More About Lights
lou.holtman wrote:
On Tuesday, March 7, 2017 at 5:11:29 AM UTC+1, Frank Krygowski wrote: http://peterwhitecycles.com/images/p...lux-II-800.jpg Still too much chroma, but a more realistic looking comparison than the aperiodical illumination of Mr. White's rustic driveway: http://baslerbikes.de/index.php/baslerbikes-2-Scheinwerfervergleich-2013-november.html That is the headlight I use and it looks exactly the same on a pitch dark street. Must be an extra-bright asphalt mix they use in NL - or simply a layer of sand. -- Merkel's new StVZO aiming instructions: crescent just below line H-H http://i.dailymail.co.uk/i/pix/2016/08/08/08/36FC213600000578-0-image-a-2_1470641631742.jpg |
More About Lights
On 07/03/17 04:22, Jeff Liebermann wrote:
On Mon, 6 Mar 2017 17:04:13 +1100, James wrote: On 06/03/17 12:26, Jeff Liebermann wrote: Well, let's do some arithmetic. If your dynamo is rated at 3 watts, and your lighting is rated at 70 lumens/watt, then the most you can perhaps deliver is 210 lumens. 6 watts will get perhaps 420 lumens. Usually, it's less as the losses accumulate. Rectification losses, optical losses, heat degradation, and connector losses all conspire to produce lower output. We know that a 3W dynamo is quite capable of delivering more power than 3W, once the bicycle speed increases. 6W from a 3W dynamo is quite achievable, and the retardation torque drops off as speed increases too. Maybe: http://www.myra-simon.com/bike/dynotest.html See "Electrical Output" graph. Kinda looks like all of them will sorta deliver 2.5 watts before the core saturates (to provide some level of voltage regulation). Further down the page is a "Low Speed Power" graph, which shows that most can produce 2.0-2.5 watts at 10km/hr. One could assume that the dynamo will deliver 4.0 watts, but that would require buying one of the few better (hub) dynamos listed, and riding at 25-30km/hr (15-19mph). If I were designing or sizing a lighting system suitable for my slow style of "cruising", I would use the worst case 10km/hr (6mph) and 2.0 watt figures. Back to electrical engineering school for you, Jeff. -- JS |
More About Lights
On Tue, 07 Mar 2017 10:38:38 -0800, Jeff Liebermann
wrote: On Tue, 07 Mar 2017 20:00:47 +0700, John B. wrote: On Mon, 06 Mar 2017 20:10:21 -0800, Jeff Liebermann wrote: On Mon, 6 Mar 2017 16:57:41 +1100, James wrote: What if I don't want to play with batteries? Then play with calcium carbide (produces acetylene gas) instead: https://www.google.com/search?q=acetylene+bicycle+lamp&tbm=isch Ahem! I don't think you should suggest acetylene gas devices to some of the folks here. After all the safe limit for acetylene gas is 15 psi, above which it tends to go BOOM! :-) I once found a patent for an acetylene lantern design that used the heated gas pressure from the burning acetylene to pressurize a reed and thus act as a horn. I don't recall if it had a built in red tail light. What keeps an acetylene lantern from blowing up and ruining a ride is that the drip of water into the calcium carbide chamber is regulated by the back pressure produced by the reaction. No water means no gas is produced. It's a gravity fed affair, that's quite reliable and should never raise the internal pressure anywhere near 15 psig. Well, yes, that sounds like a very good idea, but.... Over here you can still buy an "acetylene generator" used to provide acetylene gas for a welding torch. These use the same system "no water, no gas" that the lamps do. But unfortunately over years of use they get rusty, dusty, corroded or just clogged up and every once in a while they do explode. Usually with loss of life. (but maybe if you wear a helmet and have a bright light... :-) The light isn't for me. It's for James who wants an alternative to changing batteries. I solved my lighting problem long ago: http://802.11junk.com/jeffl/pics/bicycles/slides/bicycle-flashlight.html :-} I solvd my problems using a much simpler solution... don't ride at night :-{ The big problem with an acetylene bicycle lantern is that a typical lantern only delivers about 30 to 50 lumens (my measurements). If you need a project, build an acetylene lamp that screws into an aluminum water bottle. http://www.4bobandbob.com/pages/pics/PremierDia.gif Don't need a project. But back when I was shooting on A.F. pistol teams we used "carbide lamps" to blacken the sights. Very simple lights with a canister for the carbide and a igniter incorporated in the reflector that you could flick with your thumb. Spit in the carbide receptacle, hold your hand over the reflector for a second or two and flick the igniter. POP (sometimes BANG) and you had a nice "rich" flame to blacken the sights. Quite a bright light too. I've used one to look for things in dark corners and they seem to give off sufficient light. Much better than my old Japanese bike with the bottle generator and the incandescent light bulb anyway. And, of course, you didn't have to pedal them to have lights :-) -- Cheers, John B. |
More About Lights
On 07/03/17 06:15, jbeattie wrote:
On Sunday, March 5, 2017 at 9:57:44 PM UTC-8, James wrote: On 06/03/17 10:22, Barry Beams wrote: Burn time: What if you had five or ten hours battery time at your generator's brightness? My Oculus gives at least that much brightness, and a quickly field replaceable battery so you can put in a fresh battery. Other rechargeables leave you out of light and out of luck when the battery drains. Oculus also comes with a spare battery included. What if I don't want to play with batteries? Then you're done with the battery light discussion and may move on to helmets. Now that you mention it... I don't like putting sun screen on the top of my head because in the heat and humidity I sweat a lot and it tends to run down into my eyes and stings most painfully with sun screen mixed in. So my foam hat has big ventilation holes that let the sun light through to my scalp. If I was allowed to ride without a foam hat I could keep the sun off my scalp with a cloth cap, but that's not an option in this country. If I develop a skin cancer on the top of my head, I shall seek to sue the government, for their law makes adequate sun protection with sufficient ventilation near on impossible. -- JS |
More About Lights
On 07/03/17 11:50, Jeff Liebermann wrote:
On Mon, 6 Mar 2017 20:10:38 +0000 (UTC), David Scheidt wrote: Frank Krygowski wrote: :On Monday, March 6, 2017 at 1:37:23 PM UTC-5, AMuzi wrote: : I don't know about currents but 6V 4W bulbs for standard : dynamo systems have been around for twenty years and some : customers like them. I don't know if the dynamo drag is : noticeably greater. :6V 4W? I'm aware of 6V 3W bulbs, which are (or were) used mostly with bottle :dyno systems when driving a headlamp but no taillamp. They were an alternative :to 2.4 W in front and 0.6W in back. :I'm not aware of any common use of 6V 4W bulbs. It's a standard lantern size. http://www.rayovacindustrial.com/Products/Lights/Bulbs/K13-2TB-Krypton-Bulb-for-4D-Flashlights.aspx Ray-0-Vac K13-2TB. Made for 4D cell lanterns. 6v 3.6 watts. I couldn't find a 4 watt version. Most of what I found were 2.4 and 3.0 watt bulbs for bicycles. A 6V 3W dynamo will easily power a 12V 6W bulb, but at higher speed. In the same way, it has been tried and tested to install two 6V 3W headlights, and a switch that can bypass one light, or connect the two in series. -- JS |
More About Lights
On 3/7/2017 3:42 PM, Sepp Ruf wrote:
lou.holtman wrote: On Tuesday, March 7, 2017 at 5:11:29 AM UTC+1, Frank Krygowski wrote: http://peterwhitecycles.com/images/p...lux-II-800.jpg Still too much chroma, but a more realistic looking comparison than the aperiodical illumination of Mr. White's rustic driveway: http://baslerbikes.de/index.php/baslerbikes-2-Scheinwerfervergleich-2013-november.html That is the headlight I use and it looks exactly the same on a pitch dark street. Must be an extra-bright asphalt mix they use in NL - or simply a layer of sand. I've noticed that the asphalt does lighten in color somewhat as it ages. And I've noticed that dark road surfaces are not as visible in the headlight beam. This is true even with car headlight beams; the dark surface obviously reflects less light back to the operator's eyes. (That's probably covered in the definition of "dark.") This adds to the complexity of producing realistic screen shots of headlight beams. And it's already complex enough, because different camera exposure settings, different focal lengths, different lighting environments, etc. make one website's beam shots look quite different from another. Even if all testers used the same parameters, it might not match what the human eye perceives. If one were to develop an ASTM standard for headlight screen shots, all those and other factors would have to be uniformly controlled. Sounds like a good project for someone's masters' thesis. -- - Frank Krygowski |
More About Lights
On 3/7/2017 7:09 PM, James wrote:
On 07/03/17 06:15, jbeattie wrote: On Sunday, March 5, 2017 at 9:57:44 PM UTC-8, James wrote: On 06/03/17 10:22, Barry Beams wrote: Burn time: What if you had five or ten hours battery time at your generator's brightness? My Oculus gives at least that much brightness, and a quickly field replaceable battery so you can put in a fresh battery. Other rechargeables leave you out of light and out of luck when the battery drains. Oculus also comes with a spare battery included. What if I don't want to play with batteries? Then you're done with the battery light discussion and may move on to helmets. Now that you mention it... I don't like putting sun screen on the top of my head because in the heat and humidity I sweat a lot and it tends to run down into my eyes and stings most painfully with sun screen mixed in. So my foam hat has big ventilation holes that let the sun light through to my scalp. If I was allowed to ride without a foam hat I could keep the sun off my scalp with a cloth cap, but that's not an option in this country. If I develop a skin cancer on the top of my head, I shall seek to sue the government, for their law makes adequate sun protection with sufficient ventilation near on impossible. Now, now, now! This person in Melbourne https://pricetags.files.wordpress.co...bike.jpg?w=560 proves that it's a simple matter to have sun protection, yet to have the foam hat close enough to one's head for it's magic to be effective. ;-) BTW, I've seen the same trick used in America. So I've learned that any bike facility is a good bike facility, and a helmet anywhere near your head will save your life. -- - Frank Krygowski |
More About Lights
On Tuesday, March 7, 2017 at 5:50:32 PM UTC-8, Frank Krygowski wrote:
On 3/7/2017 7:09 PM, James wrote: On 07/03/17 06:15, jbeattie wrote: On Sunday, March 5, 2017 at 9:57:44 PM UTC-8, James wrote: On 06/03/17 10:22, Barry Beams wrote: Burn time: What if you had five or ten hours battery time at your generator's brightness? My Oculus gives at least that much brightness, and a quickly field replaceable battery so you can put in a fresh battery. Other rechargeables leave you out of light and out of luck when the battery drains. Oculus also comes with a spare battery included. What if I don't want to play with batteries? Then you're done with the battery light discussion and may move on to helmets. Now that you mention it... I don't like putting sun screen on the top of my head because in the heat and humidity I sweat a lot and it tends to run down into my eyes and stings most painfully with sun screen mixed in. So my foam hat has big ventilation holes that let the sun light through to my scalp. If I was allowed to ride without a foam hat I could keep the sun off my scalp with a cloth cap, but that's not an option in this country. If I develop a skin cancer on the top of my head, I shall seek to sue the government, for their law makes adequate sun protection with sufficient ventilation near on impossible. Now, now, now! This person in Melbourne https://pricetags.files.wordpress.co...bike.jpg?w=560 proves that it's a simple matter to have sun protection, yet to have the foam hat close enough to one's head for it's magic to be effective. ;-) BTW, I've seen the same trick used in America. So I've learned that any bike facility is a good bike facility, and a helmet anywhere near your head will save your life. http://www.aerotechdesigns.com/cycli...protector.html Reasonable accommodation for the hair-differently-abled. Not recommended for wearing in Kansas, Washington or any other US state where one could be mistaken for a Sikh. -- Jay Beattie. |
More About Lights
On 3/6/2017 2:12 AM, DATAKOLL MARINE RESEARCH wrote:
Assumptions or measured ? I forgot to respond to that question. I've measured dynamo torque vs. speed. As James says, the resistance torque of a dyno decreases as speed increases. It doesn't decrease as much as speed increases, however, so the power required still increases with speed. Example: Soubitez roller dynamo Speed (mph) 6 12 18 24 Torque (N*mm) 26.4 22.6 18.1 14.3 with 12 Ohm load Torque (N*mm) 22.6 23.4 19.6 15.1 with 24 Ohm load I found similar behavior with other dynamos. With an open circuit, drive torque did increase with road speed. -- - Frank Krygowski |
All times are GMT +1. The time now is 12:50 PM. |
Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
CycleBanter.com