Author Topic: Magnic Lite  (Read 4077 times)

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jkrienert

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Magnic Lite
« on: March 12, 2012, 09:41:47 PM »
Anyone seen this yet?
http://www.kickstarter.com/projects/dynamodirk/magnic-light-get-new-energy?ref=category
I am dumbfound as to how it would work.  After several experiments on my cycle... I suppose I will only have to wait for this kit to release to the public... hopefully at a lower price.

Wisdom?
(cheers)

Simen

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Re: Magnic Lite
« Reply #1 on: March 13, 2012, 03:41:46 AM »
I think there's a strong magnet placed right beside or in the middle of a coil (inside the 'light'), that are close to the rim. When the rim moves, the magnet creates eddy-currents in the rim that are picked up by the coil.
I will accept the rules that you feel necessary to your freedom. I am free, no matter what rules surround me. If I find them tolerable, I tolerate them; if I find them too obnoxious, I break them. I am free because I know that I alone am morally responsible for everything I do. - (R. A. Heinlein)

jkrienert

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Re: Magnic Lite
« Reply #2 on: March 13, 2012, 05:12:43 PM »
Its likely a static magnet then?

 From their site - (the inventor brothers) makes some vague references to some 20 neo's that possibly move on some sort of armature...
I have done some novice experimenting with a static setup as Simen mentioned yet wasn't able to get any output.

If the magnet was static, wouldn't the eddy currents field be DC ?  And thus, coils dont hear DC current do they?

(edit: The eddy's rotate one way approaching the magnet and then the opposite way upon leaving the magnet right?)

Cheers!

DanG

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Re: Magnic Lite
« Reply #3 on: March 13, 2012, 05:35:19 PM »
I was thinking a wobble-style armature, something well balanced but with an eccentric that would react to the stir of magnetic eddies...

dinges

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Re: Magnic Lite
« Reply #4 on: March 13, 2012, 06:28:51 PM »
There's a small alternator inside the carbon case. Instead of coupling the generator directly to the wheel (by friction, as in a bottle dynamo), it uses eddy currents to couple the generator to the rim.

There's a small wheel with a few neodymium magnets close to the rim. As the wheel turns, eddy currents are induced, causing the small wheel-with-magnets to be dragged along too, driving the shaft with alternator.

The real 'innovation' here is electromagnetic coupling of the wheel to the alternator. Which is about as new as electricity itself....

I think I'll stick with old fashioned hub alternators.... tighter coupling and much more power output. Also costing much less - even a SON hub, the non-plus-ultra when it comes to dyno hubs, is a lot cheaper than this proposed alternative.

But it is an illustration of the fact that eddy currents can be put to good use too, just as in induction heating.
« Last Edit: March 13, 2012, 06:31:22 PM by dinges »
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jkrienert

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Re: Magnic Lite
« Reply #5 on: March 13, 2012, 06:34:10 PM »
wow, dinges that probably the clearest description i have seen.
How exactly would the magnets need to be aligned for proper 'coupling'?

When I experimented a bit with this, the only rotation of the separate magnet alternator was induced by the inner-tube valve stem acting as a once per rotational flick of the rotor. I had a diametric ring magnet on a axis, and got it to rotate parallel and perpendicular. but again, it was due to ferrous componentry (valve) coupling... not eddys.

I also read on the kickstart site, that this setup works with steel rims as well.  How would that induce rotation in the alternator?

hmm..
« Last Edit: March 13, 2012, 06:36:48 PM by jkrienert »

dinges

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Re: Magnic Lite
« Reply #6 on: March 14, 2012, 11:02:02 AM »
How exactly would the magnets need to be aligned for proper 'coupling'?

I expect with the N/S-pole faces towards the rim. So the magnet field (as it leaves the magnets face) parallel with the wheel axle.

Easy to check for yourself when the eddy currents are largest: grab a neodymium magnet and a piece of aluminium (the thicker the better). Rub the magnet over it. The magnet orientation where you feel the most drag is the one where the eddy currents are the largest. More/larger eddy currents lead to tighter coupling between the dynamo and the bicycle wheel.

Quote
I also read on the kickstart site, that this setup works with steel rims as well.  How would that induce rotation in the alternator?

Steel also suffers from eddy currents. In fact, *any* electrically conductive material does. The more conductive (lower electric resistivity), the larger the eddy currents. Copper is a very good conductor, hence large eddy currents.

In steel, the effects of the eddy currents are probably harder to detect because of the large ferromagnetic effect. But definitely there.

Are you in Germany? If so, keep in mind that that 'Magnic Lite' doesn't have a StVZO approval, and probably will never be able to get one. Hence, doesn't qualify as a legal bikelight in Germany, or the Netherlands. The beam of the LED doesn't have a cut-off, radiates in all directions, hence blinds traffic. Also, a streetlegal generator needs to be able to generate 3W & 6V at a speed of 15 km/h. I suspect the Magnic Lite generates much less than that, but relies on efficient bright LEDs to produce a useful amount of light.

If you're not in Germany, NL or any other country with strict rules and regulations on bike lights , that may not be an issue for you, thought it's not nice to blind oncoming traffic anywhere, regardless of location (as that Magnic Lite would).

Personally, I love my SON28 dynohub and Philips Saferide dynamolight. No noticeable drag, lots of light without blinding oncoming traffic (it has a cut-off). StVZO approved. I ride with the lights always on, day and night, as I don't notice the extra drag of the dynamo. Incomparable to the older rim dynamos or Shimano's dynohubs. Use a proper dynohub (SON, Sanyo makes not half bad ones too, I hear) and the issue of drag/losses becomes a non-issue, below the threshold where people will notice it in practice. I've added a switch to turn lights on and off, and I can not feel *any* difference with lights on or off. Of course, there is a difference, as the watts to power the light have to come out of my legs....

Anyway, I'd use a decent dynohub and LED lamp. All the benefits of this 'Magnic Lite', little drag, but a lot of useful light. And cheaper too....

« Last Edit: March 14, 2012, 11:07:59 AM by dinges »
“Research is what I'm doing when I don't know what I'm doing.” (W. von Braun)

jkrienert

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Re: Magnic Lite
« Reply #7 on: March 14, 2012, 11:11:01 AM »
on the notion of the superiority of dynohubs, I agree.
That is why I bought a nice shima. one a year ago. 
Road with it in sleet, ice, rain, blistering heat, and in all extremes it performed flawlessly.
I have still yet to get a good light for it... But I have a heck of a foundation to work up from (IE-learn more about recent LED designs).

Why ask about the 'magnic' light? 
Well, I find physics, (especially magnetic dynamics), cycling, and concise refinement of past designs very interesting.
This generator seems to grasp alot of my interests - if not for actual purchase, but more for the concepts involved.

I still am a little mixed up on the angles of the fields.  I will try and post a small sketch this afternoon to see if someone can sort my stupidity out.

Cheers!

(edit:  Gota add to this, that front end shot of the recumbent is awesome!  Especially considering no obstructions for the illumination.  I have been relying on a bike as my only mode of travel for a while now.  I am looking forward to my increasing age implementing the more efficacious (on body) setup of a recumbent.  This of course will have to wait... for a higher paying job :(  )
« Last Edit: March 14, 2012, 11:15:31 AM by jkrienert »

jkrienert

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Re: Magnic Lite
« Reply #8 on: March 16, 2012, 09:25:42 PM »
It is interesting to note, that they are claiming better outputs than high quality hub dynamos.
Durability in this regard might be debatable, as only time can tell ... but function wise there is a point here.
The hub is at the center of the wheel with a lower coefficient of rotation than say a device at the rim where the rotational velocity is higher = more surface area exposed to a device.

just a thought.

stop4stuff

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Re: Magnic Lite
« Reply #9 on: April 11, 2012, 06:08:52 AM »

I have a vid from 5 years ago demostrating eddy current coupling.

http://www.youtube.com/watch?v=GgR0dTHLf6Q

Now why didn't I think of that light system... doh!  :o

bob golding

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Re: Magnic Lite
« Reply #10 on: April 11, 2012, 07:07:10 AM »
may be being a pedant here, but they say no friction. true, but  in order to produce  power you need energy from somewhere. so that statement isn't exactly true. if it was  then it would be in the free energy area. less friction would be  more truthfull. still a good idea though.

 ben having the idea is only half of it, having the sort of mind that says "wow how do make money out of this" is the other half. never  got that one sorted. will always be poor and happy.
if i cant fix it i can fix it so it cant be fixed.