This instructable will show you how to make a crude, but sturdy, hand cranked generator, capable of supplying  just a few watts of unregulated DC, at a potential of a few volts or so.  This generator is suitable for classroom demonstrations, science projects, lending credence to the legend that a motor can be used as a generator, and amusing children of all ages who have not seen this trick before.   

By itself this generator is basically a toy.  The operator turns the crank, and he or she produces enough electricity to light up a old style, incandescent, flashlight bulb.

No doubt there are going to be questions like:

"How can I make/modify/improve this thing so it can power/recharge my cell phone/ mp3 player/ vibrating massage wand/ etc?" 

Such things may be possible and maybe even practical,  however the goal for now is simply to light up a flashlight bulb. Any designs more complicated than this will have to wait until a later instructable.

BTW, I apologize for using a blurry picture as the "main" image for this instructable, but this actually the best photo I've got that captures this generator in action.  I'm guessing this photo is clear enough to see what's going on, but if you need a few hints:  The big blue thing in the background is Jack's tee shirt. The bright pink-white blob is the light bulb, with current being driven through it.  The almost invisible blur on the left side of the picture, is Jack's hand turning the crank.

The second pic is a still shot of the generator on my workbench.

The third is another action shot, but this time with the generator clamped in a vise so it won't move around so much and make the picture blurry.
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Looks like an excellent idea and a very nicely documented instructable. The electronic control that you are sending to "Junk" looks like it could be used for other projects too. Some useful looking components there.
Jack A Lopez (author)  Dream Dragon1 year ago
Yes. Indeed. It is very important to use every part of the buffalo. I mean, it's like, is the Great Spirit made out of buffaloes?  Good question, huh?  Fortunately cordless drill parts keep better than buffalo parts.  I mean some parts of the buffalo require refrigeration, and even then you can't keep 'em the freezer forever

In contrast,  that old drill's  MOSFET with matching its heatsink should keep for a really long time. Although I have heard rumor it's not forever either, and this is due to slow diffusion of the little dopant atoms that make N regions N-type, and the P regions P-type.   I don't recall the number of years ( or maybe it's centuries?) it takes for transistors to "go bad" in this manner.   But, you know, nothing lasts forever.

But that's a little off topic.  I think what you were saying was:  Every part of the buffalo is useful for something.
I like your sense of humour, it would win you one of my "Custom Badges" if my "Pro" hadn't run out, so you'll just have to make do with the compliment instead.

but the power MOSFET thing would make part of a computer control switch right? Obviously you'd need to isolate it with some kind of "Opto-Isolator" or something, to protect the computer... and if you wanted to run forwards AND backwards I think I'm right in saying that you'd need two of them?
What an interesting idea. I'd like to have a bottle dyno for my motorized bicycle. It runs about 20-30mph constantly, with LED & battery lights for stop and low speeds. Bottle dynos sold for bicycles are generally marked with a warning not to install on motorized bicycles as they will wear out faster.

Do you think a cordless drill motor can be made into a tire-driven or chain driven generator, esp. a DC generator for LED lights?
Jack A Lopez (author)  Yard Sale Dale2 years ago
I think a DC motor, from a cordless drill, driven in this way, would wear out as fast or faster than the bottle dyno which you say is  not recommended for a motorized bicycle.

But then I also think that if you pedal your bicycle like Lance Armstrong, that would wear out the dynamo faster too.

Anyway, the main why reason I think a motor from a cordless drill might not last as long as the bottle dynamo, is brushes.  The DC drill motor has brushes, and the bottle dynamo probably does not have these.  The brushes are always rubbing against the, whatchacalit (commutator?), and eventually they wear down.  Guessing that in the bottle dynamo the parts that wear out are the bearings. 

Or maybe the copper windings burn out from too much voltage, as a result of the dynamo turning too fastIf too much speed is the problem, the dyno could be made to turn more slowly by using a larger whatdoyoucallit, (wheel?) that rides on the bicycle tire. I.e. if that wheel that rides on tire were made larger it would turn more slowly.

The formula for this is just ω=v/r, where ω is angular speed, v is the speed of the edge of the tire (and also the speed of the road underneath the tire), and r is the radius of the little power absorbing wheel.

E.g. if that wheel thingy has a radius of 2 cm, and the bike is moving at 10 m/s (about 22 mph), then the angular speed of the little wheel is (10m/s)/(0.02m) = 500 rad/s, and that is 500/(2*pi) rev/s = (500/(2*pi))*60 = 4800 rev/min.  If instead you used a wheel with a radius of 3 cm then, at that speed, the little wheel connected to the dyno only turns at 330 rad/s = 3200 rpm

However, it may be the case that the drill motor is cheaper, especially if you already have an old cordless drill in your possession.  Also you have to build the thing that connects that motor to a wheel that rides on your bicycle tire. Presumably if you buy the bottle dynamo, it comes with whatever mounting brackets are necessary for it to ride on your tire.
Yes, bottle dynos for bicycles (aka tire generators), are known for failing at the bearings, then locking up and cutting the sidewall. Some riders avoid that by running the gear on the tread of the tire, and/or installing rubber caps on the gear ($2-20, some people use O rings) to both slow the RPM of the dyno, and protect the tire.

Tung Lin makes a $50 bicycle dyno that offers 2 12v circuits (1 for head and 1 for tail lights) and apparently can withstand running these speeds, with the gear cap.

I do like DIY stuff though.

The friction-drive unit that I have has a 1.25" diameter roller, which I am interested in using with a vacuum cleaner belt and motor. I don't know if the vacuum cleaner motor will produce anything usable though. I'll have to try it (old busted vacuum)

I have an old(er) drill too, not worth buying the battery for, but I think I'll just run a 12v cig plug and wires to it and use it for a screwdriver and polisher.
park473 years ago
Good idea.... for 2012 Doomsday when all electronics fail..... I like it.. :)
arnookie4 years ago
This would work for charging a battery if you added a diode to stop current running back to the drill. If you had a 18v drill you might be able to put some charge back into a 12v battery. Might be worth a try at least. I will test this out. I was going to add wind turbine fins to my old drill to see if it could charge batterys but never got around to it.
Going "backwards" through the drill's gearbox means that a wind turbine would have to produce a very large amount of torque, so...

That means you will have to have a very large wind turbine, but it will work

IF you removed the motor from the drill [I wouldn't do this with anything but a junk drill] then the torque requirement would be reduced greatly, BUT...

The turbine/motor would then have to be turned at very high speed to get any significant amount of output.
Kante Tech4 years ago
this could also work with a regular motor as well.
tocsik4 years ago
I knew there was a reason I've hung on to that old cordless drill all these years. Thanks for the idea. I think I'll actually try to fit it into a box so it looks less like a drill, and Make it look like it's powering some old radio tubes or something. I'm actually pretty excited about this one.