape. It's not really a choke in the conventional sense as both wires are wound together. Each wire carries current in the opposite direction and so when the currents are equal the choke does nothing, even if the currents are changing. It is a common mode choke and is definitely useful on long ac power lines where they are both able to pickup noise relative to earth. How this applies to short lines I'm not sure. Some people use them and some don't. I've never seen any figures on increase in range. The number of turns varies as well. I think you will find them on your computer power supply, how they got on to escs I don't know. They may be useful with 35Mhz and brushed motors and bad wiring layout. If they are needed I would think you need one on all servo leads and not just the esc one. It isn't a choke blocking noise from the esc dc supply to the rx.

[Delarado]

does anyone know if they serve any benefit?

My 700e and 500 both dont have one, but I left it on the Kontronic for my Goblin as I didnt want to risk anything.

It does annoy me though so If anyone can confirm it does nothing then ill remove it

[Carapau]

Ive flown my Fusion 50 with Kontroniks/Castles and Scorpions without the toroidal core and it has not been a problem at all. On 2.4g radio systems I believe it just isn't needed and from my own experiences and reading about others, the evidence seems to back this up.

[Mark_T]

On 2.4g radio systems I believe it just isn't needed and from my own experiences and reading about others, the evidence seems to back this up.

I tend to agree, but if you ask Kontronik they will tell you that you should leave them on even with 2.4GHz, so mine are still in place.

[Carapau]

Kontronik do indeed say that but I think that is probably more of an umbrella. However, as it does no harm at all in keeping it on, and it has no other effects it may as well be left on. The only time I have removed mine is when it is getting in the way of a tidy installation.

[Vikki]

It probably has more to do with the UK's EMI (Electro-Magnetic Interferrence) laws. The ESC has them because it can bang out high current pulses. These pulses can produce many harmonics and some of them wander off into the RF range and the cable then acts like an antenna. The cable is tuned because of its own capacitance and inductance. If it is found that a cable causing the EMI safe level to be exceeded then an additional inductor (the toroid ring which is made of ferrite) can detune the cable and lessen the outputted interference. We've had to go through this with our kit. We have a powerful 24V motor that is contolled by PWM (Pulse Width Modulation) and it was pushing us over the legal limit at the top end of the measured spectrum. We fitted a ferrite ring and of varying values until we found one that brought us well within the legal limits. Even just a tiny finger over the limit is a fail. I suspect this is the reason. Not so much to protect your stuff but to protect other peoples stuff.

If the manufacturer fitted a toroid then they had a reason to do so. Leave it be. If they didn't then they were within the limits and didn't need one.

[Carapau]

Sounds like the best explanation so far!

[cjcj1949]

Thanks Vikki. Did you take both wires through one ferrite such that the magnetic fields cancelled or did you use it as an inductor? I used to think it was just an inductor until I realised it was a common mode filter. I'm afraid I don't belief that any testing is involved. The high current pulses don't go down the esc to rx lead hopefully. If it is linked to detuning the rf output it would need to be different for each motor. I think you may be confusing the rc hobby with proper engineering. I hope you are correct, I know you should be. I have no faith personally and don't understand the concept of religion or how people can believe that the manufacturer knows best.

[Vikki]

Receiver and servos have their own filtering in their circuits. This is for transmitted RFI. The toroid detunes the cable. All cores go through it or are wrapped through it. Ours was blatting out all over the 200MHz region. Not good. The inductor brought us within legal limits. Sorry you think I was being religious about it, I'm talking through experience. I've been down the testing centre twice while our gear was stuffed in an anechoic chamber and it was subjected to an RFI spectrum test. The toroid worked for us. No doubt. No faith. I saw on the screen that it worked. The peaks at the 200MHz region dropped substantially.

If it's sold in the UK it has to comply with our EM laws (but a lot don't, not really, but God help them they get caught!)