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  1. #1
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    My dynamo diy setup.

    Details: Cree XP-G first gen R2 bin triple with a Cree XRE (forgot what bin it was). Martin dynamo circuit inside the steerer tube. Shimano 3D70 dynamo. 600-700 lumens setup at 20km/h.

    The entire setup.


    The head.


    The switch.




    Been using this setup for several years now, rain or shine (you probably noticed it by the rusted out screw on the switch). Works great. Haven't seen the need to upgrade the leds yet, but will probably do that when the new ones come out in the next few years.

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    pretty neat setup

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    There is no way that is 600 lumens. The LEDs you are using both produce under 100 lumens per watt, and a dynamo only produces 3 watts. It can still be plenty of light, and brighter than anything I usually see.

    It'll be at least another year before we can get a 600 lumen light from a dynamo. Cree is still working on it. When they do get 200 lumens per watt, it'll change the way we do lighting as these will be the most efficient lights around and will replace CFLs in the marketplace. Right now it is still somewhat of a tie.

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    Quote Originally Posted by zacster View Post
    There is no way that is 600 lumens. The LEDs you are using both produce under 100 lumens per watt, and a dynamo only produces 3 watts. It can still be plenty of light, and brighter than anything I usually see.

    It'll be at least another year before we can get a 600 lumen light from a dynamo. Cree is still working on it. When they do get 200 lumens per watt, it'll change the way we do lighting as these will be the most efficient lights around and will replace CFLs in the marketplace. Right now it is still somewhat of a tie.
    The electronic I'm using puts out 7 watt, not 3.

    http://pilom.com/BicycleElectronics/DynamoCircuits.htm

    That puts the wattage per led at 1.75 each, based on the spec sheets from cree, that's an average of 180 lumens per watt, theoretically 720 lumen, but accounting the real world loss from optics and whatnot, 600 lumens.

    I have another 6 cree xpg gen 2 lights to post soon, and it's definitely not 3 watts and definitely more than 1000 lumens.

    Inspired by this from ktronik at mtbr.com
    http://forums.mtbr.com/lights-diy-do...iy-413443.html


    That's 5 years ago using Cree XR-Es.

    Mine will be a lot less clunkier.



    Dynamo can definitely put out more than 600 lumens, commercial lights like Supernova E3 triple puts out 800 lumen.
    Last edited by mrbubbles; 08-16-13 at 11:35 AM.

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    Quote Originally Posted by mrbubbles View Post
    The electronic I'm using puts out 7 watt, not 3.

    http://pilom.com/BicycleElectronics/DynamoCircuits.htm

    That puts the wattage per led at 1.75 each, based on the spec sheets from cree, that's an average of 180 lumens per watt, theoretically 720 lumen, but accounting the real world loss from optics and whatnot, 600 lumens.

    I have another 6 cree xpg gen 2 lights to post soon, and it's definitely not 3 watts and definitely more than 1000 lumens.

    Inspired by this from ktronik at mtbr.com
    http://forums.mtbr.com/lights-diy-do...iy-413443.html


    That's 5 years ago using Cree XR-Es.

    Mine will be a lot less clunkier.



    Dynamo can definitely put out more than 600 lumens, commercial lights like Supernova E3 triple puts out 800 lumen.
    Apparently neither your nor the source you cited understand electronics nor basic physics. The dynamo (which provides ALL of the power) can only output 3W. You can increase voltage at the expense of current, or current at the expense of voltage; however, the total power remains the same (ignoring conversion losses).

    You are powering your LEDS with 3W of power-period.

    You are not likely (as in certainly not) getting the LUMENS you claim. Even the Supernova only claims a MAX brightness of 800 lumen. It doesn't actually provide the measurement when it is powered from a standard 3W hub...

    Further, your setup exhibits all of the problems common with battery powered lights without the advantage of being able to draw more power than a dyno can provide. Specifically, your optics waste much of the light generated on the sky and other areas you don't need light. You would be far better off with even the cheapest dyno lights that at least have properly designed optics to make use of the limited power available in a dyno set-up.

    Also, rather than misunderstanding physics and arguing about it, just pick up a cheap light meter and show us the measurements.
    Last edited by PlanoFuji; 08-16-13 at 12:22 PM.

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    Quote Originally Posted by PlanoFuji View Post
    Apparently neither your nor the source you cited understand electronics nor basic physics. The dynamo (which provides ALL of the power) can only output 3W. You can increase voltage at the expense of current, or current at the expense of voltage; however, the total power remains the same (ignoring conversion losses).

    This is false. The 3 watt rating of a dynamo comes from the German rating system which assumes a fairly low cruising speed (8mph?). A dynamo measured at the speed with a standard load (200 ohm, iirc) must put out 3W, no more, no less, and power a 6V halogen bulb. Some older sidewall dynamos had over-voltage protection, to prevent frying the bulb. Hub dynamos don't typically have that protection and can easily exceed that voltage during most of a ride. Same site OP linked to, which is a great resource for all things dynamo related, has tests of hub dynamos at different speeds and their corresponding power loads: http://pilom.com/BicycleElectronics/HubDynamo.htm


    The power of the OP's light can be measured by multiplying the saturation current (.5A) by the Vf of the LEDs at that current, which for 4 white LEDs will be in the area of 3.3*4 = 13.2V, leading to 6.6W. He could get even more by adding additional LEDs in series, which will linearly increase the total power draw, but increase the minimum speed at which saturation happens. In my experience I've found 2 white/2 red LEDs is a good compromise between peak and low speed output.


    Quote Originally Posted by PlanoFuji View Post
    Further, your setup exhibits all of the problems common with battery powered lights without the advantage of being able to draw more power than a dyno can provide. Specifically, your optics waste much of the light generated on the sky and other areas you don't need light. You would be far better off with even the cheapest dyno lights that at least have properly designed optics to make use of the limited power available in a dyno set-up.

    4 LEDs will easily have far more output than a cheapie halogen light head, optics or no optics. Versus better optimized commercial dynamo heads, most still only have one LED, so unless he is prepared to buy and chain several in series, his setup may be still more suited to his needs (the mixing of the XR-E for far lighting and XP-Gs for up close shows that he did put some thought in this.
    Finally, a big advantage of dynamo lights over battery lights is that they are always on--there is no penalty for running a dynamo light during the day, making you more visible to others.




    Quote Originally Posted by PlanoFuji View Post
    Also, rather than misunderstanding physics and arguing about it, just pick up a cheap light meter and show us the measurements.

    Light meters measure lux/brightness, not lumens/output. A better measure would be to pick up a multimeter/current meter and take some measurements while riding. Take the highest sustained current, multiply it by the number of LEDs (in series), will put this discussion to rest.


    Also, good job, MrBubbles. What color temperature are the XP-G R2s? Since you can get 4000K warm white XP-G2s (2nd gen) in the R4 bin nowadays, you could get a significant boost in output no matter what your color preference.

  7. #7
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    Quote Originally Posted by A10K View Post
    This is false. The 3 watt rating of a dynamo comes from the German rating system which assumes a fairly low cruising speed (8mph?). A dynamo measured at the speed with a standard load (200 ohm, iirc) must put out 3W, no more, no less, and power a 6V halogen bulb. Some older sidewall dynamos had over-voltage protection, to prevent frying the bulb. Hub dynamos don't typically have that protection and can easily exceed that voltage during most of a ride. Same site OP linked to, which is a great resource for all things dynamo related, has tests of hub dynamos at different speeds and their corresponding power loads: http://pilom.com/BicycleElectronics/HubDynamo.htm
    Not false. I don't think you looked at the source he cited. It has a section that claims to produce up to 10W by 'manipulating' the 3W of nominal power (constant current and assumes unlimited voltage as speed increases) from the dyno hub at least that is what my quick perusal showed. In short the power the light has available is something a little less than the power being generated from the hub, no amount of 'manipulating' is going to change that.

    In short it expects that the dyno will have no limits (zener or saturation) applied to the output voltage. The cite also only tested two different dynos.

    Quote Originally Posted by A10K View Post
    The power of the OP's light can be measured by multiplying the saturation current (.5A) by the Vf of the LEDs at that current, which for 4 white LEDs will be in the area of 3.3*4 = 13.2V, leading to 6.6W. He could get even more by adding additional LEDs in series, which will linearly increase the total power draw, but increase the minimum speed at which saturation happens. In my experience I've found 2 white/2 red LEDs is a good compromise between peak and low speed output.

    No the power of the light can be estimated, not measured, with the method you propose and then only if one also measures the temperature of the LED. Optical power measurements require an integrating sphere light meter.


    Quote Originally Posted by A10K View Post
    4 LEDs will easily have far more output than a cheapie halogen light head, optics or no optics. Versus better optimized commercial dynamo heads, most still only have one LED, so unless he is prepared to buy and chain several in series, his setup may be still more suited to his needs (the mixing of the XR-E for far lighting and XP-Gs for up close shows that he did put some thought in this.
    Finally, a big advantage of dynamo lights over battery lights is that they are always on--there is no penalty for running a dynamo light during the day, making you more visible to others.
    Few dyno lights are halogen anymore. The cheapest are using the same high cap leds the op is using. Their big advantage is they have a correctly designed optical system that places a gradated degree of the light output from near to far. A very good quality dyno light (that easily exceeds the performance of the OP's design can be had for $50...

    Yes, I am aware of the advantages of dyno lighting, because that is what I use.

    Quote Originally Posted by A10K View Post
    Light meters measure lux/brightness, not lumens/output. A better measure would be to pick up a multimeter/current meter and take some measurements while riding. Take the highest sustained current, multiply it by the number of LEDs (in series), will put this discussion to rest.
    An integrating sphere light meter is what is used to measure the output of leds (and other light sources)... That is how they derived those nice graphs in the data sheets. While an expensive instrument, there have been a number of amateur science type articles over the years detailing how to get a pretty good approximation at home.

    This is particularly important since the temperature of the LED significantly affects its ability to produce light. That is why those graphs have temperature ratings associated with them.

    Which is why dyno lights are typically have the brightness at some fixed distance in front of the light, where the light is needed while riding, it simply makes more sense than led output power which is largely a marketing gimick. That is why dyno lights with 40 lux ratings are usually superior to battery lights with 400+ lumen ratings. Heck the effectiveness of the old Halogen lights demonstrates that light output is the least important aspect of a good and useful lighting setup for a bike.

    Quote Originally Posted by A10K View Post
    Also, good job, MrBubbles. What color temperature are the XP-G R2s? Since you can get 4000K warm white XP-G2s (2nd gen) in the R4 bin nowadays, you could get a significant boost in output no matter what your color preference.
    It is a cool hack, but simply not cost effective or practical. Further, you are likely going to have near bright spots that reduce your night vision and reduce the ability to see at night--a common problem with the lighting systems with simple conical optics.
    Last edited by PlanoFuji; 08-16-13 at 03:16 PM.

  8. #8
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    Quote Originally Posted by PlanoFuji View Post
    It is a cool hack, but simply not cost effective or practical. Further, you are likely going to have near bright spots that reduce your night vision and reduce the ability to see at night--a common problem with the lighting systems with simple conical optics.
    For practicality, I made this 4 years ago, there wasn't any 600 lumen lights for dynamos that readily available 4 years ago, and I agree with you that near bright spots are very undesirable, and my setup does not have that, the optics can be changed. Riding besides a Edelux or any of the commercially available light in the 200 lumen range, this puts out more light.

    Quote Originally Posted by A10K View Post
    Also, good job, MrBubbles. What color temperature are the XP-G R2s? Since you can get 4000K warm white XP-G2s (2nd gen) in the R4 bin nowadays, you could get a significant boost in output no matter what your color preference.
    I believe they were 6000k, I find the cool white tints ideal for road conditions (ymmv), and warm white tints ideal for forest terrain. There isn't much gain to be had by upgrading now, plus I leave this bike outside, I'm not dumping more money into it than I need to.



    Here's my other setup I just recently finished.


    Triple cree xp-e r2 with medium spot 16, and triple cree xp-g r5 with medium 22. Both gen 2. Both using carclo triple cree "spot" optics (which isn't really spot at all).

    Unfortunately my carbon fork didn't have a hole in the steerer tube to stick the circuitry (martin's #10 ) in, so it's ziptied beside the front brake cable (the zipties are taped over because the zipties were clear in colour).



    Forgive the blue heatsinks, I didn't have any black ones lying around.

    2 mode front switch.



    The SP Dynamo PD-8.



    For future upgrades, I have the mounts ready.


  9. #9
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    Quote Originally Posted by mrbubbles View Post
    For practicality, I made this 4 years ago, there wasn't any 600 lumen lights for dynamos that readily available 4 years ago, and I agree with you that near bright spots are very undesirable, and my setup does not have that, the optics can be changed. Riding besides a Edelux or any of the commercially available light in the 200 lumen range, this puts out more light.
    First, let me apologize for my earlier post. A more detailed review of your reference cite reveals that it wasn't as ridiculous as I first thought, though I do find the conclusions without adequate support.

    Dynamo lights are not typically rated in lumens for a reason. The measurement is not useful and mostly an artifact of marketing. The lux ratings occur at a fixed distance from the light source (I believe 10 meters) on the ground in front of the light source. Using this the EDELUX is a 60 lux light (I believe), the most common are 40 lux (of which I have one and it meets/exceeds the brightness of my 400 lumen cygolite, with a better pattern). And I have recently also purchased a Luxos B which is rated at 70 lux and is brighter (with a much better light shape) then 800+ lumen commercial battery powered lights I have used.


    The better dynamo lights publish a light chart that shows lux rating and light shape over a two dimensional space in front of the light.

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    Quote Originally Posted by mrbubbles View Post
    Details: Cree XP-G first gen R2 bin triple with a Cree XRE (forgot what bin it was). Martin dynamo circuit inside the steerer tube. Shimano 3D70 dynamo. 600-700 lumens setup at 20km/h.
    I like your design, hot, cool and ugly at the same time.

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    Quote Originally Posted by PlanoFuji View Post
    First, let me apologize for my earlier post. A more detailed review of your reference cite reveals that it wasn't as ridiculous as I first thought, though I do find the conclusions without adequate support.

    Dynamo lights are not typically rated in lumens for a reason. The measurement is not useful and mostly an artifact of marketing. The lux ratings occur at a fixed distance from the light source (I believe 10 meters) on the ground in front of the light source. Using this the EDELUX is a 60 lux light (I believe), the most common are 40 lux (of which I have one and it meets/exceeds the brightness of my 400 lumen cygolite, with a better pattern). And I have recently also purchased a Luxos B which is rated at 70 lux and is brighter (with a much better light shape) then 800+ lumen commercial battery powered lights I have used.


    The better dynamo lights publish a light chart that shows lux rating and light shape over a two dimensional space in front of the light.

    I agree with some of the things you've said. My biggest gripe about diy is the optics, there just isn't anything out there that's optimized for road riding besides proprietary optics from dynamo light companies. If I wasn't going the DIY route, I would've just bought the Luxos U and be done with it.

    FYI, I found some commercial battery powered lights from big major brands use identically open source optics available off-the-shelf (cygolite cateye cough cough). That would explain some of the very generic looking beams out there.

    But yes, it is possible for dynamo hubs to drive setup like mine to 1200 lumens, but I have to be riding at 25km/h(on Shimano hubs)/28km/h(on SP dynamos) or higher to achieve that level.

  12. #12
    Senior Member Road Fan's Avatar
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    Quote Originally Posted by PlanoFuji View Post
    Apparently neither your nor the source you cited understand electronics nor basic physics. The dynamo (which provides ALL of the power) can only output 3W. You can increase voltage at the expense of current, or current at the expense of voltage; however, the total power remains the same (ignoring conversion losses).

    You are powering your LEDS with 3W of power-period.

    You are not likely (as in certainly not) getting the LUMENS you claim. Even the Supernova only claims a MAX brightness of 800 lumen. It doesn't actually provide the measurement when it is powered from a standard 3W hub...

    Further, your setup exhibits all of the problems common with battery powered lights without the advantage of being able to draw more power than a dyno can provide. Specifically, your optics waste much of the light generated on the sky and other areas you don't need light. You would be far better off with even the cheapest dyno lights that at least have properly designed optics to make use of the limited power available in a dyno set-up.

    Also, rather than misunderstanding physics and arguing about it, just pick up a cheap light meter and show us the measurements.
    Plano, you are assuming that the rating of the dyno is a power limiting value. I think it's instead a guaranteed level of performance at a specific road speed - the statement of compliance with the specifications of the German road law (I can't give the citation). At a higher road speed or at a lower electrical load impedance it may put out more than that. We don't know it's maximum power, short-term or long term because of several other uncertainties: we don't know if the standard (i.e. LED light) load is a matched load for any given generator, we don't know if the generator physical design is thermally limited (affects long term power output), and we don't know at what combinations of load and speed the magnetics saturate (electrical limit of the generator circuit).

    I'd say (and I cannot say I can do this at my house, I could have done it three jobs ago when I was still a power electronics engineer) test the generator by spinning the wheel at fixed speeds and loading it with known resistor loads. Observe the load waveform with a current probe (or a shunt) and an oscilloscope. Take data to indicate at what power level the current is becoming distorted, also what the RMS voltages and currents are. Since it's an AC machine, power factor must be considered in assessing output power. Just for a little more fun and understanding, probe the dyno case temperature with a thermocouple right after each test to observe temperature rise with increasing power level.

    While we're at it we should measure the Thevenin voltage and source impedance as well as the Norton current of the dyno.

    With all this we'd have a good understanding of what the dyno's capability is.

    I suspect you're exactly correct, that Mr. Bubbles' neat setup is not doing what he thinks it is, because he does not understand how the load circuit affects the generator. But now we should find the truth.

    EDIT:
    I've read it all now, and I see that while my suggestion to characterize the dyno might have some merit, it could well be that Mr B's circuit is in fact delivering the power he thinks it is.

    I don't see why the German law means you must put out 3 watts no less and no more, unless the German authorities were trying to eliminate extra-bright lights on the public roads. It that case the spec needs to ahve an upper and lower bound, and I don't recall that it does. I read it more than 10 years ago!

    Today I'd suggest just buy a Luxos B or U.
    Last edited by Road Fan; 08-17-13 at 06:32 PM.

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    Quote Originally Posted by Road Fan View Post
    Plano, you are assuming that the rating of the dyno is a power limiting value. I think it's instead a guaranteed level of performance at a specific road speed - the statement of compliance with the specifications of the German road law (I can't give the citation). At a higher road speed or at a lower electrical load impedance it may put out more than that. We don't know it's maximum power, short-term or long term because of several other uncertainties: we don't know if the standard (i.e. LED light) load is a matched load for any given generator, we don't know if the generator physical design is thermally limited (affects long term power output), and we don't know at what combinations of load and speed the magnetics saturate (electrical limit of the generator circuit).

    I'd say (and I cannot say I can do this at my house, I could have done it three jobs ago when I was still a power electronics engineer) test the generator by spinning the wheel at fixed speeds and loading it with known resistor loads. Observe the load waveform with a current probe (or a shunt) and an oscilloscope. Take data to indicate at what power level the current is becoming distorted, also what the RMS voltages and currents are. Since it's an AC machine, power factor must be considered in assessing output power. Just for a little more fun and understanding, probe the dyno case temperature with a thermocouple right after each test to observe temperature rise with increasing power level.

    While we're at it we should measure the Thevenin voltage and source impedance as well as the Norton current of the dyno.

    With all this we'd have a good understanding of what the dyno's capability is.

    I suspect you're exactly correct, that Mr. Bubbles' neat setup is not doing what he thinks it is, because he does not understand how the load circuit affects the generator. But now we should find the truth.
    No I wasn't assuming the rating was a limiting factor. I already covered what my assumptions were earlier.

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    Quote Originally Posted by PlanoFuji View Post
    No I wasn't assuming the rating was a limiting factor. I already covered what my assumptions were earlier.
    See my last post. Apologies offered!

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    Quote Originally Posted by Road Fan View Post
    I don't see why the German law means you must put out 3 watts no less and no more, unless the German authorities were trying to eliminate extra-bright lights on the public roads. It that case the spec needs to ahve an upper and lower bound, and I don't recall that it does. I read it more than 10 years ago!

    Today I'd suggest just buy a Luxos B or U.
    The German law does not require a dynamo to put out exactly 3W and no more or less...

    It is designed to make sure that AT LEAST 3W are available at a speed of about 15kph (assumed to be a typical cycling speed for commuter type cyclists) and that a certain quantity and quality of light is produced.

    What limits the power generated from dynamos are size/weight/cost, and to some extent physics.

    I'd go for the Luxos B as the best value--which I did, though I also use an IQ Fly RT senso

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    Let's put it to rest. Dynamo lights can put out lots of lumens, it just depends how fast you'll go.

    I do like that commercial light makers are coming out with high output dynamo lights.

    Besides the Supernova E3 Triple, here's another one.

    http://use1.com/exposure-lights/cycl...evo-mk1-dynamo


    This one is aimed at mountain bikers, and there's only a handlebar mount, so no fork crown mount.

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    "Jane, you ignorant ****" -

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    Plano and Roadie, you're confused because you don't have a proper model for the generator. When driving an LED or Zener load, the generator acts as a nearly constant 500mA current source, independent of output voltage (until the winding saturate, ~12Vrms for the Shimano). The booster/doubler circuit helps increase the generator's output voltage to better match the source to the load. Thevin's equivalence for a non-linear source isn't a valid analysis.
    IGH's, Dyno Hubs, LED lights and old frames

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    Quote Originally Posted by Mr IGH View Post
    Plano and Roadie, you're confused because you don't have a proper model for the generator. When driving an LED or Zener load, the generator acts as a nearly constant 500mA current source, independent of output voltage (until the winding saturate, ~12Vrms for the Shimano). The booster/doubler circuit helps increase the generator's output voltage to better match the source to the load. Thevin's equivalence for a non-linear source isn't a valid analysis.
    I was having so much fun reading their non-sense and here you ruined it!

    Besides, I thought it was a cool little project.

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    That set up looks like a great bike hacks post.. Nice job.

  21. #21
    Senior Member Road Fan's Avatar
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    Quote Originally Posted by Mr IGH View Post
    Plano and Roadie, you're confused because you don't have a proper model for the generator. When driving an LED or Zener load, the generator acts as a nearly constant 500mA current source, independent of output voltage (until the winding saturate, ~12Vrms for the Shimano). The booster/doubler circuit helps increase the generator's output voltage to better match the source to the load. Thevin's equivalence for a non-linear source isn't a valid analysis.
    @ Mr. IGH: I guess by "Roadie" you mean me. I don't see where I'm confused. I agree with you that we don't have a proper understanding of the generator and its model. I certainly do not have one. If you have one, please give a good description of it (such as in item 2 below). However, I don't see that you have presented a good model of the generator.

    1. If you are correct that the hubgen will produce a constant current into a zener load, then the hubgen must be a Norton source when in that region (below saturation) of operation. Hence in that region the generator is linear, while the load is non-linear since it isn't resistive.

    2. Do you have data that shows the saturation of the Shimano generator at 12vrms? Is the saturation independent of loading? What I'd really believe is measurements of voltage and current with resistive loads, with speed and resistance varied as parameters, and some scope photos (or the computer equivalents) to see the onset of saturation. I'd also see those as a strong basis for a generator model.

    3. I think the saturation you are talking about is due to the magnetic materials, not the winding. The winding is wire, which is copper or aluminum, and those metals do not saturate, unless you are talking about failures such as melting or insulation burning and creating short circuits. Magnetic materials, however, do saturate.

    4. Now a systems perspective: any valid generator model has to accommodate the variations in real-world use: single headlamp, headlamp with taillamp, dual parallel headlamps, series headlamps, and the variations of lighting systems with mobile device charging.

    Usually electric machines produce a higher open-circuit voltage with shaft speed. I don't see why we have to throw out that principle for bike generators. One thing it implies is that for loads with a higher input resistance than the generator winding resistance, this voltage variation will be measurable as you speed up the bike wheel.

    Keep talking?

  22. #22
    afraid of whales Mr IGH's Avatar
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    The problem is the generator isn't a linear source once the non-linear load is hooked up. If the load was a resistor taking AC power, you'd be correct. But the load is a bridge/cap and diode string. The generator doesn't see any load (runs open circuit) until the bridge diodes forward conduct Then once the generator's output voltage forward bias the bridge it's clamped at the output voltage and dumps as much current as it can. When the output cap isn't charged up enough to forward bias the LEDs, then the load is a short circuit. Once the output cap exceeds the turn-on voltage of the LEDs the load is just a clamp. None of the lends itself to the compromised model that Norton/Thevin equivalence requires.

    I've measured this in the lab but I just confirmed Martin's measurements:
    http://pilom.com/BicycleElectronics/DynamoCircuits.htm

    You can see that saturation at max power in many of the curves. confirmed in several German language websites:
    http://fahrradzukunft.de/14/neue-nabendynamos-im-test/

    The limiting technique of adding in an extra winding is how they do it with 50/60Hz AC transformer off-line battery chargers, I assume that's how they do it in bike generators.
    Last edited by Mr IGH; 04-19-14 at 10:24 AM.
    IGH's, Dyno Hubs, LED lights and old frames

  23. #23
    rugged individualist wphamilton's Avatar
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    Succinct and readable Mr IGH, your summary and the link.

    Nicely done Mr Bubbles! 6-700 lumens, especially with as simple the circuits are that IGH showed, temps me to reconsider a dynamo setup.

  24. #24
    afraid of whales Mr IGH's Avatar
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    Quote Originally Posted by wphamilton View Post
    Succinct and readable Mr IGH, your summary and the link....
    Thank you, Sir. I'm waiting for someone to bring up state space variable averaging to average the two states. I can explain why it works even worse in this application than it does for normal switched mode power supplies.
    IGH's, Dyno Hubs, LED lights and old frames

  25. #25
    Senior Member Road Fan's Avatar
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    Quote Originally Posted by Mr IGH View Post
    Thank you, Sir. I'm waiting for someone to bring up state space variable averaging to average the two states. I can explain why it works even worse in this application than it does for normal switched mode power supplies.
    Well, when I designed switchers and power systems that depended on them, state space averaging was something we depended on to properly design the system and unit dynamics. No modeling technique is perfect, but some are useful.

    But I think there are too many axes being ground here.

    Good luck to the OP with his DIY light!

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