what is a good motor/alternator/generator to use for a bike generator that's cheap (under $50, preferably under $20)?

I'm on a budget and the bike is going to be mobile so I need a cheap motor but I also need it to be light. The bike would be used to power a USB hub where any USB powered device would be charged or used. So all i need is 5 V. I don't think an alternator would work becuase they look very heavy and I would be riding about 10-20 mi. round trip. It must be light and as far as attaching it goes I intend to use an instructable on bike generators or just plumbers ties to attach it. The only instructable that met all the requirements I've named that I've seen was https://www.instructables.com/id/How-to-Charge-Any-USB-Device-by-Riding-Your-Bike/ . That motor was too expensive "We decided to stick with our Maxon 90, which was a beautiful motor, even though its cost was $275." . Thus the need for a cheap light motor to charge a USB driven device. By the way, thanks for everyone that has posted so far!

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The bike generator I made and have two instructables on would seem to meet your goals with a little tweaking of course. You can use a stepper motor and the circuit I made but with different resistors for the variable voltage regulator to get 5V. My BikeGen instructable has a standard 12V car outlet so if you had a car charger for the USB device you wouldn't need to make any changes. I built the entire BikeGen system for less than $30.

Check these out: https://www.instructables.com/id/Bike-Generator/ https://www.instructables.com/id/BikeGen/
av8tor8 years ago
It depends on how small you want to go, I would go with a Delco 10SI alternator they are very common as they were used on all Chevy engines from 1965-1980 give or take a couple years. You could probably get one at a junkyard for $15-20 At the junkyard to do a very simplified test you can take some tools, drill, and a voltmeter. Hook the drill up to the pulley end then case is ground, positive is the large insulated post coming out of the back and test, I think clockwise this sould give you 12 volts
Okay your comment seems to make the most sense to me. I was thinking I could use a car alternator, weld a mounting platform to my exercise bike, and hook it up. Help me out here...could I just hook the laternator up to a 12v car battery than? And from the battery run a line to a convertor and have ac? I am sure I'm missing something and it is not that simple. Thanks, av8tor
here is an example of the configuration of a motor on a bicycle hub hope it spaks some new ideas for directions to take
Pancake Motor (photo).jpgPancake Motor (how it works).jpg
ANDY!8 years ago
Try gettin a solar light thing and replacing the solar panel with a small motor and putting the light on the front of the bike for a headlight.
Rmcfarland8 years ago
An old stepper motor out of a printer will have a pulley on it already and will make a reasonable small generator. Use it by placing the pulley directly over the rear wheel.
ac-dc8 years ago
You need to be more clear in the purpose, your needs, what it is powering. A good cheap generator for a bike would be one specifically made as a bike generator, nothing else is nearly light enough versus current generated, size, and geared properly to strap on and use without support parts quickly costing more than $20, if not more than $50. You'd not want an automobile alternator unless your purpose is to have the bike stationary, to be pedaling it only to generate the power not ride anywhere. If that is the goal, an automobile alternator would be a reasonable choice.
alexander.m8 years ago
if you want some thing simple to make electricity then I suggest a dc motor with brushes, a dynamo or alternator would be more effective but they are hard to find. You could find a dc motor from a treadmill, a toy RC car or buy it from a local store or at http://www.robotmarketplace.com/products/motors_ungeared.html
Once you find a motor make sheer that it is a brushed dc motor by putting a paper clip on the exterior to check that it has a magnet, then weir it directly to a battery of power supply to see if it turn. If it does both of these then you have a brushed dc motor. For the best results find one that has a high voltage rating.
You could use a brushless or step motor but there harder to use.