AC + Permanent Magnet - Vibration Amplification

[vineet_kiran]

 

Your thoughts please

[Floor]

@Vineet_Kiran

Your second question. 
Your described device is already a device.

Your first question ?

Is this amplification ?

It is important to understand that amplification is just the replication of something on a larger scale, something like the way a pantograph produces an enlarged copy of a drawn figure.  Electronic amplification takes an energy input that is greater than the energy output.

Why is the motion of the spring larger with the magnet in place than with out the magnet ?

There are several reasons for this.

1. The alternating current input and the magnetic field it produces (with out the magnet) reverses before the spring has time to move,  this is due to both 1. the springs inertia and stiffness and 2. the strength and rate of change of the magnetic field you are producing. 

2. The magnet in close proximity to the electromagnet changes the inductive characteristics of the electromagnet. It is changing the shape of the wave you would see if you viewed it on an oscillascope. During one polarity of the input electric current,  the permanent magnet field is opposing the magnetic field of the electromagnet, during the other electric polarity it contributes to it. 

Electric currents in a conductor, produce a magnetic current that rotates or spirals around that conductor at a right angle or a near right angle to the direction of the electric current.

A moving magnetic force will produce (induce) an electric current in a conductor when the magnetic force  passes through the conductor.  This induced electric current is in a direction that is at a 90 degree angle to the direction of the motion of that magnetic field.

Electric voltage stimulates electric current to flow in a conductor, but the current flow is not absolutely instantaneous. The current flow will rise to it's maximum over a very brief period of time. Current lags behind voltage. (how much current can flow in a given conductor is described by OHM's law). 

The magnetic force around a conductor is a result of the current flow, and also rises to it's maximum value over a very brief period of time.  As the current is rising the magnetic force is increasing / expanding.  This briefly expanding magnetic force passes through the conductor carrying the original electric current, the same current that produced the magnetic field in the first place. 

Because an expanding magnetic force is also a moving magnetic force, the expanding magnetic force around the conductor induces a second electric current in the conductor,  as it is passing through it.  This second current is in the direction opposite to the first (original)
current. This phenomena is called inductive reluctance.  It has a counter part when an electric current decreases or is shut off, and the magnetic force around the conductor collapses, this is called inductive reactance.  Together they are called the inductive impedance of an electrical component, or impedance for short, if I am remembering correctly, this combined with a components resistance is called total resistance. 

These complex interactions of the electrical and magnetic forces in your device, can cause harmonics, that appear as high spikes of power, dispersed within intervals of lower power in the magnet force produced by your device. Harmonic spikes are always at a lower frequency than the whatever that produced them.  If the intervals of these harmonics are slow enough, they will give your flexing iron strip time to react to the magnetic force.

Please note that this response is off the cuff.  I may have misstated some part of the above. It's been a while since I had my head immersed in this stuff.   

I suggest that you verify my info through wikkipedia etc.  But I'm pretty sure that my overall explanation is sound.

                           enjoy
                                floor

[gyulasun]

Your thoughts please

Hi vineet_kiran,

I think the best word to express what happens in your setup is flux addition, i.e. the flux of the PM is added to the flux of the electromagnet in those moments whenever the magnetic pole N is created on top of the electromagnet and a S pole is created at its bottom. Of course the electromagnet poles change as per the AC excitation dictates and there is no flux addition in the moments when the top of the electromagnet has a S pole and the N pole is at its bottom.
(Years ago I checked a DC electromagnet and a PM magnet combination and found flux increase, a second permanent magnet was lifted higher in a glass tube, placed above the electromagnet with like pole at its bottom, by the combination of the fields versus the lonely electromagnet field, using the same input DC power to the electromagnet coil. You find flux addition when you attach for instance two cylinder magnets lengthwise: you get a stronger field at the top and bottom ends of the combo, also the shape of the field becomes more oval-like .)

Gyula

[vineet_kiran]

 
@gyulasun, floor

Thanks for the responses.  I think both answers are acceptable.  As floor said spring may not oscillate with same frequency when with magnet and without magnet. 

As gylasun said this is definitely a case of flux addition which we can make out just by seeing the force with which spring oscillates.

Another important thing I observed is that the permanent magnet is kicking the flux out of the core.  Without magnet you will feel that the magnetic force is only near close vicinity of the core but when you place a PM below the core, you will feel magnetic force at considerable distance above the core.

This kicking of flux out of the core  looks interesting  to me because you can make use of this  'flux out of the core'  without affecting the power input to the core ie., you can avoid the lenz effect in the core by taking flux out of the core. ( may be I am wrong - need clarification)

[vineet_kiran]

Years ago I checked a DC electromagnet and a PM magnet combination and found flux increase, a second permanent magnet was lifted higher in a glass tube, placed above the electromagnet with like pole at its bottom, by the combination of the fields versus the lonely electromagnet field, using the same input DC power to the electromagnet coil. You find flux addition when you attach for instance two cylinder magnets lengthwise: you get a stronger field at the top and bottom ends of the combo, also the shape of the field becomes more oval-like .

Gyula

@Gyulasun

I agree with that.  Even if you join two permanent bar magnets,  you will get strong poles at the farther ends and poles at the joint will be nullified.

To add a permanent magnet with AC flux,  you have to couple a diametric magnet with AC flux with magnet rotating in synchronisation with changing AC flux.  I had posted a thread with an experiment making use of this principle but surprisingly I didnot get even a single response!   Link is given below.

http://www.overunity.com/11947/super-induction/msg310932/#msg310932


Regards,

Vineet.K.