Winding a strong electromagnet

[capthook]

Redid the earlier test - results seemed inconsistent.  Battery used was an older one with lower charge (1.2V) and a DMM is not highly accurate measuring resistance of small OHMS.  So in this test I also did amp measurement in circuit and R=V/I for resistance with a fresh battery.

12' : .88v / .74a / 1.19 ohms : 0.6512w
6' x 2 : .46v / 1.44a / .319 ohms : 0.6624w

12' : 40T x .74a = 29.6AT  :  29.6AT / .6512w = 45.45 AT/w
6' x 2 : 40T x 1.44a = 57.6AT  :  57.6AT / .6624w = 86.95 AT/w
Edit: or is it 6' x 2 :((20T x .72a) x 2) = 28.8AT ?? This is the question??

191% increase in AT/w with parallel winding.

Additional testing/results/observations/comments requested !!!

- - -
TK -

"measure the current using a voltage-regulated power supply that won't sag the way a small battery does."

As resistance decreases, amps increases, and voltage decreases.

If you are powering your EM with a small battery, then this is a 'real-world' test of the operating conditions.

What is your take on the parallel winding? (2 wires that are 1/2 the length each of the original wire wound '2-in-hand')

Would you conclude that it will increase the efficiency of the EM by increasing the ampturns per watt?

What WOULD you conclude?

tx

[gyulasun]

12' of #30 AWG = 1.4 ohms
cut in half, twist the 2 ends together at each end:
6' x 2 in parallel of #30 AWG = .7 ohms

Hi,

If you cut the 1.4 Ohm 12 feet long wire in half, then you should get two 0.7 Ohm wire pieces, right?  (0.7+0.7=1.4)  And if you connect these 6 feet long wire pieces in parallel, then the resistance will be 0.35 Ohm, is that right?

How does this affect ampturns?  Xaverius has proposed it increases efficiency.... 

If I am correct with the parallel connected wires resultant resistance value, then assuming the same voltage source (like in the non parallel case), the AmperTurns should be about 2 times as many as it was in the 12 feet long wire case (because the number of turns for the two 6 feet long wires roughly halves, compared to that of the 12 feet wire turns and the current will be roughly 4 times as much than it was for the 12 feet wire, the resultant AT is 1/2*4= 2 times as many)   Assuming the voltage source inner resistance is much lower than 0.35 Ohm and little voltage drop develops across it so that the source is hefty enough to drive 4 times as many current through the quartered resistance.

rgds,  Gyula

[Kator01]

Tineskota,

of course it is done, the so called multilayer-wires. They are used for fast-power-puls-applications. See my last post.

Another user posted an american supplier of square-wire :

http://www.mwswire.com/square.htm

@xaverius : Can we agree on this : two coils on one core - where each coil has 10 windings - switched in parallell will enter the formula with  10 Turnes and no more. It resembles the mulitlayer-wires I posted above.
If you use a multilayer-wire ( 100 thin wires in parallel)  of the above spec you will not increase the Turns by 10 times 100 but only the Amperes by reducing the resistance depending of the 100 parallell inner resistance - let say by 50 % - therefore the result of the formula : Ampere x Turns = 10 Turns  x double Amperage because of 50 % less inner resistance.

LOL but I like this discussion. Yes we have to test it, , no way.

Regards

Kator01

[Kator01]

Folks,

I assumes you would use a power-sypply with stabelized Voltage , dont you ?

Kator01

[Xaverius]

So I have one long wire. I sever it in two lengthwise. Now I have 2 long wires, each with half the cross-sectional area of the original wire. Now I join the ends back together. And I have, magically, created a wire with less resistance than the original wire.

Sorry, there must be something I'm missing.

Not severed lengthwise, crosswise.  ex:  100 feet of wire would become 50 feet.