Winding a strong electromagnet

[Xaverius]

Interesting idea.  I'm not sure how to figure what the possible boost might be.  Is it something like:
The amps is half - but you are now influencing two cores - so the relative boost of each core is 50%, but you now have two cores influenced so you might see a total increase of 25% because you now have 2 magnets and are at the low end of permeability curve for each?  Not sure how to state what I'm thinking.  Could you explain your thinking a little more?

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Hoptoad!  Thanks for the link!  I've seen some stuff here and Utube that shows something similar to the effect in that link.  Can't remember the threads or links or titles etc.  Interesting idea to ponder.....

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Xaverius: yea - guess I spaced on the Gauss=Tesla conversion - used 1,000 instead of 10,000 

Yes - the Gauss listed is just a reference point - and for an absolute - would in fact be dependant on core permeability/width.  I guess a grade 2 hex bolt is somewhere in the range of 50-100u. I could convert the AT to AT/meter (show me please) and I could (throw a dart at the wall and) pick a number between 50-100 for a multiplier.    100 it is! (of course the goal is what - 2,000u electrical steel?)(and how does the permeability curve affect the calculations? Isn't 1/2 watt going to be way different than 10 watts?)(and which permeablity figure would you use? A materials specs is listed as intial, max, or the other one (can't remember it))
Now you see why it's listed as relative - you are the math guy 
The calculation I gave in the chart was a simplied one presented by a reed switch manufacturer as a way to give an approximation for AT/gauss conversion needed to activate the switch.
So in line 1 of the chart - please show me the calculation for converting 298 AT to the projected gauss. (tx)

I re-checked the # of turns for 125' ( I'm assuming you are ref. line 1 - the 22AWG).
Same result (actually 616 instead of 620)

1" = 25.4 mm
1' = .3048 m

1. Choose wire size: 22
2. input inner dimension (1/2" core): .5" x 25.4mm = 13mm
3. input coil length: 1.5" x 25.4 = 38mm
4. convert 125' to meters = 125 x .3048 = 38m
5. adjust the outer dimension slider until the wire length line shows about 38m wire length
6. observe: # turns, # of layers, resistance, and coil outer dimensions etc.

If you use two cores and wire them in parallel (360 turns each?) you will effectively use the SAME voltage but DOUBLE the amperage which will increase your consumed wattage X 2.  However you will DOUBLE the flux which will QUADRUPLE  the amount of magnetic FORCE.

AT/m: Your winding is 1.5 inches.  1.5/39(inches per meter)=.0384 meters.  If you have 360AT/1.5inches(.0384m) then H(magnetic field strength)=9375 AT/m.

Generally, the higher the wattage, the higher amperage at a steady voltage and therefore higher magnetic field strength until saturation.  The permability curve does not affect the wattage calculations, it's the other way around.  Also, I personally would use the initial permeabilty because you know that is what the minimum is, in other words the permeability will not fall below that number.  If a device will work with the initial permeability then it must work with the maximum.

Line 1 of the chart: converting 298AT to gauss:  given the length of the windings, 1.5 inches(.0384m) then H=298/.0384=7760 AT/m.  u @ 50=.00006282 for a hardware bolt, u @ 2000=.0025 for electrical steel, 7760 X .00006282=.487 Tesla/4875 gauss for  hardware bolt, 7760 X .0025=19.4 Tesla/194,000 gauss for electrical steel.  Of course electrical steel saturates at 1-1.5 Tesla so you would never reach that amount.

If you have 125 feet of wire and your bolt is .5 inches diameter then for one turn of wire, .5 x pi(3.1416)=1.57 inches/turn, which is 7.64 turns/foot.  7.64 x 125=955 turns.  Hope this helps, please let me know if I've made any errors.

[Kator01]

capthook,

another possibility here are special multi-layer-wires for fast impuls-switching :

Pay attention to the rectangular forms. This would be the optimum for the space used around the core :

http://www.pack-feindraehte.de/en/products/litzwire/litz_wires.html

I was not able up until now to find an american company with my search-enginge. This is a german manufacturer.But it will give you the idea.

Not cheap - for sure

Regards

Kator01

[capthook]

Line 1 of the chart: converting 298AT to gauss:  given the length of the windings, 1.5 inches(.0384m) then H=298/.0384=7760 AT/m.  u @ 50=.00006282 for a hardware bolt, u @ 2000=.0025 for electrical steel, 7760 X .00006282=.487 Tesla/4875 gauss for  hardware bolt, 7760 X .0025=19.4 Tesla/194,000 gauss for electrical steel.  Of course electrical steel saturates at 1-1.5 Tesla so you would never reach that amount.

If you have 125 feet of wire and your bolt is .5 inches diameter then for one turn of wire, .5 x pi(3.1416)=1.57 inches/turn, which is 7.64 turns/foot.  7.64 x 125=955 turns.  Hope this helps, please let me know if I've made any errors.

Xaverius - thanks for the calculations!!! Learning the math behind the function is of great value.

How did you figure this?  "u @ 50=.00006282"
And will 620 turns (298AT - consuming .5 watts power) on electrical steel produce (theoretically) 19.4T?  This seem excessively massive?  So one could greatly reduce the power below the already tiny .5 watt to achieve 1.9T?  And where is the width of the core/cross section taken into account?  Something doesn't seem to compute.

In the # turns calculation - you haven't accounted for wire size.  The larger the wire, the more feet of winding will be consumed per turn as the layers (and thus diameter) increase. (11 layers in the case of line 1)

Did you get the coil calculator working?
(and the yahoo toolbar install isn't from the java site, it just updates/installs your java
i_ron you might have downloaded elsewhere?)

[Xaverius]

Xaverius - thanks for the calculations!!! Learning the math behind the function is of great value.

How did you figure this?  "u @ 50=.00006282"
And will 620 turns (298AT - consuming .5 watts power) on electrical steel produce (theoretically) 19.4T?  This seem excessively massive?  So one could greatly reduce the power below the already tiny .5 watt to achieve 1.9T?  And where is the width of the core/cross section taken into account?  Something doesn't seem to compute.

In the # turns calculation - you haven't accounted for wire size.  The larger the wire, the more feet of winding will be consumed per turn as the layers (and thus diameter) increase. (11 layers in the case of line 1)

Did you get the coil calculator working?
(and the yahoo toolbar install isn't from the java site, it just updates/installs your java
i_ron you might have downloaded elsewhere?)

Hi CapNHook, glad to help out.  I tried to get Java to update last night but it wouldn't save to my browser, I'll have to toy with it later.

u=4 x pi(3.1416) x 10 x ^-7=.000001257 permeablity of air/vacuum

ur=relative permeability of other materials

ur of hardware iron= 50 x(4 x pi(3.1416) x 10 x ^-7)=.00006282

ur of electrical steel=2000 x(4 x pi(3.1416) x 10 x ^-7)=.0025

620 turns at 298AT consumes, I believe you mean .5 amperes(not watts).  Yes, theoretically it would reach approximately 19 Tesla but this is impossible because electrical steel saturates around 1.5 Tesla.  In a word, your AT is overkill, yes you could use less amperage.

The width of the core/cross section has to do with the amount of magnetic flux(webers).  The wider, the more flux.  I'm not sure of your exact application but I am working on a motor/generator and I need to produce as much flux as possible, to produce as much magnetic FORCE as possible to drive the rotor into overunity.  That is why I am using a 1 inch diameter EM, larger surface area(cross section) produces more flux, thus more force.

The number of feet of turn is the same per wire size, but you're right, the larger the gauge the more number of layers you would require.

Hope this helps, keep those cards and letters coming!

[capthook]

X - u da man!

When it comes to math - often I'll skim through it to get to the conclusions/summary at the end.

Having it translated into English is most excellent.
(I sucked at Spanish - and that's really what math is - another language.  A useable translation means an increase in the ability to 'speak' and understand it)



And yes - (line 1) .5 watt: 1.12V x .48A = .54 watts.  That's the thing - seems crazy strong for so little juice. Still seems something is out of wack?
Holding test resulted in: 3/4 lb. calculated Gauss: 4875
3/4" x 1/4" N42: 18 lb (stated spec - not tested) Gauss: 13,200
So the offered calculation would seem to imply a stronger holding force than the observed 3/4 lb?
(edit: then again, there is a difference is surface area 1/2" EM core vs. the neos 3/4"... and?)

As to application - I'm pulsing the EM in repulsion against a PM over a small airgap.
However - texts state attraction forces are stronger than repulsion.  The flux gets 'squeezed out the sides' in repulsion.  Just some side-thinking on the maybes.....