2002.07.18, 05:59 PM
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#1
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Guest
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Are Neo Magnets Better?
How is a motor affected by increasing the magnetic flux around the armature by installing rare earth magents?
Obviously you get tons of extra torque since F=nBIL (number of turns * fluxdensity * current * length of turn) but does that come at the cost of fewer max rpm - logically no since max rpm are limited by the inductance of the motor windings but i have heard otherwise, however since power = RPM x torque that would suggest that you get free power by increasing magnetic flux which seems unlikely
does it just make the motor more efficent or does it just waste more energy as eddy currents in the armature?
does anyone have experience of rare earth magents in a miniz?
If i get a postive responce on this then i plan to buy a whole load of draconius's magnets!
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2002.07.18, 06:47 PM
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#2
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Mini-Zedologist - Fear me
Join Date: Dec 2001
Location: Bristol, England
Posts: 3,610
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Neo Magnets
I don't use any of Drac's Neo magnets (yet)
I do have Squat Neo magnets on one of my NML Evader motor equipped Mini-Z's.
They do make a difference in torque without any sacrifice in RPM.
I suggest a decent motor to use your Neo magnets with.
Mini-ZRacer.com are developing a Turbo only motor equipped with bearings and Neo magnets.
Invest in a TLP Twin Turbo and get your pre-order in with Mini-ZRacer
Don't worry about shipping, both Butler and I (Both UK residents) order from Mini-ZRacer.com and the prices are on average 30% cheaper than UK LHS prices.
Shipping takes about 10 days.
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Mondo
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The UberMod is back in town...
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2002.07.18, 08:34 PM
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#3
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Moderator
Join Date: Nov 2001
Location: Goodrich MI
Posts: 6,164
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Well 0 magnets = 0 power...
The magnets in a motor fihgting, or pulling toward (depends on magnet type) are what make it go round... the voltage and amps power the electro magnet on the armature.
So if I were to put a 10x stronger magnet in the motor it would be relative to 10x stronger... not exact there are other variables, size of magnet, flux, the weather, weight of car, orbit of the moon, but for lamens sake... its relative.
The RPM and the TORQUE are actualy produced by various things in the motor... and some dont effect the one as drasticly as it does the other... there are billions of calculations and variables etc... or I would have my Mini-Z Speed calculator working correctly already with Neo magnets etc...
Depending on the motor, a 200% increase in TORQUE could potentialy be a 50% loss in RPM, based on Horse Power formulas. But since it dont realy work that way, in my tests with my magnets I didnt realy see that much of a RPM loss... it just depends on the motor I guess, the winds & turns in the electromagnet coils, the resistance, voltage, amps, etc....
Try this page.. its what I am trying to adapt into the Motor Calculator for my Mini-Z Speed Calculator... its sort of confusing and the Calculous parts are sort of over my head since I sorta never bothered to take calculous... I dont know what some of the "common" symbols are or mean... The site already has the data I need in a nice spread sheet, but they refuse to share it with public .
http://www.consult-g2.com/course.html
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2002.07.18, 09:25 PM
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#4
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Guest
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Having that spread sheet wouldn't help you much as it is for brushless motors which are a whole different kettle of fish. What i did think of was that i am going to try winding a mini-z motor with skewed laminations for smoother power delivery. Most of the symbols are just greek letters for different things like phi for flux which could be mistaken for calculus symbols. The thing that looks like a stretched 's' means integrate and a '.' means 'the vector product of' but for the most part little maths is needed to understand what is being said.
What someone really need to do is to measure the performance of some of these motors empirically - i am sure someone out there has a dyno small enough to put these motors on!
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2002.07.19, 12:28 AM
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#5
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Moderator
Join Date: Nov 2001
Location: Goodrich MI
Posts: 6,164
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As far as I know dave is... and RPM wise, not sure about torque, you can use a stock motor of same size, as the Dyno just couple the shafts together, power the motor to be tested, and hook the stock motor, the dyno.. to a multi meter...
The only symbol I realy didnt know (since most were representary symbols) was the sideways M sorta like a backward 3... I use to know what it is... and Ill feel stupid when I hear it .. probly just aunit of measure or someting hahah...
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2002.07.19, 05:45 AM
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#6
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Guest
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that is a upper case sigma - a greek 'S' which means sum, i take it you are referring to the first page where they are comparing electrical and magnetic circuits, the thing with the sigma in it is simply the general expression for V=IR basically V=I * (sum if all the resitances) which is called kirchoff's second law which states that the sum of the voltage drops across all the resitances in a circuit must equal the supply voltage - obvious really it's just the maths that makes it look difficult
regards
alex
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2002.07.19, 06:57 AM
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#7
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hehehe!..
Join Date: Jan 2002
Location: Manila,Philippines / Earth!
Posts: 479
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:ö: i guess you're right Mr. Rice, was it the 3rd law of motion? that in every action there is an equal but opposite reaction?.. , but as far as i understand it, the more powerful magnet you place inside the motor the more torque you'll get but you'll sacrifice RPM, you can't have both worlds, based on my experiment; i used a mini-4wd as a control car, and a stock armature as a control arm, variables are two different types of magnet, the stock and a silver magnet (i guess it's the same thing as neo-magnet of Mr. Drac, sorry sir, i didn't mean to offend you or something), now what i've noticed was if i use the stock magnet on the control car, the car would run at least 20-30kph (on a fully charged batt that is) then i replace the stock magnet with a silver magnet ( which is 10-20times stronger than the stock one) and re-peak the batteries, the result was the car with the stronger magnet was running somewhere 5-10kph. but climbing a steef 4ft slope? no sweat! , compared with the stock magnet installed, the car would just stop in the middle of the slope, removing some winding would increase the RPM a little bit, but not blazing fast, well i guess the best thing to do now is remove all the windings and should be replaced by a bigger wire, well on a mini-4wd, power comes directly from the battery (no esc to smoke), so a 12turn of 22-23 guage of magnet wire would turn a turtle in a rocket!!! (0-60kph in 3sec.!), but on our case (mini-z, that is) such powerful motor would fry a stock mini-z esc in a sec! will smoke turbo's either!, am i making any sense here? to sum it all up, powerful magnets are great for modified motors, powerful magnet+stock arm=high torque less rpm motor! well that's how i see it, i guess you know what to do when you have a high torque less RPM motor?, install a bigger pinion! reality check: am still on the topic? -æ
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Proud to be Pinoy!
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2002.07.19, 09:02 AM
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#8
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Moderator
Join Date: Nov 2001
Location: Goodrich MI
Posts: 6,164
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In the end the stronger magnet increases the Horse Power... and efficiency of motors. Horse Power is Torque * RPM (in lamens). Once you have the horse power you gear it for the speed and ground torque you want... reason I want to make a 1:1 ratio set muhahaha... Gota customize a 30t spur, and get a 30t pinion well in reality I would probly use 35t spur, and 20t to 25t pinion It will probly still spin the tires on start though...
And the magnet strength does improve the RPM if the armature is wound to accept it... we are not likely to do that.. so its ignored, basicly 0 magnet = 0 rpm...
And the Neo magnets are on minimum 10x stronger then the stock... at least on the Total: Flux/Gauss MagnetoMotiveForce level. They feel stronger in hand though cuz its a far cry from any normal manget , Neodymium is what is inside Hard Drives, only the HD magnets are balanced so there is no leakage, if I could do that on the motor no leakage in the flux, then there would be more flux in the motor to use . A ROUND instead of flat sided motor can might help.
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2002.07.19, 10:14 AM
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#9
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hehehe!..
Join Date: Jan 2002
Location: Manila,Philippines / Earth!
Posts: 479
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:ö: now you're talking Drac! , does that answer the question this thread about?! :enter the music of the twighlight zone wish we could add an audio to this thing!!! hehehe 1:1 "gear ratio"?! try inserting the wheel on the motor armature directly!, now that's 1:1 ratio! -æ
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Proud to be Pinoy!
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2002.07.19, 06:47 PM
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#10
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Guest
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Aahh, now that is what i wanted to hear- basically that you can get more power overall with neo's
Synopsis:
Fewer turns give more rev's and draw more current which leads to a net gain in power but less torque, increasing the strength of the magnets gives you back the lost torque and leaves you with a helluva powerful motor!
So... bulk buy drac's magnets and lets have some fun!
I would love to know what NML had to say about neo's and stronger magnets in general.
Regards
alex
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2002.07.20, 12:15 AM
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#11
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Moderator
Join Date: Nov 2001
Location: Goodrich MI
Posts: 6,164
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Ive been tempted to mount a 1:1 with out the diff.. but too hard and I would rather have the diff with control then the speed . Heck some times I use my Mini-Z as an electric eraser... (13t pinion) hehe, breaks the tires in good, but wears them out.
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2002.07.21, 03:13 PM
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#12
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Administrator
Join Date: Nov 2001
Posts: 8,497
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Just to add our findings to the mix - while the increase in magnetic force should inversely affect the RPMs, we've found that it doesn't do so at nearly the rate it "should." So adding giant magnets might shave off a comparitive few RPMs, while adding mega torque, but then we can use that torque to gear it up and make it much much faster than the original, plus have better acceleration still.
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2002.08.04, 12:12 PM
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#13
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House Plant
Join Date: Dec 2001
Location: SoCal
Posts: 843
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not really contributing to this thread....
I have a pair of neos that I use in a squat bb can with a x speed arm and it generated loads of torque. I did use the squat magnets (which I think are not real neos) which are very weak by comparison. When I installed the neos I did feel a decrease in rpm but the torque gain was worth it as I could use a huge pinion.
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