#161
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More About Lights
On 3/15/2017 11:12 PM, Frank Krygowski wrote:
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. No one analyzed this subject better than the genius Ludwig von Mises: “Opium and morphine are certainly dangerous, habit-forming drugs. But once the principle is admitted that it is the duty of government to protect the individual against his own foolishness, no serious objections can be advanced against further encroachments... Why limit the government’s benevolent providence to the protection of the individual’s body only?” Mises asks. “Is not the harm a man can inflict on his mind and soul even more disastrous than any bodily evils? Why not prevent him from reading bad books and seeing bad plays, from looking at bad paintings and statues and from hearing bad music?” and further: “He who wants to reform his countrymen must take recourse to persuasion. This alone is the democratic way of bringing about changes. If a man fails in his endeavors to convince other people of the soundness of his ideas,” Mises concludes, “he should blame his own disabilities. He should not ask for a law, that is, for compulsion and coercion by the police.” Which of course brings us right down to 2017. -- Andrew Muzi www.yellowjersey.org/ Open every day since 1 April, 1971 |
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#162
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More About Lights
On 2017-03-14 19:43, 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. The lowest resistance I measured is on my largest bottle dynamo, 6.2 ohms. That added to the cores also becoming hot and not being able to sink away much heat sets it up for a burn-out. 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. Not any speed but the usual cruise speed of a rider in decent shape. Also assuming MPPT because it really won't be possible without that. At least a poor man's MPPT where the input voltage is set to a fixed higher level such as 12V. ... That would be 10 watts for 168 minutes. Assuming 10 watts output is a comfortable ride for you, I think I can muster a little more than 10W :-) 10W wouldn't even show up in the noise for a regular rider. ... 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. 10W should be fine considering that the dynamo will then also be cooled by air streaming past. On hot days I have to ratchet down the front light anyhow when riding at low speed because else the overtemp shut-off comes on. Then the net energy draw of the power bus becomes lower and the charge controller reduced the dynamo draw to 4-5W. 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. There is no need for 27.5W but there is for 8-10W. That should be reasonably possible, else the dynamo would have smoked out during their testing. 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. That would be a show stopper in most applications. Got to have high-side current sensing. From a dynamo it's still feasible after things have been turned to DC because the hub versions usually have two ground-free terminals. Bottle dynamos unfortunately not. However, when doing MPPT there already is a micro controller which can then also perform the job of energy metering. I would not need that though, maybe just an indicator of whether the dynamo is able to feed enough for a given light setting. Even that is expendable if you have a voltmeter riding along with the Li-Ion battery. In my case I'd just have to make sure it won't get close to 7V where the electronics will eventually shut things off. 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. Nothing beats trying it on the bench, using a variable speed drill or similar. I haven't observed a sharp knee effect on any of them so far. Which probably explains the large number of bulbs I blew out in the 80's when I had to get somewhere fast. -- Regards, Joerg http://www.analogconsultants.com/ |
#163
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More About Lights
On 2017-03-15 12:39, Doug Landau wrote:
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. 1500mi? Is that really all you get out of a rear tire? I routinely got 2500mi out of Gatorskins. The CST Conquistare I put on there now doesn't look like it'll give me that many miles though. -- Regards, Joerg http://www.analogconsultants.com/ |
#164
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More About Lights
On Thursday, March 16, 2017 at 12:12:58 PM UTC-7, Joerg wrote:
On 2017-03-15 12:39, Doug Landau wrote: 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. 1500mi? Is that really all you get out of a rear tire? I routinely got 2500mi out of Gatorskins. The CST Conquistare I put on there now doesn't look like it'll give me that many miles though. I used to get 2K when I weighed 50 Lbs less I routinely get 2500-3K from a Gatorskin. I count em as 2 when figuring the mileage on my bike I -think- I've been getting slightly over 1500 from the basic conti - the 2000 or ultrasport or whatever its called these days I -think- I get slightly under 1500 from SRAM 9 speed chains. I used to get 2K from those, too, when they were Sachs 8speed. Now it seems like 1200-1400 |
#165
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More About Lights
On 2017-03-16 13:00, Doug Landau wrote:
On Thursday, March 16, 2017 at 12:12:58 PM UTC-7, Joerg wrote: On 2017-03-15 12:39, Doug Landau wrote: 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. 1500mi? Is that really all you get out of a rear tire? I routinely got 2500mi out of Gatorskins. The CST Conquistare I put on there now doesn't look like it'll give me that many miles though. I used to get 2K when I weighed 50 Lbs less I routinely get 2500-3K from a Gatorskin. I count em as 2 when figuring the mileage on my bike I -think- I've been getting slightly over 1500 from the basic conti - the 2000 or ultrasport or whatever its called these days I -think- I get slightly under 1500 from SRAM 9 speed chains. I used to get 2K from those, too, when they were Sachs 8speed. Now it seems like 1200-1400 I've got a Sachs-Sedis 7-speed chain on my trusty old road bike. A friend had one left over and it still had the old $6 price tag on it. It is almost unbelievable, that chain is now on there for more than 4000mi and it's only at 0.5% stretch. It does not want to die. I am very picky WRT chain maintenance though. Clean and lube latest every 250mi, and every 50mi on the MTB. It'll survive the cassette which is technically close to EOL and I installed it at about the same time. Although since I dremeled away the excess on the odd splines I can flip all the sprockets around and get another round out of them. Which I'll probably do since slightly more recalcitrant shifting won't bother me, having grown up in the UG days. -- Regards, Joerg http://www.analogconsultants.com/ |
#166
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More About Lights
On 16/03/17 16:44, Sir Ridesalot wrote:
On Wednesday, March 15, 2017 at 5:40:55 PM UTC-4, James wrote: At creeping speeds (less than 10km/h), I could see holes with a candle light. 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 If you need a high beam light to see enough not to bump in to things at night while you are moving at less than 10km/h ( 6 miles/h), you have really poor eyesight. Do you walk with a white cane? -- JS |
#167
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More About Lights
On Thursday, March 16, 2017 at 2:13:53 PM UTC-7, James wrote:
If you need a high beam light to see enough not to bump in to things at night while you are moving at less than 10km/h ( 6 miles/h), you have really poor eyesight. Do you walk with a white cane? This is close to the mark. But even Frank has to admit that this subject has been beaten to death since this is the 170th posting on this string. |
#168
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More About Lights
On Thu, 16 Mar 2017 10:20:43 -0700, Joerg
wrote: There is no need for 27.5W but there is for 8-10W. That should be reasonably possible, else the dynamo would have smoked out during their testing. If all you're powering are head and tail lights, 10 watts should be sufficient. However, if you're powering other devices (GPS, smartphone, rear view camera, electric shifter, fog horn, etc), then more power is better. 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. That would be a show stopper in most applications. Got to have high-side current sensing. Impediment, not show stopper. What most users have done after turning the + wire into an impromptu fuse, is to install a small isolated DC to DC inverter. The problem is that the current measuring part of the circuit needs to have some source of power to run the devices used. If one part of that power source happens to be grounded to either the + or - input of the voltage measuring part, it won't work. So, the vendor recommends either floating the input or output grounds, using independent volt and amp meters, or using an isolated power supply to power the conglomerated meter. I know that one can get such DC to DC inverters quite cheaply, but I haven't bothered to search for them. I'll post something if I find one as I think it might be useful for your battery pack and dynamo. From a dynamo it's still feasible after things have been turned to DC because the hub versions usually have two ground-free terminals. Bottle dynamos unfortunately not. However, when doing MPPT there already is a micro controller which can then also perform the job of energy metering. Yep. I've setup some cheap MPPT solar charge controllers (from eBay). The better one's have extensive monitoring capabilities, usually on an LCD or OLED display. If you're counting and budgeting coulombs, it's a good way to do it. I would not need that though, maybe just an indicator of whether the dynamo is able to feed enough for a given light setting. Easy enough. The power output of the dynamo is directly proportional to the RPM and unaffected by the load. The load might change radically, but the dynamo will only deliver XX watts at XX RPM. You could just measure the RPM, build a lookup table in some kind of NVRAM, and display the output power. Or, you could get fancy, measure the load voltage and current, and calculate the power needed to run the lights or whatever. Then compare the input power available, with the average output power needed. If there's not enough input power available, you need to shed some load, or pedal harder. Even that is expendable if you have a voltmeter riding along with the Li-Ion battery. In my case I'd just have to make sure it won't get close to 7V where the electronics will eventually shut things off. If you do go over, you might want to shed the load slowly or you might lurch forward as pedaling suddenly becomes easier. Nothing beats trying it on the bench, using a variable speed drill or similar. I haven't observed a sharp knee effect on any of them so far. Which probably explains the large number of bulbs I blew out in the 80's when I had to get somewhere fast. Yeah, I should do that. However, as I previously mumbled, I'm overloaded, busy, lazy, and uninspired right now. -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#169
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More About Lights
On Thursday, March 16, 2017 at 3:08:00 PM UTC-7, Jeff Liebermann wrote:
On Thu, 16 Mar 2017 10:20:43 -0700, Joerg wrote: There is no need for 27.5W but there is for 8-10W. That should be reasonably possible, else the dynamo would have smoked out during their testing. If all you're powering are head and tail lights, 10 watts should be sufficient. However, if you're powering other devices (GPS, smartphone, rear view camera, electric shifter, fog horn, etc), then more power is better. How about if you just wanna go uphill at 20mph? How many watts are required? https://www.google.com/search?q=fat+...zJ244tlGbRmAM: |
#170
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More About Lights
On Thursday, March 16, 2017 at 2:13:53 PM UTC-7, James wrote:
On 16/03/17 16:44, Sir Ridesalot wrote: On Wednesday, March 15, 2017 at 5:40:55 PM UTC-4, James wrote: At creeping speeds (less than 10km/h), I could see holes with a candle light. 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 If you need a high beam light to see enough not to bump in to things at night while you are moving at less than 10km/h ( 6 miles/h), you have really poor eyesight. Do you walk with a white cane? What do you mean by a high beam light? Personally, I need more than a candle to see holes in wet pavement, blow-down and gravel even when creeping along at less than 10km. YMMV. -- Jay Beattie. |
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