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All,

I'm looking for an answer to this question:

If one is to energize any electromagnet (you pick the specs) for 1 msec, what is the power consumed by the electromagnet?

vs.

If one is to energize the same electomagnet for 1 msec, but this time, with a permanent magnet (you pick the specs) in close proximity such that the permanent magnet N pole is facing the electromagnet N pole so as to repel the permanent magnet, what is the power consumed by the electromagnet?

Sorry if this is known information.  I've not been able to find it and my experimental measurement capabilities are severely limited.

Thanks in advance!

M.

I totaly depends of the coil inductance, voltage applied and what amp turns you want to reach.
Amp turns is responsible for the magnetic flux strength. It's simply the number of turns times the applied current.
If your electromagnets is e'g 80mH 1000turns and 5 ohms then it will take you 1ms to reach 10 amps when 826V is applied.
Be aware of the peak power going into the coil at fast transients, in your case it comes to 10A * 826V = 8260 Watts.
If you just use 50V and let the resistance of the coil limit the current it will take you 0.2 sec (200ms) to reach 10 amps.
The peak power at 50V is just 500 watts but it occurs during a much longer time period and uses more average power.

This is where you calculate the respons time of a coil or an electromagnet for that matter.
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/indtra.html#c2

Hi Mondrasek, if you use an electromagnet rated at .01 Henry (10mh) with a coil resistance of 5 ohms and an applied Voltage of 10 volts, then at 1ms the power consumption would be 20 watts.

If the electromagnet is energized in proximity to a permanent magnet in repulsion the power consumption should be slightly more, maybe 21 of 22 watts.  When a magnetic force (the permanent magnet) is moved away from a coil of wire(in this case caused by repulsion) it generates electricity, so the power level rises, although only slightly.

Thanks guys.  Good info.

So, say one is to take a cylindrical electromagnet with opposite pole configuration.  Set it with the North pole facing up and uncharged.  Place a perminant magnet on top so that it's North pole is down and it is in contact with and in attraction to the ferous core of the electromagnet.  When you apply an electric source to the electromagnet it should repel the perminant magnet.

How much power is required to break the attraction of the perminant magnet to the electromagnet core?  How is the power of the electromagnet related to the strength/size of the perminant magnet? 

If two perminant magnets are forced together in a vertical arrangment so as to repel, and then the top magnet is released, it will accelerate upwards to a height much greater than where it will eventually settle and hover over the bottom magnet.  Can the electromagnet/perminant magnet arrangement be made to act the same?  What is the relationship of the power consumed by the electromagnet to the strength/size of the perminant magnet to create this equal opposing force?  Does the fact that we must first break the attraction require more power to the electromagnet than if there was not the attraction?  Does the acceleration of the perminant magnet away require more power to the electromagnet due to the fact that the perminant magnet is moving through the electromagnet field?  Or will the electromagnet field generate outwords from the center of it's core and drive the perminant magnet away so that the two fields never overlap?

Thanks again for your input.

M.

Quote from: mondrasek on August 02, 2008, 08:23:12 AM
Thanks guys.  Good info.

So, say one is to take a cylindrical electromagnet with opposite pole configuration.  Set it with the North pole facing up and uncharged.  Place a perminant magnet on top so that it's North pole is down and it is in contact with and in attraction to the ferrous core of the electromagnet.  When you apply an electric source to the electromagnet it should repel the perminant magnet.

How much power is required to break the attraction of the perminant magnet to the electromagnet core?  How is the power of the electromagnet related to the strength/size of the perminant magnet? 

If two perminant magnets are forced together in a vertical arrangement so as to repel, and then the top magnet is released, it will accelerate upwards to a height much greater than where it will eventually settle and hover over the bottom magnet.  Can the electromagnet/perminant magnet arrangement be made to act the same?  What is the relationship of the power consumed by the electromagnet to the strength/size
of the perminant magnet to create this equal opposing force?  Does the fact that we must first break the attraction require more power to the electromagnet than if there was not the attraction?  Does the acceleration of the perminant magnet away require more power to the electromagnet due to the fact that the perminant magnet is moving through the electromagnet field?  Or will the electromagnet field generate outwords from the center of it's core and drive the perminant magnet away so that the two fields never overlap?

Thanks again for your input.

M.

These are good questions mondrasek. The electromagnet and the permanent magnet are interchangeable in their effects, you obviously
have to "fund" the solenoid with external energy. Field strength is measured in Gauss. A permanent magnet located near an electromagnet
will effect the current required due to higher inductance but only when the inductors field in changing, not when it is a constant. A moving
magnet in the field of inductor will induce a voltage that either adds to or subtracts from the voltage already on the inductor - that is
exactly the "generated" current. Whether the magnet is attracted to an off inductor depends on whether you use a ferrous core inside
the inductive coil to focus the magnetic flux. The magnet will be attracted to the core material but not to the inductor wire itself.
If you have a inductive coil of wire with no core switched off with no load resistance => no letnz law braking recirculation current will
occur in the wire.

If you want to know comparable Gauss between a permanent magnet and an electromagnet you need what is called a nonograph of the magnetic field strength as a function of diameter and length of the solenoid you can Google for them.  The strength is dependent on a lot of variables. A nonograph is like a multidimensional graph where  diameter, length, number of turns, gauge of wire resistance of the particular kind of wire, applied voltage ect.

A much better approach may be to do an experiment! With some regular insulated hookup you can wind a one layer solenoid
on a glass tube or a sawed off nail. Nails are not the greatest core material, Bedini SGS suggests welding rods. Put some
current through the solenoid in series a wire wound resistor or rheostat variable resister and see what it can do. Power equals
voltage times amperes. If you need some more Gauss power, then wind on some more wire turns. Make sure your solenoid doesn't
overheat. It's actually better to build your overunity machine out of solenoids first as they are completely adjustable, even though
they require DC current. Afterwords one can translate the fixed current solenoids to permanent magnets and things should operate
the same way.

I have an electronic circuit in mind that can run a Clanzer like overbalanced Wheel with solenoids wound around those eight
glass tubes. Once the wheel is turning it would be much easier to add external magnetics and watch the wheel's rpm to keep
it's power high as you go, while switching off each electronic sector as you add external magnets. If you add adjustable solenoids
first it seems almost certain one could achieve a working wheel, even though it might be very touchy dependent on field strength.
I think it makes more sense to tune a operating wheel then it does to try to make a non-operating wheel operate very close to unity.
I will post the circuit's flow diagram here once I have generate it. The hardest part is that one will need a slip-ring mechanism to get
dc current to the circuit board rotating with the center of the wheel.

:S:MarkSCoffman
 

Quote from: mondrasek on August 02, 2008, 08:23:12 AM

How much power is required to break the attraction of the perminant magnet to the electromagnet core?  How is the power of the electromagnet related to the strength/size of the perminant magnet? 

Hi Mondrasek,

Would you answer this:  Do you wish to utilize the natural attraction of your permanent magnet to the core of the electromagnet before you want to switch the electromagnet on or it is not needed for you?

Thanks,  Gyula

@mscoffman  Wow, great answer!  A lot for me to digest in that.  I look forward to your future posts.

@Gyula  I don't believe there is a need for the attraction.  I believe it could possibly help to an extent, but also the perminant and electromagnet will never actually come into contact.

The idea here is to use pulsed electromagnets as the stators in the patent design.  If the electromagnet stators can be pulsed and fire the mass switch magnets instead of perminant magnet stators there would be no approach wall that creates a negative torque.  If the BEMF can be captured when the electromagnet is turned off (ala Bendini) then the only power needed to fire the mass switch (minus losses) is that of energizing the electromagnetic field.

I am trying to understand if the mass switch perminant magnet will fire to it's maximum height due to the energy of the electromagnet current AND the perminant magnet's force.  If the resulting PE of the raised magnet is equal or less than the energy used to energize the electromagnet this is also a loss.  If the PE is greater (due to the perminant magnet field) then we have captured that energy.

Thanks again for the great input.

M.

@mscoffman,

using electromagnets instead of permanent magnets would be really convenient for prototyping and testing. However, sometimes it can be much more difficult to actually construct a device. I challenge you to design an electromagnetic WhipMag. I'm sure we could learn a lot from it.

OC

Quote from: mondrasek on August 02, 2008, 08:23:12 AM
Thanks guys.  Good info.

So, say one is to take a cylindrical electromagnet with opposite pole configuration.  Set it with the North pole facing up and uncharged.  Place a perminant magnet on top so that it's North pole is down and it is in contact with and in attraction to the ferous core of the electromagnet.  When you apply an electric source to the electromagnet it should repel the perminant magnet.

How much power is required to break the attraction of the perminant magnet to the electromagnet core?  How is the power of the electromagnet related to the strength/size of the perminant magnet? 

If two perminant magnets are forced together in a vertical arrangment so as to repel, and then the top magnet is released, it will accelerate upwards to a height much greater than where it will eventually settle and hover over the bottom magnet.  Can the electromagnet/perminant magnet arrangement be made to act the same?  What is the relationship of the power consumed by the electromagnet to the strength/size of the perminant magnet to create this equal opposing force?  Does the fact that we must first break the attraction require more power to the electromagnet than if there was not the attraction?  Does the acceleration of the perminant magnet away require more power to the electromagnet due to the fact that the perminant magnet is moving through the electromagnet field?  Or will the electromagnet field generate outwords from the center of it's core and drive the perminant magnet away so that the two fields never overlap?

Thanks again for your input.

M.

Hi, ceramic permanent magnets have a magnetic flux density of  approximately .5 Tesla, neodymium magnets have a magnetic flux density of 1 Tesla and more.  Assuming your using neodymium(the overunity builders material of choice) then your solenoid/inductor/electromagnet would need the same magnetic flux density, 1 Tesla.  Anything less and the solenoid/permanent magnet may attract even when opposite poles are together.

Ordinary unpurified iron such as found in fasteners(nails, screws, and bolts)  has a relative permeabilty of at least 50.  The formula for magnetic flux density is

Ampere-Turns/length of the core material X ur

Turns=number of turns of wire
length=measured in meters
u=permeabilty of free space/air/vacuum  4pi x 10^-7
r=relative permeability

If you are using a nail or bolt that is .1 meters long for your core material (about 4 inches) with diameter of .01 meters(about .4 inches), the cross-sectional area of the bolt/nail would be .00007854.

For iron, r=50.  r X u =.00006283.  1 Tesla divided by .00006283 is approximately 16000 Ampere-Turns/meter.  16000 X .1 meters(length of the core) is 1600 Ampere-Turns. If the coil resistance is 10 ohms and you wish to use 1 Amperes then you'll need 10 Volts.  With 1 amperes you'll need 1600 turns of wire.(1 Amperes X 1600 Turns = 1600 Ampere-Turns).

The power consumption for the coil would be 10 Volts X 1 Ampere = 10 Watts.
At repulsion when the electromagnet is energized, force is calculated like this:

F=B^2A/2u

B=Total Tesla which in this case is 1(electromagnet) + 1(permanent magnet) =2
A=in this case .00007854
u=4pi X 10^-7

F=2^2(4) X .00007854/2 X 4pi X 10^-7=125 Newtons

Something else you have to consider is the pulse rate of your electromagnet, the faster it is switched off and on the higher the Reactance which is a form of electrical resistance.  So the higher the Reactance then the more Voltage needed to produce the necessary Coil power.  One way around this is to wind multiple coils around the core and wire them in parallel.  For example if you are using 100 feet of wire for your coil, you can divide it up in to 10 foot lengths. Wind each ten foot section individually one on top of the other and attach the ends of the wires together at each end.  This will reduce the Reactance and keep the required voltage from rising.  Hope this helps.

@ Xaverius.

Excellent.  That fills in a lot of the gaps in my knowledge. 

Very kind and generous of you to spell it all out.  I realy appreciate it.

Thanks again,

M.

Quote from: mondrasek on August 02, 2008, 03:12:33 PM
@ Xaverius.

Excellent.  That fills in a lot of the gaps in my knowledge. 

Very kind and generous of you to spell it all out.  I realy appreciate it.

Thanks again,

M.

Sure, glad to help out.

X

Quote from: mondrasek on August 02, 2008, 11:20:06 AM
@mscoffman  Wow, great answer!  A lot for me to digest in that.  I look forward to your future posts.

@Gyula  I don't believe there is a need for the attraction.  I believe it could possibly help to an extent, but also the perminant and electromagnet will never actually come into contact.

The idea here is to use pulsed electromagnets as the stators in the patent design.  If the electromagnet stators can be pulsed and fire the mass switch magnets instead of perminant magnet stators there would be no approach wall that creates a negative torque.  If the BEMF can be captured when the electromagnet is turned off (ala Bendini) then the only power needed to fire the mass switch (minus losses) is that of energizing the electromagnetic field.

I am trying to understand if the mass switch perminant magnet will fire to it's maximum height due to the energy of the electromagnet current AND the perminant magnet's force.  If the resulting PE of the raised magnet is equal or less than the energy used to energize the electromagnet this is also a loss.  If the PE is greater (due to the perminant magnet field) then we have captured that energy.

Thanks again for the great input.

M.

Hi M..

Thanks for the answer. The reason I asked is that there is known "trick"  or idea to defeat the attraction between the core and the permanent magnet so that you can even get a benefit of not using extra input power to defeat it.
About 2 years ago I mentioned this idea here, see:  http://www.overunity.com/index.php/topic,1621.msg16347.html#msg16347  and the link to that old patent is here, the old link mentioned there now needs log-in, this one is not: http://www.pat2pdf.org/patents/pat3670189.pdf
(explanation in Page 12, Column 2,  from line 31 and onwards)

With some tinkering of the size of the air gap between the bottom part of the electromagnet's core and a permanent magnet placed under the core and maybe using a slightly stronger permanent magnet there than the permanent magnet to be lifted above the electromagnet, you could reduce or totally eliminate the natural attraction between the core and the upper magnet and increase the 'tossing hight'  further upwards, with the same current into the coil.
The patent is rather long and needs patience to go through but may be worth studying from other aspests too, with respect to your gravity motor.

I agree, the energy in the flyback pulse (I prefer calling it flyback pulse instead of back emf) can also be regained when the electromagnet is switched off  (ala Bedini or by others) so this is another possibility to reduce input power.

rgds,  Gyula

EDIT: here is a test I made on this idea then: http://www.overunity.com/index.php/topic,1621.msg16889.html#msg16889

From my point of understanding:

Just use an idealized model:

Driving the (superconducting) electromagnet with a current source -
you invest certain energy to establish the magnetic field.
If you do that in the presence of a permanent magnet you need more -
or less ( depends n-s configuration) energy to establish this field.
You get the same energy back if the field collapses (back emf).

As long as you dont change the mechanical issues (move coil, magnet)
there is no extra energy needed to maintain that field. ( in principal you can
(have to)
short-circuit the energized superconducting coil now - means the current
goes on forever)

This means: it totally depends on the losses from copper (current),
and iron (flux) - how much energy you need. (after the field is established)
(in realworld)

If you move permanent (repelling) magnet away from the superconducting
electromagnet - (does some physical work) - you extract energy out of the
electro magnet(field) - the current goes down, the collapsing field has less energy
to offer.
If you energize the electromagnet - and move the permanent magnet repelling
near the em - you strengthen the energy in the field, the current goes up - and
the work you performed on moving the p.m. close to the e.m. adds to the flux
and can be found as extra energy in the collapsing field of the e.m. on "turning
off".

Thats at least how it "should" work.

As long as you use idealized models - everything is quite simple.

In real world - the energies involved are dominated by losses in copper and
iron. The work to establish the field or the back-emf happens "on the way".

BTW: good question

if you take the formula n(windings) x phi (flux) = L(ind) x I (current) -
a changed flux results in different current (if the permanent
magnet would?t effect the inductivity of the e.m.)
In real world there would be 2 extrem scenarios -
1.) The p.m. increases the ind. in a way where the current is
the same or lower
2.) The p.m. doesn?t effect the ind. at all  and the curren goes up

In an attracting situation, the current x ind. product will go down,
repelling situation: product will go up.

pls. feel free to correct me - but this should make sense.

Quote from: fritz on August 02, 2008, 06:52:07 PM
if you take the formula n(windings) x phi (flux) = L(ind) x I (current) -
a changed flux results in different current (if the permanent
magnet would?t effect the inductivity of the e.m.)
In real world there would be 2 extrem scenarios -
1.) The p.m. increases the ind. in a way where the current is
the same or lower
2.) The p.m. doesn?t effect the ind. at all  and the curren goes up

In an attracting situation, the current x ind. product will go down,
repelling situation: product will go up.

pls. feel free to correct me - but this should make sense.

Hi Fritz,

When I recall my earlier tinkerings with permanent magnets' effect on air and ferrit core coils' inductances, I can say the followings: 

There is no or only negligible effect of a pm magnet placed near or inside of a air core coil's  inductance (this is simply because the permeability of any permanent magnet is pretty near to 1, max up to 1.2 for ceramic magnets.

In case of ferrite or laminated core coils (any cores with ferromagnetic properties) the effect of a permanent magnet on such coils' inductance is the same as if you apply a DC bias current through the coil: it shifts the operation point on the core's B-H curve towards the higher or lower B value (depending on the direction of the DC current or in case of pm magnet it depends on which pole you place closer to one of the ends of the core and how strong the magnet is), hence the coil's inductance changes accordingly. The limits in both cases are core saturation.

IF these can be of any help for your above thoughts, then please ponder further on with these data.

rgds,  Gyula

Looking specifically at the example that Xaverius worked up, once the electromagnet field is established we will have 125 Newtons of repulsive force.  How high will the repelled perminant magnet go?  Pick whatever mass you want for the perminant magnet.  What matters is the potential energy of the perminant magnet at maximum height of the launch, so mass does not really matter.

We have the 125 Newtons pushing up (accelerating) but decreasing exponentially as the gap between the magnets increases.  Gravity pulling down (decelerating) at a constant (for these scales) rate.  This is relatively straight forward and I'd graph it in Excel if my home computer had that.  Anyone care to do it up real quick?

But what about the time lag for the repulsive force to reach 125 Newtons?  How long does the electromagnet need to be energized in order for the perminant magnet to reach it's maximum height?  How much lower than the theoretical maximum height would that be (due to the time lag)?   How much energy did the electromagnet require for this time period?  And how much energy can be reclaimed once the electromagnet is turned of by reclaiming the current generated as the magnetic field collapses again?

Make sure you use good core material or you will loose lot's
of power when you operate your electromagnet at 1ms pulsing.
I assume there will be more than just one pulse in your setup...
More like a 1ms pulse repeated at 50-200Hz or so.
Using pure iron is bad, it will run hot and consume lot's of power.

Core Loss:
---------------------------------------------------------------------
Core loss is extremely important in soft magnetics.
Core loss represents an inefficiency,
so it is highly disdained by the designer. In
many instances, core loss will render a particular
material unusable in an application. The most
glaring example would be the high-frequency
power-conversion transformer industry, which is
dominated by soft ferrites.

Powder cores are quite useful for high
frequency power conversion inductors.
The unit of core loss in both SI and CGS systems is
the Watt.
1 watt = 1 joule per second

Core loss is realized by two major components:
Hysteresis Loss and Eddy Current Loss.
Hysteresis loss results from the fact that not all
energy required to magnetize a material is
recoverable when it is demagnetized.
The wider and taller the hysteresis loop,
the more hysteresis loss a material has.
Eddy current loss is the result of small circulating
currents (eddy currents, not unlike eddy currents
produced in the wake of a boat) that are induced
when the flux density changes in the magnetic
material (see Figure 10). The amplitude of these
small currents is dependent on the Electrical
Resistivity of the material.
---------------------------------------------------------------------
Solid iron summarized:
It has very high eddy currents loss and pretty bad hysteresis.
You might end up getting a very hot electromagnet core.

I've set up and tested two electromagnets that I had available.  One was a potted solenoid coid from a pneumatic valve.  It draws about 310 mAmp at 24 Volts.  The second is a cylindrical cored industrial electromagnet that unfortunately has both poles on the same side, one in the center, and the other around the edge of the cylinder face.  It draws about 1 Amp at 24 Volts.

Both are capable of firing a sample neo permanet magnet over 12 inches vertical when energized momentarily by an industrial 24 volt supply.  I am able to place the neo inside the solenoid, a bit above center, for maximum acceleration.  The cored electromagnet needs to have a small gap pressent between it's core and the neo or the attractive force to the core will not be overcome.

My measurement equipment is anything but sensitive enough for looking for variations in Amps and Volts on samll enough time scales to convince me that I am not missing some variations.  I would expect to see more electrical power being consumed when the electromagnets are energized to launch the permanent magnet, vs. when they are energized without the permanent magnet present.  But I am not seeing anything like that.  Of further interest is when I force the permanent magnet back into the electromagnet field or move it around in it.  This also does not cause my Amps or Volts to noticably react in any way.  This makes sense to me since there is no additional power needed by a perminant magnet if it replaced the charged electromagnet in the same experiment.

So what is going on here?  Is my measurement abilities not able to show that the electromagnet requires additional energy in order to repel the permanent magnet?  Or is it the resultant Potential Energy of the raised permanent magnet not requiring an additional equal input of electrical energy to the electromagnet?

Thanks,

M.

I don't really get what you are looking for?
Is it simply repelling a neomagnet from 12 inches distance or what?

In this case I can tell you the field outside a solenoid is extremely weak due to the extremely large airgap between ends.
You cannot force the field outside simply because most flux takes the shortest return path, right through the solid core.
The only solenoid with a strong outside field (in the tesla range) is one that is supercooled into superconducting state.
This has to do with the molecular structure of materials when being superconducting.

Simply put.
A very strong solenoid has a weak outside field that diminishes very fast a couple of millimeters above surface.

@Honk,

If either electromagnet is energized momentarily it can fire a small permanent magnet from close proximity (zero inches away) to about 12 inches away vertically.  If the same electromagnet is energized for the same amount of time without the permanent magnet in place, does it consume the same electrical energy?  So far my gross test set up appears to show that the electromagnet consumes the same electrical energy in both cases.  Is my equipment not sensitive/sophisticated enough to measure the difference, or do both cases consume the same amount of electrical energy?

Thanks,

M.

Quote from: mondrasek on August 05, 2008, 10:51:20 AM
@Honk,

If either electromagnet is energized momentarily it can fire a small permanent magnet from close proximity (zero inches away) to about 12 inches away vertically.  If the same electromagnet is energized for the same amount of time without the permanent magnet in place, does it consume the same electrical energy?  So far my gross test set up appears to show that the electromagnet consumes the same electrical energy in both cases.  Is my equipment not sensitive/sophisticated enough to measure the difference, or do both cases consume the same amount of electrical energy?

Thanks,

M.

Hi, sorry for the late reply, it's been a long weekend.  Actually the amount of energy consumed by the electromagnets should be the same regardless of whether a permanent magnet is attached

Think of it this way:  compare the electromagnet to a cannon, the black powder inside the cannon barrel is the electricity, the cannon ball is the permanent magnet.  If the barrel is pointing straight up then compare the gravitational attraction of the cannon ball to the magnetic attraction of the electro and permanent magnets.  Now fire the cannon using 10 lbs of black powder.  The black powder produces X energy.  If a cannon ball is in the barrel, then it will obtain the energy of the black powder.  If NO cannon ball is in the barrel, the black powder will still produce X energy, only this time the energy will be dipersed into the atmosphere as heat.

Also, to calculate the amount of energy in the electromagnet use: E=.5xLx(I)^2

E=Energy
L=Inductance in Henries
I= Amperage

To calculate L use: u x n^2 xA/l

u=permeabilty

continued.......

n=number of turns of wire
A=cross-sectional area of the electromagnet
l=length of the electromagnet

u=4 x pi x10^-7 for free space/air/vacuum, multiply this number by 50 for ordinary unpurified iron, most electrical steels like in your electromagnet you would multiply by around 2000, sometimes more.

By understanding more about the energy of the electromagnet you can understand better how it affects the permanent magnet.  Hope this helps.

But doesn't that mean we are gaining the potential energy of the raised perminant magnet for "free"?

Case one:  Energize an ideal solenoid using an ideal power source for .1 sec.  Then remove the power source and substitute an ideal load.  Electrical power in = Electrical power out.

Case two:  Energize an ideal solenoid using an ideal power source for .1 sec., but this time have a permanent magnet initially inside the solenoid so that when the solenoid is energized the permanent magnet is accelerated upwards against gravity (doing work).  Then remove the power source and substitute an ideal load.  Also, capture the permanent at the the apex of it's trajectory.  Power in = Power out + Potential Energy of the raised permenant magnet mass.

I believe this uses the permanent magnetic field, and not the electrical power, to do work.

My idea for a simple demonstration unit involves reclaiming the electrical power used to excite the perminant magnet rather than power a load.  Does anyone know of a simple circuit design that would allow me to pulse the electromagnet for a short time (simple mechanical or duration adjustable electrical switch) and then capture the induced EMF from the solenoid once the pulse is removed and the field collapses?

Thanks again!

M.

You can use a simple H-Bridge to pulse your electromagnet in either direction.
See page 8 at this pdf on the H-Bridge design.
http://www.powernucleus.com/application_note/topologies_overview.pdf

But if you dont need to reverse the field you can just use a plain two transistor forward stage.
http://www.coremaster.com/appnotes/an107.pdf

The inductive kickback is recovered and clamped to the input voltage by the parallel diodes within
the transistors or extra diodes externally placed outside if using IGBT transistors instead of Mosfets.

If you place a permanent magnet within a magnetic circuit (core) it will shift the hyseresis (B/H curve) of the
material (magnetizing your core) and it takes the same or more power to reverse the field by the windings....
...thus no free power in this type of design.

Thanks Honk.

The permenant magnet is place within the windings of the solenoid and held so it's center is just above the center of the solenoid.  When the solenoid is energized it accelerates the magnet away using the repulsion of the magnetic fields.  The result is Kinetic Energy in the mass of the moving permanent magnet and Potential Energy in the mass of the permanent magnet if it is raised vertically in our gravitational field.

My simple test set up uses a solenoid from a Mac air valve rated at 24 V.  Resistance is ~75 Ohms depending on temperature so it draws around ~320 mA.  Using a MacDonalds drinking straw as a guide, I can place a 1/4" dia x 3/8" long neo permanent magnet inside the solenoid.  When I energize the solenoid momentarily the neo fires up the straw and out the other end, a total travel of about 18 inches.  Unless that reaction consumed the power used to energize the solenoid, it came only from the permanent magnetic field.  It did not reduce the permanent magnetic field.

M.

Hi Mondrasek,

In your test just described, your solenoid has no any magnetic core but air core, right?

I do think that the flux from the two like poles (i.e. one from the electromagnet and the other from the permanent magnet)  sum up or add up and there is no extra demand by Nature on further input power for shooting up the magnet.  Because in this case there is even no ferromagnetic core in the electromagnet, there is no B-H curve shift possibility,  hence the coil's self inductance changes very very little (as I mentioned earlier) when the permanent magnet is inside the coil.  The input power therefore should practically remain the same in both cases.

As I mentioned to you I made a very similar test but with ferrit core solenoid and defeated the natural attraction of the upper magnet to the core by placing a similar magnet under the core to make the upper part of the core a like pole wrt the bottom of the upper magnet.  And I did not notice any input current increase to the electromagnet.  It is possible though that in a dynamic case when the on-off switching of the coil is continuous the B-H curve of the core  gets shifted and this fact can cause the self inductance of the coil change also, hence the AC impedance of the coil also periodically changes a little: this may change the input power need a little but practically at such low rate on-off sequences it can be neglected I think.

The explanation for this situation you are asking is a strange case to accept but this is how I think and I am open for further explanations, even to the contrary.  :)

rgds,  Gyula

@mondrasek


You need to look at these transfers as vectors. Vectors overlap and add to eachother but the direction
of the vector is important. If you had a scope or a VOM meter you should just look at what happens
to the voltage and current as you move just the magnet in the vicinity of the electromagnet
with no power supply attached to it. That is what the powersupply would see from that
same motion.

You would see that the magnet acts as a generator but the polarity of the pulse would be opposite
the polarity of the power supply when it is hooked up. So that little bit of energy to move the magnet
would act as a load on the supply and use up that little bit of energy, that energy would then not be
available to BEMF when the electromagnets field collapses at turn off time. So CoE conservation of
energy still lives in overunity projects. The moving magnet will charge whatever energy took it to move
and it will charge the magnetic field of the electromagnet.

On the other hand if you jammed that little magnet back down into an operating field it would turn
additional energy over to field and the power supply would see it's output voltage increase slightly.

You should understand that .333ma times 24 volts = 1/3 *24 = 8watts. (this is middle range for electronics)
You may have only 1 watt second of energy in *all* the momentum of the wheel so you are going to
have the pulse the electromagnet and then try to recapture energy as much as possible as BEMF.


--- Ok, lets say you like what you are seeing and want to try to recapture BEMF from the circuit.

The easiest way to do that would be to look at the imhotep's Morray's Vibrator battery connections and
fire the coil with one set of 12volt batteries at the appropriate time then get the BEMF minus the energy used
to move the magnet which would be recaptured into the other set of batteries. You would have H-bridge drivers
(relays) that would swap the two battery sets so now the other set is the source and the opposite is now the
one receiving the BEMF after a short delay for stabilization, ready to fire when the next arm is in position.

The beauty of this is that you will probably get Bedini OU gain during back-pulsing the battery that will
compensate for the energy lost to moving the magnet. That is, if you don't mind your wheel running on
some plain old overunity energy.


:S:MarkSCoffman

Quote from: mondrasek on August 06, 2008, 09:11:33 AM

My idea for a simple demonstration unit involves reclaiming the electrical power used to excite the perminant magnet rather than power a load.  Does anyone know of a simple circuit design that would allow me to pulse the electromagnet for a short time (simple mechanical or duration adjustable electrical switch) and then capture the induced EMF from the solenoid once the pulse is removed and the field collapses?

Hi Mondrasek,

Your simple circuit could be a monostable (one-shot) multivibrator and here are two links to such circuits:
http://uk.geocities.com/ronj_1217/cm01.html    this uses a simple CMOS  integrated digital circuit like CD4001 or MC14001 etc,  this is a quad 2-input NOR gate and everything is included in the right hand column of the link.  Instead of the BC547 transistor you may use a heftier type like 2N3055 to handle your 300-400mA coil current.  To make the ON time of the monostable variable at you way, use a 1MOhm potmeter instead of the 1MOhm resistor, R2 and you may wish to increase the value of C2 too.

Diode D1 in parallel with the buzzer shown just kills the flyback pulse you wish to capture and somehow reuse, I suggest for the time being leave the diode in place to protect the transistor and later someone will surely show a method to utilize correctly the flyback pulse. Question is how do you wish to utilize the captured energy which in the simplest case is directed to a puffer capacitor through the diode.

Here is another well known circuit for your task, using a 555 timer IC: http://www.uoguelph.ca/~antoon/circ/monovib.htm   its ouput pulse from Pin3 may go to the base of also a 2N3055 via the 4.7kOhm just like in the previous circuit and of course the collector of the transistor goes your em coil like in case of the buzzer shown, the emitter goes to the negative battery pole.

rgds,  Gyula

@mscoffman  I liked your idea about removing my source and looking at the voltage and current at that end while moving the permanent magnet through it's path near the solenoid.  That lead me to what I believe is the problem with my test set up and measurements.  I am using an industrial 24 V power supply.  This supply is likely adjusting current/voltage for the changing load and not allowing me to see the real differences between charging the solenoid with and without the permanent magnet in place.  Switching to a battery in place of the power supply should make those changes measurable, even with my less sensitive equipment.

Thanks also for the information on recapturing BEMF.

@  Gyula.  Thanks to you too for all the information!  I look forward to reviewing it.

M.

Well, no luck finding the source of the energy that is accelerating the permanent magnet by switching to a battery instead of the industrial power supply.  I tried a single 9 Volt battery.  Current is now 120 mAmps to the solenoid.  When I move the magnet in and out of the charged solenoid the voltage reading is steady at 9 volts.  If the battery is not connected I can induce voltage spikes of ~4 Volts.  An interesting thing for me was that the voltage induced in the coil as the permanent magnet is moved in the "repelled" direction is the same polarity as when the electromagnet is charged and repells the permanent magnet.

I also see no change in current with any of the experiments, but here is the weakest part of my test set up.  I have no current probe to use with the o-scope.  So I have a Fluke multimeter reading current and that may miss any transients.  But I cannot get it to read anything but the expected 120 mAmps even while pushing the magnet through the solenoid field (which should be generating +- 4 volts).

Any other ideas?  Any way to use read the amps in the test set up with the o-scope and no current probe?

Thanks,

M.

Quote from: mondrasek on August 06, 2008, 02:46:54 PM
...
When I move the magnet in and out of the charged solenoid the voltage reading is steady at 9 volts.  If the battery is not connected I can induce voltage spikes of ~4 Volts. 

Hi Mondrasek,

The 9V battery also has a very low inner resistance like a good power supply so any voltage drop caused by changing a current in the circuit it feeds is also very low, hence you cannot see it with a 3 and a half (or even a 4 and a half) digit resolution your multimeter has.

Quote
...   I also see no change in current with any of the experiments, but here is the weakest part of my test set up.  I have no current probe to use with the o-scope.  So I have a Fluke multimeter reading current and that may miss any transients.  But I cannot get it to read anything but the expected 120 mAmps even while pushing the magnet through the solenoid field (which should be generating +- 4 volts).

Well if you have the true RMS type Fluke multimeter like Fluke 87, then you may try it reading AC current in its most sensitive (ACmA) range. In this AC current range the 120mA DC current will not show up of course but you may be able to cause some small mA change when moving quickly the magnet away or towards the solenoid.  You can test this without the battery first, (especially if you do not have the RMS measuring type Fluke) by setting the most sensitive  ACmA range and connecting parallel the tips with the solenoid, then quickly moving the magnet in and out. You will hopefully see some peak mA change...  EDIT: If you see about 4V induced peaks across the unloaded solenoid, then you close the solenoid with the ACmA meter, the AC peak current will approximately be 4Vp / 75 Ohm=53mAp in the solenoid.

Here is some hint on making an AC current probe if you happen to have a higher permeability toroidal ferrit core... :
http://cappels.org/dproj/aciprobe/ACCurrentProbe.html
No need for calibration and the low value resistor termination, only would be useful for indication with your scope...

rgds,  Gyula

Gyula,

I had a bit more time to play before leaving work.  The Fluke MM I am using says it is an RMS type so I tried to set up for ACmA as you said in parallel with the solenoid. But it would not read anything when I introduced the permanet magnet to the solenoid.  It also would not energize the solenoid.  I placed it in series and I was able to see very large readings while moving the permanent magnet in and out of the solenoid, both with and without power to the solenoid applied.  I then switched back to DC and was able to witness small fluctuations to the current readings while moving the magnet in and out.  I realized that I had added some more magnets to my original permanent magnet in order to increase the mass and keep it from firing so high since I had lost it in my work area several times after failing to catch it.  So the increased length of the magnet, and possibly the strength (I added a much larger diameter magnet, one that could not enter the solenoid, to the top) are allowing me to finally get readings.

I will work on making a toroidal current probe.  I assume I can use a core from an old circuit board.  We have a junk bin of various boards in our repair department that might have one.

Any reason this type of probe will not work with DC current?

I am still thinking the sample rate on my available o-scope is not high enough to show the diference in the current traces when charging the solenoid with and without the permanent magnet present, but it is all I have now.  My father teaches at a local University and he agreed to check with their Engineering Department to see if I can use some better equipment if I need to go further.

M.

Quote from: mondrasek on August 06, 2008, 12:42:17 PM
That lead me to what I believe is the problem with my test set up and measurements.  I am using an industrial 24 V power supply.  This supply is likely adjusting current/voltage for the changing load and not allowing me to see the real differences between charging the solenoid with and without the permanent magnet in place.

Actually that is the job power supply to keep it's voltage as constant as possible even as it's input current changes.
And yes, current probes will help. Unless you have a "crappy" scope it should be fast enough for these inductor speeds.
Also if you has any choice it would be better to use FET field effect transistors like IRF511 as they have very high off
resistance and can have very low on resistance like .01 Ohms on for specials, much closer to relay contacts. FET are
voltage mode triggered and that makes them easier to understand bipolars. Bipolars (2nxxxx) are current mode controlled
and harder to design with and that control current has a cost - they are often used less efficiently.

If you want to do power measurements you need to put a resistor across the coil when you disconnect all else - make
it identical to the DC resistance of inductor.  That way you transfer maximum power, when source and output resistance
(impedance) are equal. <= read this; it answers why you seem to see no effect when you have power connected vs nothing.
A battery's job is to have very low internal impedance.  As Guyla said. Good Luck!

:S:MarkCoffman

Quote from: mondrasek on August 06, 2008, 06:50:55 PM
Gyula,

I had a bit more time to play before leaving work.  The Fluke MM I am using says it is an RMS type so I tried to set up for ACmA as you said in parallel with the solenoid. But it would not read anything when I introduced the permanet magnet to the solenoid.  It also would not energize the solenoid.  I placed it in series and I was able to see very large readings while moving the permanent magnet in and out of the solenoid, both with and without power to the solenoid applied. 

@Mondrasek,

Sorry if I was not a 100% clear with my suggestion but I meant first do a induction test without any power supply or 9V battery  and then with the battery (or the power supply), ok?
And in the without battery test, I meant you connect the ACmA meter's tips directly to the coil's wire endings (to me this means a parallel connection, there is nothing in between the meter and the coil endings, ok?) and move the magnet. This way you test the induced current because the meter as a load simply places a short circuit onto the coil and the induced current is limited only by the coil own copper resistance + some inductive reactance.
You wrote you did not see anything in this parallel connection and placed the meter in series with the coil?  You lost me here, sorry.

If you happen to have access to better instrumentation by your farther's help,  it would save you a lot effort and time on not 'tinkering' with AC current probe building, I think.

Such type of current probes do not work on DC because their principle is based on normal transformer operation so a DC current can only bias them in one or other direction on their cores' B-H curve, that is all.  It takes a current change like an AC does to get transformation on the secondary coil.

rgds,  Gyula

Gyula,

I see that I misunderstood your suggestion.  I look forward to trying it correctly.  Unfotunately I must visit a customer tomorrow and will not be able to play with my simple test set up.

When I modified your suggestion to "in series" it was only a guess that you had accidentaly said parallel and truely meant in series. 

I have access to quality ferrous toroids and built a simple AC current probe this morning but of course it did not work on this DC circuit.  I suspected as much.

At least with every failure I learn something new!  Maybe that is what I enjoy the most?

Thanks for all your support.

Any other way to see the current trace of a DC electromagnet when it is initially energized?

M.

Hi Mondrasek,

Ok, no problem on misunderstanding.

In the meantime I learned about DC current probes as well but they use Hall effect device.  See this here:
http://www.testpath.com/Categories/Current-Probes-536114.htm   and their A622 would be good for you now  :) :
http://www.testpath.com/Items/ACDC-Clamp-on-Current-Probe-for-DMMs-and-Oscilloscopes-100kHz-100A-117-283.htm

It works from DC to 100kHz AC (has no toroidal core of course).  Other types with also both DC-AC ranges but with higher upper frequency coverage use both the Hall device and the toroidal core transformer.

I would suggest a very cheap but still correct solution both for DC and AC: use a 1 Ohm (or 5 or maybe 10 Ohm) value resistor and connect it in series with your electromagnet coil and measure the voltage drop across it by your oscilloscope.  Because your coil resistance is around 74 Ohm with this coil, the additional 1 Ohm (or say 5 or 10 Ohm if you wish to increase the current measurement sensitivity)  will not modify significantly the value of the original current (or if it does, you can correct it by some calculation).
And in the 50 or 100ms scope time range you surely will see the peak currents that are made by your moving the magnet in and out of the coil while your power supply or the 9V battery also feeds the coil . 
You can use several different value resistors to arrive at the final 1, 5 or 10 Ohm value, with the correct wattage, using the digital Ohm meter of the MM, no need for a high precision single resistor which tends to be expensive too.

rgds,  Gyula

Quote from: mondrasek on August 01, 2008, 07:13:58 PM
If one is to energize any electromagnet (you pick the specs) for 1 msec, what is the power consumed by the electromagnet?
vs.
If one is to energize the same electomagnet for 1 msec, but this time, with a permanent magnet (you pick the specs) in close proximity such that the permanent magnet N pole is facing the electromagnet N pole so as to repel the permanent magnet, what is the power consumed by the electromagnet?

The power consumed is determined by Ohms Law.  See the attached pic I
find useful.
For this calculation:
P=U2/R
so if you apply 10 volts across a 5 ohm coil:
(10x10)/5 = 20 watts

Is this the thinking of your question? :
Will the electromagnet in proximity to a permanent magnet require additional energy because the field of the p.m. is 'sucking' up the field of the e.m. requiring additional input?

Has this been answered? What would be the answer?

At first blush I would have said no - but am now thinking - 'maybe'?
And why/why not?
And the variation due to induction of the moving p.m. near the e.m. windings would be negligable? (see following)

Quote from: Xaverius on August 02, 2008, 04:15:02 AM
If the electromagnet is energized in proximity to a permanent magnet in repulsion the power consumption should be slightly more, maybe 21 of 22 watts.  When a magnetic force (the permanent magnet) is moved away from a coil of wire(in this case caused by repulsion) it generates electricity, so the power level rises, although only slightly.

So the power would rise because it's in repulsion resulting in an 'opposite flow' of charge due to induction of the p.m./windings to the e.m. requiring additional energy from the power supply?  And 1 or 2 watts?  Would that be a HUGE magnet?  Or would it be more like .1 or .2 watts (or less) for a small neo (.75x.5x.25)?  The p.m. is not moving ACROSS the windings but away, so even smaller?

Interesting thread - and I have alot of questions/thoughts to follow

tx

Here's my take/thoughts.  Hoping for further clarifications/corrections/thoughts

Quote from: mondrasek on August 02, 2008, 08:23:12 AM
So, say one is to take a cylindrical electromagnet with opposite pole configuration.  Set it with the North pole facing up and uncharged.  Place a perminant magnet on top so that it's North pole is down and it is in contact with and in attraction to the ferous core of the electromagnet.  When you apply an electric source to the electromagnet it should repel the perminant magnet.

How much power is required to break the attraction of the perminant magnet to the electromagnet core?

That would depend on:
Magnet size/strength
Core surface area/composition/dimensions
Air gap

Testing would probably be easier than trying to plug numbers into formulas.
You might hang/place the p.m. BELOW the e.m. and put a potentiometer between the e.m. and power supply and adjust it until the p.m. drops.

Quote from: mondrasek on August 02, 2008, 08:23:12 AM
If two perminant magnets are forced together in a vertical arrangment so as to repel, and then the top magnet is released, it will accelerate upwards to a height much greater than where it will eventually settle and hover over the bottom magnet. 
Can the electromagnet/perminant magnet arrangement be made to act the same?

Given enough power quickly enough - it could.

Quote from: mondrasek on August 02, 2008, 08:23:12 AM
What is the relationship of the power consumed by the electromagnet to the strength/size of the perminant magnet to create this equal opposing force?

You would need to make your e.m. the same strength as your p.m.  This requires the appropriate AT (amp-turns).  This is achieved by combining the variables of:
wire size/length
# of turns
core size/permeability
coil resistance
voltage applied

This link is a java coil simulator.  It's for an aircore but is helpful for determing # turns, resistance, wire length etc.

http://www.coilgun.info/mark2/inductorsim.htm

Quote from: mondrasek on August 02, 2008, 08:23:12 AMDoes the fact that we must first break the attraction require more power to the electromagnet than if there was not the attraction?

Yes 

Quote from: mondrasek on August 02, 2008, 08:23:12 AMDoes the acceleration of the perminant magnet away require more power to the electromagnet due to the fact that the perminant magnet is moving through the electromagnet field?  Or will the electromagnet field generate outwords from the center of it's core and drive the perminant magnet away so that the two fields never overlap?

This goes to the question in your first post.  Not sure - hoping for further answers....

- - - -

Something similar I've been wondering:

The Adams motor design applies the principal that it uses less power to:
Have a p.m. attracted to the iron core of an e.m. and then pulsing the e.m. with just enough power to negate that attraction to the core allowing the p.m. to continue onwards. (kind of like turning the iron core into an air core).  Rather than using the pulsed e.m. as attraction or repulsion to the p.m.
Is this a valid principal?  Why/why not?  What might be a better principal?

tx

@capthook, thanks for all the thought and input.  I'm glad you are interested by these questions.  When I first asked them I thought I would receive a simple textbook answer or reference to experimental data that would make everything clear.  I didn't imagine this was going to be a testing/theory brain teaser.

@all

So after looking further into Bedini for a BEMF capture circuit I went ahead and made Imhotec's Bedini fan this morning.  Destroyed quite a few good fans trying to find one that had the correct coil wrap configuration as well as trying to understand the various instructions.  But it works and I'm trying it out now to recharge and old NiMH 9V that has been in a box for 6 or so years since I was last into micro electric RC planes.  That circuit is what I wanted to understand so I could apply my ideas *if* the permanent magnet does not consume an equal amount of power from the electromagnet when it is fired vertically.  I still look forward to trying everyone's ideas back at my deck at work with the test setup on Monday.

I've coorresponded with mscoffman a bit in the background as well.  He said he has some more info to forward once he has the time to collect it and pass it along.  I'm interested in his response to my questions about the Bedini SSG circuit as well.  I'm trying to understand it from a clasical EE point of view (ie without the "radiant energy" theories) for now.  I'd like to hear your opinions on that as well if you have any.

Thanks,

M.

A little tip on the way to perfection.

When you design the best electromagnet possible, used in pulsed mode you must avoid to deep winding layers.
In pulsed mode you have higher core loss than you have copper loss, due to the hysteresis of iron.
I calculated the surrounding flux of a current-carrying wire to how much it decreases by distance.
This affects the level flux that actually penetrates the core and gives you the magnetism you desire.
As you can see in the picture, you should aim for a maximum of 5mm deep winding and also try to keep it as
tight as possible to fit the most amount of copperwire. Using thicker wire gives you lesser turns at lesser
inductance and vice versa. It all depends on the speed you intend to pulse it. More turns = slower response.
The number of turn doensn't affect the flux output, lesser turn require more current and vice versa.
Most important for high flux efficiency is the winding depth. To deep winding gives a lot of copper loss at
small gain in flux output.

http://www.imstrading.com/cgi-bin/flux-graphs?page=fluxgraphs

I put a 1.6 Ohm resistor in series with the solenoid per Gyula to read the votage drop across it as an indirect way of measuring current in the solenoid circuit.  I'm not really interested in the absolute values, just the difference in the current over time as the permanent magnet is accelerated away from it's starting position inside the solenoid.  Again, I did not see the results I expected.

Without the permanent magnet inside the solenoid the voltage measured across the solenoid and the in-line resistor both rise to their steady state values and hold when I press the switch connecting them to the 9V battery.  The o-scope traces look exactly like a square wave.

With the permanent magnet inside the solenoid the voltage measured across the solenoid and the in-line resistor both rise to the same values initially.  But the voltage across the in-line resistor then drops slightly before returning back to the expected steady state value.  The shape of the curve of this voltage drop and it's return to normal appears to be a nice parabola.  I assume the drop in the voltage curve represents is the permanent magnet accelerating and the return icurve representss the two magnetic cores increasing in distance.

So does this mean the current to the solenoid actually decreased as the permanent magnet was accelerated away?  Did the power consumed by the solenoid actually decrease as it did work upon the permanent magnet?  Or where (oh where) is the measurment error now?

Thanks,

M.

test

@modrasek;

If that is what you measure then that is probably it. One thing to think about is the
fact that the magnet has two poles and what does the solenoid see as it accelerates
the magnet through itself. It could be that the solenoid's stronger field actually forms
lenz current in the magnet. That bounce could also be from the power supply recovering.
See a better method below.

So if you see a decrease in current it maybe true. Don't forget that energy is measured
in "milliwatt seconds" and time plays a factor, if you have to keep the solenoid energised
longer to fire the magnet and increase the field then it has potentially used more total
energy.

IMHO you will not see overunity when an electromagnet accelerates a magnet. You will
see overunity if one PM lifts another. (but then lose momentum of the wheel trying to
pull them away from one another). There is also Smot runner gain, but one hasn't (yet)
extricated the runner to get it to the beginning of the track array.


@ALL

If you want to see overunity energy production from the Bedini
Fan I recommend use of acid/lead storage batteries or Gel Cells
for both the source and the charging battery as the overunity
part occurs due to battery chemistry. Don't use strange battery
chemistry ..and then say that the overunity part doesn't work,
please.

Small Acid/Lead Batteries are available in those automotive jump-start
units and small grey or orange Gel Cells are available in building
emergency lights that come on when the utility power fails. I like
the small batteries used in ICE motorcycles. They also make 9Volt
size acid/lead's I believe. 9volt batteries are probably too
small to support the fan well but it's worth a try.   

imhotep's Bedini Fan is an excellent experimental device as it doesn't
have an electrical interference footprint much larger then a normal
DC fan. imhotep's Morray's Vibrator Overunity Light unit also is
an excellently simple device, some experimentation will be required
to modify the base unit for other applications however. See
imhotep's youtube.com videos for more details on building these devices.
A Bedini Fan might be a valid manufactured product...overunity included!
Rather then build a Bedini SGS motor which I don't consider a good
experiment why not include *your own* electrically run wheel motor as
an actuator in a custom version of a Morray's Vibrator circuit?

imhotep's videos:

http://www.youtube.com/user/kojsza


The principal being demonstrated;

http://uk.youtube.com/watch?v=qaCk0jK--8s


----

Magnetic Pulse Experiment

The following experiment should let one see then pulse from a magnet
in a straw accelerating away from being fired by a solenoid coil when
you apply power through a switch. This isn't easy to do experiment but
here goes;

Remember that a capacitors store power proportional to it's voltage
while inductors store power proportional it's current. So it is
easier to think about inductor equations in terms of current.

What we are going to do is look at the current flowing through
two coils simultaneously and use one coil as reference and
subtract that from the coil that accelerates the magnet using
functions available on most oscilloscopes. The "invert" and "add"
channels functions.

a) you need;
   two identical solenoid coils and if you don't have scope current
   probes we can use two "current transformers" instead. (see Wikipedia)

http://en.wikipedia.org/wiki/Current_transformer

   A valid current transformer is a 20KHz bandwidth audio transformer
   line-to-load transformer with a 600 ohm impedance primary
   (audio line = 600ohms) and a 1.6 ohm secondary or the lower
   the better. I would say 100Watt audio transformer
   (audio bandwidth = 0->20KH) you then must solder a 600 ohm 5watt
   resistor across the 600 ohm primary or match the primary resistance
   in a way that is won't accidentally disconnect else a current
   transformer can become a shock hazard and damage equipment. Now
   connect the low resistance secondary(s) in series with coil(s)+power
   supply and attach one each primary+resistor to each of two scope voltage
   channels.

b) now flip the "invert" switch on the reference scope channel

c) find the "add" channels button on the scope

d) the "invert"+"add" now equals "subtract" one channel signal from
   the other

e) now one has to adjust the gain of the channels so that the pulse
   visible then the power supply is "fired" into the two solenoids
   then adjust the channels so that the difference is as small as
   possible when there is nothing fired from both solenoids.

f) You can validate that swapping the straw and magnet between
   solenoids should create a plus going pulse when the magnet
   is in one and a minus going pulse when it is the other.
   The magnet uses most energy at the beginning to accelerate
   therefore the pulse.

g) you can also watch as a magnet flies-by with an some other inductive
   coil attached to the scope. There will be a bidirectional pulse
   at the moment the magnet flies past, with the zero transition
   at the point of closest approach. The Bedini Motor 2n3055 transistor
   circuit uses a sense coil that works this way.


:S:MarkSCoffman

Quote from: mondrasek on August 11, 2008, 02:07:27 PM
.... The o-scope traces look exactly like a square wave.   

Hi Mondrasek,

It seems like a square wave first but if you change a little on the timebase of the scope then you can see a typical exponential voltage (i.e. current) curve every inductance produces.  See this link where you can find a series LR circuit with typical current-voltage curves in the function of time. Notice that the value of R in Figure 2-10A  includes the DC copper resistance (if I recall it 75 Ohm in your case) plus your 1.6 Ohm series inserted resistance too. Here is the link:
http://www.tpub.com/neets/book2/2c.htm

Try to reach similar scope pictures on your scope like in Fig. 2-10B  and then you may proceed to the tests with the inserted magnet, ok? 

Edit: I just noticed that on the next page of the link there is the typical exponential curnet curve shown in Fig.2-11 here: http://www.tpub.com/neets/book2/2d.htm   

Quote
With the permanent magnet inside the solenoid the voltage measured across the solenoid and the in-line resistor both rise to the same values initially.  But the voltage across the in-line resistor then drops slightly before returning back to the expected steady state value.  The shape of the curve of this voltage drop and it's return to normal appears to be a nice parabola.  I assume the drop in the voltage curve represents is the permanent magnet accelerating and the return curve represents the two magnetic cores increasing in distance.
So does this mean the current to the solenoid actually decreased as the permanent magnet was accelerated away?  Did the power consumed by the solenoid actually decrease as it did work upon the permanent magnet?  Or where (oh where) is the measurment error now?

When the magnets starts moving up, it obviously starts inducing current in the coil and if you see the current reducing parabolically during this time it should mean the current consumption for these moments also reduces. Interesting. Maybe the position of the magnet where it starts kicking out from the coil influences the current reducement? would stand to reason.  It would be interesting to see the shape of the curve in the same time base scope set where you already can nicely see the coil exponential current curve without the magnet.

rgds,  Gyula

@mscoffman.  Great information as always.

@Gyula.  I was able to see the correct exponential curve when adjusting the timebase as you suggested.  Unfortuantely I was working with another unfamiliar o-scope since the one I had played with earlier was out in the field with a technician doing actual work (not my desk experiments).  This new scope was taking too much time to learn and the only way to see the current drop due to the magnet on screen was to change the timescale so that the exponential curve was compressed to look like the square wave.

I was very interested by the current drop, but as mscoffman says, this drop is over a much longer time period than I would have expected compared to the saturation rate of the circuit.  Interesting effect, but what could it be good for?

I was curious if I could keep the circuit/solenoid charged only as long as the current drop was occuring.  In a failed attempt I replaced my mechanical switch with a custom design, utilizing the perminant magnet as a switch contact.  I placed the two wires oringally connected to the switch into the bottom of the tube supported by other elements so that they were contacts that would be bridged by the permanent magnet.  With this in place I then was able to move the solenoid up and down the straw to different locations with respect to the permanent magnet, into repelling and attracting, up and down configuarations.  When the solenoid pushed or pulled the magnet upwards it would break the circuit and allow the magnet to fall again, re-connecting the current.  The result was interesting at best.  The resultant pulses of current applied to the solenoid would only raise the magnet a less than noticable amount, though you could hear and see the vibration and arcing.  So the switching frequency was fairly high.  Putting the multimeter across the solenoid in AC mode caused readings from several hundred milliVolts to several Volts above the DC supply Voltage.  I'm not sure if that was due to the moving permanent magnet, the BEMF, or both.  But it was interesting all the same.  I'd like to see a similar setup that allowed the solenoid to to be energized for longer.  I don't see this as being easily possible with a mechanical set up and instead would require a variable rate switching circuit.  Again, I'm not sure what this would accomplish, but now I'm just playing while trying to think where the current drop effect could possibly be useful.

Thanks again to everyone for all the info and ideas.

M.

Quote from: mondrasek on August 12, 2008, 04:10:12 PM
  I'd like to see a similar setup that allowed the solenoid to to be energized for longer.  I don't see this as being easily possible with a mechanical set up and instead would require a variable rate switching circuit.  Again, I'm not sure what this would accomplish, but now I'm just playing while trying to think where the current drop effect could possibly be useful.

Hi Mondrasek,

The monostable circuits I referred to earlier would serve you as variable rate switching circuits ( http://www.overunity.com/index.php/topic,5279.msg119307.html#msg119307 ).

This way you could nicely approach the different L/R time values, adjusting shorter, similar or longer times to see the effect on the current shape.

rgds,  Gyula

I was hoping to avoid making solenoids but it looks like I'll have to in order to investigate some ideas further.  Where is the best place to get magnet wire on the net, especially with different color enamel in case I need to do bifilar ones?

Maybe on ebay the cheapest? 

http://business.listings.ebay.com/Wire-Cable_Magnet_W0QQsacatZ100180QQsocmdZListingItemList

http://stores.ebay.co.uk/Brocotts_Winding-Wire_W0QQcolZ4QQdirZ1QQfsubZ11474544QQftidZ2QQtZkm

http://cgi.ebay.com/eBayISAPI.dll?ViewItem&item=160268215204

rgds,  Gyula

I've ordered wire numerous times from both of these:

http://www.bulkwire.com/

http://stores.ebay.com/swords-science-treasures

Thanks again guys.  Magnet wire is on order.

I plan on testing some solenoid wrap configurations for my own knowledge.  But also, I am particualrly interested in wrapping a very long solenoid.  I want to see what happens to my previous test arrangement where I fire a permanent magnet from inside a long solenoid using repulsive magnetic fields.  From what I have tested earlier the current draw of the solenoid decreased as the PM accelerated.  If the solenoid was infinite in length, how far would the current draw drop?

All ideas and suggestions welcome!

M.

So I learned very quickly that my long solenoid appears to have magnetic affects mostly at the ends, so the middle is kind of a dead zome, similar to the tri-force arrays.  Many of you probably knew that already.

I've been playing with a couple of Imhotep's Bedini fans and threw my new long solenoid into that circuit in place of the re-charge battery.  It seems to have resulted in a resonant circuit.  I have no idea how it is working so I am again asking for assistance with understanding this strange behavior.  The details are here:  http://imhotepslabs.freeforums.org/viewtopic.php?f=3&t=34

As always, I appreciate your input.

M.

Hi Mond, glad to see you are still experimenting.
It's pretty easy to send that 2n3055 circuit into feedback self-oscillation; that's probably what's happening with yours. Also it's pretty easy to blow those transistors with these circuits, so buy a bunch. And they do vary some in their characteristics; sometimes an out-of-control oscillation can be fixed simply by trying a different transistor. Component layout, lead length, and so forth can also have a big effect on feedback oscillations.
I agree that you should use a current-monitoring resistor with your 'scope to do current measurements. If your scope is a modern DSO, it probably has math functions available that can do (roughly) correct power calculations for you, given the voltage vs. time from one channel and the current (voltage drop across the resistor) vs. time from the other channel. The digital multimeters like the Fluke can be pretty good at RMS values--in a certain frequency range!-- but doing the math in the DSO is usually more accurate, as the DMM usually assumes a sinusoidal input and yours won't be.
By connecting the two circuits of your bifilar wound coil in series, you have converted it into a monofilar coil.
The power to accelerate the PM out of the solenoid comes from the power supply, not the PM. You will be able to measure it eventually, as your technique and equipment improves.
You've gotten some very good answers in this thread.

mondrasek -

Any updates on your launching of a PM with a coil?

What are you final conclusions? 
Is there increased power draw from the air coil when the PM is present (and launched) vs. when it's not?
(The last I read is you had concluded the power draw may have actually decreased due to induction in the coil windings by the PM that was beneficial/power consumption decreasing)
What about using a long cylinder PM?

Any other thoughts, planned pursuits with this etc?

Sorry capthook, but I never got back to further testing on that.  What I ultimately wanted to do involved two new areas for me, one being launching the PM from a coil, and the other being reusing/reclaiming the electricity used to energize that coil.  I started a couple learning projects on the second part and never got back to the magnet launch (yet).  I am actually following your thread on winding a strong electromagnet very closely in the hopes that you and Xaverius might end up doing it for me!  I'd offer to help by continuing my original experiments but I find myself limited by the equipment and knowledge that I have at hand right now.  If I ever get back to it before you or someone else does, I'll be sure to let you know.

M.