The wife of a friend wondered what one could do with a bicycle wheel as a wind generator so I started to build one in tinkering mode. I removed half of the spokes leaving a fairly reasonable set for a maybe-ok angle on them. Since then it occurred to me to look on youtube and there are several there already, for example
although he doesn't have that hooked up to a generator yet. This one is cool:
This was a bit annoying and not a bicycle wheel, yet educational:
and I'd recommend it to anyone interested in this topic.
Ok with that proper stuff out of the way, back to my redneckish project. Of course the blades, for lack of a better word, on the bicycle wheel are not ideal, though there is a possibility of extending outward. I removed the bearings and synched it up so the threaded shaft can no longer turn freely, planning to couple to the generator shaft (not the same diameter, argh, well ok, slap forehead and press on). The idea is to just see what can be done with fairly easily available materials. The pipe dream would be to inspire tons of people to build something simple for themselves. So, even though I have some DC motors that I think would work well as generators, wanted to have something easily obtainable by the average household, so I dropped in to the local wrecking yard and picked up a radiator fan unit from some sort of Chevy vehicle, 1991. (Windshield wiper motors have a worm drive and not too easily removable gear housing that made them less practical, fuel pump is messy, couldn't find an automatic antenna motor, any others?). Wanted to find a newer fan motor, figuring newer would be more efficient, ran out of patience in the oily mud. Anyway, the fan itself was nice after some cleanup though I figured it wouldn't do well as a wind turbine, for several reasons (including, only about 14 inches in diameter) so I removed that part and am left with the motor, or in this case generator.
Turning the fan by hand when it was still on there I could only get about a volt out of it. No worries. Using a hand drill at max, just
10.5 volts. Now worries. The drill says 0-2500 RPM. At 2500 that's some pretty ******
* strong wind, rare, bummer. So hence the question.
By the way this motor/generator has permanent magnets. Turning it slowly by hand you can feel the tug as pole pieces line up with the magnets and move past them. Not all radiator fans are like that and I'm not sure what the others are up to. Actually, without taking this one apart you can look through gaps and see the magnets and coils and inside, I'd guess 16 gage wire.
I was thinking one can pulse DC at a fast rate into a transformer and rectify the output for higher voltage DC (and proportionally lower current), with some degree of power loss in the process ("switching" power supplies). Figured there might be off-the-shelf units for that. Or it might be cool to hack a computer power supply, which I think are the switching type. I'm not familiar with solid state DC-to- DC converters.
Originally I was thinking something more primitive. Charge a cap from the generator and when the voltage reaches 3.2 or so, a zener diode triggers a transistor which both closes a switch to allow the contents of the capacitor to dump into a step-up transformer and simultaneously opens (stops) the zener path to not blow it out or waste energy. Or maybe that isn't necessary for the zener trigger side, as mentioned just use a FET instead? Or even a resistor to limit the current. So then, once the pulse into the transformer is triggered, there will be some output, however, it has to be repeatedly pulsed, can't just leave it flowing steadily or the transforming stops. Maybe charge 4 caps in parallel and discharge them in series.
I feel like a guy with a couple of hammers looking at a grand piano figuring maybe hitting it a certain way a concerto will emerge, knowing pretty much exactly enough to be dangerous.
Was hoping for a unit to buy, 3-6 volts in, and intermittently 13.8 out. Current becomes an issue? How much here, I'm not sure. Donno how best to measure the current output capabilities of the generator. Do think I have a precision 1 ohm resistor laying around somewhere if that helps. Just using my VTVM I didn't have to spin very fast with the drill to reach 8 amps (max 10 for the ammeter and didn't want to blow the fuse). That's with virtually no load. The coil, just hooking up to the two wires, measured .4 ohms.
Hmm, now after seeing that last video mentioned above I'm thinking I might prefer to scan the neighborhood for one of those exercise equipment treadmills with the "Free" sign on them next to the street by someone ready to just return to their cheese puffs. Sounds like they have fine DC motors/generators.
Now I had all of this written and was about to send, then googled DC- to-DC converters and found
Got to wondering if one could be pulled out of a dollar cell phone from the thrift shop. Eah cripes, no, seems would be too small to handle much current.
Thanks for the responses and kudos to anyone figuring they could help put this more on track (or is that this moron on track, lol).