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Author Topic: Back-EMF Manifesto - A Key, hidden in plain Sight.  (Read 21821 times)

tinman

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Re: Back-EMF Manifesto - A Key, hidden in plain Sight.
« Reply #30 on: February 24, 2018, 12:18:31 AM »
 author=dieter link=topic=17611.msg517059#msg517059 date=1519398260]


Quote
This isn't so much about you being wrong, but much more about a somewhat pathetic attitude to jump in and call people idiots, "proofing" that every word they say is wrong while diverging from the thread subject.

When i referred to !idiots!,i was referring to those that post web pages full of garbage.

I have not diverged from the subject--which is Back-EMF Manifesto -->something you continue to mix up with inductive kickback,which it is not.

Magluvin

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Re: Back-EMF Manifesto - A Key, hidden in plain Sight.
« Reply #31 on: February 24, 2018, 04:51:29 AM »
Here is where I am with the various 'emf's' we are discussing.....

For some strange reason, going to electronics at a vo-tech school 10th through 12th grade, and then 2 years at Electronic institute of Pittsburgh, all back in the early 80s, I had gotten the impression that the currents produced in the coil after taking away the input were reverse currents, never really thinking or even getting close to considering the FE ideas back then of such presented on this and other sites. We didnt cover that in votech with solenoids, relays and switching supplies. We didnt really do much in the supply area in Pittsburg either. Just solenoids and relays using snubbers to dissipate the coils self developed emf's when power was taken away. It was strange in a way that I was sure that it was a reverse current that the diodes were redirecting back into the coils, for reasons that the HV developed could harm a driving transistor or other sensitive circuitry. If they had conveyed the ideals properly and I just had it wrong, well I have to assume that it was the words flyback and back/counter/reverse emf that jilted me. Naturally they might have some influence, as we have seen over the years here, including me, on the idea that the currents out of the coil were reversed when power is taken away. All the "we would want to keep these hv potentials from feeding 'back' into the circuit" etc, etc. Had me going until around 10yrs ago and I was in utter shock to find out and test otherwise. Maybe it was that I didnt grip the importance of thinking on electron flow all the time in this game and just put more effort into + and - and paying attn to voltage/current limits and such in circuits. It wasnt really until I was jolted by actual facts that it is now a first and foremost thing to be concerned with in all electrical/electronic things that I en devour in to now, for the last 10 years. Either schools were just that bad at getting us to be on the the 'first and foremosts", or I was just a 'you big dummy', as Fred Sanford says. ;D But over the last 10 years, I have seen many many many others that seemed to be in the same position and train of thought that I was in. MANY!. I mean how can this be with sooo many others also? Are, or were we all just big dummy's? Why is it that soo many have the idea that the currents out of the coil are reverse of what was being put in? Fly'back'? Reverse emf? back emf? Even 'counter' emf???  Even well knowing that a diode would only conduct with the neg potential at the cathode and positive at the anode and still not seeing the kind of simple puzzle that the circuit of the coil and snubber and input circuit represent. I cant remember all the exact details of the learning sessions on the use of snubbers on relay and solenoid coils, but I do recollect that we didnt stick with that subject much longer than to just understand that the diode was necessary to protect other circuitry the coil was involved with from the hv potential of the coils when input was disengaged from the coil and then we moved on. Switching supplies and dc to dc converters were most likely just coming into play in the 80s to blend in as common electronics knowledge then, as I dont recall any of that really. Or, I just didnt take a lot of interest in it and just did what I did to pass the grade. I dunno.  But I was definitely in the belief that the output of the coils was a reverse flow of currents compared to the input.

I didnt get into doing anything really with electronics other than my own things till I was 26. Job at vcr/electronics repair shop. Bout 7 years and then car audio got me hooked. Like I got good at fixing car amps, with switching supplies, and vcrs had them also, but it never dawned on me as to visualizing the current flow in the operations of these circuits, but I knew how to fix them, thinking I fully understood them. Like I understood polarities and specs for transistors, diodes, caps. I understood ratios of step up and down transformers and the like, but never went as deep into it all till I came here and was corrected. I argued it at first and for some time. And searching for the truth forced me into a position of having to look deeper to find out what was what. But now I know.

I consider back emf and counter emf and reverse emf to not have anything to do with the coils output when the input is removed. Counter/back/reverse emf is the emf developed in the coil by way of self induction and the cause of the delay from the 'time' the input was applied to the coil, up until the point of max field and max currents reached dictated by the resistance of the coil/circuit.  Cemf, the term I prefer, as it most resembles the 'opposition'(counter) to the input of the coil that makes the coils self induction 'impede' the input during a period of time depending on the inductance value. After truly finding out these things, I made my own terms that I use here at times for the coils current outputs. Field(magnetic) Collapse Currents or even FEMF for Forward EMF. I prefer to call them Collapse Currents as I understand that the opposition(impedance) to input is due to the 'outward' growing magnetic fields of each winding cutting all the other windings, and when the input is taken away, that field collapses inward thus producing forward currents in the coil, opposite of the previous cemf opposition currents developed when the field was initially expanding outward and impeding the input. So yes! Absolutely! When the input is taken away from the coil, the output currents of that coil are forward going currents in reference to the initial input current that was taken away. To me this is ingrained. This is fact. This is real. I can see it in my mind. I see the fields expand and collapse. I see the currents flow in the circuit in my head.

Flyback is a term that was developed to describe the flyback of the trace in a crt of an oscilloscope or a television set. Somehow I suppose that the flyback transformer maybe had some ideological influence on bringing the term to life elsewhere in electronics. But I dont consider it to be an actual term we should use when considering pulsing coils and what and which way the currents flow in the process.

When I truly found that the coils output was actually forward and not reverse, I freaked. I was all up into a conspiracy of it all. I was angry! I thought, 'what was it that they taught me back then? Were they hiding something??? And why?? Was there a secret to FE there??  I mean really if you think about how many others have had the same false conclusions over the years here alone, maybe there was a conspiracy to it all. ???   But these days I just believe it is just a mass misunderstanding that has/had come about due to the not really knowing what these 'emf' terms mean, along with the toss in of the term flyback, that seems to instill the ideas into peoples heads most likely before they really get into firstly visualizing the electron/current flows and magnetic field expanding and collapsing functions during the circuit operations. Yup. Im nuts. Im seeing things. :o ;D

I visualize the current flows. I visualize the mag fields building, collapsing and interactions. In 'this business' it is a must. Fixing vcr's, amps, tv's, etc, it is not necessary to visualize that way of such things.  But it is a requirement when developing things and designing parts, coils, semiconductors, OU devices, etc. And here we are. ;)

So people that want to dip their toes in these waters need to dig in and try to get into having those visions of electron/current flows, and magnetic fields, physics of all natures necessary to understand things 'here' and be able to discern whats real and whats fake or even identify others and your own mistakes along the way.

Ok.  Nuff said for me on that today.

Mags

Magluvin

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Re: Back-EMF Manifesto - A Key, hidden in plain Sight.
« Reply #32 on: February 24, 2018, 05:11:31 AM »
And I think Falstads Circuit Sim, which shows current flow in the circuits operations is a great tool for learning to visualize the current flow in circuits.

Mags

Magluvin

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Re: Back-EMF Manifesto - A Key, hidden in plain Sight.
« Reply #33 on: February 24, 2018, 05:40:23 AM »
Now, very quickly as I have a job to work on tonight, below is how I see the way mag fields engage the core of a toroid or any closed loop core and how the fields of a say primary winding on the left side of the core can 'cut' a secondary on the right side of the core. All the action is in the hole of the core, other than leakage on the outer sides. ;D So no, I dont believe that the mag field is only in the core.  The core is only a path material that allows the fields to come together and be able to make sharp turns, etc.  When we look at the field mushroom out of the end of a magnet, those like fields repel and are pushed outwards away from one another. A magnetic core 'helps' to negate or better to say, reduce that like field repulsion that happens outside a magnet or a core and allows the fields to be denser and to bend and turn in the cores path much much easier than when the fields are outside the magnet or core. That is my contention on that subject. ;)

Mags

Magluvin

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Re: Back-EMF Manifesto - A Key, hidden in plain Sight.
« Reply #34 on: February 24, 2018, 08:54:11 AM »

 Why is it that soo many have the idea that the currents out of the coil are reverse of what was being put in? Fly'back'? Reverse emf? back emf? Even 'counter' emf??? 

Mags

Woops. Forgot a big one.  Inductive Kick'back'    ;) ;D

Mags

forest

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Re: Back-EMF Manifesto - A Key, hidden in plain Sight.
« Reply #35 on: February 24, 2018, 11:03:13 AM »
Someone should confirm it Magluvin. Proof is simple but a long core is needed. If indeed flux is passing in center hole of core then the secondary could be very loosely wound on the opposite leg of core and still get more induction then in the same arrangement of coils without core.

tinman

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Re: Back-EMF Manifesto - A Key, hidden in plain Sight.
« Reply #36 on: February 24, 2018, 11:40:37 AM »
Someone should confirm it Magluvin. Proof is simple but a long core is needed. If indeed flux is passing in center hole of core then the secondary could be very loosely wound on the opposite leg of core and still get more induction then in the same arrangement of coils without core.

Yes,a loosely wound secondary will produce an EMF across it-->but it is not the magnetic field that is the cause of this EMF across the secondary.


Brad

partzman

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Re: Back-EMF Manifesto - A Key, hidden in plain Sight.
« Reply #37 on: February 24, 2018, 03:46:09 PM »
Now, very quickly as I have a job to work on tonight, below is how I see the way mag fields engage the core of a toroid or any closed loop core and how the fields of a say primary winding on the left side of the core can 'cut' a secondary on the right side of the core. All the action is in the hole of the core, other than leakage on the outer sides. ;D So no, I dont believe that the mag field is only in the core.  The core is only a path material that allows the fields to come together and be able to make sharp turns, etc.  When we look at the field mushroom out of the end of a magnet, those like fields repel and are pushed outwards away from one another. A magnetic core 'helps' to negate or better to say, reduce that like field repulsion that happens outside a magnet or a core and allows the fields to be denser and to bend and turn in the cores path much much easier than when the fields are outside the magnet or core. That is my contention on that subject. ;)

Mags

One of the best papers I've found on this subject which closely agrees with your analysis is attached below.  The authors Edwards and Saha have done much bench work and theoretical analysis on the S flow or power flow in wire, coils, transformers, capacitors, and even including core flux diffusion.

Regards,
Pm

Edit:

sm0ky2

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Re: Back-EMF Manifesto - A Key, hidden in plain Sight.
« Reply #38 on: February 24, 2018, 05:23:08 PM »
Tinman is right


The current will flow in the direction of the inducing current
But the voltage potential in in the reverse direction.


It may be easier to think of it as a series-parallel configuration
For instance, in a simple case of:
a voltage source (battery),
a switch
and an inductor (R)


When the switch is closed, the inductor voltage is in series.
(-) facing the (+) of the battery, (+) facing the (-) of the battery.


when the switch is open, the inductor voltage is in parallel
(+) facing (+), and (-) facing (-).


Current is in the same direction as the closed circuit.


sm0ky2

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Re: Back-EMF Manifesto - A Key, hidden in plain Sight.
« Reply #39 on: February 24, 2018, 05:35:10 PM »
What is interesting is when you saturate the coil with magnetism rather than inducing current


In this case, the direction of current of the collapsing field is determined by the direction of winding.
it will follow left/right hand rules, respectively.


This is because of the c dependency of electromagnetism
which is not present in permanent magnetism.
(Einstein’s relativity doesn’t allow for greater than c interactions)


sm0ky2

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Re: Back-EMF Manifesto - A Key, hidden in plain Sight.
« Reply #40 on: February 24, 2018, 06:04:06 PM »
That is my interpretation of the effect discovered by Emil Lenze
of magnetically induced electricity.


And the description of the Zeeman effect described by Hendricks Lorentz
of electrically induced magnetism. (electric dipole)


Both of which are covered in Maxwell’s equations,
and brought into relativistic perspective by Albert Einstein


“Back-EMF”, is therefore relative to the observer.


In electrically induced magnetism, it is relative to the inducing current.


In magnetically induced electricity, it is relative to the motion between
the magnetic field and the conductor.


The inductive losses (from our perspective) are between the inductor and free
space in the first case.
And resistive to the motion in the second case.
Both are of equivalent magnitude.

tinman

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Re: Back-EMF Manifesto - A Key, hidden in plain Sight.
« Reply #41 on: February 25, 2018, 03:33:38 AM »
 author=Erfinder link=topic=17611.msg517132#msg517132 date=1519488628]



Quote
Unfortunately, and I am sure it comes as no surprise to you, I cannot agree with anything that you are suggesting.
..

Well,we agree on one thing-->it comes as no surprise.

 
Quote
I guess I could elaborate, but doing so will lead nowhere as we both know.

Well that i dont know until you elaborate.
Although the past says we will disagree,the future may see us agree,but where we look at things from a different angle.

Quote
You suggest that one look to the electric field....help the community to understand your perspective of it and how and more importantly why you feel it and not magnetism is where attention should be focused.....

As i have stated before,the magnetic field is a bi/product of current flow.

We can produce an EMF across a conductor without the magnetic field,as the electric field is what produces that emf.The magnetic field is only produced when a current starts to flow through that conductor.

The electric field is the force that produces work,and the magnetic field is the impedance upon that force.

Quote
If you will, start by defining the electric field....

I can not,as i do not fully understand it yet-much the same as no one yet is able to define what the magnetic or gravitational force is.


Brad

tinman

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Re: Back-EMF Manifesto - A Key, hidden in plain Sight.
« Reply #42 on: February 25, 2018, 04:33:40 AM »
One of the best papers I've found on this subject which closely agrees with your analysis is attached below.  The authors Edwards and Saha have done much bench work and theoretical analysis on the S flow or power flow in wire, coils, transformers, capacitors, and even including core flux diffusion.

Regards,
Pm

Edit:

Hi PM

I read that paper,and like most other's,i believe it is wrong.


Brad

Magluvin

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Re: Back-EMF Manifesto - A Key, hidden in plain Sight.
« Reply #43 on: February 25, 2018, 05:05:05 AM »
author=dieter link=topic=17611.msg517053#msg517053 date=1519386197]

And about the use of the term "Back-EMF", the reverse current of a collapsing field

No-that is not BEMF-->that is inductive kickback,or flyback as some call it,and the current flow is in the same direction as it was when connected to the source.

as well as the inductive impact of a secondary field like in a motor (Lenz Drag etc.) it's both the same thing, only the cause is a diffrent one.

No,they are not the same thing at all.

,
Wrong again.
BEMF is the self induced EMF an electric motor produces.
The lower the BEMF value,the higher the value of current an electric motor will draw.
The higher the BEMF value,the lower the value of current the motor will draw.

And what makes this harder,is bullshit like this
https://ipfs.io/ipfs/QmXoypizjW3WknFiJnKLwHCnL72vedxjQkDDP1mXWo6uco/wiki/Counter-electromotive_force.html--> For example, the voltage drop across an inductor is due to the induced magnetic field inside the coil.[1][2] The voltage's polarity is at every moment the reverse of the input voltage.

What a crock of shit that is.
The CEMFs polarity is the same as the sources polarity--not bloody opposite/reverse.
If it were opposite,then we would have a huge current draw as soon as we attached the source voltage.Just take two 1.5 volt batteries,and connect them so as the negative of one is connected to the positive of the other,then connect the remaining two end to each other--so connect the two batteries in series-->then see what happens.

Only when the source EMF is disconnected,do we get a reverse voltage across the coil,as the field is now collapsing.

No wonder so many people have a hard time trying to work all this out,when you have idiots posting shit like that on websites all over the internet.

That link doesnt work for me. Id like to see what they had to say or show but it doesnt apear to work.

Mags

Magluvin

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Re: Back-EMF Manifesto - A Key, hidden in plain Sight.
« Reply #44 on: February 25, 2018, 05:30:44 AM »
One of the best papers I've found on this subject which closely agrees with your analysis is attached below.  The authors Edwards and Saha have done much bench work and theoretical analysis on the S flow or power flow in wire, coils, transformers, capacitors, and even including core flux diffusion.

Regards,
Pm

Edit:

Looked at it and will have to go over it again.

I like this one....

Mags