not getting expected voltage, ideas?

[theTinker]

hi, i was wondering if sum1 might be able to tell me if this sounds right.

ive built part of my alternator(single rotor) and have my magnets attached(evenly space), its 12 magnets

(1 * 0.5 * 0.25 inches) and im now doing my test coil.  the problem is i seem to be only getting 0.3 volts, below are the details of what i have.

i have made 100 turns of 26SWG wire. now this is the first one i have built to this stage so i was basically just aiming for voltage which is why i used such a high turn. the ohms is 1.8 per coil. when i spin it by hand, it spins about 3-5 times per push . it seems faster than i expect the wind to spin it. the rotor diameter is 10 inches. airgap is about 1/5inch-1/8inch(slight wobble)

thanks for any tips on why the votage is so low.

[Flux]

For a single rotor with no return path for the flux you have little hope with such small and short magnets. I have no idea of your speed but what you have got doesn't seem unreasonable.

Unless you make it dual rotor with or without magnets on the second disc it will never be much other than a toy. The gap you have between magnets and coil is large for such magnets and you don't say how thick your coils are.

Flux

[Experimental]

Hi Tinker,

   Flux has given you the "BIG PICTURE", all I can add to that is -- on thin magnets, very close tolerances are critical, so your wobble is very bad news -- this can perhaps be cured, partly, by shimming your rotor to get it to run true -- then as he stated, add another rotor on the front!!

   I have built several small gens, with about the same size wire and number of turns -- I finally wound up with number 20 wire -- but 10" seems very large diameter, for such small magnets and coils though!!??

   The last small mill I built, was 6" rotors, 8 magnets (total 16) and six coils of 20 gage wire of 75 turns 3/8" thick stator -- with a clearance of about .030 between the rotors and stator, wired three phase

   Magnets were 1" X 1-1/4" X 1/4" thick neos and works extremely well, but as you can see -- really close tolerances !!

   Don,t be discouraged though, just keep working with it and try to get that rotor as straight as possiable and build another rotor for the front -- if you can afford it, you might want to consider larger magnets with heavier coils at this point -- with 10" hubs, you could build a real power house !!

   At any rate, keep building, Bill H.....

[theTinker]

cheers for the help lads

as long as it wasnt sum mistake im missing then im happy enough with it,

i should of made it dual rotor, but it actually started out as just a basic wood work project. ive never built anything before so i was just trying to make the frame, didnt particularly use measurments as i had no idea what joints or supports i needed.

i agree the rotor was too big, but it was just sumthing i had in my backgarden from a kid. the coils actually had more line on the top of the wedge than the "legs"

ill defnitely keep at it then, i will be getting sum larger magnets soon, my gear isnt sized up to each other, it was more of just wat i could get my hands on fast.

thanks again for the info.

[theTinker]

let me add

later i might throw up sum pics, i was just mostly checking how to build a frame, and i managed to build a nice and sturdy one and a bearing with sum wood and sum pvc pipe. holds my rotor and stator securely, and the wobble was just sumthing i glued wrong.

ps: anyone who starts a wooden frame should have a saw first (unlike me)

[terry5732]

Your peak voltage may  be a little more than you are measuring. You might try to rectify and put in a capacitor - may be different. You can increase the output of your coils by coring or backing them with mild steel.

[jlt]

are your magnet roters wood or steel.

[theTinker]

the rotor is a steel disc brake, the stator is plywood.

[theTinker]

woot, i got it up to 2 volts!!! i actually made red light! if u were all really small people it might even be classed as a red star!