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Small-Town windmill makes good, lights LED
By dhagerty, Section Wind Posted on Sun Mar 13, 2005 at 10:10:32 PM MST
Ornamental windmill generates electricity in my front yard

I'm stoked. My cheap ornamental windmill lit an LED. Ok, it's not on the same lines as F=ma, but it's cool.
I bought a small, cheap windmill in hopes of generating power. Here's the first
half of the story Story here
I got output rated in millivolts with the first go. It was discouraging and embarrassing. PHinker, a friend and co-worker (and a more experienced head with these things) wound a stator, cast it in some resin and presented it to me. Well, it worked. Since we're all visual sorts (admit it), I'll get to the pictures.
From a distance:

The windmill stands about shoulder height. Version 0.9 found me making several new guy mistakes, such as not enough windings and not backing my magnets with ferrous materials. This is version 2.0, which has

7 inch saw blades for ferrous backing

3 phases of windings wound using Ed's method of winding coils

A bridge rectifier ($1.99 at Radio Shack

A 1000 mf capacitor (also from radio shack

Yesterday, in the stiff wind we have here in Boulder County, my wife commented that she noticed a red firefly in the front yard (she didn't know I'd set it up in the yard).
Here's some closeups.
From the back.

Notice the LED

I got about 5 volts depending on the wind. My next step is to build a little "LED voltmeter" for lack of a better term. The more wind, the more lights. I am also going to wind another stator as I nicked the stator for one of the windings and it does not conduct. I also am using ceramic magnets (cheap, cheap), and I want to step up a bit.
I really do have a life. Honest

Small-Town windmill makes good, lights LED | 9 comments (9 topical)

Re: Small-Town windmill makes good, lights LED (3.00 / 0) (#1)
by richhagen on Sun Mar 13, 2005 at 04:54:22 PM MST

Congrats on the LED. So you've got a little voltage there, do you know how much amperage your little mill is putting out. You might be able to make an array of LED's for a yard light, depending on the current you get with modest winds. Maybe rig it to charge a 6 volt battery and build a simple circuit with a Cadmium Sulfide light variable resistor and a couple or three fets and a cmos and gate to turn the lights on only at night and only when the battery voltage is above a certain level. Kind of like the circuitry in a solar yard light. Just ideas, but maybe they're of use to you. Rich Hagen
'A Joule saved is a Joule made'

Re: Small-Town windmill makes good, lights LED (3.00 / 0) (#3)
by Peppyy on Sun Mar 13, 2005 at 09:25:49 PM MST

Isn't it exciting when that led lights up for the first time! I have a yard full of them now. Mine are mostly parts built around a motor tho. I guess I should really build myself a genny someday.

Lot's of fun!
Pep
[ Parent ]

Re: Small-Town windmill makes good, lights LED (3.00 / 0) (#2)
by BT Humble on Sun Mar 13, 2005 at 05:17:04 PM MST

My next step is to build a little "LED voltmeter" for lack of a better term. The more wind, the more lights.

This will probably work for you - to make it read a lower maximum voltage, use a smaller value of Zener diode. For your application, I'd guess a 4.5V Zener and reducing all of the resistor values by half would be a good start. To light 3 of the LEDs requires about 30mA.

http://www.fieldlines.com/story/2005/2/3/63131/25107

BTH

Re: Small-Town windmill makes good, lights LED (3.00 / 0) (#4)
by dhagerty on Sun Mar 13, 2005 at 09:36:50 PM MST

While I don't know what I'm getting out of it, amperage-wise, I doubt it's a lot. I put 2 LEDs on it, and it seemed to visibly dim both. LEDs aren't exactly high-amperage devices :-). I like the circuit that BTH posted, and I believe I'll pinch it. I'm also going to have to rewind my stator for other reasons. At that time, I may buy me some real magnets rather than the little cheesy ones I'm using here.

Dave

[ Parent ]

Re: Small-Town windmill makes good, lights LED (3.00 / 0) (#5)
by hiker on Wed Mar 16, 2005 at 02:46:13 PM MST

try a little dual rotor on your next try--this one lights up a 12v 50watt headlight real bright -using 6 mags per rotor--with 6 coils -single phase-ceramic mags..
hooked up a 400 watt 28volt landing light to it just for the heck of it --and was surprized it powered up--on the dim side ..

WILD IN ALASKA
[ Parent ]

Re: Small-Town windmill makes good, lights LED (3.00 / 0) (#6)
by Vernon on Sat Mar 19, 2005 at 09:08:09 AM MST

This is my idea on a wind generator in simple schematic form. The rotor is a 1/4 inch thick steel disk with milled depressions in which the round magnets are attached with a light press fit and epoxy. The schematic shows two but as many pairs of round magnets as desired can be used. The stator consists of a laminated bar of transformer steel obtained perhaps from a junk distribution transformer, it could also be made of a number of mild steel welding rods bound together in some way. The coils are wound around the stator. Using wood, rubber feet or other non magnetic material in the flux path greatly reduces the flux and the voltage obtained. Poles should be arranged to alternate the direction of flux through the stator with the flux lines going through the center of the winding as shown. A drawback of this concept is the parking of the magnets over the stator and high starting torque ... since it is decorative "propping" to get it going in light wind is not a huge problem. Once rotating the inertia of the steel disk and blades will carry it through the "cogging" point.

[ Parent ]

Re: Small-Town windmill makes good, lights LED (3.00 / 0) (#7)
by nanotech on Wed Mar 23, 2005 at 08:52:16 PM MST

You know? You've given me an interesting idea!! I have a set of solar powered LED driveway lights!! (see where I'm going?)

Here in northern Minnesota there's quite a lot of the year that the little solar panels only give enough of a charge to light the LED's for about 20 or 30 minutes. Even under a full day of bright sunlight they only stay lit for about 2 or 3 hours.....

Now, if I set up a couple small windmills like you have and make a couple miniature versions of Hugh Piggott's design and coupled them into a bank of NiCad batteries all in parallel. Then run the output of them to the individual lights (which already have a slot in them for a NiCad "AA"). The lights have thier own built-in daylight sensor, so they'd only be drawing power when they needed it!! :D

Thank you for the idea!! now where did I put those VCR DC motors at???
__________________________________________
My ship finally came in, but it was the Kobayashi Maru!

Re: Small-Town windmill makes good, lights LED (3.00 / 0) (#8)
by ghurd on Thu Mar 24, 2005 at 10:55:15 AM MST

Part of your solar light problems are the crappy batteries they put in them. (500mah)
Change them to NiMh (2000mah) for better results... but them you will find the solar is too small.
Then the wind helps!
just a thought.
G-

[ Parent ]

Re: Small-Town windmill makes good, lights LED (3.00 / 0) (#9)
by ghurd on Thu Mar 24, 2005 at 11:01:18 AM MST

It looks like it could have eddy current problems.
Does the rear plate rotate with the magnet rotor? (no problem)

Is the rear plate fixed? (problem)
It should be laminated to stop current from flowing around in circles in the back plate. When it flows around in the back plate, it is not flowing as much in the coils.

I really want to see this bugger do 12 volts!
G-

Small-Town windmill makes good, lights LED | 9 comments (9 topical)

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