BEMF current reversal.

[bistander]

@bistander,

Both Igor's and Lidmotor's LED'S are reverse biased. The back spike travels from the coil through the LED to the positive pole of the power source in each circuit. The positive pole acts as a "ground" for a reverse polarized current emanating from the field collapse, right?

No Allen, that is not right. Igor's circuit is a mess. No further comment from me. Lidmotor has it right. The diode is reverse biased when the switch is closed and conducts when the switch opens. When the switch opens, the battery is out of the circuit. Suggest you study buck converter. You're just using a rotor mounted magnet to commutate the switch. Interesting toy but I see no use for the contraption.

Regards,

bi

[Ufopolitics]

Nice Thread Allen...

Nice thread Allen...

Even though this "Dilemma" about the collapsing magnetic field in a coil and the current flow, the voltage reversal or the field... is such an old one...and still it has not been revealed or understood in its entirety...

As I understand Current does not "flow" anywhere...current (I) or Amps...is just a Sectional Measurement on a given conductor which means the "population" of electrons in that cross section.

Voltage doesn't flow either...it is just the measurement between V1 and V2 or two points in a given piece of conductor...or circuit.

But we still keep referring to current and voltage "flows"...I guess is given by trying to find a proper understanding of the whole thing.

The only truth is that the only "thing" that really flows...are the Electrons through the wires.

One fact is known...and able to be demonstrated...Voltage polarity does reverses (at the end terminals of coil, inductor) when field collapses.

I just have a very simple question...

What happens to magnetic polarity whenever we reverse the input voltage polarity at the coil end terminals?

As I also know that everything depends on the coil core type...and many other parameters...


Regards to all



Ufopolitics

[bistander]

@bistander,

Here's another even more basic video by Lidmotor. Please have a look at this video and comment on the direction of flyback as outlined by Lidmotor. Lidmotor states that: "When the switch opens up, the energy pulls back in the other direction".

https://www.youtube.com/watch?v=F9NnPa6uryg

This guy has the LED wired as a freewheeling diode in a basic chopper circuit. Current flows in the same direction through the coil during both on & off periods of the switch. The coil voltage reverses when the switch opens.

The energy during both switch states is used to rotate the rotor and make heat in the resistive circuit elements.

[Allen Burgess]

Comment from Lidmotor.

Comment from Lidmotor:

"I know what you are talking about. Reed switches have a nasty habit of welding together --in the CLOSED POSITION! Bad situation. That is another reason that I found this homemade one very interesting. If I keep the power down on it the thing keeps working. The flyback return circuit may have something to do with it. The arc welding doesn't happen. The LED steel wires are plated with some metal that might also help. Don't know".

@bistander,

Both Igor's and Lidmotor's LED'S are reverse biased. The back spike travels from the coil through the LED to the positive pole of the power source in each circuit. The positive pole acts as a "ground" for a reverse polarized current emanating from the field collapse, right?

[Allen Burgess]

LED Reed Switch Motor.

@bistander,

Here's another even more basic video by Lidmotor. Please have a look at this video and comment on the direction of flyback as outlined by Lidmotor. Lidmotor states that: "When the switch opens up, the energy pulls back in the other direction".

https://www.youtube.com/watch?v=F9NnPa6uryg

[bistander]

Looks like it is an AC circuit. He mentions high frequency. Power supply stays connected and has circuit elements like capacitors. I'm not interested in analyzing it. But if you want to, I suggest using a scope.

{edit} I watched the video again. It is pretty low quality. But I guess there is a spinning magnet near the coil. If this changing flux links the coil then there will be a generated voltage in the coil per Faraday's Law and its polarity would in fact oppose the supply voltage according to Lenz. This voltage is summed with the induced voltage in the coil caused by the changing current and coil inductance.

I don't think this guy knows what he's doing. If he is attempting to freewheel through the LED, he's located it incorrectly. Also LEDs make for poor switches.

bi

[Allen Burgess]

Bemf

@bistander,

Here's a video from Igor Moroz:

https://www.youtube.com/watch?v=vWvI7T7h3tk

Can you please help explain how Igor's explanation contrasts or compares with your fine analysis?

[bistander]

Inductor

Hi Allen,

Your terminology is confusing. "BEMF current"? What is it? A voltage? Or a current? Can't be both.

The behavior of voltage across the inductor and current through the inductor is well established during the storing of energy (building the magnetic field) and during the decaying of the energy (collapsing magnetic field).



As you can see, IL (current through the inductor) is in the same direction for both the storage and the decay phase. VL (voltage across the inductor)is opposite polarity for the decay phase.

Hope that helps,

bi

{edit of 7/24/2016} I now regret making this post. I never had any contact with Allen before this thread. I was simply trying to help him by providing useful reference material and suggestions. For no good reason Allen became rude and insults me. He says not to bother him with facts because he wants to invent new ways. Allen doesn't know what he's talking about and doesn't want to know. My advice is to avoid him.
Also many of Allen's statements are incorrect or false. I wouldn't believe anything from him.

[Allen Burgess]

mispelling.

Another important point is that Mr."Know-it-All Tinman" consistently misspells the verb "does" as the medical term "dose"; Something else that has helped keep everyone completely bamboozled.

[Allen Burgess]

"Citfa" got me booted off the OU site falsely maintaining that BEMF current traveled in the same direction as the initial EMF. Now "Tinman" is using my theory that BEMF current is reversed and traveling in the opposite direction.

Here's "Tinman's" latest version:

"If the coil is ideal,then the CEMF should always equal that of the EMF,by way of the induced currents by both-correct.
So this being the case, at T=0,there would have to be a current rise,and that rise in current value must start from 0. Through the transition to 800ma?second,it must first produce a current value much less than that--it must start from a value of 0. As soon as a current rise started taking place,due to the EMF(before the maximum value of 800ma/second),it would induce a CEMF that results in producing a current that is in opposition to that of the EMF induced current."


Here's what Tinman had to say about it in November of 2015: "No Synchro,the current dose not reverse direction"No Synchro,the current dose not reverse direction-->only the voltage across the coil/inductor inverts. You apply a current in one direction to build the magnetic field around the inductor= current to form magnetic field. Then when the supply current is cut off,the magnetic field collapses,and creates a current flow=magnetic field changing in time to create current flow through the inductor. As the magnetic field around that inductor has not inverted (swapped polarities),then the current flow remains in the same direction.

Brad