Number of turns for 2-coil 24v stator?

[fordfasterr]

Hi all, I have been working on a project to build a small generator out of a spin bike that I ride at home.

I have the strong magnets, however they are quite small (about the size of a dime, but twice as thick) so I need to build some small coils.

Anyway, I need to know how many turns to put on each coil to get about 24-30 volts.  I will then rectify it as usual. I have 400 feet of 24 awg green magnet wire. (I hope this will work!)

If the first two coils work, and I get a voltage  then I will simply build 2 more coils and wire them in parallel to keep the 24 volts using a 2nd rectifier.  I might even build a 3rd to see if I can still keep the thing moving with more load..

Can anyone chime in, PS: This is my very first generator build.

( I have a 24-36v grid tie inverter with a dump-load connection that I will be connecting to the generator) ...

[hiker]

what kind of alt are you trying to build ?
dual rotors-single ?
2 coils? 4 coils? or 6 coils?
you  could just build a simple single phase alt--ide go with at least 8 coils...
maybe 80 winds per coil--8 mags per rotor.........hard to tell what you have planed...?  just a guess your going to put the mags on the bike rim and coils off to the side-top ?  might want to double stack those mags for a little extra power..
good luck.........

[fordfasterr]

Here are the pictures of the spin bike rig:

I still don't know how many turns to put on each coil to get +/-24vcd after rectification.

[Mary B]

I see room for a 12 magnet 9 coil setup, could be one or two sided. Is the bike wheel made from steel?

[fordfasterr]

Answer to post above:  yes, it is made of steel.


I really should be more clear as to what I actually need help with.

My best guess is that the easiest thing to do here for starters is to simply create a single coil, wind it up x # of turns and then test it out...


Based on the results, I can add/remove more turns as needed to get the the right number of turns necessary.


Of course you don't see the magnets on here yet... I'm waiting to position them once I have somewhat of a decent coil assembled.. 

[hiker]

heres a simple setup up...used auto flat belt---mounted on the flywheel down
to any dc or ac motor you might have--you can make a pully from plywood
to get the right gear ratio...good luck  ....

                   http://www.youtube.com/watch?v=iC9op-nWxPE

[fordfasterr]

I have considered the idea, but then how will I learn more about generators?


It would be of much more value to me if I made it myself from scratch rather than strapping a belt to a generator. 


Another option I was thinking about could be to arrange the magnets so that they produce only DC power.  iE, face all of the magnets in just one polar direction so that I don't have to run the coils through a bridge rectifier.

What do you the experts here have to say about this approach?

[Mary B]

I would mount 12 magnets on the wheel, wind 12 coils and mount it as close as possible. Won't be very efficient but you would learn a lot. Look at the axial air core alternator in the wind section for ideas.

[hiker]

heres a old 8 and 6 dual rotor alt i made years ago--coils wound from plastic coated wire-not mag wire..  cheap ceramic mags...
6 coils 8 mags per rotor 3 phase...fun stuff
i really dont think your going to get any real power from your little mags mounted on the flywheel- with coils mounted above..are you going to mount the coils on some kind of steel band--or not...the steel will attract more of the magnetic field up to the coils[more power output]--but will also induce some drag as well..
had the same idea awhile back--was going to use ceramic mags doubled up[side by side]..and some sort of steel backing for the coils..  well have fun..its always a blast to see your own cereation come to life.....  ITS ALIVE........................

    http://www.youtube.com/watch?v=LSdOwSBXKGg