I think the Magnic light folks claim it is worse efficiency and power output than a hub generator, but because Magnic Light uses the rim (they claim) as part of the generator, it can be quite light weight, and for many riders that is a good trade-off.
Magnic Light: contactless bicycle dynamo light
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I think the Magnic light folks claim it is worse efficiency and power output than a hub generator, but because Magnic Light uses the rim (they claim) as part of the generator, it can be quite light weight, and for many riders that is a good trade-off.
On September 25th, Dirk updated Kickstarter:
He writes about a 5-week delay due to supplier quality problems on the magnet assembly. With the delay, he is expecting parts this coming week. Dirk also writes about ongoing testing, about recent adjustments to the design and that the patent attorney adviced not to publish pictures, yet.
Let's see what next week reveals !
He writes about a 5-week delay due to supplier quality problems on the magnet assembly. With the delay, he is expecting parts this coming week. Dirk also writes about ongoing testing, about recent adjustments to the design and that the patent attorney adviced not to publish pictures, yet.
Let's see what next week reveals !
AnAppleSnail
Flashlight Enthusiast
That is odd. " why can't the engineers build this" is the last gasp of each perpetual motion scheme. I hope this us real, because it could work, even if it is limited. However, most countries who honor patents also protect patents under application. Odd advice from an attorney, assuming that I am correct.
Steve K
Flashlight Enthusiast
thanks for the update. The comment about having trouble with suppliers certainly seems consistent with my engineering experiences, especially when working with a supplier for the first time.
I hadn't seen the "micro" version before. Looking at it, it makes me think that the spinning armature w/magnets is surrounded by a large winding. I hadn't considered that arrangement before.... it'll be interesting to see what the design is really like, and how close my guesses were.
Well, it looks like it revealed nothing. A month has passed again with no updates in Kickstarter, and according to the comments, no updates or survey (that was promised to be sent long time ago) via email either. The light was funded 7 months ago and the first lights were supposed to be delivered in July. It is the end of October now, and there is no clue about possible shipping dates yet. Some patient people there, I guess.
Of course, delays can happen with new products. It is usually understandable. The lack of communication, however, usually isn't.
Steve K
Flashlight Enthusiast
an update on Nov 1st. New plastic housings. Looks nice enough, but can it compete with the glamour of carbon fiber??
http://www.magniclight.com/magniclight/index.php/en/news-en/50-final-design
http://www.magniclight.com/magniclight/index.php/en/news-en/50-final-design
The patent (actually it is "Gebrauchsmuster" = petty patent) can now be seen here.
So basically, the generator contains a disc magnet that is being rotated by (magnetic) drag from the rim.
A coil surrounds the rotating magnet, delivering energy to the electronics / the LED.
Now that the paperwork is done, the invention should be protected and we should soon see products going out.
So basically, the generator contains a disc magnet that is being rotated by (magnetic) drag from the rim.
A coil surrounds the rotating magnet, delivering energy to the electronics / the LED.
Now that the paperwork is done, the invention should be protected and we should soon see products going out.
The need to have alternate directions for magnets in the radial direction underscores the ferromagnetic operation. For the Eddy current, the consistent orientation, all N inwards and S outwards (or the other way around) would have been optimal. Incidentally, I've got magnets in the meantime to test both options, but this has been to low on the priority radar to pursue compared to other interesting issues in the surrounding. I wonder how false claims affect the validity of a patent - in any case something for courts to consider if anybody bothers to copy this dubious technological advance.
Just built a little light following the published principle, using all standard parts:
M6 steel nut, fitted with magnets all around. This is the rotor.
M5 stainless steel bolt, to go thru the rotor
Old mains transformer, modified to E-core (I-elements removed), LEDs attached to what was the primary.
Holding the rotor by the M5 bolt, bringing it close to a rotating rim, makes it spin.
Bringing the transformer close to the spinning rotor, makes the LEDs light up.
I tried different polarities of the rotor magnets:
N-S-N-S-N-S works fine,
N-N-N-N-N-N also does something but is far not as effective as the option above.
I'll see if I can get a video uploaded, 2morrow.
M6 steel nut, fitted with magnets all around. This is the rotor.
M5 stainless steel bolt, to go thru the rotor
Old mains transformer, modified to E-core (I-elements removed), LEDs attached to what was the primary.
Holding the rotor by the M5 bolt, bringing it close to a rotating rim, makes it spin.
Bringing the transformer close to the spinning rotor, makes the LEDs light up.
I tried different polarities of the rotor magnets:
N-S-N-S-N-S works fine,
N-N-N-N-N-N also does something but is far not as effective as the option above.
I'll see if I can get a video uploaded, 2morrow.
The published setup is consistent with the expectations in the posts here - few of us actually tried out a rotating magnet. Otherwise your parts represent pretty much what I have now. As to the orientation of the poles, if Magnic were to work on Eddy currents, then the uniform NNNNNN configuration would have been optimal for generating spin but to generate current you would still need NSNSNS, e.g. by putting two rings on one axle, one for generating spin and another for converting that spin into current. Most telling would be whether you can get more spin out of alternate or uniform poles, leaving the current generation as the secondary issue.
The cookies in the photo look just like those I ate a moment ago, baked by a German collaborator.
Filming it worked out fine. Here's the link to the video of my homebrew Magnic Light in operation.
Note that the LEDs light up fairly steady, there's no low-frequency flicker. So the frequency of the AC that's being generated is not linked to the rim joint
or the spoke holes of the rim. It's much higher. The speed of the wheel equals 15 km/h.
I've used my motorized test-wheel for the film. Here's a close look at the rotor in the test setup:
Unlike yesterday, I managed to light up the LEDs even without an inductor core. Better, because this doesn't slow down the rotor so much and prevents motor magnets catching on to the core.
http://i168.photobucket.com/albums/u200/Vankoff/Magnic/MagnicAirCore.jpg
Your image is too large and has been replaced with a link. Please resize and repost.
See Rule #3 If you post an image in your post, please downsize the image to no larger than 800 x 800 pixels. - Thanks Norm
To 2_i: You suggested that a N-N-N-N-N-N-rotor would create more spin than a N-S-N-S-N-S-rotor. Trying this is a little tricky, because the rotor magnets don't stay in place when the rotor spins. But lots of hotmelt got me there and I found that you are wrong: The rotor didn't spin well, much slower than with the N-S-N-S-N-S-configuration. Makes sense to me, as N-N-N-N-N-N doesn't send much flux through the rim.
Finally, I tried a N-S rotor with bigger magnets. Once running, this worked better than my N-S-N-S-N-S-rotor but it didn't easily start to spin. From this I conclude that a N-S-N-S-rotor would probably perform OK, and that stronger magnets are generally better as one would expect.
Bottom line: The Magnic Light principle works really well. Hopefully, we soon see more products based on this.
Note that the LEDs light up fairly steady, there's no low-frequency flicker. So the frequency of the AC that's being generated is not linked to the rim joint
or the spoke holes of the rim. It's much higher. The speed of the wheel equals 15 km/h.
I've used my motorized test-wheel for the film. Here's a close look at the rotor in the test setup:
Unlike yesterday, I managed to light up the LEDs even without an inductor core. Better, because this doesn't slow down the rotor so much and prevents motor magnets catching on to the core.
http://i168.photobucket.com/albums/u200/Vankoff/Magnic/MagnicAirCore.jpg
Your image is too large and has been replaced with a link. Please resize and repost.
See Rule #3 If you post an image in your post, please downsize the image to no larger than 800 x 800 pixels. - Thanks Norm
To 2_i: You suggested that a N-N-N-N-N-N-rotor would create more spin than a N-S-N-S-N-S-rotor. Trying this is a little tricky, because the rotor magnets don't stay in place when the rotor spins. But lots of hotmelt got me there and I found that you are wrong: The rotor didn't spin well, much slower than with the N-S-N-S-N-S-configuration. Makes sense to me, as N-N-N-N-N-N doesn't send much flux through the rim.
Finally, I tried a N-S rotor with bigger magnets. Once running, this worked better than my N-S-N-S-N-S-rotor but it didn't easily start to spin. From this I conclude that a N-S-N-S-rotor would probably perform OK, and that stronger magnets are generally better as one would expect.
Bottom line: The Magnic Light principle works really well. Hopefully, we soon see more products based on this.
Last edited by a moderator:
lampeDépêche
Flashlight Enthusiast
- Joined
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Dear Martin,
Thank you so much for performing that experiment, and for video-taping it so that others can watch.
This is very exciting--I was always inclined to believe the magnic-light people, but ocular proof is even better.
Yes--I hope we see lots of products based on this, and I hope the magnic-light people get moderately rich along the way!
Thank you so much for performing that experiment, and for video-taping it so that others can watch.
This is very exciting--I was always inclined to believe the magnic-light people, but ocular proof is even better.
Yes--I hope we see lots of products based on this, and I hope the magnic-light people get moderately rich along the way!
Steve K
Flashlight Enthusiast
Nice work Martin! An excellent demo!
My impression of the Magnic, based on their photos, is that the windings are in a vertical plane (assuming that the rotor axis is also vertical). I've been wondering how the number of poles affects the magnitude of the flux passing through the winding. Haven't decided if 2 or 4 is the magic number, but I suspect that 6 and above isn't the answer.
I've also wondered about optimizing the windings. The goal is to maximize the change in flux over time, so the usual approach is to have the poles in the winding and/or winding core match the number of poles in the rotor. My impression was that there was a single winding, and no core material, so I'd think that there would be just a N-S pair on the rotor. As noted, this is harder to get started.
All in all, an interesting problem! I'm still very interested in learning the details of the Magnic design!
My impression of the Magnic, based on their photos, is that the windings are in a vertical plane (assuming that the rotor axis is also vertical). I've been wondering how the number of poles affects the magnitude of the flux passing through the winding. Haven't decided if 2 or 4 is the magic number, but I suspect that 6 and above isn't the answer.
I've also wondered about optimizing the windings. The goal is to maximize the change in flux over time, so the usual approach is to have the poles in the winding and/or winding core match the number of poles in the rotor. My impression was that there was a single winding, and no core material, so I'd think that there would be just a N-S pair on the rotor. As noted, this is harder to get started.
All in all, an interesting problem! I'm still very interested in learning the details of the Magnic design!
OK, I've done the belated experimentation of my own and admit that the Eddy effect can indeed contribute a usable power. To speed up my experimentation I reversed the problem and mounted a diametrically magnetized disk magnet onto a variable speed Dremel tool and approached with that tool either a thick alu strip (1/8" thick) or a rim of a wheel with stainless steel spokes. The disk had a radius of 1.2 cm and a thickness of 6 mm. I set the tool at its lowest speed of 5K RPM which represents 5000*2*pi*1.2cm/60s = 6.3 m/s = 23 km/h on the rim of the magnet. When approaching the tool to an alu strip I could exert a finite force on that strip. I measured the force by placing the strip standing on a postal scale and by approaching the rotating magnet to the strip, so that the Lenz-law force was acting downward. The extra weight on the scale was of 20-25g which translates to up to 0.025kg*9.8m/s^2=0.25N. The power from that force is up to P=F*v=0.25N*6.3m/s, which is up to 1.5W. I do not how much electric power you can get out of this but my guess would be about a half, i.e. 0.75W which is enough to produce some light.
My magnet was relatively expensive one at $7, N42, and presumably you cannot afford better ones in this kind of commercial product. The magnet could be a bit thicker, but the rim is thinner than my strip and they need to have more poles because they must avoid flicker with their magnets getting quite stationary. More poles reduce efficiency.
I next approached my rotating magnet to the rim of a bicycle rim and I could put it into moderate rotation even when there was no steel joint around. When the joint was passing by, there was a sudden jolt to the rotation. In the end I think that both, the Eddy current and ferromagnetic, effects contribute to the Magnic light operation. Definitely, though, the Eddy current contribution is not negligible at typical bicycle speeds so they were OK to put that into the patent.
Martin: Did you check that your nipples, eyelets and spokes are not ferromagnetic? These can deliver power relatively uniformly on account of the ferromagnetic effect.
Otherwise, I continued experimentation producing more numbers and the main is the partition: When using a Magnic type arrangement, with a bicycle wheel that lacks ferromagnetic components, except for the steel insert closing the rim, of the order of 58% of power from the Magnic device is produced by the ferromagnetic effect and about 42% by Eddy currents. The error in my measurements can be easily 5-10%.
I found it hard to experiment directly with the rim, because of the inability to suppress the operation of one of the effects, ferromagnetic or Eddy. A round radially magnetized magnet would eliminate the ferromagnetic effect, but commercially you cannot get strong radially magnetized magnets, so you need to arrange individual magnets along a radius in a circle, i.e. e.g. N out, as I suggested to Martin. In practice this, however, does not work, because the resulting field of the manets is not uniform in angle and the ferromagnetic effect remains sizable in spite of the effort.
With this, I gave up experimenting with the rim, and took instead an alu plate, about 2 mm thick and mounted it on a drill. I mounted six N42 cube magnets 9mm on the side, onto a brass circle and arranged them with the alternating poles out, as in the Martin experimentation or in the Magnic patent. I placed my rotor under the rotating alu plate, either with or without a steel nut glued on top of that plate. The axle of the rotor was connected to a bobbin to which a string with a hook was tied. On the hook I hanged washers to test how much torque I could get from the rotor. The drill driving the alu plate was operated at 1720 RPM and I placed the rotor under a location about 27 mm for the center of the rotating plate. That gave the equivalent bike speed of 1720*60*2*pi*27*10^-6=17.5 km/h. The nut that was glued to the top of the plate was chosen so that it would occupy the same fraction of the circumference as the steel insert in the rim. The washers that I could hang on the string, so that they would be lifted or at least suspended in the air, without or with the nut glued to the top of the plate, are shown in one of the linked photos. The weight of the washers + hook + string was measured in the two cases to be 5g and 12g. In the first case only the Eddy effect operated and in the second - both Eddy and ferromagnetic. The weights tested the torques and correspondingly the powers that this or similar rotor could deliver without and with the ferromagnetic effect. The ratio 5/12 yields 42%.
To complete the measurements I tried to have a nut attached to a material that did not provide a conducting path for Eddy currents. With the ferromagnetic effect alone, however, the operation of the rotor was too jerky to make proper measurements. I increased the drill speed twofold and then the ferromagnetic effect alone would allow to lift the same washer as with the Eddy and ferromagnetic effects together at half the drill's speed. Still the operation was quite jerky and unreliable, so I could not really tell more in that measurement that the effectiveness of the ferromagnetic effect due to an insert was not inconsistent with being about as strong as Eddy.
One test that I tried was to put my rotor on top of a regular bottle dynamo. There was no way to activate this way the dynamo at regular bicycle speeds. One can say that the emergence of a Magnic type dynamo is completely due to the LED revolution and their low power requirements. The LEDs open new options for power delivery.
Above my numbers, when there are steel spokes or nipples, the ferromagnetic effect should overwhelm Eddy.
Click here for photos.
Otherwise, I continued experimentation producing more numbers and the main is the partition: When using a Magnic type arrangement, with a bicycle wheel that lacks ferromagnetic components, except for the steel insert closing the rim, of the order of 58% of power from the Magnic device is produced by the ferromagnetic effect and about 42% by Eddy currents. The error in my measurements can be easily 5-10%.
I found it hard to experiment directly with the rim, because of the inability to suppress the operation of one of the effects, ferromagnetic or Eddy. A round radially magnetized magnet would eliminate the ferromagnetic effect, but commercially you cannot get strong radially magnetized magnets, so you need to arrange individual magnets along a radius in a circle, i.e. e.g. N out, as I suggested to Martin. In practice this, however, does not work, because the resulting field of the manets is not uniform in angle and the ferromagnetic effect remains sizable in spite of the effort.
With this, I gave up experimenting with the rim, and took instead an alu plate, about 2 mm thick and mounted it on a drill. I mounted six N42 cube magnets 9mm on the side, onto a brass circle and arranged them with the alternating poles out, as in the Martin experimentation or in the Magnic patent. I placed my rotor under the rotating alu plate, either with or without a steel nut glued on top of that plate. The axle of the rotor was connected to a bobbin to which a string with a hook was tied. On the hook I hanged washers to test how much torque I could get from the rotor. The drill driving the alu plate was operated at 1720 RPM and I placed the rotor under a location about 27 mm for the center of the rotating plate. That gave the equivalent bike speed of 1720*60*2*pi*27*10^-6=17.5 km/h. The nut that was glued to the top of the plate was chosen so that it would occupy the same fraction of the circumference as the steel insert in the rim. The washers that I could hang on the string, so that they would be lifted or at least suspended in the air, without or with the nut glued to the top of the plate, are shown in one of the linked photos. The weight of the washers + hook + string was measured in the two cases to be 5g and 12g. In the first case only the Eddy effect operated and in the second - both Eddy and ferromagnetic. The weights tested the torques and correspondingly the powers that this or similar rotor could deliver without and with the ferromagnetic effect. The ratio 5/12 yields 42%.
To complete the measurements I tried to have a nut attached to a material that did not provide a conducting path for Eddy currents. With the ferromagnetic effect alone, however, the operation of the rotor was too jerky to make proper measurements. I increased the drill speed twofold and then the ferromagnetic effect alone would allow to lift the same washer as with the Eddy and ferromagnetic effects together at half the drill's speed. Still the operation was quite jerky and unreliable, so I could not really tell more in that measurement that the effectiveness of the ferromagnetic effect due to an insert was not inconsistent with being about as strong as Eddy.
One test that I tried was to put my rotor on top of a regular bottle dynamo. There was no way to activate this way the dynamo at regular bicycle speeds. One can say that the emergence of a Magnic type dynamo is completely due to the LED revolution and their low power requirements. The LEDs open new options for power delivery.
Above my numbers, when there are steel spokes or nipples, the ferromagnetic effect should overwhelm Eddy.
Click here for photos.
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With the Magnic Light generator being nothing more than a magnet-fitted rotor inside a coil (not a clawpole arrangement), I wondered if such a thing hasn't been made before. I've been looking around for a few days and actually found such a generator inside a Chinese-made LED shower head !
I opened the head to access the generator+LED assembly, took it out and removed its turbine cage, then stripped the turbine wheel.
Holding the little generator close to a spinning Al rim indeed does light the LED (!), see the video !
I have to admit, my wheel must spin at 40 km/h to light up the LED nicely, but then this generator device hasn't really been optimized for use as a bike light. However it works, and it has been there before the Magnic Light. Is there anyone deep enough into patent law as to say if this is then "prior art" and anyone can use this dynamo concept ?
The LED shower head cost me EUR 11.50 (bought in Germany). Now it's not just a generator-LED thing but a SEALED generator-LED thing plus a whole shower head too. Gives an indication of the cost we can expect when China mass-produces bike lights (or phone chargers, ..) based on this principle !
Thinking of what could be possible in the future, I imagine wheel sensors for wireless bike computers where the sensor is completely battery-free and works without a spoke magnet, detecting the wheel rpm through the rim joint. Another cool product would be bike computers with permanently backlit displays, the backlight powered by energy from the wheel sensor (wired one, in this case). And wireless shifting, where the generator assists a battery in the actuator-electronics, extending battery life dramatically....
To 2_i: My wheel's eyelets are ferromagnetic, but there's no noticeable force b/w magnets and eyelets if the wheel is stationary. So the eyelets shouldn't be a big contributor. And yes, the rim joint is noticable, but this only exists once per rotation and is not so pronounced that the light flickers much. So without being very scientific there, I feel that a wheel with no eyelets and no rim joint produces more or less the same amount of power. But of course, one has to test it to be very sure.
I perfectly agree, when you say that the progress in LED efficiency is a critical contributor to the success of this dynamo concept. The LED revolution has had a lot of impact in the last few years. It also made CPF grow tremendously.
I opened the head to access the generator+LED assembly, took it out and removed its turbine cage, then stripped the turbine wheel.
Holding the little generator close to a spinning Al rim indeed does light the LED (!), see the video !
I have to admit, my wheel must spin at 40 km/h to light up the LED nicely, but then this generator device hasn't really been optimized for use as a bike light. However it works, and it has been there before the Magnic Light. Is there anyone deep enough into patent law as to say if this is then "prior art" and anyone can use this dynamo concept ?
The LED shower head cost me EUR 11.50 (bought in Germany). Now it's not just a generator-LED thing but a SEALED generator-LED thing plus a whole shower head too. Gives an indication of the cost we can expect when China mass-produces bike lights (or phone chargers, ..) based on this principle !
Thinking of what could be possible in the future, I imagine wheel sensors for wireless bike computers where the sensor is completely battery-free and works without a spoke magnet, detecting the wheel rpm through the rim joint. Another cool product would be bike computers with permanently backlit displays, the backlight powered by energy from the wheel sensor (wired one, in this case). And wireless shifting, where the generator assists a battery in the actuator-electronics, extending battery life dramatically....
To 2_i: My wheel's eyelets are ferromagnetic, but there's no noticeable force b/w magnets and eyelets if the wheel is stationary. So the eyelets shouldn't be a big contributor. And yes, the rim joint is noticable, but this only exists once per rotation and is not so pronounced that the light flickers much. So without being very scientific there, I feel that a wheel with no eyelets and no rim joint produces more or less the same amount of power. But of course, one has to test it to be very sure.
I perfectly agree, when you say that the progress in LED efficiency is a critical contributor to the success of this dynamo concept. The LED revolution has had a lot of impact in the last few years. It also made CPF grow tremendously.
Martin, the lack of flicker is not an evidence for the lack of contribution from the joint, if your rotor is not providing much resistance. As an example consider a standard bottle dynamo working off a wet bicycle rim. If the terminals of the dynamo are open, the roller will usually rotate fine. Only after you connect a matching lamp, the roller will start slipping, demonstrating insufficient friction force under the conditions. In my tests, I load the rotor until it stops or even starts rotating against the driving plate. In maximizing the power extraction from the Magnic dynamo, it certainly has to be severely loaded - that will be by the backward field from the induced current in the inductor.
As to the patent law, application of existing technology in a novel fashion will be usually patentable.
2_i, thank you for your elaborate measurements above. They tell me that between wheels, there could be a substantial differences in the amount of energy extracted. So it could happen, that one wheel (with nearly no ferromagnetic elements) yields just 42% of another wheel (with lots of ferromagnetic elements).
Consequently, any design should be made in a way that tolerates such differences. With LED light sources, it shouldn't be a stopper.
And what a pity it ain't "prior art".
Consequently, any design should be made in a way that tolerates such differences. With LED light sources, it shouldn't be a stopper.
And what a pity it ain't "prior art".
Martin: I tried to measure the effect of ferromagnetic spokes and it turned out that the effect, though noticeable when the magnet passes by the rim in the vicinity of a spoke, is not that great on the average - about 10%. For the measurement I went back to the diametrically magnetized round magnet mounted on a Dremel type tool. The tool was again operated at 5K RPM (equivalent to 23 km/h of bike speed) and I approached to the distance of about 5 mm to a rim. Now I hanged various masses from the rim, testing how much the rim could pull up. That gave me the average force of the pull of the magnet on the rim and I could work with the portion of a rim where the joining steel insert was absent. I took two rims, one with steel spokes and another with stainless. The rim with steel spokes could pull just slightly more, 11g vs 10g for the other wheel (that is washers + hook + string). Again my error is >5%.
For the photo of the setup look here.
Steve K
Flashlight Enthusiast
The heck with bike lights.. now I want a light for my shower!
That is the neatest/weirdest thing I've seen in a long time. It boggles my mind that there is a big enough market for LED showerheads to allow them to be produced. I'm also amazed that someone must have said "Do you know what the world needs?? A small LED in their showerhead!"
okay, go back to the discussion of bike lights. I'll just sit here and dream of shower lights.
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