In my research to make an alternator for my Savonius VAWT wind power project, I learned there is a great deal of mystery around making them. I even read one article that referred to home brew alternators as a dark art shrowded in mystery. I dont think it is all that poetic but I did agree that for a novice with no real electrical background that it seemed a mystery. Kind of like a cookie recipe, you know there are things like flour, eggs and sugar, but how does it go together? What job does each ingredient do? How is it mixed or assembled?

From my experimenting, which is not over by the way, I found that this simple excercise was the most revealing.

You will need a huge magnet like used in a wind power project. The rest is available through normal hardware store or RS. I'm sure a good sized speaker magnet would probably work if you have a sacrifice to make.

1 small spool magnet wire (about 30 feet of 24AWG)
1 bulb from or for a keychain flashlight (two refills for $1 around here)
1 Neodymium magnet 1inch x 2inch and 1half inch thick (about $10 plus shipping and any tax)
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Step 1: Get wire off the spool and re-wind it

This seems like a goofy idea, the wire is already so neatly wound on the spool. The problem with the spool is the big hole in the middle. You need to re-wind the wire with a nice small hole and relatively flat.

The idea is to expose as much wire to the highest concentration of magnetic field as possible without shorting the wire in the coil. This is why we use magnet wire. It isnt magic wire that makes electricity, it is just that magnet wire has a much thinner sheath and its usually made of enamel.

The extra thin sheath allows you to cram more wire in the same space as you would regular wire.

The attached mov file is my drill coil winding jig in action.
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ok so do you know the song bangarang and the kid that has the electricity coming from his hand I want to have something like that.
The Bulldog3 years ago
Couldnt you better use a Diode bridge so it will burn when you go eitherways...?
Bluexadema5 years ago
for future reference just use a lighter and burn off a half an inch or so

it makes sure the whole contact is clear and its much faster, decent instructable though
bhunter736 (author)  Bluexadema5 years ago
I actually tried burning but found I needed to use sandpaper to clean the carbonized enamel from the wire anyway.  This stuff is so small it really is very little effort to clean with sandpaper.
jonafrank5 years ago
add a capacitor instead of the bulb to store charge and dont forget the diode to retain charge in this way u can store energy
El Mano6 years ago
If you want to purchase some good magnets, then go here. Where can I get info on how alternators work in a way a novice would understand? I can't find much on "how to build an alternator" (or a dynamo, for that matter). Only "this is what alternators do: blah, blah, etc. No information describing how and why they create AC in language an amateur could understand.
joe_61 El Mano5 years ago
THe best way I've seen AC explained was an upside-down 10-speed with the chain marked in one spot. As the mags move across the coil the field pushes and pulls the electrons back and forth in the wire. If you jog the pedals the same way keeping the marked part of the chain in a range of a few inches the pulses will spin the wheel faster & faster.
bhunter736 (author)  El Mano5 years ago
Hi, I will just take a second to describe why alternators make AC. Imagine you have two of these coils, wound exactly the same, sitting in the same position. Now imagine you flip one of them over so that the coil is wound in the opposite direction of the other. When the magnetic field traveling past them is the same, the opposite direction of flow will be generated in them because of their orientation, mirrored positions. The reason we like to make AC is because the current generated is stronger the more variance in magnetic flux, so in turn the most effective way to accomplish this mechanically is by the simple orientation of the coils or the magnets. Often, with a permanent magnet alternator, we flip flop the magnets and make all the coils the same. Imagine how inefficient it would be to pedal a bicycle if both pedals were in the same orientation, it would be like hopping and not like pedaling. AC is like offsetting the pedals by 180 degrees to create the most optimal use of the mechanical change. Potentially the same energy is there, but with the 180 offset we are more efficient at collecting it. Now if you are thinking, the magnetic flux is still coming from the same source at the same distance so why would it follow the direction of the wire, you would have a good question. The electrons traveling around a copper atom are always going the same way by nature. This means if we set a few free by inducting a magnetic field, they will pick up their direction by the spin of the electrons on the atom. Since this is naturally occurring we can pretty much count on the result to be predictable. So don't over think it. Let it sink in that this is how it happens and worry about the rest in physics class.
knight life6 years ago
Thanks , it is really wonderful . I will try to make one like that -
DanLoney7 years ago
magnet wire is just copper wire right? cant you just get that from radio shack?
bhunter736 (author)  DanLoney7 years ago
Magnet wire is just copper wire, but the insulation is a thin coating of enamel instead of thick pvc like normal wire. Yes it is available at RS, but when you need this much, you will probably want to order it from somewhere.
ok cool thats what i thought, and i was wondering what kind of magnets i should use, i was looking at the N42 1/4" thick with 27lbs of pull force, but i saw yours was 1/2" thick, would mine be sufficent for making my prototype?
bhunter736 (author)  DanLoney7 years ago
The 1/4" thick ones will probably be ok. I have not tried them. - I think I answered this in an Orangeboard. : )
hahahahaha oops, soory i didnt see that message in my inbox doh!
RyanPotter8 years ago
Correct me if I'm wrong, but doesn't this produce an AC current? If so, you'd need an AC to DC converter to power your LED.
What is an AC to DC converter? It is at the most basic level just a diode which half wave rectifies the current from AC to DC. More complex devices will contain about 4 diodes and some smoothing capacitors.
bhunter736 (author)  scotty37858 years ago
True. However I don't use an LED, see the flashlight in the photo... I use its 1.5V bulb.
cant you just put a few rectifiers on it and than that will put it to in the tic tac light???
bhunter736 (author)  girrrrrrr27 years ago
You can, but this is pulsing DC, always the same side of the magnet passing the coil. This is really a great experiment from Fariday to illustrate how electricity is made in a permanent magnet generator or alternator. Current is only made as the field from the magnet is in motion passing the coil. This is a good starter experiment if you want to learn how electricity is generated and how it flows. Use an LED and discover that it will work with the magnet held one way but not the other. LEDs are a form of rectifier in that they only light when power flows the right direction.
By using only one side of the magnet, you're only limitating the flux to half the potential between 0 and Fmax, if you're using both sides, you get -Fmax to Fmax, but because the currant generation is based on the derivative of the flux, you'd see surrant going in both dircetion in both case... To us this current shape, maybe put 2 leds in opposing polarity... It would go darker when the magnet is reaching the end of its course though...
bhunter736 (author)  RyanPotter8 years ago
Because the magnet I use is charged through the thickness, and Im always passing the same side over the coil, it is pulsing DC. However, this isn't the point of the experiment. Use a flashlight bulb so direction and AC/DC are not factors. Keep it simple, this is to show how electricity is created in the most basic fashion.
Well, i=L df/dt
f being the magnetic flux, When the amount of flux is increasing, you get the currant to flow in a certain way, when it is decreasing, it flows in the other way....
So you get an alternative current whatever the polarity of your magnet is...
An LED is a rectifier of sorts. If exposed to ac it will only light when it is "forward biased" and allowing curent to flow. When it is "reverse biased" it blocks the current flow up to it's breakdown point, if that is exceeded on a standard diode or an LED, it smokes. I think that was a "mini mag-lite" style light bulb that was being used though.
Derin fuzvulf7 years ago
and we only see the led light,we do not notice it is flashing
it's not an led, bro
An LED can be powered by AC current ;) But it won't be on half the time :P
bhunter736 (author)  RyanPotter8 years ago
The flashlight bulb is not directional like an LED. The AC/DC issue isn't really the point. This is just an exercise to show the less electrically savy how electricity is made.
erichimmler8 years ago
Does it produce more electricity if you make a larger version.
bhunter736 (author)  erichimmler8 years ago
First improvement for this set up to make more power would be more coils of wire. Thinner wire in longer length to fill the same space will make more Volts. Thicker wire in the same space will make more Amps. It is a bit of a balancing act for what you want. There is room for more of the same size wire in the field than I have shown here. So you could use longer wire and a little more area to get more Volts and Amps. This only works until you exceed the magnetic field and then you are creating resistance and actually cutting down the power. Good Question. : )
erichimmler8 years ago
next time try to use more than 2 pictures please
bhunter736 (author)  ich bin ein pyro8 years ago
I'll try to get one of me holding the two items, but I couldn't hold the camera and coil and magnet at the same time... When I can get an extra hand from someone, I'll add the third photo.
check if your cam has a timed thing mine has one the allowing up to 10 seconds
bhunter736 (author)  ich bin ein pyro8 years ago
Check out the last step, I added video a couple days ago.
i see now why you couldnt take a picture of it i found another use take off the LED and replace it with steel wool its an instant fire or those deserted island scenes hope this helps
bhunter736 (author)  ich bin ein pyro8 years ago
LOL : ) Hopefully if I have access to wire and a specialized magnet on a deserted island, I would have presence of mind to carry water proof matches. Its a good point though. PS - Its not an LED, its a flashlight bulb.
ive seen on myth busters they make fire with steel wool and a 9 v battery and you could replace that with your contraption and with the contraption you can start it whenever vs. a battery where it automatically starts
and this can also be used i havnt tried it yet but you can use the coil off of those cheap rechargeble flashlights see here

salvaging a "fake shake flash light" by hoopajoo
you will have to replace the batteries with a real cylinder magnet of course which can be gotten here

sourcing rare earth magnets by trebuchet03

i love connecting instructables !..! *.* !..!
bhunter736 (author)  ich bin ein pyro8 years ago
I saw that episode too. I love that show. Actually my 3year old son loves it too. Which makes me love it even more! You are right about the coil from the flashlight, that set up is made for a lot lower mAh but would work perfectly. That type of flashlight is essentially this experiment bottled up for resale with a capacitor usually, not the button batteries as apparently show up in the $1 version. I guess the cheapo light cheats with batteries because they are cheaper than a neodymium cylinder magnet big enough to do the job. Thanks for the connective input... get it... : )
what i would do is connect like 3 or 4 of these little magnets to make a big one and..... haha i got the 10th chain
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