#121
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More About Lights
On 15/03/17 01:41, Joerg wrote:
On 2017-03-13 17:19, 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. Not true. As I said before the lights on the MTB and the road bike are standard off the shelf. The diffusor lenses I installed were also off the shelf. Swapping the plain plastic against those is not something that qualifies as "work" because it merely involved screwing off a ring and then screwing that back on. Like putting relish on a sausage which doesn't alter the sausage. The new WTB saddle is also unmodified. And the panniers. And the speedometers. And ... Yes, a lot of cycling gear is designed wrong or built in an inferior quality but not everything. Therefore, your statement "absolutely NOTHING" is not correct :-) "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:" Huh? Indeed. -- JS |
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#122
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More About Lights
On 2017-03-14 13:10, James wrote:
On 15/03/17 01:41, Joerg wrote: On 2017-03-13 17:19, 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. Not true. As I said before the lights on the MTB and the road bike are standard off the shelf. The diffusor lenses I installed were also off the shelf. Swapping the plain plastic against those is not something that qualifies as "work" because it merely involved screwing off a ring and then screwing that back on. Like putting relish on a sausage which doesn't alter the sausage. The new WTB saddle is also unmodified. And the panniers. And the speedometers. And ... Yes, a lot of cycling gear is designed wrong or built in an inferior quality but not everything. Therefore, your statement "absolutely NOTHING" is not correct :-) "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:" Huh? Indeed. Read the above again. There are lamps and then there are batteries and then there are battery holders. Very different things. Yes, a large chunk of bicycle accessories is flimsy and unfit for serious use but some is fit as-is. -- Regards, Joerg http://www.analogconsultants.com/ |
#123
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More About Lights
On 3/13/2017 5:58 PM, Doug Landau wrote:
So he's a tweak snob. I point my saddle 1 degree to the right 'cuz my left nut is bigger. Wow, were you using a digital vernier caliper to measure that? |
#124
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More About Lights
On Tuesday, March 14, 2017 at 5:32:39 PM UTC-7, sms wrote:
On 3/13/2017 5:58 PM, Doug Landau wrote: So he's a tweak snob. I point my saddle 1 degree to the right 'cuz my left nut is bigger. Wow, were you using a digital vernier caliper to measure that? LOL Naw I knew that from years of playing with myself |
#125
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More About Lights
On 3/13/2017 7:49 PM, jbeattie wrote:
On Monday, March 13, 2017 at 5:36:49 PM UTC-7, Frank Krygowski wrote: 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! As close as I can get to an anecdote is the guy I saw a night or two ago here in SLC who was mostly invisible until his dyno light lit up. It didn't have any stand light. He was turning across traffic, and I didn't hit him -- but a little more warning would have been nice. As a cyclists, I suspect that you do take more care in looking for cyclists that are not legally lit. |
#126
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More About Lights
On Tue, 14 Mar 2017 10:46:19 -0400, Frank Krygowski
wrote: On 3/13/2017 11:00 PM, Jeff Liebermann wrote: I was thinking of building a benchtop dynamometer sized for bicycle lighting. I don't have the equipment to calibrate it so I could measure overall efficiency, but certainly can make comparative measurements of the input power(s) required to light an oversized load or bulb. Basically, just a DC motor with a DC wattmeter on the power leads. http://www.ebay.com/itm/122373782338 (Yet another project that I'll never finish). What are you intending to measure? Input power to a bike dynamo? Ideally, overall efficiency of the lighting system and verification of the simulation and dynamo model. Mechanical power (watts) in, as simulated by an electric motor vs optical power out, measured in lumens or lux. The main exercise would be calibrating the major components so that the measurements would be accurate and meaningful. It would be something like the Friction-Facts chain and lubricant test fixture in: http://www.friction-facts.com/equipment-overview Oh swell, all the links are broken. 2nd best: http://www.bikeradar.com/news/article/friction-facts-measuring-drivetrain-efficiency-35694/ or something like this: http://pages.jh.edu/news_info/news/home99/aug99/bike.html but with the gearing replaced by a dynamo. I vaguely recall a Friction-Facts web page mumbling something about calibrated motors and generators being rather expensive. Initially, the simulation part didn't seem too difficult. Just some non-linear parts, such as core saturation and LED light output, needed to be accommodated. I added kinematics model, so that changes in wheel diameters and gearing could be shown. Well, after entering idealized versions of all the possible formulas and parameters into a spreadsheet to estimate the complexity, I decided that building a dynamometer was far too messy for my available time, work area, and abilities. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#127
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More About Lights
On Tue, 14 Mar 2017 07:54:26 -0700, Joerg
wrote: On 2017-03-13 20:00, Jeff Liebermann wrote: On Mon, 13 Mar 2017 12:38:07 -0700, Joerg wrote: 55V at 500mA. This is encouraging. That's 27.5 watts out of a 3 watt dynamo. I was impressed, until I converted 136 km/hr and found that it was 84.5 mph. With a rocket assisted bicycle, I might be able to do that. Well, yeah, they just wanted to see where the limit is. I guess the enameled copper wire inside would smoke out if you kept that speed for long. Only the resistive part dissipates power in the wi P = I^2 * R = 0.5^2 * 2 = 0.5 watts So, it won't be the wire that gets hot. However, the cores in saturation are going to get warm. Offhand, I don't know how to calculate how hot. However, this means I should be comfortably able to milk 10W or more out of such a dynamo on a long downhill stretch and maybe north of 5W during regular rides on flat terrain. IOW there seems to be nothing that inherently limits things to the usual measly 3-4W. Maybe. Let's pretend that the test demonstrates that the dynamo can deliver 28 watts for perhaps 60 minutes before blowing up. Assuming constant energy (Joules or watt-seconds) at any speed. That would be 10 watts for 168 minutes. Assuming 10 watts output is a comfortable ride for you, you would have about 3 hrs of bright light before the dynamo self-destructed. Actually, it would probably be more like 4 or 5 hrs since the system is not adiabatic and the heat radiation efficiency of the dynamo case is time dependent. The author is mostly correct about hubs not going into saturation as easily and bottle dynamos. However, they do go into staturation, just at a higher RPM. If that happens above 84mph I shall be happy :-) Dream on. If you look at the dynamo speed vs power curves at: http://www.myra-simon.com/bike/dynotest.html They all begin to go into saturation at 15 to 20 km/hr. At 136 km/hr, the dynamo will produce 27.5 watts, but the rest of the input energy will be wasted in core saturation heating. If you paint flames on the fenders, maybe other riders will think the burning dynamo is normal. http://www.ebay.com/itm/122373782338 (Yet another project that I'll never finish). That is a neat little instrument. Yep. I don't have one yet, but it's a real temptation to install one on all my various unmetered power supplies and battery packs. However, there's a catch. The common ground is positive (+), not negative. You can see that in the schematic: https://img.alicdn.com/imgextra/i3/121163002/TB2NoBogpXXXXahXpXXXXXXXXXX_!!121163002.jpg where the + leads of both the "DC in" and the load are connected together. The only ways I could make it work in a negative ground system was either an isolated power source, isolated load, separate isolated power supply to run the meter, or a DC-DC inverter. Anyhow, I don't think a dynamo can easily be simulated until you start with a mechanical model of it and that gets into COMSOL and other really expensive modeling software. Maybe possible with MathCad which I have but rarely use so I became rusty there. Yep. That was pretty much my conclusion. Jim Thomson posted this Pspice component model: https://groups.google.com/forum/#!topic/sci.electronics.design/yPVvclIIirQ which I have been unable to convert to LTSpice. He seems to just put a sharp knee where the dynamo starts to go into saturation. That's probably good enough to get started. The rest is mechanical and rather messy if I add nonlinearities, friction, and air resistance. I do have one advantage with a hub dynamo. I can characterize it as a motor on the bench and then simply invert the derived functions to produce a generator. That might be a worthy shortcut. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#128
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More About Lights
On Mon, 13 Mar 2017 15:19:22 -0400, 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! There are no such tales because a cyclist that is not in motion could be considered a pedestrian. "Pedestrian Deaths Make Up a Rising Share of U.S. Traffic Fatalities" http://usa.streetsblog.org/2016/03/09/pedestrian-deaths-make-up-a-rising-share-of-u-s-traffic-fatalities/ "In a typical year, nearly 5,000 Americans are killed while walking". I wonder how many of those were actually cyclists walking their bicycles or waiting at a stop sign or signal (with or without a stand light)? -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#129
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More About Lights
On Tue, 14 Mar 2017 12:09:27 -0400, Frank Krygowski
wrote: But the point I was discussing was whether too brief or too dim standlights really kill or seriously injure _stationary_ bicyclists. I've never heard of such a case. I think it's yet another exaggerated danger. Bicycle lighting seems to be divided into "see where your going" and "be seen" parts. Standlights are in the "be seen" part. If so, then using a relatively narrow forward facing headlight is inadequate and a poor substitute for all around "be seen" type lighting. So far, no driver has tried to kill me while I'm stationary, but it's possible. To help prevent such a threat, I would need all around illumination because I don't know from what direction the driver might approach and I do NOT need to see where I'm going (because I'm not going anywhere). Some kind of flashing headband, flashing arm bands, or maybe downward facing flood lights to illuminate an area. Maybe an LED illuminated vest, which is now popular among highway workers: https://www.amazon.com/HIGH-VISIBILITY-VEST-COMPLIANT-REFLECTIVE/dp/B01L2US0EY https://www.amazon.com/SE-EP08L-Illuminated-Flashing-Feature/dp/B008WAE2XQ https://www.amazon.com/SE-EP07L-Flashing-Illuminated-Safety/dp/B004J663A2 I don't know which type of "be seen" lighting might be most effective, but any of the aformentioned would be better than a dim forward facing standlight. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#130
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More About Lights
On 15/03/17 13:43, Jeff Liebermann wrote:
On Tue, 14 Mar 2017 07:54:26 -0700, Joerg wrote: On 2017-03-13 20:00, Jeff Liebermann wrote: On Mon, 13 Mar 2017 12:38:07 -0700, Joerg wrote: 55V at 500mA. This is encouraging. That's 27.5 watts out of a 3 watt dynamo. I was impressed, until I converted 136 km/hr and found that it was 84.5 mph. With a rocket assisted bicycle, I might be able to do that. Well, yeah, they just wanted to see where the limit is. I guess the enameled copper wire inside would smoke out if you kept that speed for long. Only the resistive part dissipates power in the wi P = I^2 * R = 0.5^2 * 2 = 0.5 watts So, it won't be the wire that gets hot. However, the cores in saturation are going to get warm. Offhand, I don't know how to calculate how hot. Do you mean eddy currents in the core? -- JS |
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