testing coil
By blueyonder, Section Newbies Posted on Thu Dec 6th, 2007 at 11:52:58 PM MST
it works good i think

been searching the board for coil output. and i did find sum great stuff put there by others  thanks guys.     so what is my problem. well i am my own problem as i cant find a coil winding output for all the bits i have .   so ive made a list of all the bits i am putting together.    6 foot prop made from hugh piggot plans . scaled down from 8 foot    9 inch dia x8mm thick rotor  one off.    8 n42 magnets  2" x1" x1/2"    6 coils  recycled wire.       so its a single rotor and i want it to charge 12 volt.   i have just finished potting the rotor. in mould withh resin etc.   a while ago i stripped a old transformer down and got the wire from it to make coils.    i made coil winder and wound coils  .    80 turns 15 awg.   its what it said in the book.  but it also said to use n35 magnets.  but i got n42 as the price was much cheaper.   i dident go with the plans . couldent aford to as n35 was more expensive.   but to try help things out a bit i used 8mm steel disc 9".   now for the hard bit. what i am doing is just using what i can get and what i have.     so 2 coils each phase   3 phase. star outlet .       so what i will hopefully have is a nice small mill charging at 12 volts and more.    here is my problem.    i put the rotor in the lathe.  made up a coil holder and put a multimeter set at ac.    first i wanted to make sure the coils worked ok.  thay did.  so what i dont know is are thay giving to much voltage.      to little voltage or maybe i can just make up the stator with the coils as thay are.         coils  1   rpm 165.  1.28 ac  rpm 330  2.66  rpm 605.              2             1.32 ac           2.70              3             1.43              3.02              4             1.34              2.70       4.70              5             1.34              2.59              6             1.46              3.09       5.50.    all is at ac  when i tried dc only one coil coil no 4 it gave 4.70 ac but only 4.15 dc 605 rpm.   now to try explain a bit more . four coils wound from 15 awg.    two coils wound from 18awg two in hand. inside transformer this thinner wire was at the bottom.    so at 330 rpm it al adds up at ac over 15 volts not spot on but im happy with my first atempt.      the coils no 3-6 are wound from 18awg and give more power out.   shall i take sum wire of the 18awg  so thay give the same volts as the other four.   will less turns make less volts. for the two odd coils.   remember i was lucky to evan get sum coils for nuthing from old trans.    maybe i will get sum help here and can evan things out.   things i dont know are speed at the prop in real winds.    like cut in speed and stall speed not understanding this yet    but from macanical point of view it might work ok.    or can i make this a poll.      all in favour stick it all in the mould and glass it up.      all in favour tweek it up  and put in mould.      all in favour put it in the bin.    in my spare time i will cut two 12" discs for twin rotor.  but thinks that will be next year sumtime.    so far i have one percent knowledge about windmills. its not a lot. but      when i get to two percent i will know twice as much as i do now.    i just better say i dont mean this to be a real poll.  but yah or nay will do fine.      thank you all.

testing coil | 6 comments (6 topical, 0 editorial)

Re: testing coil (3.00 / 0) (#1) by blueyonder (windwoodgood at yahoo dot co dot uk) on Thu Dec 6th, 2007 at 08:04:02 PM MST (User Info)

looking at the above post ive put a few words on there i mean a lot for me any way.   dont know if i am any good at trying to explain things in words.   but as thay say a picture can say a 1.000 words  . yes kurt i know thay can also say  a 1.000 megabite.  but i think i got this resizing thing going my way now.    if pictures are still oversize  please say. i have a cd with photoshop but it just gets me more confused. i am better with a pair of scissers for making pics smaller  the light colerd copper wire is the 18awg . there a bit more bulky.   also is it ok to put the three wires that get joined tegether.  one from each phase   can i put them at the center edge of stator instead of on the outside.   the other three that come outside will be ok.   i would rather ask for a bit help  than just do it and not knowing if its ok.   my nieghbours dont like burning smoke smell .        cheers its a ill wind that dos no good

Re: testing coil (3.00 / 0) (#2) by electrondady1 on Fri Dec 7th, 2007 at 08:09:23 AM MST (User Info)

blue yonder,  are the number of turns in each coil exactly the same? what is the resistance of the two inhand coils in comparison to the single strand coils? in order to charge a 12 volt battery it requires about 14 volts d.c. for a three phase alternator as you are doing. it's coil voltage x the number of coils per phase times 1.74 = phase voltage times 1.4 for the rectification to d.c. minus 1.4 for the voltage drop through the rectifiers going backwards to get the coil voltage required . 14 + 1.4 over1.4 over1.74 over two= 3.16 volts per coil its been a while since i tried that   please  google the archives to double check the numbers. it looks to me like you will need a whole other rotor in order to charge at 12 volts in 3phase with those coils at the rpm you are working with. perhaps you might consider going with single phase. that would require a coil for each magnet. 14volts minus 1.4 over1.4 over 8 = 1.37volts a.c. per coil. [ Parent ]

Re: testing coil (3.00 / 0) (#3) by electrondady1 on Fri Dec 7th, 2007 at 08:21:34 AM MST (User Info)

sorry , i misunderstood your graph. it looks as though you may be getting enough volts for 3 phase from the individual coils . there may be some issues if the different coils have different turn counts and different resistance.  i never tried that before. [ Parent ]

Re: testing coil (3.00 / 0) (#4) by Flux on Fri Dec 7th, 2007 at 02:08:05 PM MST (User Info)

I take it that this is a single rotor as in Hugh's 4ft machine. I think you are pushing your luck a bit to try and use it with a 6ft prop. If you have scaled the 8ft prop then it will be faster than the intended 4ft prop and that will partly make up for the lower speed due to increase in diameter. I am sure it will work perfectly well as long as you can make it furl in low enough wind. I don't think you will stop it with a brake switch. DON'T FORGET if you use a larger prop than the design intended you will need to alter the alternator offset and tweek the furling. Flux [ Parent ]

Re: testing coil (3.00 / 0) (#5) by kurt on Fri Dec 7th, 2007 at 03:30:27 PM MST (User Info)

pictures are sized great thank you!! http://www.reresource.org/ IRC

Re: testing coil (3.00 / 0) (#6) by blueyonder (windwoodgood at yahoo dot co dot uk) on Fri Dec 7th, 2007 at 05:25:20 PM MST (User Info)

i am so happy that pics are no longer a problem. thats made me feel a bit better.    i have sum more details that might help understand this hybrid bird.    i started it of with a mini brake drum . it was going onto the hugh piggot body .  i mean the metal frame. yaw pipe and furling tail.   but brake drum was a bit close to yaw pipe so i set it at 6". that is center of   prop shaft to center of yaw pipe.    so maybe that can help with furling.   i found out the bits i had were not going to make power.   so i started again this time looking at converting what i had to the hugh piggot 4 foot mill.    but using n42  but just single rotor.   the recyled coils were never ment to be used.  i just wanted the practice .    aswell as making a coil winder.   the OHMS  i dont understand . but with menny differant test meters thay all show   a reading of 0.04 . every one has the same reading .   it dont make sence to me but will to sumone .   so maybe the prop i have will be to big.  well i do have a air-x  prop i got on ebay. plastic carbon and black in colour.  it would go on no problem. its got its own hub.   i forgot to say the reading i got at 605 rpm was 4.70 volts ac. then i put bridge rec   on the two coil wires and then checked output dc. it went down to 4.15 dc..     the other thing i need to ask again is. can i join the three start wires and put the wires at the center of the stator.   then take other three out the side edge  like i mean the outside edge.   when i get it done the stator . do i need connect it to a battery to measure the output or just . test the dc comming from bridge recs.  would the 6 foot prop be ok with two rotors.    this stator is allmost free only a bit resin and glass.   but if i made new stator with two rotors . only six coils.  with n42 and 8mm backing plate and six foot prop.   what wire would be best and how menny turns.  stator would be 1/2" thick.   i feel im more like a office  worker sitting here at keyboard.    but with spelling like mine would soon be brushing the floor.   never done so much typing .   but as thay say  practice makes perfect.    cheers all. its a ill wind that dos no good

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