Electromagnetic Induction in Solenoid Generator Coils

[Sephiroth]

When the moving magnet is inside the coil the peak voltage is maximum when the moving magnet is a little away from the coil the voltage decreases. When the magnet drift apart starts to decrease the voltage on the coil until it reaches the lowest peak , negative voltage.

I asked earlier but didn't get an answer. It sounds like you are saying the voltage is at its peak when the magnet is directly over the coil? The voltage isn't maximum when the magnet is in the coil... when the magnet is directly above the core the voltage is zero... have a look at the graph I posted here.

at TDC the voltage is zero.

[lanenal]

It seems you are thinking that voltage is proportional to the strength of magnetic. Unfortunately this is not true. Without movement (that is, change), there will be no voltage no matter how close the coil is to the magnet.

I agree with Seph on this point.

...

When the moving magnet is inside the coil the peak voltage is maximum when the moving magnet is a little away from the coil the voltage decreases. When the magnet drift apart starts to decrease the voltage on the coil until it reaches the lowest peak , negative voltage (virtual south)

[darkwizard]

The moving magnet (WITH MOVEMENT OF COURSE) generates a half cycle wave when the north pole magnet passes inside the coil. When the moving north pole magnet is just inside the core of the coil the voltage is max.

[darkwizard]

I am not a Teacher, you will have to take some lessons on magnetism

[darkwizard]

I found this :

Is very interesting

http://education.jlab.org/jsat/powerpoint/lenzs_law.ppt

Obviously it has some several errors.

[Sephiroth]

I found this :

Is very interesting

http://education.jlab.org/jsat/powerpoint/lenzs_law.ppt

I find this interesting too....

Basic AC Generator

[ren]

Regardless of where the wave is in relation to the passing magnet it should be apparent to all here that energy can be collected/utilised this way.

Sep, you are right, when the magnet is at top dead center there is no voltage. But thats because the rotor isnt moving yet!lol. Under motion it may or may not give the same results (I havent studied the wave forms yet) but regardless, the rotating magnetic field does induce into the coil, which in turn can store charge. Rick F's "self runner" discussed this somewhat and he also noted that the timing had to be just right.

It makes sense to me that the waveform should be as DW said. I can see how the magnet should be inducing maximum voltage at tdc and that voltage should rise and fall according to its proximity. Im not sure however that this is infact the case! I had a great graph around here of this, except I cant find it!

Sep your graph indicates a different story. Tell me, how did you perform your measurements?


EDIT: Maybe thats the reason, Good site Sep. Note the INDUCED FIELD STRENGTH is 90 degrees out of phase to the OUTPUT VOLTAGE! (This is measured no doubt on a closed circuit load of course, something that doesnt happen here) )

[Sephiroth]

Regardless of where the wave is in relation to the passing magnet it should be apparent to all here that energy can be collected/utilised this way.

Sep, you are right, when the magnet is at top dead center there is no voltage. But thats because the rotor isnt moving yet!lol. Under motion it may or may not give the same results (I havent studied the wave forms yet) but regardless, the rotating magnetic field does induce into the coil, which in turn can store charge. Rick F's "self runner" discussed this somewhat and he also noted that the timing had to be just right.

It makes sense to me that the waveform should be as DW said. I can see how the magnet should be inducing maximum voltage at tdc and that voltage should rise and fall according to its proximity. Im not sure however that this is infact the case! I had a great graph around here of this, except I cant find it!

Sep your graph indicates a different story. Tell me, how did you perform your measurements?

Ren, maybe I am just crazy or something but I can see that it is the way I describe!

ok, you have experience with window motor coils right? Well you know that when a north pole sweeps past one side of a window coil it will generate the maximum voltage when the magnet is closest to the coil (TDC in a sense).

But now look at a solenoid coil. There is a bunch of wires going in one direction on one side of the core, and the same bunch of wires going in the opposite direction on the other side of the core. In this case, when the magnet is at TDC, voltage is being induced in two polarities at the same time... therefore voltage is zero at TDC.

[darkwizard]

You are showing a closed magnetic system, with a big armature, the induced magnetic field of the magnet in the core isn't in phase with the voltage.

Test it yourself.

[darkwizard]

Very big stator core of the coil , dephasing problems. The Induced voltage in this case is 0.

[darkwizard]

Voltage always is one , not two in the same coil.

[ren]

But now look at a solenoid coil. There is a bunch of wires going in one direction on one side of the core, and the same bunch of wires going in the opposite direction on the other side of the core. In this case, when the magnet is at TDC, voltage is being induced in two polarities at the same time... therefore voltage is zero at TDC.

DW, I am not saying you are wrong here. I actually think Sep and you may both be right, to a certain degree. Seps link above shows that there is a difference between induced field strength and Output voltage. Phase shifting I believe. But this is with the closed loop system, you are right.

Yes I have experience with window cores. And they seem to trigger @ TDC, so what is triggering them if the voltage is supposedly @ O dot?

Your comments on the solenoid I do not understand however. To me the solenoids wires are all going the same direction, clockwise or anti clockwise.

The shift in phases can account for both your understandings. Now why does it occur like this......

[Sephiroth]

DW, I am not saying you are wrong here. I actually think Sep and you may both be right, to a certain degree. Seps link above shows that there is a difference between induced field strength and Output voltage. Phase shifting I believe. But this is with the closed loop system, you are right.

Yes I have experience with window cores. And they seem to trigger @ TDC, so what is triggering them if the voltage is supposedly @ O dot?

Your comments on the solenoid I do not understand however. To me the solenoids wires are all going the same direction, clockwise or anti clockwise.

The shift in phases can account for both your understandings. Now why does it occur like this......

Please forgive my crude sketches

[ren]

I see what you are saying Sep. And that makes sense to me too somewhat. But I am not sure about the appearance of your sine graph. For a monopole motor they would only spike one way yes? And if this is the case, are there two bumps/spikes per magnet pass? Draw that graph again and show me a straight up north pole rotor signal. Or is it the same as what you have drawn?

Interesting

[Sephiroth]

I see what you are saying Sep. And that makes sense to me too somewhat. But I am not sure about the appearance of your sine graph. For a monopole motor they would only spike one way yes? And if this is the case, are there two bumps/spikes per magnet pass? Draw that graph again and show me a straight up north pole rotor signal. Or is it the same as what you have drawn?

Interesting

Here you go...



Though it is a little bit more complicated than that... you may be wondering why the low voltage just after TDC is enough to trigger the base of the transistor, but it isn't enough just after the peak voltage.

Well, basically the induced voltage by the rotor magnets just initiates the triggering of the base. Once the base has been triggered then current starts flowing through the primary coil. This induces current in the trigger coil in the opposite direction to the current in the primary and this induced current keeps the transistor open as the coil energises. Once the magnetic feild has almost reached its peak then the induced voltage from the primary isn't enough to keep the transistor active so it cuts off... then current starts flowing in the opposite direction in the trigger circuit (through the 1N4001) and forces the transistor to stay off even if the induced voltage from the rotor magnets is enough to keep it open.

Does that make sense? I made a video explaining the basics a while ago...

YouTube - Understanding the Bedini Circuit