Open discussion for projects on this forum.

[citfta]

Hi artv,

A coil be itself cannot produce BEMF. A coil moving through a magnetic field will have induced in the coil a voltage that is proportional to the strength of the magnetic field, the speed of the coil moving, and the number of turns of the coil. Now how are we making the coil move through the magnetic field? If we are driving the coils with some mechanical force like the way a generator works then we are producing a voltage that can be used to power an electrical load of some kind. As soon as we start to use that power the voltage induced will cause current to flow. The flow of current will in turn now create a magnetic field that is attracted to the one the coil is moving through. This is known as the Lenz effect. I know on this forum and on Youtube it is sometimes called BEMF but that is not correct because it is not opposing anything except the physical movement of the coil.

If you can, find a small DC motor like a blower motor from a car or something similar you can mount a handle on the shaft or some way to spin the motor by hand. Now give the motor a good spin. Crank it up as fast as you can get it to go. You will see it is easy to do. Now connect a small bulb like a taillight bulb to the two leads of the motor. Now crank or spin it again and see the difference. This is the Lenz effect. It takes some physical force to move the current through the load.

Now let's get back to our coil moving in a magnetic field. Instead of turning the shaft with the coils with an outside force let's put some current through the coil. When we put current through the coil it now produces it's own magnetic field that will either be attracted to or repelled away from the existing magnetic field. In a DC motor the commutator and brushes allow us to keep moving that field from one coil of the armature to another and thus we are able to keep the armature turning. So now what happens we have the coil moving through a magnetic field just like in the generator. Except now we are using the coils themselves to create a field that is causing the movement. Because the coils are moving through the magnetic field they are also having a voltage induced back into them from the magnetic field. Because of the laws of magnetic force work in a certain way this induced voltage is always opposite the applied voltage. This is what BEMF really is. It can never be stronger than the applied voltage unless the load starts driving the motor instead of the motor powering the load.

In a lot of the electric vehicles there is a circuit that allows us to use the BEMF to recharge the battery when the vehicle is going downhill. Technically it is not really BEMF because we are actually just turning the motor into a generator when going downhill. This is called regenerative braking.

I do not understand what you mean by your last two statements. What are you asking about 2 or 200 coils? And your statement that any loss is a form of magnetic interaction I don't understand either so you will have to explain what you meant or what you were asking.

Later,
Carroll

[shylo]

Hi Carroll, If a coil produces bemf ,...It will have a polarity,
Why can't you rebound waves off each other?
I still can't see how any of this is possible.
Bemf is opposing ,can it be used to drive?
Why not have 2 or 200 coils ,the loses , where are they?
Any lose is a form of magnetic interaction, which produces power, if used the right way?
artv

[citfta]

Hello padova,

By your own admission you are new to this forum. And your small number of posts confirms this. So you really don't know anything about me or anyone else on this forum. I am on this forum because I have seen with my own eyes things that didn't seem possible. I have been actively involved in building and working on many projects on this forum. So you are mistaken about me being stuck in the mud.

Now you have accused me of writing all kinds of rubbish about DC asymmetrical motors. Where did I write that? Show me one quote where I wrote rubbish about DC asymmetrical motors. You say you are not into motors so how do you know what is rubbish and what isn't. You are correct in your assumption that I have a problem with Dufo. I don't have a problem with his motor. My problem with him is because of his attitude and his constant belittling of anyone that doesn't bow down to him.

The burden is now on you. Show me where I wrote any rubbish about DC asymmetrical motors.

greetings

Citfa and company, what's yours game?
You so blindly wrote all kind of rubbish about DC asymmetric motors,
and yet here you are, in this forum. It seems that it is too late for you,
considering your ages, to change your mind, nothing wrong whit that, just add to that some respect
towards true researchers nothing more.
With these conventional BS know you're not going anywhere.
It's like you're stuck in the mud.
I can only figure it out what a bunch of **strubating monkeys can learn something from you.

I'm steel newbie here, but you people, in a few posts here are so offensive.
Even worse than one who just copied someones work and started new thread.
So funny.

I couldn't care less, anyway I'm not into motors. so it's just small observation, and it's just a part of that, the rest you figure out by yourself.

Carroll

By the way I don't have any "ages" I have only one. I am 69 years old and have worked on motors for over 50 years.

[citfta]

Hi artv,

Well there probably isn't any easy way to measure the BEMF or calculate it. You could measure the current going to the armature and then if you knew the resistance you could figure the voltage drop across the armature and subtract that from the applied voltage to get the value for the BEMF. But the thing to remember is this value is going to change any time the load changes or the speed changes. So there really is no need to try and figure it out.

The video where the guy says as soon as power is applied the BEMF is generated is incorrect. The BEMF is only generated when the armature is turning. So for a short while the BEMF is not even there and only gets to full strength after the motor is up to full speed.

Your question about wasting 85 volts is a good one. Let me try to explain it this way. The BEMF acts like a governor to control the motor speed. Now let's say your car has a 500 HP engine in it. Now in normal driving you are the governor. You control how much of that HP is being used at any one time. Now let's say it takes 50 HP to move your car on level ground at 45 mph. Are we wasting 450 HP?

Now to your question about BEMF and a generator. First thing is most electricians refer to the loading of a generator as the Lenz effect and not BEMF. I know it is called BEMF on this forum and on Youtube a lot. But there is a lot of garbage both places. Now what would happen if we wind one coil clockwise and one counter-clockwise and install them in a generator. They will both produce drag on the generator when connected to a load. The only difference will be one will have the opposite polarity of the other. But the drag will still be the same.

I am enjoying our discussions and if you have any more questions just ask.

Later,
Carroll

[shylo]

Hi Carroll, I was searching the web but didn't find how do you know the value of the bemf?
A simple video the guy said as soon as power is applied to a dc motor the windings generate opposite to the applied, subtract the opposite from the applied and that is how much voltage the motor is actually using to run.
100 volts applied , 85 volts opposite, so 15 volts going through the windings, and since the resistance of the windings doesn't change ,the current draw goes down.
But this is a waste of 85 volts.
Can a diode not block the bemf? But where would it go?
Also I seen a guy that said in generators the bemf is only produced when you attach a load. The coil creates its' own field when loaded that opposes rotation.
So why not just wind 2 coils CW & CCW draw off each coil at the same time so the one coil will oppose in one direction and the other in the opposite direction cancelling both oppositions?
Thanks for your help.
artv

[mbrownn]

greetings

Citfa and company, what's yours game?
You so blindly wrote all kind of rubbish about DC asymmetric motors,
and yet here you are, in this forum. It seems that it is too late for you,
considering your ages, to change your mind, nothing wrong whit that, just add to that some respect
towards true researchers nothing more.
With these conventional BS know you're not going anywhere.
It's like you're stuck in the mud.
I can only figure it out what a bunch of **strubating monkeys can learn something from you.

I'm steel newbie here, but you people, in a few posts here are so offensive.
Even worse than one who just copied someones work and started new thread.
So funny.

I couldn't care less, anyway I'm not into motors. so it's just small observation, and it's just a part of that, the rest you figure out by yourself.

(snip) I cut my 5 minute rant as it would only pour fuel on the fire.

On asymmetry in motors, I dont understand what all the fuss is about, for any motor to work there has to be asymmetry in one form or another or the motor would not turn. I understand the use of physical asymmetry and some of the advantages it gives, thankfully the asymmetry I use seems to be sufficiently different as to not bother people too much.

@ padova, Im not attacking you or anyone else on this forum but its not good to use personal attacks on an open forum.

[padova]

greetings

Citfa and company, what's yours game?
You so blindly wrote all kind of rubbish about DC asymmetric motors,
and yet here you are, in this forum. It seems that it is too late for you,
considering your ages, to change your mind, nothing wrong whit that, just add to that some respect
towards true researchers nothing more.
With these conventional BS know you're not going anywhere.
It's like you're stuck in the mud.
I can only figure it out what a bunch of **strubating monkeys can learn something from you.

I'm steel newbie here, but you people, in a few posts here are so offensive.
Even worse than one who just copied someones work and started new thread.
So funny.

I couldn't care less, anyway I'm not into motors. so it's just small observation, and it's just a part of that, the rest you figure out by yourself.

[citfta]

I didn't mean to imply I thought it would work for a Lockridge device. I just thought it was an interesting find. It sounds like you have made some good progress on the Lockridge device. Good luck on that. I will look at the link you posted and check it out.

Later,
Carroll

[mbrownn]

Hi mbrownn,
Sometimes I type faster than I think and vice versa.

Me too

If I recall correctly you were doing a lot of research on the Lockridge device. If that is correct, where you ever able to get that going or come close to getting it going? I still would like to do some work on that when I get some of my other projects finished.

Im still working on it when funds allow.

Briefly I had it motoring and generating on DC, AC and pulsed DC. Nothing overunity, but in some circumstances it was getting quite efficient. I posted about the DC operation of it here without referring to the lockridge device http://www.energeticforum.com/renewa...eresting+motor

I just found a very old, very big alternator made by Delco that has the three phases brought out to the outside so it must have been used with a separate set of diodes. I am not sure if it is of any real use but I am going to hold onto it in case I find some way to use it.

Later,
Carroll

Not sure that would work, It needs to be the type of VW generater that was mentioned or a starter/generator like you get on tractors or golf carts, at a push a four pole starter motor, which is what I have been using.

I can say with confidence that the Lockridge device wasn't a hoax as reported by some, there are too many things that have come together and worked just from the pictures shown of it.

[citfta]

Hi mbrownn,

Glad to have your contributions. That is what this thread is about. So all ideas are welcome here. It is for sharing ideas and thoughts. Sometimes I type faster than I think and vice versa. You may catch my mistakes and that is OK too.

If I recall correctly you were doing a lot of research on the Lockridge device. If that is correct, where you ever able to get that going or come close to getting it going? I still would like to do some work on that when I get some of my other projects finished.

I just found a very old, very big alternator made by Delco that has the three phases brought out to the outside so it must have been used with a separate set of diodes. I am not sure if it is of any real use but I am going to hold onto it in case I find some way to use it.

Later,
Carroll

[mbrownn]

However the motor will have no torque

There is no contradiction here with what I said, it depends on the position of the brushes.

Sorry crifta for adding to your thread, I get quite excited with what you can do with this type of motor

[mbrownn]

I think I see what your saying. Because the field windings produce a weaker magnetic field due to less current, the armature sees less opposition therefore it spins faster and creates a larger bemf?
Do the field windings create an opposite field when the supply is disconnected?
Sorry I'm not very good at expressing my thoughts.
Not sure if you saw my post ,since we posted at the same time.
Back 3 or 4 about the old generator?
Thanks artv

With Universal type motors there are many different ways to wire them up, I think I have tried them all. Yes you can power the armature alone and the motor will still run. In this situation you can use both field coils as generator coils, but be careful not to exceed the continuous rated amps in the armature or it will burn up. I have never had an armature self destruct with overspeed because I switch off before that happens. I would recommend that people experiment with these motors with all the different combinations of wiring. There is so much to be learned from them.

[citfta]

Hi Shylo,

I did miss your post about the generator. My post under that one was to mbrownn.

To answer your question about the armature current what you said would be correct if the armature is locked so that it can't move. Then the current would be a direct function of the voltage and resistance just like you calculated. And that is called the locked rotor current rating. This rating is used to calculate the protection device (fuse or breaker) that is needed to keep from burning up the motor.

However as soon as the rotor starts to turn because the rotor windings are moving in the field created by the field coils then the BEMF is generated which reduces the current going through the armature windings. As the armature turns faster and faster the BEMF increases until it balances out the applied armature voltage minus the power needed to power the load and overcome friction and other losses.

So if we reduce the field current then the BEMF being generated is less for the same speed so the armature current will go up until the faster speed is reached. At locked rotor the current is the same whether there is any field current or not. However the motor will have no torque and would not be able to turn the load and would quickly overheat if the protection device did not shut off the current to the motor. Although as I said industrial motor controls will not allow voltage to be applied if there is no field current. So there is a form of double protection there.

Thanks for your questions. Few free to ask for more help if anything is not clear.

Carroll

[shylo]

I think I see what your saying. Because the field windings produce a weaker magnetic field due to less current, the armature sees less opposition therefore it spins faster and creates a larger bemf?
Do the field windings create an opposite field when the supply is disconnected?
Sorry I'm not very good at expressing my thoughts.
Not sure if you saw my post ,since we posted at the same time.
Back 3 or 4 about the old generator?
Thanks artv

[citfta]

Hi Shylo,

I am not sure I understand what you are asking, but yes if you reduce the voltage going to the armature then the amperage will drop and the motor will turn at a slower speed.

If your reduce the voltage going to the field then the current through the field will drop because as you said the resistance stays the same. However because of the weaker field the current through the armature will go up until the armature reaches a higher speed that will generate enough BEMF to balance the higher current going through the armature.

If that didn't answer your question then please clarify your question and I will try again to answer it.

Carroll