Overunity Device using Magnets in the 1920's ?

[Mr.Entropy]

G'day all,

Perhaps one of you electronics guys can answer this one.

Given the same current, is there a difference in the magnetic field strength between a high impedance electromagnetic coil (say above 1 Kilo-Ohm, many windings with very thin wire) and a low impedance coil (say 100 Ohm, fewer windings, thicker wire)?

Hans von Lieven

Hi Hans,

When you run current through your coil, the energy goes into 2 places -- resisitive heating of the wires, and into the magnetic field.Ã,  The energy that heats the wires is lost, but the energy that goes into the magnetic field is not -- if you don't use it to power some device, then the coil gives it back to you when you stop powering it.

In order to make efficient use of your coil, then, you must ensure that only a small portion of the power you put in goes into resistive heating.Ã,  You will need to be able to calculated the coil's inductance to determine this.Ã,  Your coil is essentially an air core solenoid, and there are many applets on the net that will do that calculation for you.Ã,  Assuming an air core might give you an inductance value that is too small, but that's an error on the safe side.

If you're driving the coil with an AC waveform, then ensuring that most of the energy goes into a the magnetic field means ensuring that the inductive reactance is high compared to the DC resistance, since power lost = current^2*resistance, but power stored in the field = current^2*reactance.Ã,  Ã, The reactance in ohms is 2*pi*f*L, where L is the coil inductance in Henries, and f is the AC frequency in Hz.Ã,  Notice that your coil is more efficient when you drive it with a higher frequency, but the mechanical systems you're trying to drive will have a pretty low frequency limit.

If you're driving the coil with DC voltage pulses, then you have to use a different calculation.Ã,  It's not a standard formula, so I'll work it out below.Ã,  Given your coil inductance L, DC resistance R, and pulse width T seconds:

dI/dt = V/L
so instantaneous current during the pulse is I = Vt/L
instantaneous power in = VI = VVt/L
so average P_in = VVT/2L
instantaneous loss =Ã,  I^2 R = RVVtt/LL
so average P_loss = RVVTT/3LL

so average P_loss / P_in = 2RT/3L

Cheers,

Mr. Entropy

[hansvonlieven]

G'day all,

Sad news. 

The motor, as designed DOES NOT WORK ! The results of some tests I did it show clearly that it is not a goer in its present form. I will write my tests up. I just want to issue this warning now already so no-one wastes time and money on a dud.

Back to the drawing board, and haven't we all been there before. 

Hans von Lieven

[nightlife]

hansvonlieven, did you get any positive results from any of the concept?

[hansvonlieven]

G?day all,

Well, as they say:  ?The best laid plans of mice and men?.?

As it is the motor is a dud. I should have known! I have no excuse other than getting carried away with what turned out to be a stupid idea

Let me tell you how I found out.

When I published my first test concept I used discrete magnets instead of the horseshoe magnet as specified in the Freischwinger. Post 19, page 2 in this thread.

Tak22 expressed doubts about this. He said: ? I'm still not sure this can be done without a horseshoe style magnet. Can't know for sure until tried I guess.? Post 20, page 2.
I decided to test this. In my tests I used several configurations.



Here are the seven configurations I tried.
Fig. 1   shows the horseshoe arrangement as in the original Freischwinger.
Fig. 2   shows the use of two discrete magnets in horizontal alignment.
Fig. 3   shows the use of a bar magnet.
Fig. 4   shows the use of two discrete magnets in vertical alignment.
Fig. 5   shows the use of two discrete magnets in vertical alignment with a steel bar.
            connecting the magnets, thus mimicking a horseshoe magnet.
Fig. 6   shows the use of a magnadur magnet. (Magnadur magnets are ceramic
             magnets with their poles on their flat faces).
Fig. 7   shows the use of two magnadur magnets connected with an iron yoke.

In contrast to the Freischwinger the reed did not move inside an air coil. I simply wound the coil directly on the reed itself as I was not interested in the detrimental effects in relation to sound fidelity. All I wanted to test was movement.

This is where it showed up that the motor as designed does not work. In all instances the application of a forward or reverse current sent the reed in the appropriate direction up to the strongest point of attraction, the dreaded ?stick point?. At this point, I erroneously thought, that the application of a reverse current will propel it further. This worked well, but only in one direction, in the direction away from the midpoint!



This means of course that the horseshoe arrangement in the motor is out. As the reed approaches the magnet there is a counter force which cannot be eliminated with a pulse. Perhaps this could be overcome with inertia from a flywheel, but that is not the idea here. On the other side of the magnet it is an asset, since a pulse applied there aids rotation.

Does that mean the motor is doomed?
Not at all. It just needs a bit of revamping. My tests indicate that this can be done. I will write up my test results and the changes to the design shortly. I just wanted to show now why it does not work as designed before someone tries to build it.

Hans von Lieven

[sparks]

    Ampere-turns will give you the flux density of the coil. With negligible difference other then resistance losses when smaller gauge wire is used.  I use to rewind electric motors and when in doubt always went to the largest diameter wire we could get in the stator slots to avoid overheating.  AWG to metric diameter wire conversion was always fun.