Wind power from an 18" windmill

[dhagerty]

For no other reason than curiousity, I decided to make a windmill generator from yard windmill of the type that you buy at Harbour Freight for $30.00.  I read this web site,  bought the "Hugh" book and ventured into the garage.

Here's the first stator and rotor:

The stator consisted of 8 coils of 20 turns of #20 wire.  The stator didn't work (especially after I drilled through one of the wires), so I created another stator:

I put a voltmeter on one of the coils, spun the windmill and got nothing out of it.  I'm going to try more turns, a ferrous core for the stator, and maybe a ferrous backing for the rotor.

The coils are wound on 8 plastic table leg tips (the little gadgets that go on the bottom of the table leg to stop it from scratching the floor).

My current problem is:

   
• put voltmeter on one of the coils
  
     
• spin the rotor
  
     
• note that I'm getting no voltage, according to my digital voltmeter
  
  

My physical and electrical configuration is:

   
• 8 magnets
  
     
• 8 coils wound on table leg tips
  
     
• gap of perhaps 3/16 of an inch
  
     
• 20 turns of #20 wire on each of the 8 coils
  
     
• rotor and stator roughly 6" across.
  
  

In other words, single phase electricity.

One more picture:

[drdongle]

The back plate for your magnets needs to be steel...not wood, you'll find that works a lot better

[electrondady1]

you should be getting some thing. make shure your mags are nsnsnsns .  also make shure the coils can cover two mags at a time . make shure the coils are wired inside to inside outside to outside. just took another look at the photo.i think your coils are way too  small. electricity is only produced when a coil can cover two mag poles

[wooferhound]

20 turns is not enough, something closer to 100 turns

and 20 gage wire is border line too small.

The coils should be bigger than your magnet,

the magnet should be able to fit inside the coil.

Looks like ceramic magnets, don't expect too much from this type magnet.

as mentioned above, mount your magnets to a steel plate.

If you put ferrous metal insided your coils, it will make startup difficult.

[hiker]

try #17 wire about 85 to  100 turns per coil..

heres a shot of my minnie stator--single phase dual rotor-12 mags'[6 per rotor]

and 6 coils..yours is set up for single phase--8 coils 8 mags--your coils should be wired up to read--first coil--clockwise-secound coil -counter clockwise --and so on.

you will end up with only two wires--start and finish..wire all coils in series..

my minnie mill is only about 85watts--lights up a single 12v 50watt headlamp bright..

but not as bright with two..thats with ceramic mags...

next one will be three phase with neo mags..

ps: put some iron behide your coils--even strapping tape works--just tape one side of it then roll it up in a big coil --then mount this behind your coils..and mount your mags to a metal disk..a 7" saw blade should work for yah...just super glue them on there....good luck..

[ghurd]

I am doing the same darn thing with the bigger 22" one!

I'll agree with most the all ready mentioned problems.

Get 2, maybe 3, saw blades behind the magnets.

Put some laminate behind the coils. Scotch tape on steel strapping, rolled up in a donut, to be as tall (thick?) as the magnets. There should always be steel across from the magnets, very close behind the coils.

(laminate pics from Windstuff Ed's site...

http://www.windstuffnow.com/main/alt_from_scratch.htm

diff coils, but the lamanates show nice)

The hole in the coil should be as big as a magnet.

You need a LOT more turns. Maybe 100 per coil.

Me and Woof will have to thumb wrestle about the wire size.

I think #20 is plenty for this, maybe even #24.

There just isn't much power available in an 18" blade, with a 6" hub.

This is a slow blade, so you need lots of turns to get to 12v.  With heavy wire, the coils get too large, the distance between everything gets bigger, and there just isn't much space there to work with.

I'm afraid the high coil resistance is a necessary evil in this one.  Half the power gets used up in the coils, but without all the turns there is no 12v!

We will just have to be happy with ANY current at 12v!

Now for the questions.

What are you doing about the bearing slop?  Mine is really bad, needing a huge air gap to keep things from rubbing each other.

Looks like you threaded the factory... ummm... 'axle'?  Did the slop get worse?

BTW, the bearings are not very replacable. I totally ruined one set getting them out for a closer look.  I always start with at least 2, so I still have a spare blade!

G-

[DBGenerator]

I made something that is about the size of what you have there.  Check out my diary.  I think it's labeled Generator #2.  Those size magnets may not be able to excite enough electrons through 20AWG.  I should get one of those from HF.  I am working on PVC blades.

Dave

[dhagerty]

>What are you doing about the bearing slop?  Mine is really bad, needing a huge air gap to keep things from >rubbing each other.

>Looks like you threaded the factory... ummm... 'axle'?  Did the slop get worse?

You are correct in that I threaded the shaft/axle/whatever-it is.  In my windmill, a 7/16-NC die fit over the shaft, but was rather loose.  This has the excellent effect of cutting threads but not decreasing the diameter of the shaft at all.  I got a nut with the nylon insert and used that for a precise tension adjustment.  At one point, I was considering using another shaft.  I got some threaded stock with the intent of welding it into place.  The threaded stock was REAL sloppy, so I shimmed it with a .38 case that I had sawed (yes, I have other hobbies :-) )  The brass from the .38 case was the perfect size for a shim.

Another suggestion is 2 nylon nuts with a jam nut for each.  I taper them toward the bearing with a mill file so they don't bind quite so bad.

>BTW, the bearings are not very replacable. I totally ruined one set getting them out for a closer look.  I >always start with at least 2, so I still have a spare blade!

The bearings on mine really stink, too.  Lowest bidder, I suppose.

I'm going to try several of the suggestions here; they're good.  Thanks.

               Dave

[billf]

Hmmm I've been thinking about doing something like this to my yard mill for some time. Should work great for charging those little yard lights. If you orient the mags properly and wire the coils right you should get something usable. Goop up the bearings with boat trailer grease-might help. Looks good.

[keep the smoke in the parts]

super cool, every one has thought of this but not dune anything."props" to you and good luck...and yes i also bought one at harbor frate tools and now I am eye n it as I type. I have also seen good bearings at ACEE Hardware but a little pricee.I like a good project keep'apostin

[ghurd]

I mostly gave up on mine this way, from scratch.  I don't have some of the tools it should really use.  Maybe I'm just too picky.  I may go at it again...

I have a couple little conversions to go on the tower and blades (a lot easier).  Should have been long done.  The silliest problems just stop any progress for me.

They should be on sale again soon.  I got the big 8' ones for $22.50 each!

G-

[wooferhound]

Another thing . . .

make sure you set your meter to read AC volts if you're reading straight off of the coil.

And another thing . . .

your AC frequency will be quite low and your meter may not be reading the voltage correctly. It would be better to run the output through a bridge rectifer with a filter capaciter and set the meter to read DC volts.

[dhagerty]

Success!

Kudos to www.fieldlines.com/story/2005/3/5/24544/42024"> Paul for his stator.  Thanks to the aforementioned stator, I now own about 1/2 a volt, give or take (well, it's on loan).  In the "to do" column are to do some fit and finish such as

   
• remove the brads that Paul used to wind the coils


   
• Move the coil closer to the magnets


   
• Put in even more iron to increase the flux

Lessons learned

•  use as many turns of wire that you can get away with.  Then double it



•  With something this small, placement is critical.  Spend a lot of time in setup.
  
  
• Find a way to squish the coil as flat as possible, then pour the resin.  The general idea is to get the coil as close as possible to the magnet as you can

These suggestions are well-known to the regulars on this web site.  I'm a new guy, so I 'm just reiterating that they know what they're talking about.  I'm pretty happy.



Dave

[ghurd]

There still has to be a problem, I believe.

That stator should be getting quite a bit more than 1/2v.

Check the wiring. It should be connected 3 phase star / wye.

Test each phase seperately for volts, they should all be the same.

(10 coils and 10v, 1v / coil, on 2 phases. But the 3rd phase has 8v, that means the 8v phase has 1 backwards coil. Or maybe 2 shorted out coils.)

Check the resistance of each phase- they should be close to each other.

Maybe one or more of the coils is connected backwards?

Each backwards coil cancels out a good one, then the whole system gets out of whack.

If a paper clip sticks to the metal behind the magnets, you need more metal back there.

I can't tell in the stator pic's.  What coating on the metal did he use for the laminates?

If electric can get through the lams, that is where the power is going, eddy currents.

I have never seen lams in that way.  That direction.  If they are individually insulated, maybe its OK.  Flux, UGL, anybody but me, would know a lot more.

If the lams are plastic coated coat hangers(?), I wonder how much metal is in there compared to the space. For 1 thing, it's round, leaving space between them, and the plastic is going to use a lot of space too.  Just sound like not much total metal in the space available.

If it is wired right, and none of the coils is backwards or shorted, I would change the lams.

After going over everything 3 times, and not finding a problem, maybe rectify the 3 output seperately, add a large capacitor to the output of each bridge, and connect them in series. It should add the voltages, but reduce the amps. Again, I don't know how well that would work- it's just what I would try.  I think it was maybe Jerry who did this to get more volts, and it worked for him.  Some guys do it that way for low voltage stepper motors too.

I am keeping a close eye on this one. Quite excited someone else is trying it too.

G-