please help ghurd or anyone about axial flux

[awk]

@ flux
sir i have a digital mutimeter
i have put my magnets in nsns manner
i will post a pic soon.

[awk]

i only put seven mag for test

[awk]

the space between coil and rotor

[awk]

coil is 30 turns of 26awg
the magnets are spinning but no result

[snake21]

i think that the coil should be closer as possible to the magnets.and also the voltage generated is an a/c voltage,see if your multimeter is rightly set to ac voltage.

[hiker]

why do you have two clips on each coil leg ?
you dont show in the picture where those leads go?
you may be shorting out your coil......therefore no output!

[hiker]

one more time.sorry.is the extra lead going to your l.e.d.s--may need a few more winds to power up a  l.e.d

[ghurd]

Spread the proper quantity of magnets (12?) out evenly around the disk.
Get the coil closer to the magnet.

I expect the voltage being generated is short enough in duration the meter does not display it.
G-

[Flux]

The coil is a long way from the magnets, the voltage will be small.

I have to ask the obvious stupid question " have you scraped away the enamel from the wire where you have connected the clips?"  try yor meter on ohms range to be sure that you jhave actually managed to connect the coil.

Flux

[bj]

So now I have to ask a really dumb question---what is the return path for the flux?  As usual, I'm probably missing
something?

[Flux]

With a single rotor there is no defined flux path, it will pass from one magnet to the next by the shortest leakage path. To get much flux linking the coil the coil has to be close to the magnet. Somewhere beyond  a magnet thickness from the surface little flux penetrates the coil. That is partly why the yest coil should be very close to the magnet.

Single rotor machines don't use magnets effectively and coils thicker than the magnet will link very little flux in the part remote from the magnet, most of this region adds resistance with little gain in volts.

Apart from absolute simplicity or where magnets are more powerful than necessary the single rotor is best avoided.

Flux

[Bruce S]

coil is 30 turns of 26awg
the magnets are spinning but no result
(Attachment Link)

I wanted to say that I have one of these DMMs too, it will not give any results without the coils spinning constantly. It has a setting for 200Vac and 750Vac.
If you can, go find a hobby shop and see if they have a cheap-O meter that has the swing arm rather than digital, set it for the lowest setting, usually involves moving RED wire to different hole on meter.
As Flux and others have said, move the coil as close as possible to magnet, maybe only use envelope or couple pieces of paper as gauge then spin. 
The swing arm should move either way then.

Best of luck. Nice setup tho .
Bruce S

[bj]

Thanks Flux, sorry to butt in.

[awk]

@ HIKER
i have connected the coil legs to multimeter probe by a crocodile clip
u see red and black probe of multimeter these are connected by coil leg via croc clip.
i have set my meter to AC value.

@FLUX
SIR i have removed the enamel properly from the top end coil resistance is about 3 ohm.

@bruce
ok i will find a analogue meter then post result and put the coil as close as possible.

[awk]

         i have wind a new coil 30 turns of 15awg wire.
         but again no results.
   
      i put the coil that close, it is touching the mag when spinning. 
 
    for some exp i shorted both the ends for a thin wire it become hot after some spin what that mean
   
is current is producing or voltage but it not coming on meter.

 coil is also deflecting from the mag when spinning.

[awk]

  one more question does it is necessary to touch the coils in stator.side by side

 in my 10 inch rotor when i evenly space 9 coils,they have a gap in between of about 1 inch in between.

 coil dimension are
 round in shape
 inner dia about 3 cm
 outer dia about 6 cm

[Bruce S]

         i have wind a new coil 30 turns of 15awg wire.
         but again no results.
   
      i put the coil that close, it is touching the mag when spinning. 
 
    for some exp i shorted both the ends for a thin wire it become hot after some spin what that mean
   
is current is producing or voltage but it not coming on meter.

 coil is also deflecting from the mag when spinning.

I would back the coil off by just a few papers thickness, touching is bad, will ware the enamel off and mess with magnets.
Yes spinning and wire getting hot means current flow.
Kinda proves the meter issue.

[dave ames]

 hey awk,

 looks like you are having fun and learning lots along the way. that's the way to go!

something caught my eye with your setup..may or may not be an issue?
that cool adjustable coil winder thingy than you reversed the shoe on and are holding your coil with, is it metallic? could be we are getting some weird cancellation there? any chance of trying a block of wood or plastic for the mount?

it's all good fun!
cheers, dave

[kurt]

need an analog meter and your in the united states head to your local radioshack they will most likely have this one
http://www.radioshack.com/product/index.jsp?productId=2999093

i keep one of those in my truck to use when the battery dies in my fancy digital meter at the most annoying time possible (always happens that way) it works good for a cheep analog meter. the big plus of an analog meter is it does not need a battery to measure voltage it only uses the battery for ohms.

[awk]

 i bought a analogue meter from my friend and check VAC @10 meter
 when i spin it very hard it gives .1vac and the needle goes a little up.
 
 i wound a wire on studs of by hub and then jerk the wire off with a real massive force.it only show .1vac.

                what is effect of no of turn on a coil?

             is it necessary to touch the coil in stator?

@dave ames

the coil winder is not magnetic magnet is not attaching with it i think it is aluminum and by the way i have check coil in my hand while spin but no volts.

[awk]

    i get some thing on my meter

  i made 80 turns of 18 gauge wire and put in on single rotor test it gives 0.3 volts and when i spin it hard 0.8 on my meter.

     i want to increase volts to 2.5 vac per coil. 
     
       any suggestion?   

[Flux]

Well at least you have got it working.

With 12 coils ( 16 magnets) and 2.5v per coil you will have cut in at 24v. Is that what you want?

If so then make sure you have all magnets fitted you only had half in the picture. keep the coil close to the magnet and see what you get.
From then on it is ratios, if you get 1v and you need 2.5 then you need two and a half times the number of turns.

You will do better with another spinning disc with no magnets used to direct the flux. You have very little magnet so don't expect too much, you will need lots of turns of fairly thin wire so your power out will be small. Anything to improve the flux path will help, single rotors are as bad as you can get.

Still no idea of your speed from your description but you may not be that fast. I can hand crank things to about 250 rpm fairly easily but that is after a lot of practice you may be slower than this and your tiny prop will probably have to go faster.

Flux

[awk]

 

  sir i want a 12 v system because i have only 24 mag 12 on each rotor.

  by my previous work i got 0.8 vac by 80 turns of 18 gauge i want it to make at least 2.5 vac.
 
   i want some rpm measuring technique i can not get a tachometer here in karachi easily do u have any electronic ckt about rpm.

[ghurd]

I suggest reading Flux's last comment again.

If each coil gives 2.5V then it will be better suited to a 24V system.
You will want 1.25V per coil for a 12V system.

Testing with the other magnet rotor installed will be more accurate, and greatly increase the voltage.
I do not believe coil testing with a single disk will do any good if the finished machine will use 2 disks.

RMP circuit.
A free world wide shipping US$3 bicycle computer from ebay.
Set the wheel circumference to 167cm.
Set the speed display to kph.
10.4 kph means 104 RPM.  21.6 kph means 216 RPM.
G-

[Flux]

Sorry I forgot you have 12 poles. Then you have 3 coils in series not 4.

In that case you need about 2v per coil for 12v cut in.

You should be able to get a good idea of speed by cranking and watching time.

60 rpm ( 1 turn /second) will be too slow. 2 turns/sec ( 120 rpm ) may give you some sort of a reading but you should be able to manage 3 turns/ sec or 180 rpm. That should be fast enough to get you some readings but your meter may not be too accurate at low ac voltages.

You could deliberately wind with many more turns than you need to get a better voltage for your measurements. You can then scale it down to what you want. You may need thinner wire but that doesn't matter to deal with cut in voltage.

You will probably have little luck with tachometer circuits with slow hand cranking. Even an optical tachometer would be very erratic at such low speeds with the speed variation of hand cranking.

Flux

[Flux]

Yes as Ghurd has pointed out, if your final machine is to be dual rotor you should really be testing with both magnet rotors.

Typically you will get something like half volts with one magnet rotor but it does depend very much on the thickness and position of the coil. With such thin magnets you may well get significantly more than double with both magnet rotors fitted.

You are very much stuck with the discs and magnets so it makes sense to finish the magnet rotors and assemble then as for the final machine then try your test coil and you will get more accurate results.

Flux

[awk]

hi
 some good results
 
         i made both the rotors and put a coil for test coil is 80 turns of 18awg
     
        i spin it with my hand gently  0.5v on meter
                 then i spin it hard i get 1.0
 
      then i again spin it very hard i get 1.9v

   the air gap between mag is 20mm.]
 
   i know i would get good result in 10 mm because mag thickness in 5mm.

 now someone tell me to put coils in delta or star

 thanks
 

[Bruce S]

hi
 some good results
 
         i made both the rotors and put a coil for test coil is 80 turns of 18awg
     
        i spin it with my hand gently  0.5v on meter
                 then i spin it hard i get 1.0
 
      then i again spin it very hard i get 1.9v

   the air gap between mag is 20mm.]
 
   i know i would get good result in 10 mm because mag thickness in 5mm.

 now someone tell me to put coils in delta or star

 thanks
 

awk;
Good to see that you're now getting results.
Now is a good time to do some reading.
Here is a VERY good write up on just what you're looking to do. It a PDF so you can read online or d'load and print it out.
http://www.sparweb.ca/Forum/AXIAL_FLUX_HowItWorks.pdf

Cheers;
Bruce S

[awk]

i have download the page months ago but can any one explain it more.

what is effect of series star parallel star , series delta & parallel delta.
i know that current is same in series and voltage is same in parallel.

but how to hook coils together,there are total 6 wires come out of stator in 3 phase 9 coil

[awk]

http://www.youtube.com/watch?v=0M-0BtCv3ns

check my coil test video air gap is 17mm.
coil is 75 turns of 18awg wire

can any one suggest rpm.

[ghurd]

It looks like about 200RPM from here.

You are severely underestimating the effect of the air gap.
10mm (two 5mm) of neo needs to be about 10mm between neo faces.  Even 12mm will have a drastic reduction of voltage.  17mm is far too large.
It would not surprise me if the voltage nearly doubles with the air gap set properly.
G-

[awk]

 sir problem is that i would not get 75 turns in 8mm thickness coil i will make a new coil and then post results and lower my magnets to 10mm.

 thanks for suggestion

[ghurd]

Reduce the gap to 10mm and try the 30 turns of 26awg coil again.
G-