Back EMF vs Collapsed Spikes.....

[z_p_e]

@z_p_e

I found that capacitive discharge makes things move faster. I mean if I hit my small TPU mock-up with 12 volts DC from my power supply, nothing much happens, but when I charge a capacitor to 12 volts and discharge it into the same TPU, I can feel the vertical wires flex or kick and I can hear a pop.

Grumpy says an inductor will discharge EMF and a capacitor will discharge MMF. Can you give an example of an inductor that can discharge enough of something to be called a discharge. Would the stator coils of a 3 hp DC motor qualify as an inductor cause I saw this discharge back into our on/off switch and smash it to bits.

Capacitors and Inductors are beautifully complementary.

You could call an inductor a "flux capacitor".

When an inductor is energized, the source voltage appears instantly across it, whereas the current, and hence flux takes time to increase. After fully energizing your coil with a steady DC for eg. and you cleanly disconnect it from the supply, the IK results in a reverse voltage, which again appears instantly across the coil terminals. The magnitude and duration of this reverse voltage is proportional to the amount of flux that was stored in your "flux capacitor" the moment the input current ceased, AND the amount of load across its terminals. It is the current and flux that "discharges" in an inductor during this phase.

The psuedo corollary in a sense is that capacitors work much the same way, but in reverse to inductors. Capacitors take time to charge to their source voltage, but the highest current required is at the instant juice is connected to it. When the cap is discharged, again the current is instantly at a max, whereas the voltage discharges at its natural rate.



According to Maxwell, and the way I usually regard it, is EMF is simply the potential difference across something. The other way it is generally regarded is through Faraday's law of induction, in that a moving magnetic flux will induce an emf in a conductor. EMF -> Volts

A nice simple definition I found on another forum for MMF is:

In simple terms, magnetomotive force is the effort exerted in creating a magnetic field. Increasing either the number of turns or the current in the coil will increase the mmf. The same changes will also increase the flux if the medium in which the coil is can carry more flux. To find the magnitude of the mmf a formular

mmf=turns x current

Now to summarize Grumpy, he said (and I add):

A discharging inductor -> Strong EMF -> Volts/Potential -> Faraday's induction
A discharging capacitor -> Strong MMF -> Amp-turns -> change in flux

So Grumpy can correct me if need be, but I think he is saying the following:

From what I mentioned above, a discharging inductor yields its highest (strongest) potential (or EMF) at the moment forward current ceases. A discharging capacitor on the other hand, yields its highest (strongest) current (and hence MMF) at the moment it's connected to it's load.

Hope that was helpful.

Darren

[Grumpy]

ZPE is correct.

Yes, you need a very large inductor.  The circuit that this energy is discharged into is very important to produce the desired effects.

Tesla seems to have preferred the Leyden Jar (capacitor) and stated that it's discharge was stronger than any explosive.

[quantum1024]

@ZPE - Perhaps I misunderstood you. Sorry.

You have mentioned "IK" several times,  perhaps this too is misunderstood, what does this stand for?

why then did Tesla use capacitive discharge instead? I don't know, but my best guess would be that, because he was using such high potential, that this was the easiest way to handle it, he did discharge it through another conductor according to his patents, perhaps this has something to do with it. The unloading of large capacitance in a very short burst into an inductor was a prime factor perhaps in creating the OU effect. best guess...

Capacitors and Inductors are beautifully complementary. YES!!!

@wattsup - The edwin gray system used capacitive discharge. in 3 phase. see patents.

@EMdevices - LOL - AHAAAA!!!!!!! Got it..... the lights turn on..... "shift"

@ZPE: I'm glad I asked the question of what MMF was, thank you for your description!!! YES this all makes sense now... 

Thank you all for your comments!!

[allcanadian]

@quantum 1024

why then did Tesla use capacitive discharge instead?

What everyone is describing is called Teslas "method of conversion" that is to charge an inductor with intermittent DC current, and collect the inductive discharges in a capacitor. When an inductor is charged with DC current the intensity of its magnetic field is described by the "amp-turns" of the coil and when the magnetic field discharges the voltage it produces is described by the "rate-of-change" of the flux. The important thing to remember here is that the discharge current has an infinate potential and can charge the capacitor to 40 times the supply voltage or more. It gets even more interesting when you consider what happens as the capacitor charges, whenever the capacitor voltage exceeds the supply voltage the inductor must "transform" more current into potential or voltage and at some point the inductive discharge can become pure potential, that is no current flow. I believe this is the "why" of teslas method of conversion, that is to charge a capacitor using a minimum amount of current. The question nobody seems to want to ask is "what qualities does this discharge current have that seperates it from conventional current?".  One clue is that this discharge current of thousands of volts discharged in an instant will obliterate all semiconductors in its path and in its surroundings as well, it will vaporize small copper conductors too.

[Grumpy]

Energy (not power) Energy