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More About Lights
On 3/13/2017 2:06 PM, Joerg wrote:
Then you'd be back to this inferior dynamo lighting which goes out at the traffic light, or uses dimmed or short-lived light if there is a supercap installed. Where are the tragic tales of cyclists who are seriously injured or killed because their dynamo standlights were too dim or too short-lived? Somehow those tales have failed to make it into the safety literature! -- - Frank Krygowski |
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#102
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On 2017-03-13 11:50, sms wrote:
On 3/13/2017 11:06 AM, Joerg wrote: snip That's how some cheap Chinese chargers work. And a lot of non-Chinese chargers as well. Not good as that is no lomnger single-fault safe. It is as if you'd control a pump via tripping a GFCI when a certain fill level has been reached. Technically there are two safety circuits. First, with an 8.4V output charger you're limiting the charging voltage to 4.2V per cell. That doesn't really work because then the charge current would all but vanish towards the end, a charge would take forever. You've got to monitor cell voltage twice, once from the charger side and then in the cell protector circuitry. ... Second, the protection circuit on each battery, or on the battery pack, limits the voltage to 4.2V per cell just in case someone plugs in a higher voltage charger. The usual bicycle packs have only one such supervisor ciruit and then the bare cells. I think the simplest dynamo to Li-Ion 2S pack circuit would consist of only three parts. A 2A Schottky bridge. A filter cap. An 8.2V, 5W zener diode. I don't think you even need a current limiting resistor because the dynamo isn't going to put out much more than 500mA. Zeners have huge tolerances. I wouldn't do that. If you must use a shunt limiter at least employ a TL431 plus a big transistor or FET. Those are way more accurate and just as cheap. I don't think you gain much with a buck switcher unless you're often putting out dynamo voltage well in excess of 6VAC, or unless you want to do 5.25V for USB charging. You're going to lose some power with the switcher which is likely to be only 85%-90% efficient. You'd gain a lot. An old trick for well-trained commuter cyclists was to hang two lights in series for 12V which resulted in a lot more power and thus light. For slower pace one lamp could be shorted out. You could stick in a Murata LXDC55FAAA-203 http://power.murata.com/data/power/LXDC55FAAA-203_data_sheet_E.pdf instead of the zener and do a USB version also with only three parts. But I know that you love designing your own switchers. $3.50? Mon Dieu! :-) My main gripe would be the 14V limit. I'd like this to be able to go a tad higher for long downhill stretches. I don't enjoy designing switchers all that much anymore after having done 50-100 professionally. Gets boring. I'm in shock when I see the prices of some of these dynamo to USB adapters, since the parts cost is only a few bucks. http://www.sinewavecycles.com/products/sinewave-revolution I often have the impression that cyclists get taken advantage of. However, in this case the produced quantities will likely be so low that they have to charge a lot. It's not going to be a roaring market success. Here's someone that did it DIY but using a linear regulator. http://www.14degrees.org/diy-bicycle-dynamo-usb-charger-for-smartphones-and-battery-packs/ One of my bicycle rear lights (homemade) contains two MC34063. Not terribly efficient but it can safely be used to a little over 30V and costs 50 cents even if you only buy one. Can be pilfered from scrapped electronics. Diodes Inc makes one on steroids that goes ... hold on to your hat ... to 180kHz :-) At lower output levels, a dynamo could even run a 2 cell battery powered light if the batteries were removed. Then you'd be back to this inferior dynamo lighting which goes out at the traffic light, or uses dimmed or short-lived light if there is a supercap installed. No, I'm more thinking of a way to have a good light but with dynamo back-up should the batteries go flat. As well as charging the batteries during daytime riding when all you're using is the DRL flash mode. That would be my goal. I have good lighting on both bikes but on the road bike it would be nice to have a dynamo in the game. Like a hybrid car which combines gas and electric. Over the course of a long ride 50% of the juice would come from the dynamo and 50% from the battery, allowing to use half the number of cells. Should I ever ride more than 5-6h I could dim the front light and milk the dynamo for 80-90% of the budget. Or use more MUP where I can turn the lights off and then the dynamo would deliver a net average of 100%, only the road sections where I need full bore and have to wait at signals would need to be covered by the battery. Unfortunately, since dynamo lights are so rare in the U.S. we end up with sub-standard lighting with poor beam patterns, low intensity, no flash mode, and inferior brightness when stopped or riding slowly. I thought it was interesting that Barry Beams mentioned that his light could work, at less than full intensity, off of dynamo output. He may have a compelling product for dynamo users that want a brighter, safer, light but that still want the assurance of not being caught out with flat batteries. Even Frank realized the need for better lights and bought an Oculus. And while the Oculus may not be a bargain battery powered light (even though the price is still pretty reasonable), it's a lot less than dynamo lights that are not as good. I'd keep my lights as-is, MagicShine clones with diffusor lenses. The dynamo would just be added into the mix, doing the same as the alternator on a car except at standstill. -- Regards, Joerg http://www.analogconsultants.com/ |
#103
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More About Lights
On 2017-03-13 11:55, Jeff Liebermann wrote:
On Mon, 13 Mar 2017 11:06:18 -0700, Joerg wrote: A dynamo is essentially a current source where you can let the voltage scoot up until a point is reached where the current drops off so much that the total power begins to drop. Like MPPT for solar generation. Not exactly a current source. More like a resistor (coil resistance) in series with an easily saturated inductor[1]. The problem is that the bicycle dynamo operates over a range of frequencies, while the typical solar charge controller operates at a fixed frequency. The inductive reactance of the dynamo winding appears at variable series resistance that increases as the dynamo goes faster. There are also substantial differences in operating frequency between bottle and hub dynamos: http://www.pilom.com/BicycleElectronics/HubDynamo.htm "Hubs rotate at a much lower frequency than bottles, and though they have more poles to somewhat compensate, they still end up delivering a much lower frequency. At 15 km/h, the B&M Dymotec6 bottle dynamo (8 poles) outputs 168 Hz AC while the Shimano DH-3D71 hub dynamo (28 poles) outputs only 28 Hz at the same speed. At 8 km/h, a 28 pole hub is down to 15 Hz, which causes visible flicker of the light" However, in your link they say, quote "Hubs don't go into saturation easily so that at moderate to high speed, they develop a higher voltage than bottle dynamos, assuming they are not loaded with the typical 6 V / 3 W lights. To see whats possible, I ran a Shimano DH-3D71 at 136 km/h in a test stand. The voltage generated was sufficient to ignite a fluorescent tube and subsequently drive it at 55 V and 500 mA". 55V at 500mA. This is encouraging. Highe power at high voltage also works with bottle dynamos. I have tried with a Soubitez and a Ruhla dynamo, never a hub dynamo though because I never had one. Also, the dynamo iron and number of turns are selected so that the dynamo saturates at some point near the operating speed and load. The idea is not so much to regulate the AC output, as it is to reduce mechanical resistance at higher RPM's. I could make 12V filament lighting glow like halogen at high speed. I tried to build an LTSpice model that simulated a real dynamo and failed. I couldn't make it act like my bottle dynamo bench tests and various online graphs. Maybe I'll try again this week. I'm suppose to be on a (medical) vacation right now. It's best to try that out on the bench, using a rechargeable drill and such. [1] SON dynamo driving MOSFET bridge: https://www.flickr.com/photos/kurtsj00/8480800746/in/photostream http://www.candlepowerforums.com/vb/showthread.php?355392-Spice-code-for-dynamo-output "CPF is currently closed for maintenance". The author uses 0.1Hy in series with 2 ohm at 30 Hz. When I swept the 30 Hz over a 10 to 50 Hz range, it didn't look much like a dynamo. -- Regards, Joerg http://www.analogconsultants.com/ |
#104
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More About Lights
On 2017-03-13 12:19, Frank Krygowski wrote:
On 3/13/2017 2:06 PM, Joerg wrote: Then you'd be back to this inferior dynamo lighting which goes out at the traffic light, or uses dimmed or short-lived light if there is a supercap installed. Where are the tragic tales of cyclists who are seriously injured or killed because their dynamo standlights were too dim or too short-lived? Somehow those tales have failed to make it into the safety literature! As we all know reports of fatal car-cyclist collisions are notoriously short on details. You claim to be something like a "teacher for safe cycling" yet you don't know or ignore the most basic safety precautions. Astounding. Actually, sad. -- Regards, Joerg http://www.analogconsultants.com/ |
#105
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More About Lights
On 3/13/2017 12:50 PM, Joerg wrote:
On 2017-03-13 12:19, Frank Krygowski wrote: On 3/13/2017 2:06 PM, Joerg wrote: Then you'd be back to this inferior dynamo lighting which goes out at the traffic light, or uses dimmed or short-lived light if there is a supercap installed. Where are the tragic tales of cyclists who are seriously injured or killed because their dynamo standlights were too dim or too short-lived? Somehow those tales have failed to make it into the safety literature! As we all know reports of fatal car-cyclist collisions are notoriously short on details. You claim to be something like a "teacher for safe cycling" yet you don't know or ignore the most basic safety precautions. Astounding. Actually, sad. Unless their is a case-controlled, double-blind, study, Frank won't believe that increasing visibility at night, both for seeing and being seen, is beneficial. Following that to its logical conclusion, he should be opposed to any lighting at all. Or at least he should be able to provide a chart of accidents versus lumens to prove that there is no benefit to a cyclist improving his or her conspicuity and his or her ability to see the road and off to the sides. Yet there are numerous studies that have been cited in this group that do prove the benefits of better conspicuity. |
#106
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More About Lights
On 2017-03-13 13:08, sms wrote:
On 3/13/2017 12:50 PM, Joerg wrote: On 2017-03-13 12:19, Frank Krygowski wrote: On 3/13/2017 2:06 PM, Joerg wrote: Then you'd be back to this inferior dynamo lighting which goes out at the traffic light, or uses dimmed or short-lived light if there is a supercap installed. Where are the tragic tales of cyclists who are seriously injured or killed because their dynamo standlights were too dim or too short-lived? Somehow those tales have failed to make it into the safety literature! As we all know reports of fatal car-cyclist collisions are notoriously short on details. You claim to be something like a "teacher for safe cycling" yet you don't know or ignore the most basic safety precautions. Astounding. Actually, sad. Unless their is a case-controlled, double-blind, study, Frank won't believe that increasing visibility at night, both for seeing and being seen, is beneficial. Following that to its logical conclusion, he should be opposed to any lighting at all. Or at least he should be able to provide a chart of accidents versus lumens to prove that there is no benefit to a cyclist improving his or her conspicuity and his or her ability to see the road and off to the sides. Yet there are numerous studies that have been cited in this group that do prove the benefits of better conspicuity. The topper was a car driver. It was foggy and she was tearing down a freeway. One passenger said "That's dangerous to drive so fast here, you can barely see!" ... "Oh, that's ok. Because the others won't see much either". -- Regards, Joerg http://www.analogconsultants.com/ |
#107
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More About Lights
On Monday, March 13, 2017 at 2:09:05 PM UTC-4, Joerg wrote:
On 2017-03-12 15:21, James wrote: On 13/03/17 01:57, Joerg wrote: On 2017-03-11 16:28, Sir Ridesalot wrote: You need to look again at more modern stuff because many dynamo hub standlights are quite bright for the time they stay on usually a ferw minutes or so if needed. But then again absolutely NOTHING ever works for you off the shelf. Wrong, it does and I have written about it here in the NG. I bought a Cree XM-L based light each for the road bike and the MTB. Of course, since almost nothing in the world of cycling is very robust or complete this had to be spiced up. Both lights got diffusor lenses because they will otherwise blind others and the light distribution wasn't to my liking. Big deal, you just buy diffusor lenses and install them. Then the battery holders are lousy. This took a little more work but nothing that can't be done with a trip to the hardware store and basic hand tools: http://www.analogconsultants.com/ng/bike/Battbox2.JPG You just proved Sir's point. Well done Joerg. Huh? I made it quite clear that my solution works. It does very well. -- Regards, Joerg http://www.analogconsultants.com/ Because NOTHING works for you umn.ess you modify it. Cheers |
#108
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More About Lights
On 3/13/2017 4:08 PM, sms wrote:
On 3/13/2017 12:50 PM, Joerg wrote: On 2017-03-13 12:19, Frank Krygowski wrote: On 3/13/2017 2:06 PM, Joerg wrote: Then you'd be back to this inferior dynamo lighting which goes out at the traffic light, or uses dimmed or short-lived light if there is a supercap installed. Where are the tragic tales of cyclists who are seriously injured or killed because their dynamo standlights were too dim or too short-lived? Somehow those tales have failed to make it into the safety literature! As we all know reports of fatal car-cyclist collisions are notoriously short on details. You claim to be something like a "teacher for safe cycling" yet you don't know or ignore the most basic safety precautions. Astounding. Actually, sad. Unless their is a case-controlled, double-blind, study, Frank won't believe that increasing visibility at night, both for seeing and being seen, is beneficial. Oh, come on, Stephen. People getting hit because their standlights are too dim? We don't even have anecdotes about that! -- - Frank Krygowski |
#109
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More About Lights
On Monday, March 13, 2017 at 5:19:14 PM UTC-7, Sir Ridesalot wrote:
On Monday, March 13, 2017 at 2:09:05 PM UTC-4, Joerg wrote: On 2017-03-12 15:21, James wrote: On 13/03/17 01:57, Joerg wrote: On 2017-03-11 16:28, Sir Ridesalot wrote: You need to look again at more modern stuff because many dynamo hub standlights are quite bright for the time they stay on usually a ferw minutes or so if needed. But then again absolutely NOTHING ever works for you off the shelf. Wrong, it does and I have written about it here in the NG. I bought a Cree XM-L based light each for the road bike and the MTB. Of course, since almost nothing in the world of cycling is very robust or complete this had to be spiced up. Both lights got diffusor lenses because they will otherwise blind others and the light distribution wasn't to my liking. Big deal, you just buy diffusor lenses and install them. Then the battery holders are lousy. This took a little more work but nothing that can't be done with a trip to the hardware store and basic hand tools: http://www.analogconsultants.com/ng/bike/Battbox2.JPG You just proved Sir's point. Well done Joerg. Huh? I made it quite clear that my solution works. It does very well. -- Regards, Joerg http://www.analogconsultants.com/ Because NOTHING works for you umn.ess you modify it. So he's a tweak snob. I point my saddle 1 degree to the right 'cuz my left nut is bigger. Cheers is right |
#110
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More About Lights
On Mon, 13 Mar 2017 10:14:55 -0000 (UTC), Duane
wrote: jbeattie wrote: On Sunday, March 12, 2017 at 7:57:46 AM UTC-7, Joerg wrote: On 2017-03-11 16:28, Sir Ridesalot wrote: On Saturday, March 11, 2017 at 10:38:39 AM UTC-5, Joerg wrote: On 2017-03-10 19:40, Sir Ridesalot wrote: On Friday, March 10, 2017 at 7:52:30 PM UTC-5, Joerg wrote: Snipped With or without dynamo I'll never ride without a battery because then it's lights out when waiting at an intersection. Very bad at night. Now, about the bicycle air conditioner ... :-) -- Regards, Joerg http://www.analogconsultants.com/ Most decent dynamo ights these days have a standlight that'll run for several minutes when the bicycle is stopped. I have seen that in Germany. Standlight was very dim though. I prefer it to be lit normal like it is on my bikes. -- Regards, Joerg http://www.analogconsultants.com/ You need to look again at more modern stuff because many dynamo hub standlights are quite bright for the time they stay on usually a ferw minutes or so if needed. But then again absolutely NOTHING ever works for you off the shelf. Wrong, it does and I have written about it here in the NG. I bought a Cree XM-L based light each for the road bike and the MTB. Of course, since almost nothing in the world of cycling is very robust or complete this had to be spiced up. Both lights got diffusor lenses because they will otherwise blind others and the light distribution wasn't to my liking. Big deal, you just buy diffusor lenses and install them. Then the battery holders are lousy. This took a little more work but nothing that can't be done with a trip to the hardware store and basic hand tools: http://www.analogconsultants.com/ng/bike/Battbox2.JPG Why would I want inferior light when I can have a Cree XM-L that affords me almost the same quality light as a motorcycle has? This light doesn't just offer a few minutes of "standlight", it offers north of five hours of light at full blast, whether the bike move or not. I also have a power outlet on the bike. Hmm, I've managed without a battery box, outlet and motorcycle light on a road bike for like 50 years. I was riding up and down narrow canyons and city streets today without so much as a blinky. The one car that pulled out in even a semi-perilous fashion did so while looking straight at my son and me. No question of our location on the road. I get cars doing the same thing when I'm in a car. They think they can beat you into traffic. You gotta love the way he starts out telling Sir that Sir is wrong and then doing exactly what Sir said that he does. :-) I seem to get by with off the shelf equipment though I readily admit that I haven't seen a mountain lion in ages. But you probably aren't riding up mountain sides, leaping rocks and riding through rivers, usually at 20 mph, either. -- Cheers, John B. |
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