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Author Topic: 16 TURN,10 TURN. WHATS THIS ALL ABOUT  (Read 2773 times)

portside II

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16 TURN,10 TURN. WHATS THIS ALL ABOUT
« on: February 08, 2007, 11:25:34 AM »

I am just a bit confused ,well a lot.whats the difference with the esc's and motors and the windings .I have seen some esc's for different motors /windings and wondered what the difference would be regarding starting and control ie an esc for 24 turns against one with 4 turns would the higher one have a softer start and the lower one handle higher power ,as with motors/windings the less turns the more torque/power the more turns the less torque but higher revs .
I have prob got it all the wrong way round so could some one please explain in (plain English) laymans terms  ??? ???
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Telstar

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Re: 16 TURN,10 TURN. WHATS THIS ALL ABOUT
« Reply #1 on: February 08, 2007, 02:12:55 PM »

From Michael Faradayís (uncaged)  discovery mathematicians tell us, the force on a conductor (wire) in a magnetic field is proportional to the current going through the wire, and the length of wire in the field. (Iím sure some cows or sheep may be in there too).
It didnít take long to work out if you put the same wire through the magnets twice the force doubled, and hence a coil with 10 turns through the magnets gave 10 times the force (for the same current). Force times distance is torque. (distance being the distance of the conductor from the shaft). So, good motors have big (strong) magnetic field and lots of windings to give lots of torque to turn propellers. NOT QUITE.

In most motors used in models the magnetic field is fixed (permanent magnets) and canít be varied, so you get what you pay for, high quality permanent magnets arenít cheap but modern ceramic magnets are pretty good.

So lots of windings for a good motor. Again NOT QUITE.

 The number of times the wire is wrapped round the armature pole is limited by the space available, but if you use thinner wire you can get more turns in. ( good lots of turns =lots of torque). However Georg Simon Ohm (of ohmís law fame) gets into the act he tells us that ( among other things) that the resistance of a conductor(wire not musician) is R= γ*l/a (γ is resistivity of the material, usually copper) l, is length and a, cross section area of  conductor.   Problem long lengths of thin wire have high resistance and will limit the current through the motor, also thin wire has a habit of melting (like fuse wire) if you pass too much current through it. Also thin wire is not very strong and may be thrown off the armature by centrifugl force as the motor spins (it could be glued in place, but cost matters)

Motor makers juggle to give motors that :-
will curry the current without burning out (thick enough wire)
are small enough to fit in the model (not too thick wire)
are reasonably cheap (not too complicated to make)

I think it was ďslot car racersĒ who first found that if they unwound the armature coils on normal production motors and rewound them with less turns of thicker wire they could get the edge on their competitors (less resistance more current)  and from there the interest in the number of turns was developed, then with the development of electronic speed control (remember slot cars had variable resistor controllers) the internal resistance of the motor became important. So the number of turns is a non technical indication of  internal resistance.  Remember the lower(smaller) the resistance of the motor the greater the potential current, so the less turns the larger the current.   
FETís used in ESCís are prone to being ďspikedĒ by pulses of high current that motors take when starting up ( one Ripmax ESC 120 amp continuous  440 amp peak 18 to 36 turns ) so when using low resistance (small number of turns) it is possible to spike ( kill, damage, render useless) the FETís and the controller with starting and reversing currents while not exceeding the carefully measured normal load current
.
Instead of an ESC manufacturer saying do not use with motors of less than 0.01ohm (a purely random number on my part) they tend to say suitable for 6 to 12 turn motors.
Unfortunately not all motor manufacturers tell you how many turns are on there motors. OOPs

I hope my slightly askew explanation (or perhaps rambling) doesnít  give too many ďexpertsĒ hypoplexia  and if nothing else gives a few wry smiles.

Fair weather and calm water
Tom
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Tug-Kenny

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Re: 16 TURN,10 TURN. WHATS THIS ALL ABOUT
« Reply #2 on: February 08, 2007, 03:21:16 PM »


It doesn't get any better than that.  You can come on my boat anytime. Well put Tom   ;D


Ken
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HS93 (RIP)

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Re: 16 TURN,10 TURN. WHATS THIS ALL ABOUT
« Reply #3 on: February 08, 2007, 03:40:05 PM »

Except that some are 16x3 or 10 x 2  etcand somemay just say 6 turn but most of the motors with a low number of turns are multiple winds ,they also use different gauge wire ,its so that in car racing you can get different characteristics for different types of circuits.  they can be a nightmare as you have to take the timing in to account which will effect revs and current draw.peter
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Re: 16 TURN,10 TURN. WHATS THIS ALL ABOUT
« Reply #4 on: February 08, 2007, 04:22:58 PM »

So it's a case of suck it and see then  :o :o
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Doc

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Re: 16 TURN,10 TURN. WHATS THIS ALL ABOUT
« Reply #5 on: February 08, 2007, 10:11:41 PM »

'Telstar's explanation pretty well says it.  What it 'boils' down to is that the number of turns on a motor doesn't really tell you anything useful as far as ESC's go, or anythiing else for that matter.  Good advertising, I guess, but I'm not so sure that's a recommendation except for the advertising company, sort of.
 - 'Doc

Not meaning to make fun of anyone!  But this is a pretty good example of 'dumbing-down'.  Not a 'bad' way of gtting someone interested, but it doesn't take into account that there's a lot of learning to do to really make any sense of something.  So, when do you want to do that 'learning'?  Before or after you sink some money into it?
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justboatonic

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Re: 16 TURN,10 TURN. WHATS THIS ALL ABOUT
« Reply #6 on: February 08, 2007, 10:13:47 PM »

Generally speaking, the fewer winds the motor has, more power the motor will take and hence run faster ie max RPM's will be more for a 10 x 2 that a 27 x 1.

For longer runs use motors with 27 x 1 turns, for faster motors (which will mean your batteries wont last as long between charges) use less turns ie 19 x 2 etc.

For motors with fewer turns, you need a more expensive ESC and one which will handle the 'hotter' motor.
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portside II

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Re: 16 TURN,10 TURN. WHATS THIS ALL ABOUT
« Reply #7 on: February 09, 2007, 10:22:21 AM »

Well thankyou Telstar i don't know what to say your explanation has left me speechless !!!
After reading your reply i was about to report you to the moderator for been too darn clever  thankyou
i just wish they would leave things alone (agh i sound like my dad) what is wrong with the old fashioned  amps .
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FullLeatherJacket

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Re: 16 TURN,10 TURN. WHATS THIS ALL ABOUT
« Reply #8 on: February 09, 2007, 04:33:07 PM »

Portside
The clue is in the question. "Proper" model boat ESCs are rated in Amps (usually continuous current rating). Those which are advertised as suitable for X or Y number of turns are probably R/C car speed controllers and may not be suitable for boat use. If in doubt, shout. There's almost certainly someone on this forum with experience to help you.
Suit yourself.
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justboatonic

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Re: 16 TURN,10 TURN. WHATS THIS ALL ABOUT
« Reply #9 on: February 09, 2007, 07:53:32 PM »

  Hi. Mtronics \ Msonic do separate car and marine speedos. Even the car speedos are waterproof resistant. The main difference is the car speedo will only handle up to 9.8volts whereas the marine speedos will take 12v.

And no I have no connection with them!
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BobF

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Re: 16 TURN,10 TURN. WHATS THIS ALL ABOUT
« Reply #10 on: February 09, 2007, 09:03:48 PM »


And there's always how many poles to consider as well  ;D

Bob
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Re: 16 TURN,10 TURN. WHATS THIS ALL ABOUT
« Reply #11 on: February 09, 2007, 09:04:36 PM »

The other difference between car and boat ESC's is there is a delay in going into reverse on car ESC's not a lot of help on a scale course
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maninthestreet

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FullLeatherJacket

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Re: 16 TURN,10 TURN. WHATS THIS ALL ABOUT
« Reply #13 on: February 10, 2007, 09:32:09 AM »

Tom
Excellent. Many thanks.
Man in the street
Thanks for finding that link to Mabuchi's website - the video is first-class and should be compulsory viewing for all users of electric motors.
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Telstar

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Re: 16 TURN,10 TURN. WHATS THIS ALL ABOUT
« Reply #14 on: February 10, 2007, 10:35:56 AM »

Hi
maninthestreet
great website, their video explains things much better than my ramblings. The section on Phase in the Mabuchi website is the bit that is called in modelers terms(at least the car modelers) timing

Fair weather and calm water
Tom
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