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Forum Index : Windmills : horizontal windmill
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makourain Senior Member  Joined: 19/04/2006 Location: Posts: 111 |
after reading the post by glenn, i imediately set forth to build mini mill with the floppy drive motor. as far as the windmill building process goes, its all done apart from the tail fin. but when i tested to see if the blades spin in the wind, i stuck it infront of a pedistal fan on maximum and the windmill moved about 90 degrees and stopped. so i gave it a bit of a spin and away it went, it got very fast. why does it need someone to give it a spin in order for it to work? |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Hi Makourain. We call that "cogging". It happens when the magnets line up with the stator. It may be ok and start up by itself once out in the wind on a little mast. If you find the windmill never starts up by itself, and needs a little kick by you to get going, then you need a bigger blade. Bigger blade has more power, so it will help get past this "cog". You've just made a big step. Learning by building. By building this little windmill you have already learned about cogging, one of the biggest problems we all face with our windmills. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| makourain Senior Member Joined: 19/04/2006 Location: Posts: 111 |
thanks for that, i would never have known that if you didnt tell me, because there is no mention of cogging anywhere that iv seen. i have 2 small dc motors, one is smaller than the other. the smaller one produces more voltage with the same rpm. in front of my pedistal fan the bigger motor produces 0.11 volts. when i stick the blades of the windmill on the smaller motor it produces about twice that. Rule of thumb.. the next trick for me is to make the car alternator in to a windmill, ill use a car battery to start it and then see what sort of things it can run. ill post pics of my windmill when i get the camera :D |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Before you start on your next project, you really must get as much info as you can. I would highly recommend you visit my Links page http://www.thebackshed.com/Windmill/Links.asp, go to each site and read them through. You'll find a heap of info there and it will save you a lot of time and money in the long run. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| makourain Senior Member Joined: 19/04/2006 Location: Posts: 111 |
i got my minimill and stuck an 2 LEDs on it, one going each direction so one of them would glow no matter which direction the motor was going. i spun the motor (without propellar) in my fingers in both directions and it made the LEDs glow. but i couldnt make the propeller spin fast enough to make the LEDs glow. so i hopped in the car when dad went up to get some food and stuck the thing out the window. it spun so fast that it rattled and at about 10kmp/h it spun without needing me to give it a help. then dad went down the main road and when he got up to 60kmp/h the whole thing broke apart and bits went up in to the air, leaving me with the tail fin and the piece of pvc that the tail fin connects to. my dad and i went back down the road to have a look for the pieces (lucky there was almost no traffic) and found them all, the propeller still attached to the motor and the LEDs with their wire in separate places. lucky the blades hadnt shattered or gotten run over. but, even with the thing spinning super fast at 60kmp/h wind it still didnt make either of the LEDs glow :( needless to say, im going to read every single page listed on the links page. getting as much info as possible is why iv asked all these questions. --------------------------------------------------------- iv seen these fisher and pykal direct drive motors being used as good alternators for wind turbines, my question is why are they good for a wind turbine? and is it possible to make one yourself? |
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Chris Senior Member Joined: 12/09/2005 Location: AustraliaPosts: 146 |
Makourian the motor will only spin one way, and if by a chance it does spin the other way. It wont matter once the voltage hits the rectifiers. It will still come out the same polarity. If your LED's arnt glowing then, they may be connected backwards. Or you might have a dodgey motor/connection somewhere. As for making a stator out of wood. I guess anything is possible. It would have to be strong though. However, the reason why they use metal or "laminations" is for the special magnetic properties it has. |
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| makourain Senior Member Joined: 19/04/2006 Location: Posts: 111 |
the 2 LEDs were put in so that no matter which direction the motor was spinning, one of them would light up. spin it one way the green one lights up, spin it the other way and the red one lights up. if i make that weird shape out of metal than the coils will be touching it, or does the wire in the coils have a special coating on it to stop it from touching each other. coz it looked like just a bunch of coiled wire, it would just be a big block of metal. but if its got coating on it, then i can easily make that weird shape out of metal. then all i need to do is hook all the coils up as shown on the f&p page for rewiring a stator. then stick them to those plates that at the bottom of the rotor and have little bits of metal to brush against them for output :) and have magnets around the outside. but, do i need 1 magnet for every coil, or do i just need 2 big ones? if i make my own stator, would i be better off using a disc break or a wooden or pvc wheel with bolts in? do the coils have to be right at the edge of the little legs or can they be spread further back, if they can be further back it will give me more room to to put more coil on. |
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| RossW Guru  Joined: 25/02/2006 Location: AustraliaPosts: 495 |
Ahhh. This makes it sound like a permanent-magnet *BRUSH* type DC motor. These suckers generally have quite high starting torque requirements compared to a brushless AC motor, and probably arn't the best option for a windgen because of the (relatively high) maintenance required.
The wire used in virtually all motors, generators, transformers,
coils etc, is a special wire called "enamel coated" wire. This is a
very thin insulating layer put onto the copper. It lets you wind it
against itself without shorting, and (to a point) against a metal
former without shorting. There is a limit though, and if voltages are
high, usually an additional protective layer (often just a sheet of
plastic or mylar) goes between the coil and the metalwork.
You don't need brushes. Indeed, anything that *TOUCHES* anything
else is bad. It causes friction. Friction saps your power and causes
wear. Leave the coils stationary and move the magnets, then you don't
need brushes! Wooden stators would have very, very poor magnetic properties. Your
generator may produce some output, but not much. It's not just a matter
of having "some metal there", it's the type of metal and where it
"conducts" the magnetism. Just like electric circuits have current
paths and current flow, so magnetic circuits have equivalent magnetic
circuits and paths. You need to encourage them where flow is good, and
discourage them where it is bad (eg, eddy currents take power and do
nothing but produce heat, so you want to discourage them!)
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| makourain Senior Member Joined: 19/04/2006 Location: Posts: 111 |
[quote]Wooden stators would have very, very poor magnetic properties. Your generator may produce some output, but not much. It's not just a matter of having "some metal there", it's the type of metal and where it "conducts" the magnetism. Just like electric circuits have current paths and current flow, so magnetic circuits have equivalent magnetic circuits and paths. You need to encourage them where flow is good, and discourage them where it is bad (eg, eddy currents take power and do nothing but produce heat, so you want to discourage them!) so does that mean a disc brake is ok? or do i need a special kind of metal. and if i use a disc brake can i use bolts or do i have to cut the disc brake? |
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| makourain Senior Member Joined: 19/04/2006 Location: Posts: 111 |
thin tin as the tail fin, everything else as per instructions. i apologise for the image quality [quote]Leave the coils stationary and move the magnets, then you don't need brushes! what do you mean by not needing brushes? and if i move the magnets around instead of the stator then wont the wires coming out the back of the thing be spinning around? i dont understand |
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| Chris Senior Member Joined: 12/09/2005 Location: AustraliaPosts: 146 |
Keep the stator stationairy, and spin the magnets. If you where to wire this up as a motor it would require some electronics to get it to spin correctly. However, we want generators. So all we need to do is rectify the output. Google these terms (or better yet go to howstuffworks): Brushed motors, brushless motors, permanent magnet motors. There is heaps of names for them. How stuff works is a great site id go there first. |
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| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
(earlier) you said:
to which I replied:
Then YOU said: You said: "little bits of metal to brush against them" - this
suggested to me you were trying to copy the brushes found in your old
dc motor. These "brushes" are simply NOT REQUIRED in this application.
Ok. A generator, alternator or transformer, indeed just about any electro-mechanical device, relies on the "relative motion" between a magnetic field and a conductor. A generator and motor are basically the same animal, except one takes electrical energy in and makes mechanical energy out, the other does it back the other way. Often, a machine designed to do one, can (and will) work perfectly well the other way around. So, a slot-car engine will spin if you put electrical power into it, or produce electrical energy out if you spin it (mechanical power in). If you have a coil, and a magnet, you can create voltage output if you move EITHER the coil OR the magnet. So, if you have a machine with a bunch of coils, and a magnet, you can EITHER move the coils OR move the magnets - as long as the two are moving <i>RELATIVE TO EACH OTHER</i> you get output. Since it's (electrically) a lot easier to hard-wire the coils and doesn't require brushes, most generators (alternators) actually have the windings/coils ("Stator") as the stationary bit, and spin the magnets. So.... put your magnets on the shaft that spins with the propeller and leave the windings fixed to the body of your machine. Does that clear it up? |
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| makourain Senior Member Joined: 19/04/2006 Location: Posts: 111 |
basically what i want to know is, how do i turn the 3 wires from this and also, what are all of these different kinds of magnets? neodynium, rare earth. what kind of magnets do speakers have? and how good would a magnet i make myself by sticking a magnet on a piece of metal be? also, can i use a brake disc for the stator? could i also use a piece of wood or pvc with bolts come out the edge? |
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| Chris Senior Member Joined: 12/09/2005 Location: AustraliaPosts: 146 |
Argh makourian, your jumping in the deep end to fast buddy.  You really need to learn the basics on how motors work, how electro magnets work, and how magnets work. Building your own generator is a bit pointless when its not that difficult to get a decent motor like the F&P smart drive at a decent price or even for free and get a pretty decent output.. When you build your own motor, its not just a matter of slapping some coils on a stator, making a magnetic hub etc. You have to have the right amount of coils or you will get to much or not enough voltage/current. You have to space your magnets correctly or your magnetic field will be all over the place saturating the coils in magnetic flux. Which will leave you generating very little power. You have to get things to spin perfectly centre etc... Im sure I, and alot of other people hear would suggest you use a F&P smart drive first, then once you have that sucker up and flying. If your still contempt on building your own. Then do it. |
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| makourain Senior Member Joined: 19/04/2006 Location: Posts: 111 |
i know how electric motors and magnets and electro magnets work, the problem is that there arent any smart drive motors around here. im in western australia and iv never seen one, where would be a good place to find one? a tip? |
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| RossW Guru Joined: 25/02/2006 Location: AustraliaPosts: 495 |
It doesn't need to be a F&P. "Stepper" motors are a good option too, as are just about any permanent-magnet AC motor. Ie, just about anything with permanent magnets but without brushes. For really low power, stepper-motors out of hard disk drives will do. For higher power, larger motors are good. Carriage drive motors from dot-matrix printers, or motors from ye olde tape drives. At a guess, a good place to start for a (specifically) F&P would be your local whitegoods repair centre. Check with whoever SELLS F&P washing machines, ask them who the local service agent or repair dude is, and contact him. |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
This topic was getting a bit big so I've closed it, was taking too long to load. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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