Wheel hub dynamo delima

[jkrienert]

Hello,
   This forum has been so informative.  I have learned as much here as one might invest in time at a school, so thank you to all the members.
   OK, down to biz.
   I have a concept for a on-board rear wheel hub bicycle dynamo.
   There are two main componets, situated based on my novice understanding of power generaton through magnetics and inductors(coils).
   First, the metal tray with recycled hard drive magnets situated about its circumference.
             A total of 8 magnets are set around the rim of the platter; they are poled circumferential with their arc.
   Second, the armature which is a substitute for the common dual stators in wind generators.  It is a small pack of disc magnets that are magnetized axially, and are situated on a small bearing arm respective of axis.
             As the platter rotates on the wheel hub, the perpendicular armature acts somewhat like a magnetic worm gear that turns in sync with the hub array.  
   Third, My plan is to have a coil (s) placed in the arc shape, maybe 3 total for a 3-phase circuit in the end, meaning each coil has a matching armature behind it.  Shouldn't this rear magnet help to direct the alternating
             field more directly through the coils without having the ability to mount a secondary platter (as stated before, much like the dual rotor stator setup for some of the wind Gen's discussed on here)?
     Now my problem...
             I have tried three types of coils; one old auto relay, one wound by hand on a small ferrous bolt, and another wound around a nonferrous (obviously) piece of cardboard.  With each trial, a small low power
             led was used to check voltage.  I realize this is ac, but a led works well for testing purp.  When each of these coils was placed between the interacting magnet plate and arm no voltage was shown.  Even when reversing polarity to be sure, still no effects shown.   I feel like there is something simple that I am overlooking in my modifiyed version of a simple gen.
Any comments, fixes, or ideas?

[jkrienert]

[jkrienert]

[Norm]

 See no way this could work.....
Norm

[artv]

Hi Jk,.....where did you have the coil positioned, when you were testing??
Also in that picture it looks like the hd magnets are sandwhiched between two plates??...the rotating disk causes the ,three stacked disc mags to rotate??.........artv

[jkrienert]

The coil was tested in between the rotating armature and spinning platter.
Yes, the small 3magnet arm moves based on the platters/wheels rotation.
Also, the hd magnets are set around the circumfrence of the bigger round plate.  The wheels spokes and the tension from threding the plate to the hub hold them in place well with no adhesive.

Update:  I moved my testing to just the  bare plate by removing the arm completly from the setup.
             A salvaged auto relay lights a small 1.5v LED very brightly.
             Would mounting three relays in succesion and wiring them three phase be an efficant means for DC power (for charging and direct current)?
             Or maybe there is some other unknown method (to me) that I should try?

(goal of project, is to supply a steady current to either small recharging circuit, or directly wiring to riding lights.  Thus aleviating the hassel I am having having to buy batterys so much. 
 Tired of temporary purchases like non-rechargable batterys.)

[Flux]

You should be able to do something if you go about this correctly.

The spinning magnet thing is going nowhere, forget it. I have seen this silly idea proposed before.

You are dealing with quite low rotational speeds with a bicycle wheel and I suspect the silly spinning magnet idea was to try and overcome this, it just won't work.

You need to build something like a small axial machine, preferably with dual rotors but a single rotor may work. you need coils fixed to the bike frame running close to the magnets just like the stator of a normal dual rotor alternator but in this case single phase is probably the most sensible way to go.

With engineering I see no reason why you couldn't make a very nice device that would work well, after all the Sturmey-Archer dynamo worked well and that only had an Alnico ring magnet that was way less powerful than even a small HD neo. Not sure how lucky you will be without engineering, the sticky tape and string issues limit your possibilities a great deal but even then with led lights available today I think it is still realistic.

Forget the novel concepts and go back to first principles and you will be well on the way.

Flux

[jkrienert]

Thanks for the support flux!
Planning on workin on this more this week.
Will post an update in a few days.

Cheers!

[ghurd]

WindStuffNow Ed posted about a 'popcorn' alternator like you proposed.
It was a long time ago.
G-

[gotwind2]

A noble effort,
I like bike dynamos too.
You could save a lot of time and effort and simply buy one of the latest 12v 6 watt 'Tung Lin' dynamos.
I have one, they will charge a 12v SLA battery for lighting e.t.c.
$20 from http://www.bikeworldusa.us/Generator-12V-6W-Bicycle-Light-Power/M/B000OBWMGK.htm
Pretty unbeatable.
They are a 4 pole single phase alternator, ceramic magnets.

[Bruce S]

A noble effort,
I like bike dynamos too.
You could save a lot of time and effort and simply buy one of the latest 12v 6 watt 'Tung Lin' dynamos.
I have one, they will charge a 12v SLA battery for lighting e.t.c.
$20 from http://www.bikeworldusa.us/Generator-12V-6W-Bicycle-Light-Power/M/B000OBWMGK.htm
Pretty unbeatable.
They are a 4 pole single phase alternator, ceramic magnets.

Now where would the fun be in that  ?
They are nice though.

[jkrienert]

Wow, nice reminder about those bottle dynamos.
They are pretty efficient little packages, and likely something I should consider.

Something comes to mind though now that you mentioned it.
If you have one on hand, what kind of frictions are associated with having to turn the spindle on these type of generators?
I only ask, because of how identical the armature I had original installed was to one of these in mechanical motion.
If its reasonable simple to turn with little cogging or stiffness, I am pondering ordering one, and modifying it into a non-contact style
generator.  Working on the basis of having a diametrically magnetized ring magnet mounted atop the plastic contact wheel.
Thus when the platter on the wheel hub turns, the close (but not touching) proximity of the bottel dynamo tip (with ring magnet) would rotate in sync.

Why not just get one and slap it on as is?  I was always fazed by these things because the surface friction added in pedaling.  That is my general canvas here
for trying to paint a generator that is close to zero physical contact = low friction.

So yea, if someone has one of these bottle dynamos, and could take a Minuit to check the force needed to turn the core with say, just your fingers, I would highly appreciate it.

Cheers!

[jkrienert]

whoa.
Big updates.
Took advice, so i went to the local recycler and paid for an old printer (stepper motor/bottle dynamo).
In adition to two old relay coils mounted on the same bracket have givin me quite a generator!

I will post a photo tomorrow, but my basic setup right now is just the organs without the connections beyond.
As follows:
Stepper motor w/magnetically induced axial motion (no friction) = 5-10v dc (through d-bridge) at 200-1000 mah.
The two coils are spaced perfectly to be wound in series and produce 4-10v ac (not regulated yet)

I am wondering if anyone has ideas on how to regulate the two inputs for one power supply?
Thanks.

[jkrienert]

vahoo!
Much progress from past posts.
Restarted from scratch-and redesigned the whole dig.
This picture shows the setup a little before where it is now (w/only two coils).


It currently is now three coils. The coils are from an old boiler gas valve (love repurposing someones already acheieved works!)
At first I was trying delta to ramp up the current, then star to test- but both gave me a problem; in that
the coils possitions respective of the magnetic platter are not in the '120 degrees' range nessicary for 3-phase to work.
I was stuck with odd waves clashing wave then discovered something. I could rectify each coil individualy, then combine them in parrallel or series DC.

Finally got to the point where parrallel was best, as it would provide the needed current for illuminating 2-3 high lux LEDs. 
My mechanical gearing is 56 input-14output.  So at 90 rpm drive - its 360 rpm output. There are 8 dual pole faced magnets on the platter, so 16 alternating poles.  Meaning - for every rotation, each coil recieves 8 full ac waves (right?)
 Heres the current results with my cheap multimeter (rpms are marked from input)):
     Slow (30rpm): 4vdc at 90mah
     Medium (90rpm): 9vdc at 175mah
     Quick (120rpm): 17vdc at ? (meter dose not read above 200, but I would guess 250-300mah)
Im really happy with the output, and now I need to figure out the circuit bits (not my forte).
Hopeing to have a super capacitor after regulation so when stopped in traffic LEds still get some
power.  Wondering if a buck converter will be required in here somewhere...

Any thoughts? Experiance? Slander ?

Cheers.
     

[Flux]

Might be worth looking at the small print on the commercial LED drivers. if they will work over your range of inputs then it may save you having to design your own circuit.

To make best use of the super capacitor then I do suspect a simple buck converter would make for a lot higher efficiency.  In the end you may get a far easier solution with Ni Cd or NiMh and a crude zener shunt to deal with excess charging current.

The other way would be to look at Amanda's led driver circuit ( basically constant current) and see if you can run that from the super capacitor, it would give you a reasonably high input impedance but without the power conversion of the buck converter. It was always the adding of the storage bit that complicated cycle dynamo circuits. If you can manage without storage then just clamp the output with a zener or an active zener, the winding reactance and resistance will limit the current.

Nice to see that you have made a lot of progress. I don't think I would have reversed alternate HD magnet, that way you would have had twice as many poles and it looks to be a better match to your coils, but if you have plenty of power then no need to worry.

Flux

[jkrienert]

sounds like some good ideas flux.

Where can I find 'Amanda's led driver circuit' ?

As far as the alternating magnets...Im glad you noticed and mentioned it. Really weird, but upon testing and putting it together, they would not stay in an alternating possition layout.  So i put it together once with glue forcefully, and all it put out meager amounts of juice.
I was a little worried, then let the magnets do the talking.
They 'wanted' to be in the pattern shown and to my suprise, the output went over tripple what I was trying the other way.  I am wondering if I am getting some weird anomalies due to the opposing pole fields on the metal plate.

Any thoughts or insight on seeing something to this degree before?

I will do some research in the next couple days on circuits, and get back with a rough diagram.

cheers!

[ghurd]

sounds like some good ideas flux.

Where can I find 'Amanda's led driver circuit' ?

http://fieldlines.com/board/index.php/topic,131217.0.html

As far as the alternating magnets......... Any thoughts or insight on seeing something to this degree before?

Yes.  3 thoughts.

First.  "The coils are from an old boiler gas valve (love repurposing someones already acheieved works!)"
The size each pole of the HD neos is more suited to your coil's size in that configuration.

Second.  I have a feeling you have some misunderstandings about HD neos like those.  They have 2 poles per face usually.

Third.  "I could rectify each coil individualy, then combine them..."
As in Individually Rectified Phases?  IRP?  Jerry rigged?
We knew that.  Or more accurately, most of the old guys knew that.


Looks good.
I am impressed it makes that much power in that type of assembly.
G-

[jkrienert]

Thanks for the link!

HD magnets are pole'd thru thickness and circumfrence right?  4 quartered?

IRP/jerry riged! Hah!  That is right.
Each coil goes through its own bridge, then I have the three bridge outputs wired in parrallel.
My dumb version of AC delta wirings benifits in DC (current boost).

Misstakes turn into discovery if you look at them right.
Thank goodness!

Cheers one and all.

[ghurd]

HD magnets are pole'd thru thickness and circumfrence right?  4 quartered?

I do not understand what that means.

If you look at the next to the last photo you posted above, showing the disk and HD neos, you will notice a 'line' in the middle of each of the magnets.
On one side of the line, North is facing the camera.
On the other side of the line, South is facing the camera.

It is not visable with most HD neos.
I expect the line is from "dust" or something sticking to the neo face.
The black paint makes it more visable in the photo.

This is what you have now,




It is almost the same as what you show above in reply #2, 'outside armature gif'.
The magnets would have laid in place as shown in 'outside armature gif' if they were flipped over.
HD magnets can be confusing.
G-

[Flux]

I see what you have done, that is logical.   I assumed you were using magnets all the same, I didn't consider you might be using the pairs from each drive.

Flux

[jkrienert]

I have become quite confused, but feel i have figured things out... I hope!
As mentioned, forcably gluing the magents wasnt giving adequit output.
Letting the magnets 'talk' is giving a much better output because...?

The poles you added to the photo instill what I though was going on. 
Meaning, the hodge podge of magnets I recycled, seemed to have slightly differnt polaritys in respect to their overall shape.

But taking a small (1 pole for each face-through thickness) disc magnet, I am getting something of a different nature.
They seems to all be identical in face poling flipped or flopped, and the switching is creating one big pole between the two meeting halfs.
So rather then 16 alternating poles to the platters face, I have 8.

So - to clarify what I see going on:
8 identical HD magnets on the platter. Each with two outward faceing poles.
positioned with opposing poles touching results in a flux of one combined 'big' pole (probably with some wacky field lines to spare)

What I ment by 4-quarted was, if you took a quarter and put heads and tails on one side, then the same on the other - that is what I gather to be the case.  The would be alternating per side - IE - heads on one side, equals tails on the other, and vise versa.

Hope that made a few cents.
Im wondering if my opposing poles is somehow throwing flux into the coils more so than if they were all alternating.

To try and see whats going on in 3 demensions, I will probably swoop by the store today and get a bottle of mineral oil/clear thick viscosity oil (baby oil).
Ive got some 0000 steel wool, and I plan on chopping it up in a coffee grinder into ferric-dust.
Add this to the mineral oil - And you got a sweet field viewer! (making sure bottle is clear, and one face is spray painted white for contrast.

I will try and post some photos, and details tonight or tomorrow showing this experiment - and also the setup as current.

Cheers!

[jkrienert]

Every magnet on the platter is poled in this manner.

Now I am wondering what the flux lines 'look' like.
As mentioned, when I pass a small disc magnet around the circumference, it is a very steep and strong sine wave motion grouped by each pair of like poles.
I drew some lame pictures trying to figure what path the flux lines might follow. More for curiosity's sake, but I feel like the strength of the output through the coils
has something in conjunction with the mushing (technical jargon) of the flux lines into the stators cores.
this one, or...


Im leaning towards this one.


my luck, their both wrong.

all the best.

[Flux]

I am not sure which way you found to be the best. In your original diagram you showed your magnets labeled N S N S N S all the way round. This gives poles the size of the actual magnets on the magnet pair group.

In your supposed flux diagram in the last post you show the other arrangement with the arrangement being   N  SS  NN  SS  NN etc, where you have half the number of poles but each pole is made twice the area of the magnet on the block.

Which method works best depends on the span of the iron circuit you have in the middle of your pick up coils. The "poles" of the pick up coil need to span the same dimension as the distance from center to centre of the real magnet poles ( in technical terms the coil pickup needs to span a pole pitch).

I can't post drawings here but your idea of flux lines in the illustrations is way off the mark.  You would need to show more of your magnets to be able to draw a sensible flux path for the arrangement shown as the flux passes from one N pole group to the S pole group.

In your drawing the two adjacent blue poles would act as one big blue pole ( say it is a N pole then the flux would leave there and return to the next S pole ( which would be two adjacent yellow blocks ).

Either way of mounting the magnets will work fine but the coil arrangement will be twice the span in the case with half the poles.

Not sure I have helped here, it does need drawings to explain. my description to you may be about as confusion as your talk or quarters to me, I am not even familiar with the currency.

Flux

[jkrienert]

I must admit, I am slightly embarrassed about my stupidity here.
Thankfully their are folks willing to teach and share knowledge.
I appreciate it.

Well, Im still not quite to sure why the output of my coils would be more with the 8 pole tray.  The cores of the coils are only about a 1/4 inch, and the span of the
dual poles is probably 1 inch. 

I guess I have much learning to resolve on this...

[Flux]

I don't know exactly how your coils are arranged but I suspect you have coils with a central iron core but these are mounted on to a steel strip. In which case the flux will link from one coil to the other(s) via the steel backing strip and this will result in a lot more flux linkage than with the coils supported with no closed flux circuit.

The thing with any form of generator is to try to keep the magnetic circuit as closed as possible, air is the worst thing for flux to travel in, iron and similar ferromagnetic things are a thousand times better than air and the weak point will be the air gap. It can't be avoided with rotating things, but you try to keep it as small as possible. If your coils are not linked at the back, the flux is seriously reduced and it looks to the magnets as one huge air gap.

It will be the span of the iron circuit comprising your coil poles and the linking back plate that need to be proportioned to the distance between magnet poles not the iron cored bit that the coil is wound on.

For signal devices such as speed sensors and phonic wheels you can get away with simple cored coils in proximity to a magnet, but if you want power rather than just volts then you need to refine the magnetic circuits.

Flux

[Bruce S]

Let me say, I have watched this with great interest since we (wife, daughter, me) ride bikes as do a bunch of people here at work.

I use NiCds in our bikes with little fold-able solar panels for recharging when available and this seems to be a novel idea for possible re-purposing those panels.
In the IT world there is a saying "YOU can't fix stupid" so since you're learning and getting results from help given here, I can say you are a Newbie NOT stupid 
There's tons of stuff here that even I feel to be a Newbie about, makes learning all the more fum!!

NOW: to the current setup that is getting results.
 What I believe you have and FLUX PLEASE tell me if I'm way off on this!!
The coils that you repurposed seems to have been just the right size for the HDD magnets flux path or pole size.
IF you look closer at the pics from the last one that had I think just two coils you can see that one coil is just the size, that when passing over 1/2 the HDD magnet say N as it reaches the S side it's just ready to flip/flop or cause the needed reversal.
This is quite possibly why if you leave them the way they are you are getting the best results of output.
The "Jerry Rigged/IRP" setup is also the best for the output.
For charging a set of lawn light NiCds which normally come in at 1.2Vdc 500 - 600mA a quick constant voltage circuit could be built using a 78xx for the output. I'm certain you will not be generating the max current of 1A so if a surface mount chip would work out well.
Nice work!
Bruce S
 

[jkrienert]

Well,
   I drew up a quick diag. of the coil and mount.
  
   You can see, that there is no actual contact between the core-and the supporting armature.
    By moving a small disc magnet in the height range of the steel arm above the tray- there is still
    a significant amount of magnetic field felt.
    If the arm had direct metal contact to the cores-would I be working with less loss of flux away from the coil?
    What might be a factor in this, is that both coils position is over the same mark in polarity. (both over N roughly)
    [I now realize this might be a design mistake made before the fact - as I could probably have smoother output if they were
     alternately positioned (N - S), right?]
    
     Also, the picture shows anything ferric colored in gray tones.  So the small mounting bolts also
     might be doing something with the fields (although probably very little?)
  
    The thought of having Ni-cads is probably a good idea.  I'm having some complications right now, trying to solve the same issue
    of constant power with super-capacitors in parallel.  Ni-cads might be a simpler cheaper option.
 
    [Bear in mind-that the magnets are positioned on a ferric(chrome) plate as well. Though it might help to 'focus' the fields towards the coils?]
 
     Thanks for the support.  It is received with the highest respect in return.

Cheers,
Joe

    
    
 
  

[jkrienert]

I need to get some clearer photos up this afternoon.
It will likely provide much in the way of able-ing your help.
On top of the wealth already shared.
Again, thanks.

joe

[Bruce S]

Joe;
I can't seem to find the LED ratings you posted. Could you repost those here, please. Thanks
There could be a way to work the Caps if you have enough of them and free.
FREE is good.
For Using Cap I generally use ones that have twice the highest voltage the circuit will produce.
Then depending on the LED Vf and current needs a quick little math, GHURD does it in his head  while driving  )
It could still be possible to use them.
 I use NiCds cause I have 100s of them.
Cheers

[Flux]

Can you do another drawing like the one above but showing the position of all three coils in relation to the magnets. Not a lot of use commenting on the 2 coil layout is you have changed to 3.

Good clear pictures may help but a good drawing like that one may be more useful.

Although your coil cores don't actually touch the mounting steel they are close enough for a lot of flux to pass fairly easily.

As shown it that diagram the spacing is not ideal for single phase, but the spacing may be ok with 3 coils.  On such a small alternator I suspect single phase may be as good as trying to get 3 phase as far as output is concerned unless ripple is an issue, which it won't be if you include nicads as a store. For the supercapacitors the smoother rectified 3 phase may be better.

Flux

[jkrienert]

Free capacitors?
What planet are you from?!
Do you welcome earthlings?

Currently, the capacitors I have on hand (could budget some for the needed ones though) are:
        (x5) 5.5v 1F
        (x2) 2.7v 10F
        (x2) 2.7v 150F (probably not exactly what I need, although the LEDs would burn forever)
The LED I am planing on are
        (x1-2) 3.7v at 700mah max [front]
        (x1) 3v at 500mah max [rear]

Of course, these are subject to change, as I found a source for CREE emitters for really good prices nearby.

but please, Gurd if you can - wait for a road-stop

cheers.

[jkrienert]

here is a quick layup.
Going to rip out some photos in a couple hours.
cheers.

[Flux]

Yes that is not far out for a single phase layout. You may be able to improve things a bit by putting the coils marginally closer together but it may not show much improvement.

Ideally it would be better to link all 3 back sides of the coils by a piece of steel plate. The two on the same bracket are probably linked fairly well, the other probably isn't good although there may be some linking via a lot of long iron work.

Perhaps by luck, but you seem to have come to a good working arrangement.

Flux