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How to install LED eyes on a wooden lawn deco bird and power it with wings that move and rotate with the wind? Answered

We have a flamingo bird, a wooden lawn ornament (of course), called a "Whirlygig" by some, whose wings rotate when the wind picks up. I would like to know if there is a way to harness the energy from the rotating action of the wings to power a couple of LED lights used as the eyes on the bird. When the wind picks up, the wings begin to rotate very fast and at the same time, the LED eyes would glow brightly. The body of the bird is a flat piece of 3/4 inch wood so a 9 v battery wouldn't fit well and would interfere with the rotating wings.
Could the rotating wings accommodate some sort of dynamo effect to power the LED eyes? What about some bare copper wires glued to the inside of the wings and a magnet glued to the body? With the rotating wings and copper wires, wouldn't there be enough voltage to power a couple of LEDs? A solar panel would be nice but we want the eyes to light up at night when the wind picks up. Any ideas?


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Jack A Lopez
Jack A Lopez

Best Answer 10 years ago

You could build a dynamo to power a couple of LEDs. This is possible.  Probably the easiest way to do this would be using permanent magnets on the rotor (the part that moves), and some number of coils on the stator. This way the design is "brushless".  No wires have to run to any moving parts. No moving contacts, or brushes, are required.

If you've never done anything like this before, you might be surprised by the very large number of turns (maybe a few thousand) it takes on a single coil just to get enough voltage (~2 or 3 volts) to light a single LED.

Well, technically speaking the number of turns (N) is just one of three factors affecting the induced voltage.  The other two are the strength of the magnet, and the speed at which it moves past the coil. The actual equation is attached as a picture below.

Also instead of building a dynamo from scratch, (Here "scratch" means rare earth magnets and fine gauge enameled magnet wire.) you might be able to modify an existing brushless motor, like the kind found in an old floppy disk drive, or computer cooling fan, e.g.


10 years ago

It sounds like you have it all sorted, although I would fix the magnets to the wings, and the coils to the body, then you don't have to mess about with sliding connections for the wiring.

Try googling for a thing called a picoturbine, which is a small cardboard windturbine project, designed to light a few LEDs.