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Ferrite coils.

https://youtu.be/5GmwJjam0lQ?t=737

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Michael Barclay06/01/2019 21:40:10
80 forum posts
36 photos
Could someone please explain how the use of ferrite coils would fix the problem of syncranization in twin motor setup.as used in the video. Any other info on problems to be wary of in twin motor setup would be helpful. Thanks in advance. Mike.
Chris Bott - Moderator06/01/2019 22:24:38
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Chris Bott - Moderator06/01/2019 22:27:52
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Michael, have a look at this article

Daithi O Buitigh06/01/2019 22:54:30
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1362 forum posts
49 photos

I'll hazard a guess here and point out that ferrite cores installed like that would smooth out any voltage spikes coming from tjhe other power egg

Michael Barclay06/01/2019 23:04:40
80 forum posts
36 photos

Thanks for the replies guys. The article simplifies things nicely and the ferrite coil smoothing out voltage spikes was my guess Daithi but I have not seen them mentioned on any other utube twin motor setups so just wondered why he needed to use them on his setup.

PatMc07/01/2019 00:13:07
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4295 forum posts
524 photos

Surely they are simply RF suppressors that are fitted as standard on a number of ESCs, in fact not particularly aimed at multi motor models use at all.

Daithi O Buitigh07/01/2019 00:38:53
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1362 forum posts
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Posted by PatMc on 07/01/2019 00:13:07:

Surely they are simply RF suppressors that are fitted as standard on a number of ESCs, in fact not particularly aimed at multi motor models use at all.

Yes Pat, that is the normal case but in this instance the guy said his motors wouldn't sync. It's possible that he had an electrically 'noisy' one and that was causing the interference and de-synchronisation

gangster07/01/2019 10:22:52
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985 forum posts
17 photos

As PatMc says the primary use of ferrite cores is to attenuate high frequency interference. To simply remove low frequency interference and spikes would take many turns on a serious piece of iron. Ferrite chokes need to be tuned to the frequency that we wish to eliminate or attenuate. That is course in an ideal world where the issue is so severe. In many cases just to be partly effective gives the cure we are looking for and indeed removing that last straw will save the camel. This may indeed be the situation here. Having said all that don’t be afraid to experiment add more turns double or treble up on the number of cores. Also remember there are hundreds of different types of ferrite core. Use the wrong one and you might as well use a polo mint. Having said that a polo mint could be effective at a higher frequency eg 2.4 G but that ain’t the issue here

Allan Bennett07/01/2019 10:53:37
1595 forum posts
44 photos

The OP didn't mention (so far as I can gather) exactly what 'problems' he had with synchronization. In my experience using same make/model ESCs, same make/model motors, and same make/model props I've never had any pairs that have run at anything other than almost-identical rpm, as judged by performance of the model and by listening to the 'beat'.

If the ferrite ring is having a beneficial effect in the OP's case, is it because it's stopping some spurious signals getting to the receiver, or stopping some spurious receiver signals getting to the ESC? If the latter, why is the receiver giving corrupted output signals?

Ever since I changed from 35MHz to 2.4GHz I've actually removed the ferrite rings where they were fitted, to save weight and to make the wiring tidier.

Michael Barclay07/01/2019 11:01:21
80 forum posts
36 photos

Hi Allan. I did not have any problems with synchronization but the guy who posted the video on youtube said he had encountered problems and therefore fitted the ferrite coils. I was just wondering what problem he might have had that caused him to fit ferrite coils and if anyone else had encountered the same problem. Mike.(op)

Chris Freeman 307/01/2019 11:09:17
315 forum posts
445 photos

I had a problem with motors not starting at the same time on the Pancake which resulted in the motors running at different RPM's. I was then told that you need to plug in the batteries and switch on the RX power if a separate power source with the TX SWITCHED OFF. Once the RX has power then switch on the TX and the ESC's will arm and run at the same speed. Some say the throttle should be at full throttle and once you throttle back the ESC's will arm?

Michael Barclay07/01/2019 18:40:57
80 forum posts
36 photos

Sounds like a good tip Chris. Thanks.Mike.

Allan Bennett07/01/2019 20:36:13
1595 forum posts
44 photos
Posted by Chris Freeman 3 on 07/01/2019 11:09:17:

I had a problem with motors not starting at the same time on the Pancake which resulted in the motors running at different RPM's. I was then told that you need to plug in the batteries and switch on the RX power if a separate power source with the TX SWITCHED OFF. Once the RX has power then switch on the TX and the ESC's will arm and run at the same speed. Some say the throttle should be at full throttle and once you throttle back the ESC's will arm?

All ESCs I've used need ideally to be 'taught' what the throttle range is on your setup, and for all of them it's done by switching on the Tx first (you should always do that, for safety), setting its throttle to full speed, then powering up the receiver that's controlling the ESCs (you may also need to power up the motors, if the receiver has it's own independent power supply). When the ESCs beep, shut the throttle down to zero, and the ESCs will probably beep again indicating that they've learned what the full range is. With some you can then go ahead and fly; with others you have to power down the receiver and then re-start it.

With a single-engine model it often doesn't matter if you haven't gone through this process because all you'll probably notice is that your motor needs a bit of throttle before it starts. But with multi-engine models it's vital.

Michael Barclay07/01/2019 22:26:45
80 forum posts
36 photos

Thanks Chrsi. Will remember that. Have only built single engine planes until now. My next scratch build will most likely be the Handley Page Hayford. I like these oldies. Building Focker v23 at the moment, 50" span in Depron. Last build was Se5a in depron. I like that one as it flies great. Also did a scratch build copy of the Flair Magnatilla in Depron. Great trainer. I have more than 100 flights with that and no crashes. Thanks for the tips. Mike.

Chris Freeman 308/01/2019 04:16:56
315 forum posts
445 photos

Nice projects Mike. These are the 2 aircraft that used the set up described, the pancake needed perfectly synchronised motors to fly. I tried swapping speed controls and re arming all without success. p1010347.jpg

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