Open discussion for projects on this forum.

[mbrownn]

I think I understand, so you effectively get 40 turns per coil instead of 20?

[HuntingRoss]

Hello boys 'n' girls.

I only read the first post on this thread a long time ago and assumed it was a 'discussion' not expecting project development. To my surprise we seem to be working on similar projects.

Ok sorry for the bad description. 16 comm sections ,16 slot armature , 2 pole stator. Hook wire to comm #1 ,go straight down in the slot , across 180 to the opposite slot and back up. Fill the slots, I could only fit 20 turns, once this first two slots are wound, I then start my second coil in the next slot to the left, fill the 2 slots and then hook the end to comm#9.
So slot 1-9, 2-10 ,hooked comm#1 , comm#9.
Hope that's clear.
artv

Hi Shylo

My understanding of your description is a lapping pair of 8 pole coils in series, connected to a single commutator in series such that when voltage is applied between Comms #1, #9 energising the coils to north repulsion (or south attraction) and when rotated 180° Comms #9, #1 energise the coils to south repulsion (or north attraction).

I'm so happy that I'm not the only one playing with this set up.

Happy Hunting

mark

[citfta]

Hi Mark and welcome to the thread. Actually I started this thread so anyone could freely discuss any project on this forum or any project they wanted to share. As you may have noticed sometimes posters on this forum don't want anyone discussing what they are working on. So you can discuss those projects here. The only rule is to please keep the discussions to the technical side of the project and not any personal attacks.

I have been following your posts as well as Midaz's posts. I have just finished doing some testing of a motor that has almost no BEMF. I will be posting some pictures and info a little later today. You might find the info interesting.

Later,
Carroll

[HuntingRoss]

Hi Mark and welcome to the thread. Actually I started this thread so anyone could freely discuss any project on this forum or any project they wanted to share. As you may have noticed sometimes posters on this forum don't want anyone discussing what they are working on. So you can discuss those projects here. The only rule is to please keep the discussions to the technical side of the project and not any personal attacks.

I have been following your posts as well as Midaz's posts. I have just finished doing some testing of a motor that has almost no BEMF. I will be posting some pictures and info a little later today. You might find the info interesting.

Later,
Carroll

Thanks for the welcome Carroll. No worries about personal attacks, that is not my 'style'.

I will be interested to see your results. I've just flown through mbrownn 'interesting motor' thread having found this one...I haven't worked with wound stators, only PM...and the splitting the case sounds a little hardcore for me with tools to hand.

Happy Hunting

mark

[citfta]

A few pages back I posted some info about BEMF and how that helps to control motor speed and current. From that discussion I got an idea how to make a motor that had almost no BEMF. Some people seemed to think that would be a good idea. So I decided to check it out.

I recently got a scooter motor made by Hong Yung Co. Ltd. This is a great little motor for experimenting with. Unlike most of these small motors the magnets are not epoxied in. They are held in place by some plastic pieces. I will post a picture at the end of this post so you can see what I mean. The advantage of this is you can move the magnets around to try different configurations of armature winding.

Like most of the scooter motors I have taken apart this one has 4 magnets and four brushes. The top and bottom magnets are north facing in and the two side magnets are south facing in. There is a brush at the top and another at the bottom that are both feed from the same lead and the two side brushes are feed from the other lead. Testing this motor with no load on it it drew 1 amp on an analogue meter.

The first thing I did was to take the back off the motor and drilled two holes in it and separated the brush leads so that I now had 4 separate leads to rearrange in any way I wanted to try them. Feeding power to the two original leads now meant I was only powering 1/4 of the armature. Putting a meter on the other two leads gave me a voltage that was less than the supply voltage. For all practical purposes this voltage would be the same as the BEMF being generated in the power section of the armature. By adding some external magnets to the section of the housing where the armature was acting as a generator I was able to raise the generated voltage above the supply voltage. This also caused an increase in the supply current. I could draw power from those leads but that also caused an increase in supply current.

My next modification was to try and rewind the armature in a way that should generate almost no BEMF. I surmised that if I wound each pole piece of the armature separately since I would have wires going both directions near each other they should not have any or very little BEMF generated. I have also included a drawing of how I wound it and a picture of the armature.

My first trial was with only two coils as shown in the drawing. I first swapped the bottom magnet with one of the side magnets. This was so the rotor would function properly with the fields generated by the armature current. So my magnets were now N,N,S,S instead of the original N,S,N,S.

When I applied power the motor did not rev up like it did before and the current was slightly over 5 amps. A big difference. I also measured the voltage at the brushes on the side. Since there was now no connection directly back to the power through the windings I am sure this was a good indication of the BEMF being generated. The voltage on the side brushes was only .55 volts. So my theory was correct that winding each pole separately did almost totally eliminate the BEMF.

My next question was what would happen if I added two more coils 90 degrees from the first two. I added those coils and tried again. This time the current went up to over 10 amps! This was with only four coils and they were pulsing every 1/4 turn of the rotor. My generated BEMF was only slightly higher.

I then connected the brushes so that all four of them were in series and got the current back down to about 5 amps again. The ten amps was with only the top and bottom brushes supplying power. The motor also has very low torque compared to the original. I could stop it with my bare hands.

My next project will be to rewind the armature following the method suggested by Mbrownn. His method eliminates the connections from one coil to the next and allows for some BEMF to be generated. So we will see what that shows with this nice little experimental motor.

Carroll

PS: Thanks to Shylo for trying this for me first. I just wanted to take it a little further and see what would happen.

[shylo]

Mbrownn, yes that's right.

Hi mark, 40 turns attached to comm 1&9 ,coil is 4 slots total, next coil is the same but connects to 3&11 and so on.

Hi Carroll, The first time I wound that style (a few years ago) I wound 2 strands of wire at the same time in opposite directions. It ran for a very long time. I only wish I had taken one of the coil leads and connected them to the comm section of opposite polarity to fire next to the fire of the first.
Sorry that probably doesn't make sense.

My testing today, I've got the amp draw at .75 . The collector brushes when loaded do shorten run time and increase amp draw. Motor ran for over 7 hours, on and off, today and barely got warm.
More to try yet.
artv

[mbrownn]

Mbrownn, yes that's right.

It is possible to weaken magnets if you get too strong a field in the armature although I doubt you can do it with such a small armature.

[shylo]

Hi Mbrownn or anyone, I was wondering what the magnet pole is where the can has been separated. So let's say the bottom is projecting out a N, then the top has to be projecting out a S right?
So when I place the top half onto the bottom with spacers added (to make up for the lost material in the can due to cutting) the lines of attraction basically go straight across the armature with no power being applied correct?
When power is applied to the armature my coil is setup to attract , but what does that do to the lines that were straight , but are now altered by the armature field? Also my coil is completely off before the next is fired , so do the lines return to straight across for an instant?
Also I tested many different types of materials for the spacers, I ended up using several little neo's 6 on each side , so now when the armature is not powered are those straight across line now pear shaped ,half to the left and half to the right?
Sorry it's just every time I do something ,I end up with more questions.
Thanks artv

[mbrownn]

Hi Mbrownn or anyone, I was wondering what the magnet pole is where the can has been separated. So let's say the bottom is projecting out a N, then the top has to be projecting out a S right?

yes.

So when I place the top half onto the bottom with spacers added (to make up for the lost material in the can due to cutting) the lines of attraction basically go straight across the armature with no power being applied correct?

Not sure what you mean, top half of what? bottom of what? what do you mean by can? is it the motor case? Try to be specific as its so easy to misunderstand.

When power is applied to the armature my coil is setup to attract , but what does that do to the lines that were straight , but are now altered by the armature field?

Like electricity, magnetism passes on the path of least resistance. It is easier for flux to pass through the core of a coil in attraction than to take a more direct route through iron.

Also my coil is completely off before the next is fired , so do the lines return to straight across for an instant?

If I understand you correctly, this may be the case, but it takes a little time to do so. if our speed is fast enough, this effect will get less.

Also I tested many different types of materials for the spacers, I ended up using several little neo's 6 on each side , so now when the armature is not powered are those straight across line now pear shaped ,half to the left and half to the right?
Sorry it's just every time I do something ,I end up with more questions.
Thanks artv

Im not sure what you mean, dont worry about asking questions, that is how we learn. If you ask me about something I haven’t thought about, i have to think about it and I learn.

Sorry about not being able to answer everything, I didn’t understand your questions. You need to be more specific with your descriptions and keep asking.

[Matthew Jones]

Also my coil is completely off before the next is fired , so do the lines return to straight across for an instant?

No!! They stay polarized at the last charged position . To remove any magnetism you must short out the coil electrically or remove the current left over to a lower source of voltage in the same polarity.Then the iron is demagnetized except for trace charges from near by coils.
And in fact the FASTER the motor goes the more polarization you have to deal with..Depolarization takes time especially in soft iron.

If your goal is BEMF free you only have 1 choice, make sure the coil is shorted longer than it is charged. There is no other way.

Matt

[mbrownn]

No!! They stay polarized at the last charged position . To remove any magnetism you must short out the coil electrically or remove the current left over to a lower source of voltage in the same polarity.Then the iron is demagnetized except for trace charges from near by coils.
And in fact the FASTER the motor goes the more polarization you have to deal with..Depolarization takes time especially in soft iron.

If your goal is BEMF free you only have 1 choice, make sure the coil is shorted longer than it is charged. There is no other way.

Matt

Is this what is known as residual magnetism?
This does make some sense but how does shorting the coil remove magnetism?

I believe that residual magnetism in an armature causes drag.

I have always assumed that laminated iron suffers less from this problem, but is it true?

[shylo]

So that is what I'm seeing ...magnetism is a product of time and gravity?
Any thing causes drag is , gravity?
Shorting a coil , just reverses the process causing equallibrium, for as long as the short is applied, then production takes place ? Since were forcing it.
Has anyone ever tried to make a motor or gen that works in reverse?
Run it equal , and then force it out of balance?
The testing I'm seeing is saying that when I think it should happen , it is doing the opposite. It should charge but it doesn't.
Do the fields of permanent magnets, just collapse ,or gradually diminish?
Electro-magnets , are there or their not, a PM is there all the time.
If you pull more out of a generating coil, than what you put into motoring a coil and they're wound in conjuncton, and their wound to assit each other...
Will that not work?

[mbrownn]

I asked for it Ill do my best to answer.

So that is what I'm seeing ...magnetism is a product of time and gravity?

No one has yet proved what magnetism is, we know it acts as a force and can induce current to flow in a wire. We are also discovering that it is far more complex in its makeup than we imagined.

Any thing causes drag is , gravity?

We don’t know what gravity is other than it is a weak force.

Shorting a coil , just reverses the process causing equallibrium, for as long as the short is applied, then production takes place ?

Shorting a coil will allow any voltage or current in it to dissipate, so any resuting magnetic effects will dissipate also.

Has anyone ever tried to make a motor or gen that works in reverse?
Run it equal , and then force it out of balance?

A motor is a generator and a generator is a motor. Run a motor in reverse, ie your input is mechanical, and it generates. The same goes for a generator. Im not sure what you mean by the second question.

The testing I'm seeing is saying that when I think it should happen , it is doing the opposite. It should charge but it doesn't.
Do the fields of permanent magnets, just collapse ,or gradually diminish?

The field of a permanent magnet will last for hundreds of years provided it is not overheated, shocked or exposed to a very strong field in another direction.

Electro-magnets , are there or their not, a PM is there all the time.
If you pull more out of a generating coil, than what you put into motoring a coil and they're wound in conjuncton, and their wound to assit each other...
Will that not work?

Energy is always conserved. ie power in = power out. Asymmetry often lets us throw the balance a little more in out favour. Motors and generators are to some extent, open systems. This means that some of the energy we put in is lost. in exactly the same way we can get a device to take environmental energy and give it to us, a heat pump is a good example. Doing the same thing electrically, is what most of the threads on this forum are about.

What we have to do is to make the working conditions of a generator coil take environmental energy and convert it to usable electrical power. A solar panel does this, and I believe that in the right conditions a coil can do this.

The powered field coil in my device is an attempt at doing this, but that alone is not enough. The same can be said of a self exciting generator and I have combined the two and still it isn’t enough. I call this the MADMAG (Motor Assisted Dynamo, Motor Assisted Generator). Pulsing so that we have inductive kickback is another method and so is a transformer. All of these are in my device but is it enough? only by building and refining it will we know.

[Matthew Jones]

Is this what is known as residual magnetism?
This does make some sense but how does shorting the coil remove magnetism?

I believe that residual magnetism in an armature causes drag.

I have always assumed that laminated iron suffers less from this problem, but is it true?

Because it converts the magnetic flux (Which is moving in typical iron circles) into charge and burns it off. Laminates reduce eddy currents which are a direct 50% loss in flux at the point of build up. Eddy current look like a whirlpool. Half going in the right direction the other half not. Smaller eddy currents less loss.

Shorting eliminates them too.

Shorting allows the inductor to peak its capacity every time its fired.

Matt

[maxc]

Because it converts the magnetic flux (Which is moving in typical iron circles) into charge and burns it off. Laminates reduce eddy currents which are a direct 50% loss in flux at the point of build up. Eddy current look like a whirlpool. Half going in the right direction the other half not. Smaller eddy currents less loss.

Shorting eliminates them too.

Shorting allows the inductor to peak its capacity every time its fired.

Matt

Is it necessary too short the coil if you know it stopped oscillating?