Electromagnet Question

[gyulasun]

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

[mscoffman]

@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

[gyulasun]

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

[mondrasek]

@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.

[mondrasek]

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.