Felipe La RottaI just got an old dynamo and a light from the Bicycle Store, just for $5000 COP (2.54 U.S. dollars). You may ask “-What the hell is a dynamo?” Well, a dynamo converts movement into electrical current, and is part of a family of devices called “generators”. Without that physical principle, forget about your loved Playstation 5, home theater and microwave oven.
One would expect that such awesome thing would be too hard to explain without using nerd terms, but in fact is very simple
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How generators Work
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Around any piece of wire where electricity is flowing, a magnetic field is generated.
The law also works in reverse. If you take a magnet and rotate it near a wire, electricity will start flowing through the wire.
Yeap, you got it. The dynamo’s rotor (spinning by the force of the wheel) is attached to a magnet. The magnet, in turn, induces electrical current on an adjacent coil
This is a picture of the inside of the Dynamo. The rotating magnet is on the center, and fixed copper coils are around it
Turning the dynamo by hand is useless, your hamster wheel will not do any better. Is like pushing a car with the finger. A generator needs high RPM’s to work, that’s why they are driven by enormous windmills, gasoline or steam engines.
Energy could neither be created nor destroyed. If you need more power, you should borrow it from somewhere else. With no load, spinning the rotor is very easy. As more load is added, you need to apply more force on the generator to complete each turn.
That’s why I used a Dremel to reach the required speed/force for my tests.
I strongly discourage you from doing the experiment shown below. But if you do it, please fasten all the parts and use proper hands and eye protection. Avoid the temptation of accelerating the Dremel, always use THE LOWEST speed (otherwise, nice sharp pieces will be flying towards you).
As you can see, more speed means more volts. That may sound great, but it isn’t: electrical devices may burn up, or mechanical parts will tear apart if the speed is excessive.
Goodbye theory, now comes the practice.
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The headlight
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Along with the dynamo, I got a very old headlight. Sorry by not showing the mounting process, they did it for free at the bicycle store.
It even includes spare bulb inside!
Some water and soap later, good as new
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Generator Mounting
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Fasten the dynamo to your bicycle frame. It should include the required clamp and srews, if not, you have been tricked mate.
Turn your bycicle upside down, and crank the wheel to make sure electricity is generated
Forget about turning upside down the bycicle, ride it downhill!! (If the left brake is damaged and the right hand is busy with the camera, is even more fun)
The thing is working fine, it was a good investment. At this point, the last step is wiring the dynamo and the lamp permanently. Do it as follows:
(Click on the image to enlarge)
I know is a extremely generic drawing, I can’t do one for your specific lamp. The only important thing to remember: If your lamp’s case is metallic (like mine), maybe is part of the circuit. Keep that in mind to avoid short circuits.
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Speed vs. voltage issue
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This model works for old incandescent bulbs, but there is a serious disadvantage: Insufficient speed, the light will not glow. Too much speed, and the light will blow up. Imagine that for your state-of-the-art, brand-new LED – Xenon lamp!
In the second part, we will fix that problem
