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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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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/ |
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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? |
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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 |
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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. |
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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 |
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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 |
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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 |
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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 |
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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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On Wed, 15 Mar 2017 15:14:56 +1100, James
wrote: 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? Nope. I meant hysteresis losses. Eddy currents do contribute to losses by "bucking" the build up and collapse of the magnetic field, but most of the heat is produced by hysteresis losses: https://www.quora.com/What-is-hysteresis-loss-Where-does-the-loss-actually-occur See an induction heater or stove for an extreme case of heat being generated by eddy and hysteresis currents: https://en.wikipedia.org/wiki/Induction_heating -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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On 15/03/17 16:15, Jeff Liebermann wrote:
On Wed, 15 Mar 2017 15:14:56 +1100, James wrote: 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? Nope. I meant hysteresis losses. Eddy currents do contribute to losses by "bucking" the build up and collapse of the magnetic field, but most of the heat is produced by hysteresis losses: https://www.quora.com/What-is-hysteresis-loss-Where-does-the-loss-actually-occur See an induction heater or stove for an extreme case of heat being generated by eddy and hysteresis currents: https://en.wikipedia.org/wiki/Induction_heating Hysteresis losses are different from saturation. Saturation shouldn't occur if the core has been adequately designed to accommodate all the permanent magnet flux & MMF. -- JS |
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On Wed, 15 Mar 2017 16:45:57 +1100, James
wrote: On 15/03/17 16:15, Jeff Liebermann wrote: On Wed, 15 Mar 2017 15:14:56 +1100, James wrote: 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? Nope. I meant hysteresis losses. Eddy currents do contribute to losses by "bucking" the build up and collapse of the magnetic field, but most of the heat is produced by hysteresis losses: https://www.quora.com/What-is-hysteresis-loss-Where-does-the-loss-actually-occur See an induction heater or stove for an extreme case of heat being generated by eddy and hysteresis currents: https://en.wikipedia.org/wiki/Induction_heating Hysteresis losses are different from saturation. Saturation shouldn't occur if the core has been adequately designed to accommodate all the permanent magnet flux & MMF. Most (not all) dynamos are designed to provide some form of self-regulation. This made sense back in the days when the load was just a simple 6v incandescent light bulb. It wouldn't do to have Kamakazi downhill speeders producing enough revolutions to have the dynamo belch 12VAC and burn out the bulb. Fast forward to today, and we no longer use incandescent lights on dynamos. Most (not all) LED lamps have built in regulators and really don't need to have the dynamo perform any additional regulation. However, the industry is conservative, and things change very slowly. Kinda like the automobile industry requiring 25 years to get rid of the buggy whip socket. So, we still have dynamos that intentionally designed to NOT produce a linear increase in output for high RPMs. Fortunately, the problem is not universal. http://www.pilom.com/BicycleElectronics/HubDynamo.htm Notice the 2nd graph of Hub vs Bottle Power. The Shimano DH-3D71 hub dynamo produces a linear increase in output power with no saturation visible. (However, at my cruising speed of 15 km/hr, it only produces 4 watts and is therefore only a slight improvement over the common bottle dynamo). Hystersis loss is core saturation loss. What happens is that at some point, adding additional current to the coil and core does produce an increase in the magnetic field. Magnetic domains will change direction when current is applied, but are not terribly thrilled with the idea. Their resistance to this change in current and direction is hysteresis loss. This additional current (and power) has to go somewhere since it can't be used to build a changing magnetic field. So, it gets converted into heat. Eddy current losses are the result of changes in magnetic field, not changes in applied current. When the magnetic field finally decides to change direction and AFTER hysteresis losses are produced, the resultant magnetic field breaks up into small magnetic loops or eddys. Adjacent eddys fight each other resulting in repulsion. The energy required to overcome this repulsive force are the eddy current losses. As I understand it, the favored core material is some form of mu-metal or permalloy which saturate nicely at low currents: https://en.wikipedia.org/wiki/Mu-metal I'm not sure this is the material as some description suggest that it's "cold rolled dynamo silicon sheet steel" or the same stuff used in the E/I laminations of a common AC power transformer. It's after midnight. I give up for tonite. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
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On Wednesday, March 15, 2017 at 3:07:41 AM UTC-4, Jeff Liebermann wrote:
On Wed, 15 Mar 2017 16:45:57 +1100, James wrote: On 15/03/17 16:15, Jeff Liebermann wrote: On Wed, 15 Mar 2017 15:14:56 +1100, James wrote: 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? Nope. I meant hysteresis losses. Eddy currents do contribute to losses by "bucking" the build up and collapse of the magnetic field, but most of the heat is produced by hysteresis losses: https://www.quora.com/What-is-hysteresis-loss-Where-does-the-loss-actually-occur See an induction heater or stove for an extreme case of heat being generated by eddy and hysteresis currents: https://en.wikipedia.org/wiki/Induction_heating Hysteresis losses are different from saturation. Saturation shouldn't occur if the core has been adequately designed to accommodate all the permanent magnet flux & MMF. Most (not all) dynamos are designed to provide some form of self-regulation. This made sense back in the days when the load was just a simple 6v incandescent light bulb. It wouldn't do to have Kamakazi downhill speeders producing enough revolutions to have the dynamo belch 12VAC and burn out the bulb. Fast forward to today, and we no longer use incandescent lights on dynamos. Most (not all) LED lamps have built in regulators and really don't need to have the dynamo perform any additional regulation. However, the industry is conservative, and things change very slowly. Kinda like the automobile industry requiring 25 years to get rid of the buggy whip socket. So, we still have dynamos that intentionally designed to NOT produce a linear increase in output for high RPMs. Fortunately, the problem is not universal. http://www.pilom.com/BicycleElectronics/HubDynamo.htm Notice the 2nd graph of Hub vs Bottle Power. The Shimano DH-3D71 hub dynamo produces a linear increase in output power with no saturation visible. (However, at my cruising speed of 15 km/hr, it only produces 4 watts and is therefore only a slight improvement over the common bottle dynamo). Snipped -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 I remember burning out bulbs with my bottle dynamo if I rode really fast. I also remember the slipping problems when the wheels were wet even when I used the rubber boot sold to go on the bottle dynamo roller. Hub dynamos today really seem to fall down at slow speeds. Cheers |
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Sir Ridesalot wrote:
:I remember burning out bulbs with my bottle dynamo if I rode really :fast. I also remember the slipping problems when the wheels were wet even :when I used the rubber boot sold to go on the bottle dynamo roller. Hub :dynamos today really seem to fall down at slow speeds. Mine work fine from walking speeds. They produce more light at higher speeds, but at slow speeds you don't need it, because you're not moving fast. -- sig 85 |
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On Wednesday, March 15, 2017 at 7:53:52 AM UTC-7, David Scheidt wrote:
Sir Ridesalot wrote: :I remember burning out bulbs with my bottle dynamo if I rode really :fast. I also remember the slipping problems when the wheels were wet even :when I used the rubber boot sold to go on the bottle dynamo roller. Hub :dynamos today really seem to fall down at slow speeds. Mine work fine from walking speeds. They produce more light at higher speeds, but at slow speeds you don't need it, because you're not moving fast. I sometimes need light most at slow speeds, when I'm creeping up hills and trying not to fall into giant pot holes. -- Jay Beattie. |
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On Wednesday, March 15, 2017 at 9:45:34 AM UTC-7, jbeattie wrote:
On Wednesday, March 15, 2017 at 7:53:52 AM UTC-7, David Scheidt wrote: Sir Ridesalot wrote: :I remember burning out bulbs with my bottle dynamo if I rode really :fast. I also remember the slipping problems when the wheels were wet even :when I used the rubber boot sold to go on the bottle dynamo roller. Hub :dynamos today really seem to fall down at slow speeds. Mine work fine from walking speeds. They produce more light at higher speeds, but at slow speeds you don't need it, because you're not moving fast. I sometimes need light most at slow speeds, when I'm creeping up hills and trying not to fall into giant pot holes. -- Jay Beattie. Where are you on Strava |
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On Wednesday, March 15, 2017 at 12:45:34 PM UTC-4, jbeattie wrote:
On Wednesday, March 15, 2017 at 7:53:52 AM UTC-7, David Scheidt wrote: Sir Ridesalot wrote: :I remember burning out bulbs with my bottle dynamo if I rode really :fast. I also remember the slipping problems when the wheels were wet even :when I used the rubber boot sold to go on the bottle dynamo roller. Hub :dynamos today really seem to fall down at slow speeds. Mine work fine from walking speeds. They produce more light at higher speeds, but at slow speeds you don't need it, because you're not moving fast. I sometimes need light most at slow speeds, when I'm creeping up hills and trying not to fall into giant pot holes. -- Jay Beattie. Ditto. Or ride off the edge of the trail and down the side into the river. Chers |
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On Wednesday, March 15, 2017 at 10:28:52 AM UTC-7, Sir Ridesalot wrote:
On Wednesday, March 15, 2017 at 12:45:34 PM UTC-4, jbeattie wrote: On Wednesday, March 15, 2017 at 7:53:52 AM UTC-7, David Scheidt wrote: Sir Ridesalot wrote: :I remember burning out bulbs with my bottle dynamo if I rode really :fast. I also remember the slipping problems when the wheels were wet even :when I used the rubber boot sold to go on the bottle dynamo roller. Hub :dynamos today really seem to fall down at slow speeds. Mine work fine from walking speeds. They produce more light at higher speeds, but at slow speeds you don't need it, because you're not moving fast. I sometimes need light most at slow speeds, when I'm creeping up hills and trying not to fall into giant pot holes. -- Jay Beattie. Ditto. Or ride off the edge of the trail and down the side into the river. You mean like this, except at night? https://www.youtube.com/watch?v=Fmb6OvejAC0 |
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On 3/14/2017 9:35 PM, Jeff Liebermann wrote:
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 OK. You may be aware of Andreas Oehler's approach, but in case you're not, what he built was essentially a big flywheel that could be used to stand in for a bike wheel and drive a bike dynamo of any design. He used a data acquisition system to record dyno electrical output as well as angular deceleration of the flywheel. That allowed computing retarding torque resulting from the dynamo, thus (coupled with angular velocity) the power consumption. I used a much simpler method. I mounted dynamos in a frame that pivoted on the dyno's rotational axis, and used a lever arm of known length pressing on a scale. Force on the scale gave torque, and known rpm enabled calculation of power. But my method didn't include losses from the friction drive. Andreas's method does. Output power was measured electrically, in Watts. If you try to measure lumens, you'll have a much harder job, and the efficiency (lumens/Watt) of the LED will enter into things. I'm not sure you want that or not. And lux isn't a power measurement, of course, so you can't get a true efficiency that way. -- - Frank Krygowski |
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On 3/15/2017 10:53 AM, David Scheidt wrote:
Sir Ridesalot wrote: :I remember burning out bulbs with my bottle dynamo if I rode really :fast. I also remember the slipping problems when the wheels were wet even :when I used the rubber boot sold to go on the bottle dynamo roller. Hub :dynamos today really seem to fall down at slow speeds. Mine work fine from walking speeds. They produce more light at higher speeds, but at slow speeds you don't need it, because you're not moving fast. That's my experience too. The last time I recall not having enough light at low speeds was in a dark campground with a pre-halogen dynamo light with lousy optics. That was about 1980, IIRC. With the modern LED dynamo lights, it's never even come close to happening, even at walking speed. -- - Frank Krygowski |
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On 3/14/2017 10:57 PM, Jeff Liebermann wrote:
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)? I suspect the answer is zero. Especially those waiting at stop signs or signals. But a cyclist walking his bike _is_ a pedestrian, and has no more legal or practical need for a light than a pedestrian does. Sometimes when walking at night, I'll carry a small flashlight. But people do not normally do that. Think back to the last few times you parked your car and walked from the car to a store or movie theater at night. -- - Frank Krygowski |
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On 3/14/2017 11:15 PM, Jeff Liebermann wrote:
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. Thing is, nobody's demonstrated any need for so much stationary "be seen" light, beyond the usual "well, it _could_ happen" safety inflation mentality. We're facing the same mentality regarding our local forest preserve. Some people want to cut down every dead or dying tree within 100 feet of any trail because, well, it _could_ fall on somebody and kill them. Sheesh. -- - Frank Krygowski |
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On Wednesday, March 15, 2017 at 2:05:09 PM UTC-4, Frank Krygowski wrote:
On 3/14/2017 10:57 PM, Jeff Liebermann wrote: 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)? I suspect the answer is zero. Especially those waiting at stop signs or signals. But a cyclist walking his bike _is_ a pedestrian, and has no more legal or practical need for a light than a pedestrian does. Sometimes when walking at night, I'll carry a small flashlight. But people do not normally do that. Think back to the last few times you parked your car and walked from the car to a store or movie theater at night. - - Frank Krygowski I see a lot more people at night wearing a reflective vest or carrying a flashlight than I did five or ten years ago. It seems too that a lot of pedestrians are very concerned about distracted drivers. Cheers |
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On Wednesday, March 15, 2017 at 2:08:49 PM UTC-4, Frank Krygowski wrote:
On 3/14/2017 11:15 PM, Jeff Liebermann wrote: 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. Thing is, nobody's demonstrated any need for so much stationary "be seen" light, beyond the usual "well, it _could_ happen" safety inflation mentality. We're facing the same mentality regarding our local forest preserve. Some people want to cut down every dead or dying tree within 100 feet of any trail because, well, it _could_ fall on somebody and kill them. Sheesh. -- - Frank Krygowski I remember the Soubitez (sp?) ads from the 1980s that showed a stopped bicycle without a front light at an intersection at night and another image of the Soubitez dynamo light with the standlight. The ad was about how much safer yuo were with the Soubitez dynamo because others could see the light whilst you were stopped or just starting up again. So this perceived need for a safety standlight on a dynamo powered light is nothing new. Cheers |
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jbeattie wrote:
:On Wednesday, March 15, 2017 at 7:53:52 AM UTC-7, David Scheidt wrote: : Sir Ridesalot wrote: : : :I remember burning out bulbs with my bottle dynamo if I rode really : :fast. I also remember the slipping problems when the wheels were wet even : :when I used the rubber boot sold to go on the bottle dynamo roller. Hub : :dynamos today really seem to fall down at slow speeds. : : Mine work fine from walking speeds. They produce more light at higher : speeds, but at slow speeds you don't need it, because you're not : moving fast. : :I sometimes need light most at slow speeds, when I'm creeping up hills and trying not to fall into giant pot holes. I assure you the potholes in Chicago are as least as big as yours, and my lights are fine for finding them as slow as I can ride a bike upright. Perhaps your hub is defective. -- sig 102 |
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On Wednesday, March 15, 2017 at 10:20:10 AM UTC-7, Doug Landau wrote:
On Wednesday, March 15, 2017 at 9:45:34 AM UTC-7, jbeattie wrote: On Wednesday, March 15, 2017 at 7:53:52 AM UTC-7, David Scheidt wrote: Sir Ridesalot wrote: :I remember burning out bulbs with my bottle dynamo if I rode really :fast. I also remember the slipping problems when the wheels were wet even :when I used the rubber boot sold to go on the bottle dynamo roller. Hub :dynamos today really seem to fall down at slow speeds. Mine work fine from walking speeds. They produce more light at higher speeds, but at slow speeds you don't need it, because you're not moving fast. I sometimes need light most at slow speeds, when I'm creeping up hills and trying not to fall into giant pot holes. -- Jay Beattie. Where are you on Strava No Strava. No Garmin. My cyclometer is broken. I might as well be back in the stoneage. -- Jay Beattie. |
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On Wednesday, March 15, 2017 at 12:19:18 PM UTC-7, jbeattie wrote:
On Wednesday, March 15, 2017 at 10:20:10 AM UTC-7, Doug Landau wrote: On Wednesday, March 15, 2017 at 9:45:34 AM UTC-7, jbeattie wrote: On Wednesday, March 15, 2017 at 7:53:52 AM UTC-7, David Scheidt wrote: Sir Ridesalot wrote: :I remember burning out bulbs with my bottle dynamo if I rode really :fast. I also remember the slipping problems when the wheels were wet even :when I used the rubber boot sold to go on the bottle dynamo roller. Hub :dynamos today really seem to fall down at slow speeds. Mine work fine from walking speeds. They produce more light at higher speeds, but at slow speeds you don't need it, because you're not moving fast. I sometimes need light most at slow speeds, when I'm creeping up hills and trying not to fall into giant pot holes. -- Jay Beattie. Where are you on Strava No Strava. No Garmin. My cyclometer is broken. I might as well be back in the stoneage. -- Jay Beattie. Strava's just for fun. I don't use a cyclometer any more. I just count rear tires and multiply by 1500 now. |
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On 3/15/2017 2:43 PM, Sir Ridesalot wrote:
On Wednesday, March 15, 2017 at 2:05:09 PM UTC-4, Frank Krygowski wrote: On 3/14/2017 10:57 PM, Jeff Liebermann wrote: 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)? I suspect the answer is zero. Especially those waiting at stop signs or signals. But a cyclist walking his bike _is_ a pedestrian, and has no more legal or practical need for a light than a pedestrian does. Sometimes when walking at night, I'll carry a small flashlight. But people do not normally do that. Think back to the last few times you parked your car and walked from the car to a store or movie theater at night. - - Frank Krygowski I see a lot more people at night wearing a reflective vest or carrying a flashlight than I did five or ten years ago. It seems too that a lot of pedestrians are very concerned about distracted drivers. Sure. Safety inflation is a real thing. Ten years ago, walking on a sidewalk did not trigger a need for a luminous vest. Now I see people wearing those things even on sidewalks. So why the change? Is it because it's really gotten so much more dangerous? I doubt it. Pedestrian fatalities did jump up a bit in the last year for which I find NHTSA data (2014) but they jumped up to a number less than the one for 2004. -- - Frank Krygowski |
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On 3/15/2017 2:48 PM, Sir Ridesalot wrote:
On Wednesday, March 15, 2017 at 2:08:49 PM UTC-4, Frank Krygowski wrote: On 3/14/2017 11:15 PM, Jeff Liebermann wrote: 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. Thing is, nobody's demonstrated any need for so much stationary "be seen" light, beyond the usual "well, it _could_ happen" safety inflation mentality. We're facing the same mentality regarding our local forest preserve. Some people want to cut down every dead or dying tree within 100 feet of any trail because, well, it _could_ fall on somebody and kill them. Sheesh. -- - Frank Krygowski I remember the Soubitez (sp?) ads from the 1980s that showed a stopped bicycle without a front light at an intersection at night and another image of the Soubitez dynamo light with the standlight. The ad was about how much safer yuo were with the Soubitez dynamo because others could see the light whilst you were stopped or just starting up again. So this perceived need for a safety standlight on a dynamo powered light is nothing new. As I recall, that system failed in the marketplace. The idea might have existed in a few minds back then, but it wasn't common enough to be commercially successful. The same could be said of many present "safety" devices. You'd have gone broke trying to sell "walker safety vests" in the 1970s or 1980s. Ditto little hammers to let you break your car window if you were trapped inside. Or foam pads to put on the corner of every hard object your toddler might walk by. Or bathtub mats that say "HOT" when the water is, well, hot. But all those things have been sold recently. -- - Frank Krygowski |
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On 3/15/2017 2:57 PM, Frank Krygowski wrote:
On 3/15/2017 2:48 PM, Sir Ridesalot wrote: On Wednesday, March 15, 2017 at 2:08:49 PM UTC-4, Frank Krygowski wrote: On 3/14/2017 11:15 PM, Jeff Liebermann wrote: 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. Thing is, nobody's demonstrated any need for so much stationary "be seen" light, beyond the usual "well, it _could_ happen" safety inflation mentality. We're facing the same mentality regarding our local forest preserve. Some people want to cut down every dead or dying tree within 100 feet of any trail because, well, it _could_ fall on somebody and kill them. Sheesh. -- - Frank Krygowski I remember the Soubitez (sp?) ads from the 1980s that showed a stopped bicycle without a front light at an intersection at night and another image of the Soubitez dynamo light with the standlight. The ad was about how much safer yuo were with the Soubitez dynamo because others could see the light whilst you were stopped or just starting up again. So this perceived need for a safety standlight on a dynamo powered light is nothing new. As I recall, that system failed in the marketplace. The idea might have existed in a few minds back then, but it wasn't common enough to be commercially successful. The same could be said of many present "safety" devices. You'd have gone broke trying to sell "walker safety vests" in the 1970s or 1980s. Ditto little hammers to let you break your car window if you were trapped inside. Or foam pads to put on the corner of every hard object your toddler might walk by. Or bathtub mats that say "HOT" when the water is, well, hot. But all those things have been sold recently. None anywhere near as lucrative as Pet Rocks (a product of similar utility but more trendy) Regarding Soubitez standlights of the 1980s, devastatingly unpopular. http://www.yellowjersey.org/photosfr...t/soustan1.jpg http://www.yellowjersey.org/photosfr...t/soustan2.jpg -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
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On Wednesday, March 15, 2017 at 12:17:31 PM UTC-7, David Scheidt wrote:
jbeattie wrote: :On Wednesday, March 15, 2017 at 7:53:52 AM UTC-7, David Scheidt wrote: : Sir Ridesalot wrote: : : :I remember burning out bulbs with my bottle dynamo if I rode really : :fast. I also remember the slipping problems when the wheels were wet even : :when I used the rubber boot sold to go on the bottle dynamo roller. Hub : :dynamos today really seem to fall down at slow speeds. : : Mine work fine from walking speeds. They produce more light at higher : speeds, but at slow speeds you don't need it, because you're not : moving fast. : :I sometimes need light most at slow speeds, when I'm creeping up hills and trying not to fall into giant pot holes. I assure you the potholes in Chicago are as least as big as yours, and my lights are fine for finding them as slow as I can ride a bike upright. Perhaps your hub is defective. Perhaps I do have a defective hub. Unlike Chicago, though, I'm riding home up little goat roads that are between a 6-10 percent grade and that are really a collection of patch and broken pavement. http://tinyurl.com/zo6hq6e Scoll up the road. A lot of the patched sections are now holes after the snow storms. With wet pavement, it's hard to see the holes. Even when perfectly dry, it's not that great. -- Jay Beattie. |
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On 15/03/17 18:07, Jeff Liebermann wrote:
On Wed, 15 Mar 2017 16:45:57 +1100, James wrote: On 15/03/17 16:15, Jeff Liebermann wrote: On Wed, 15 Mar 2017 15:14:56 +1100, James wrote: 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? Nope. I meant hysteresis losses. Eddy currents do contribute to losses by "bucking" the build up and collapse of the magnetic field, but most of the heat is produced by hysteresis losses: https://www.quora.com/What-is-hysteresis-loss-Where-does-the-loss-actually-occur See an induction heater or stove for an extreme case of heat being generated by eddy and hysteresis currents: https://en.wikipedia.org/wiki/Induction_heating Hysteresis losses are different from saturation. Saturation shouldn't occur if the core has been adequately designed to accommodate all the permanent magnet flux & MMF. Most (not all) dynamos are designed to provide some form of self-regulation. This made sense back in the days when the load was just a simple 6v incandescent light bulb. It wouldn't do to have Kamakazi downhill speeders producing enough revolutions to have the dynamo belch 12VAC and burn out the bulb. Fast forward to today, and we no longer use incandescent lights on dynamos. Most (not all) LED lamps have built in regulators and really don't need to have the dynamo perform any additional regulation. However, the industry is conservative, and things change very slowly. Kinda like the automobile industry requiring 25 years to get rid of the buggy whip socket. So, we still have dynamos that intentionally designed to NOT produce a linear increase in output for high RPMs. Fortunately, the problem is not universal. http://www.pilom.com/BicycleElectronics/HubDynamo.htm Notice the 2nd graph of Hub vs Bottle Power. The Shimano DH-3D71 hub dynamo produces a linear increase in output power with no saturation visible. (However, at my cruising speed of 15 km/hr, it only produces 4 watts and is therefore only a slight improvement over the common bottle dynamo). Hystersis loss is core saturation loss. What happens is that at some point, adding additional current to the coil and core does produce an increase in the magnetic field. Magnetic domains will change direction when current is applied, but are not terribly thrilled with the idea. Their resistance to this change in current and direction is hysteresis loss. This additional current (and power) has to go somewhere since it can't be used to build a changing magnetic field. So, it gets converted into heat. Eddy current losses are the result of changes in magnetic field, not changes in applied current. When the magnetic field finally decides to change direction and AFTER hysteresis losses are produced, the resultant magnetic field breaks up into small magnetic loops or eddys. Adjacent eddys fight each other resulting in repulsion. The energy required to overcome this repulsive force are the eddy current losses. As I understand it, the favored core material is some form of mu-metal or permalloy which saturate nicely at low currents: https://en.wikipedia.org/wiki/Mu-metal I'm not sure this is the material as some description suggest that it's "cold rolled dynamo silicon sheet steel" or the same stuff used in the E/I laminations of a common AC power transformer. It's after midnight. I give up for tonite. You seem to be confusing current and magnetic flux. What is used to alter the characteristics is the inductance of the alternator coil. -- JS |
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On 16/03/17 03:45, jbeattie wrote:
On Wednesday, March 15, 2017 at 7:53:52 AM UTC-7, David Scheidt wrote: Sir Ridesalot wrote: :I remember burning out bulbs with my bottle dynamo if I rode really :fast. I also remember the slipping problems when the wheels were wet even :when I used the rubber boot sold to go on the bottle dynamo roller. Hub :dynamos today really seem to fall down at slow speeds. Mine work fine from walking speeds. They produce more light at higher speeds, but at slow speeds you don't need it, because you're not moving fast. I sometimes need light most at slow speeds, when I'm creeping up hills and trying not to fall into giant pot holes. You are an anomaly. At creeping speeds (less than 10km/h), I could see holes with a candle light. -- JS |
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On 3/15/2017 4:45 PM, James wrote:
On 15/03/17 18:07, Jeff Liebermann wrote: On Wed, 15 Mar 2017 16:45:57 +1100, James wrote: On 15/03/17 16:15, Jeff Liebermann wrote: On Wed, 15 Mar 2017 15:14:56 +1100, James wrote: 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? Nope. I meant hysteresis losses. Eddy currents do contribute to losses by "bucking" the build up and collapse of the magnetic field, but most of the heat is produced by hysteresis losses: https://www.quora.com/What-is-hysteresis-loss-Where-does-the-loss-actually-occur See an induction heater or stove for an extreme case of heat being generated by eddy and hysteresis currents: https://en.wikipedia.org/wiki/Induction_heating Hysteresis losses are different from saturation. Saturation shouldn't occur if the core has been adequately designed to accommodate all the permanent magnet flux & MMF. Most (not all) dynamos are designed to provide some form of self-regulation. This made sense back in the days when the load was just a simple 6v incandescent light bulb. It wouldn't do to have Kamakazi downhill speeders producing enough revolutions to have the dynamo belch 12VAC and burn out the bulb. Fast forward to today, and we no longer use incandescent lights on dynamos. Most (not all) LED lamps have built in regulators and really don't need to have the dynamo perform any additional regulation. However, the industry is conservative, and things change very slowly. Kinda like the automobile industry requiring 25 years to get rid of the buggy whip socket. So, we still have dynamos that intentionally designed to NOT produce a linear increase in output for high RPMs. Fortunately, the problem is not universal. http://www.pilom.com/BicycleElectronics/HubDynamo.htm Notice the 2nd graph of Hub vs Bottle Power. The Shimano DH-3D71 hub dynamo produces a linear increase in output power with no saturation visible. (However, at my cruising speed of 15 km/hr, it only produces 4 watts and is therefore only a slight improvement over the common bottle dynamo). Hystersis loss is core saturation loss. What happens is that at some point, adding additional current to the coil and core does produce an increase in the magnetic field. Magnetic domains will change direction when current is applied, but are not terribly thrilled with the idea. Their resistance to this change in current and direction is hysteresis loss. This additional current (and power) has to go somewhere since it can't be used to build a changing magnetic field. So, it gets converted into heat. Eddy current losses are the result of changes in magnetic field, not changes in applied current. When the magnetic field finally decides to change direction and AFTER hysteresis losses are produced, the resultant magnetic field breaks up into small magnetic loops or eddys. Adjacent eddys fight each other resulting in repulsion. The energy required to overcome this repulsive force are the eddy current losses. As I understand it, the favored core material is some form of mu-metal or permalloy which saturate nicely at low currents: https://en.wikipedia.org/wiki/Mu-metal I'm not sure this is the material as some description suggest that it's "cold rolled dynamo silicon sheet steel" or the same stuff used in the E/I laminations of a common AC power transformer. It's after midnight. I give up for tonite. You seem to be confusing current and magnetic flux. What is used to alter the characteristics is the inductance of the alternator coil. That's how I've seen it explained, with appropriate equations. Since AC frequency increases with speed, the inductive reactance due to the coils increases with speed. That fights the tendency for more voltage from higher magnet-to-coil velocity. -- - Frank Krygowski |
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On Wed, 15 Mar 2017 14:08:44 -0400, Frank Krygowski
wrote: On 3/14/2017 11:15 PM, Jeff Liebermann wrote: 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. Thing is, nobody's demonstrated any need for so much stationary "be seen" light, beyond the usual "well, it _could_ happen" safety inflation mentality. We're facing the same mentality regarding our local forest preserve. Some people want to cut down every dead or dying tree within 100 feet of any trail because, well, it _could_ fall on somebody and kill them. Sheesh. I have worked in area where it is probable that no one has ever cut down a tree until we arrived and there never was a problem with dead or diseased trees falling down. One problem with cutting down trees that "could" fall down is that in a hurricane many perfectly healthy trees get blown down. Perhaps the cutting of all trees taller than the average human "could" lives. And, of course, banning the ownership of bicycles "could" save ~900 lives a year. -- Cheers, John B. |
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On 3/15/2017 7:39 PM, John B. wrote:
On Wed, 15 Mar 2017 14:08:44 -0400, Frank Krygowski wrote: On 3/14/2017 11:15 PM, Jeff Liebermann wrote: 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. Thing is, nobody's demonstrated any need for so much stationary "be seen" light, beyond the usual "well, it _could_ happen" safety inflation mentality. We're facing the same mentality regarding our local forest preserve. Some people want to cut down every dead or dying tree within 100 feet of any trail because, well, it _could_ fall on somebody and kill them. Sheesh. I have worked in area where it is probable that no one has ever cut down a tree until we arrived and there never was a problem with dead or diseased trees falling down. One problem with cutting down trees that "could" fall down is that in a hurricane many perfectly healthy trees get blown down. Perhaps the cutting of all trees taller than the average human "could" lives. And, of course, banning the ownership of bicycles "could" save ~900 lives a year. A bicycle ban? How's that 100-year worldwide Heroin ban working? -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
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On Wed, 15 Mar 2017 19:46:28 -0500, AMuzi wrote:
On 3/15/2017 7:39 PM, John B. wrote: On Wed, 15 Mar 2017 14:08:44 -0400, Frank Krygowski wrote: On 3/14/2017 11:15 PM, Jeff Liebermann wrote: 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. Thing is, nobody's demonstrated any need for so much stationary "be seen" light, beyond the usual "well, it _could_ happen" safety inflation mentality. We're facing the same mentality regarding our local forest preserve. Some people want to cut down every dead or dying tree within 100 feet of any trail because, well, it _could_ fall on somebody and kill them. Sheesh. I have worked in area where it is probable that no one has ever cut down a tree until we arrived and there never was a problem with dead or diseased trees falling down. One problem with cutting down trees that "could" fall down is that in a hurricane many perfectly healthy trees get blown down. Perhaps the cutting of all trees taller than the average human "could" lives. And, of course, banning the ownership of bicycles "could" save ~900 lives a year. A bicycle ban? How's that 100-year worldwide Heroin ban working? Works great! Allows a considerable number of common ordinary people to make a "decent" living. True the demand does seems to be decreasing but the widening the demand for amphetamines, which can be made at home rather than waiting for a crop to ripen and getting all bound up with buying futures and warehousing raw materials. As an aside, do you think anyone wants the "war on drugs" to be won? Examples: U.S. Coastguard budget (numbers adjusted to 2013 dollars): 1950 - $1,439,312,446 2013 - $ 7,051,054,000 The total DEA budget is difficult to ascertain but: The total budget of the DEA from 1972 to 2014, according to the agency website, was $50.6 billion. The agency had 11,055 employees in 2014. For the year 2014 the average cost per arrest made was $97,325. An estimate by The Cato Institute, in 2010, states that the legalizing of drugs would save roughly $41.3 billion per year in government expenditure. Or to put it a different way, The War on Drugs is costing the U.S. an estimated $41.3 billion dollars a year. Do you think that anyone wants all that lovely lolly to disappear? -- Cheers, John B. |
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On 3/15/2017 11:05 PM, John B. wrote:
On Wed, 15 Mar 2017 19:46:28 -0500, AMuzi wrote: On 3/15/2017 7:39 PM, John B. wrote: On Wed, 15 Mar 2017 14:08:44 -0400, Frank Krygowski wrote: On 3/14/2017 11:15 PM, Jeff Liebermann wrote: 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. Thing is, nobody's demonstrated any need for so much stationary "be seen" light, beyond the usual "well, it _could_ happen" safety inflation mentality. We're facing the same mentality regarding our local forest preserve. Some people want to cut down every dead or dying tree within 100 feet of any trail because, well, it _could_ fall on somebody and kill them. Sheesh. I have worked in area where it is probable that no one has ever cut down a tree until we arrived and there never was a problem with dead or diseased trees falling down. One problem with cutting down trees that "could" fall down is that in a hurricane many perfectly healthy trees get blown down. Perhaps the cutting of all trees taller than the average human "could" lives. And, of course, banning the ownership of bicycles "could" save ~900 lives a year. A bicycle ban? How's that 100-year worldwide Heroin ban working? Works great! Allows a considerable number of common ordinary people to make a "decent" living. True the demand does seems to be decreasing but the widening the demand for amphetamines, which can be made at home rather than waiting for a crop to ripen and getting all bound up with buying futures and warehousing raw materials. As an aside, do you think anyone wants the "war on drugs" to be won? Examples: U.S. Coastguard budget (numbers adjusted to 2013 dollars): 1950 - $1,439,312,446 2013 - $ 7,051,054,000 The total DEA budget is difficult to ascertain but: The total budget of the DEA from 1972 to 2014, according to the agency website, was $50.6 billion. The agency had 11,055 employees in 2014. For the year 2014 the average cost per arrest made was $97,325. An estimate by The Cato Institute, in 2010, states that the legalizing of drugs would save roughly $41.3 billion per year in government expenditure. Or to put it a different way, The War on Drugs is costing the U.S. an estimated $41.3 billion dollars a year. Do you think that anyone wants all that lovely lolly to disappear? To make a sort of meta-point: People often claim that the discussions here are worthless. In particular, because nobody here ever changes their mind. But it's partly because of information I've gotten here (corroborated elsewhere) that I now believe most drugs should be legalized. I think the U.S. should more or less follow the Portugal strategy, with perhaps some minor modifications. -- - Frank Krygowski |
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On Wednesday, March 15, 2017 at 5:40:55 PM UTC-4, James wrote:
On 16/03/17 03:45, jbeattie wrote: On Wednesday, March 15, 2017 at 7:53:52 AM UTC-7, David Scheidt wrote: Sir Ridesalot wrote: :I remember burning out bulbs with my bottle dynamo if I rode really :fast. I also remember the slipping problems when the wheels were wet even :when I used the rubber boot sold to go on the bottle dynamo roller. Hub :dynamos today really seem to fall down at slow speeds. Mine work fine from walking speeds. They produce more light at higher speeds, but at slow speeds you don't need it, because you're not moving fast. I sometimes need light most at slow speeds, when I'm creeping up hills and trying not to fall into giant pot holes. You are an anomaly. At creeping speeds (less than 10km/h), I could see holes with a candle light. -- JS Must be nice to be blessed with such perfect vision! many of us find that we need a prety bright light in order to see where we're going and the obstacles to avoid at night. that's not to mention that it's nice to be able to see critters on theroads or trails in time to slow or stop to avoid running over them. Personally, I like a supplemental High beam light so that ican see a longer way down an unlit very dark road on a moonless night so I can see the skunks at the side of the road or on the road well BEFORE I startle them. YMMV Cheers |
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