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Post by flippyff on Aug 2, 2015 21:19:21 GMT
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Post by domh245 on Aug 2, 2015 21:46:24 GMT
Interesting, presumably they are referring to the fitting of LED tubes when they refer to more advanced lighting technologies?
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Chris M
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Post by Chris M on Aug 2, 2015 22:13:56 GMT
I suspect that they're open to various solutions people have. I'm sure LED will be one of them, but halogen or other technologies are not being ruled out at this stage.
My impression is that they just don't have the data or understanding they need a the moment to fairly rule anything in or out
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Post by fish7373 on Aug 2, 2015 22:50:45 GMT
Hi picc line is all ready looking in to LED saloon lighting FISH7373
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Post by Deleted on Aug 28, 2015 22:20:48 GMT
LED lighting does actually pay off on trains due to the reduced electrical load. Amtrak has been able to add additional cars to diesel hauled trained on the US West Coast routes by switching to LED lighting. Train length was being limited by available head end power and switching from fluorescent to LED cut the wattage per car enough to add cars. On an electric line, HEP is obviously not an issue but the reduced wattage could still pay off by either reducing system loads or allowing capacity for other equipment like air conditioners.
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Post by spsmiler on Aug 30, 2015 0:30:17 GMT
might need different cctv anywhere where there is LED lights.
I say this because...
1) most types of LED destination blinds in buses, trains and trams seem to be flashing when filmed (unless still image at 1/60 or below)
2) when I filmed the Christmas lights at my local shopping centre they also seemed to be flashing.
Simon
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class411
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Post by class411 on Aug 30, 2015 7:36:18 GMT
might need different cctv anywhere where there is LED lights. I say this because... 1) most types of LED destination blinds in buses, trains and trams seem to be flashing when filmed (unless still image at 1/60 or below) This is because of the way the display is driven by a multiplex signal. It would not apply to static LED arrays used for general illumination purposes. This is odd. Unless the lights were part of a changing display (even if it was static at the time it was being filmed), in which case, again, it might be multiplexed. Generally, unless being driven by a badly designed PWM dimmer, an LED lighting system should produce a steady light. It is by far the best system for general illumination. Good LED's are vastly more reliable than halogen or xenon. Although there are problems with cheap imports that have been built down to a price, and manufacturers giving dishonest 'equivalent' figures, neither of these should apply to a large contract such as TFL would be specifying.
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Post by Deleted on Aug 30, 2015 14:31:43 GMT
One of the major selling points of LEDs is that they have very fast response times. So with traditional styles of light bulb, you basically put a current through a piece of metal, which heats it until it glows. As a result, if you take the current away, it takes a relatively long time for the glowing to fade away. If you then return the current, it takes a relatively long time for the metal to heat back up again and start glowing properly. Whereas LEDs switch off and switch back on again much faster. This makes them ideal for dynamic signage and stuff.
It does, however, have a disadvantage. Unless your LEDs are driven off of a steady, DC supply, the LEDs will respond quite well to the voltage changes and will brighten and dim, and brighten and dim. The human eye cannot detect this in normal operations, but certain camera set ups can.
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Post by norbitonflyer on Aug 30, 2015 15:06:06 GMT
Unless your LEDs are driven off of a steady, DC supply, the LEDs will respond quite well to the voltage changes and will brighten and dim, and brighten and dim. The human eye cannot detect this in normal operations, but certain camera set ups can. Assuming mains frequency of 50Hz, the LEDs are flashing every 1/50th second (i.e they are alternately light for 10 milliseconds, and dark for 10 ms). Persistence of vision - the same thing that allows us to see a movie as continuous motion rather than as a slide show, and an old-style cathode ray TV picture as a picture rather than a moving dot - allows us to see this flashing as a continuous light. However, a camera shutter speed (or the digital equivalent) of anything less than 1/100 second (which is not particularly fast: my not particularly-special Pentax could do 1/1000 sec) would easily coincide with a dark period.
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class411
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Post by class411 on Aug 30, 2015 17:03:52 GMT
One of the major selling points of LEDs is that they have very fast response times. So with traditional styles of light bulb, you basically put a current through a piece of metal, which heats it until it glows. As a result, if you take the current away, it takes a relatively long time for the glowing to fade away. If you then return the current, it takes a relatively long time for the metal to heat back up again and start glowing properly. Whereas LEDs switch off and switch back on again much faster. This makes them ideal for dynamic signage and stuff. It does, however, have a disadvantage. Unless your LEDs are driven off of a steady, DC supply, the LEDs will respond quite well to the voltage changes and will brighten and dim, and brighten and dim. The human eye cannot detect this in normal operations, but certain camera set ups can. Unless your LEDs are driven off of a steady, DC supply, the LEDs will respond quite well to the voltage changes and will brighten and dim, and brighten and dim. The human eye cannot detect this in normal operations, but certain camera set ups can. Assuming mains frequency of 50Hz, the LEDs are flashing every 1/50th second (i.e they are alternately light for 10 milliseconds, and dark for 10 ms). Persistence of vision - the same thing that allows us to see a movie as continuous motion rather than as a slide show, and an old-style cathode ray TV picture as a picture rather than a moving dot - allows us to see this flashing as a continuous light. However, a camera shutter speed (or the digital equivalent) of anything less than 1/100 second (which is not particularly fast: my not particularly-special Pentax could do 1/1000 sec) would easily coincide with a dark period. Whilst both of the above are absolutely correct, it should be pointed out that only a total moron would produce commercial LED lighting system running off AC or unsmoothed DC. Although persistence of vision is quite good at smoothing out flickering lighting when looked at straight on, it does not (for very good evolutionary reasons) do the same thing with peripheral vision. A very high proportion of people would notice something amiss if they were sitting in a carriage illuminated by unsmoothed AC. LU would be plagued with complaints of nausea and headaches if the tried anything so foolhardy. It should also be noted that the cost of smoothing capacitors would be relatively microscopic in relation to the cost of the entire lighting system.
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Post by norbitonflyer on Aug 30, 2015 17:15:36 GMT
Whilst both of the above are absolutely correct, it should be pointed out that only a total moron would produce commercial LED lighting system running off AC or unsmoothed DC.. Quite so. However, scrolling displays often have clock frequencies much slower than the shutter speed/scan rate of modern cameras which can lead to odd results on photographs. (If QI is to believed, pigeons have much less persistence of vision then we do, which is why they have to bob their heads when walking (so that their eyes are stationary relative to the ground for at least part of the time) - and also why you shouldn't take them to the movies. )
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class411
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Post by class411 on Aug 31, 2015 7:57:10 GMT
Whilst both of the above are absolutely correct, it should be pointed out that only a total moron would produce commercial LED lighting system running off AC or unsmoothed DC.. Quite so. However, scrolling displays often have clock frequencies much slower than the shutter speed/scan rate of modern cameras which can lead to odd results on photographs. Indeed. In fact, you can often detect the effect yourself if you rapidly scan such a digital display (it gets more noticeable the larger the display). It's more effective if you just move your eyes.
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stapler
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Post by stapler on Aug 31, 2015 10:27:02 GMT
It took them a while to get the fluorescent lighting right in the 60s, as I remember it - prone to strobing. Many hankered back to the yellow light the incandescent bulbs (in some cases in glass shades) gave out. And replacing incandescent fittings on the New Works line stations in the 80s was an aesthetic disaster.
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Post by superteacher on Sept 12, 2015 10:28:45 GMT
I'm sure I saw a 1992 stock carriage with LED lighting recently.
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Post by rsdworker on Sept 12, 2015 11:04:01 GMT
I'm sure I saw a 1992 stock carriage with LED lighting recently. oh so next time try catch one because i never see Led lights in Uk trains recently = mostly old fashioned lights
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Post by Deleted on Sept 12, 2015 14:07:59 GMT
might need different cctv anywhere where there is LED lights. I say this because... 1) most types of LED destination blinds in buses, trains and trams seem to be flashing when filmed (unless still image at 1/60 or below) 2) when I filmed the Christmas lights at my local shopping centre they also seemed to be flashing. Simon You can see LED signals clearly without any flicker in the S stock cab CCTV so it must depend on the LED's used.
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class411
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Post by class411 on Sept 13, 2015 6:58:21 GMT
might need different cctv anywhere where there is LED lights. I say this because... 1) most types of LED destination blinds in buses, trains and trams seem to be flashing when filmed (unless still image at 1/60 or below) 2) when I filmed the Christmas lights at my local shopping centre they also seemed to be flashing. Simon You can see LED signals clearly without any flicker in the S stock cab CCTV so it must depend on the LED's used. Single LED's used as indicators won't flicker. It's the 'dot matrix' type displays that flicker because they are multiplexed.
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Post by flippyff on May 31, 2016 21:52:56 GMT
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stapler
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Post by stapler on Jun 1, 2016 10:40:55 GMT
The 92TS don't have CCTV, do they?
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Post by Deleted on Jun 1, 2016 10:58:32 GMT
The 92TS don't have CCTV, do they? The Central line's 92s certainly don't at the moment. The Waterloo and City line's do.
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stapler
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Post by stapler on Jun 1, 2016 11:23:57 GMT
They probably should have, in case of any in-train incidents. Would it be expensive to install, given that the 92s are likely to last longer than once anticipated?
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class411
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Post by class411 on Jun 1, 2016 11:25:02 GMT
The 92TS don't have CCTV, do they? The Central line's 92s certainly don't at the moment. The Waterloo and City line's do. Yes, well those bankers would be up to all sorts if someone wasn't keeping an eye on them.
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Post by brigham on Jun 1, 2016 11:43:41 GMT
I have an LED bulb at home, and the light from it is quite pleasant. Can LED lights be made grim enough for use in railway carriages?
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stapler
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Post by stapler on Jun 1, 2016 12:11:56 GMT
Class411, fraid the Bankers travel on the Central Line as well as the W&C. And the W.....s
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class411
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Post by class411 on Jun 1, 2016 13:00:35 GMT
Class411, fraid the Bankers travel on the Central Line as well as the W&C. And the W.....s I was a joke.
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Post by 315 on Jun 1, 2016 18:55:05 GMT
TfL Rail have been upgrading the saloon lighting on the 315'S to LED and have retro fitted grilles to prevent the bulbs from smashing when bags are place on the overhead racks.
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Ben
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Post by Ben on Jun 2, 2016 0:32:38 GMT
The interesting thing about using LED bulbs on the system will be the ability to replace incandescent style bulbs directly, retaining the energy saving aspect of fluorescent and combining with the shape/form of incandescent fittings. So, the earlier comment about fluorescent fittings ruining the aesthetic of Holdens' stations in the 80s, may in the future (with the right will design and will) cease to be an issue.
Indeed, given the tiny size of individual LEDs, form factors need not be limited to any existing idea. For example, in a tunnelled corridor that takes a bend, the lighting could follow the centreline continuously without breaks.
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Post by brigham on Jun 2, 2016 15:58:37 GMT
In corridors, different coloured LEDs could be introduced at intervals, to show which route leads where. Yellow for the Circle, for instance, and blue for Piccadilly. Just like the route lanterns at King's Cross. (Are they still there?)
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stapler
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Post by stapler on Jun 2, 2016 17:19:11 GMT
<<In corridors, different coloured LEDs could be introduced at intervals, to show which route leads where. Yellow for the Circle, for instance, and blue for Piccadilly. Just like the route lanterns at King's Cross. (Are they still there?)>>
These were in several places on LU in the 50s = as I remember it, they never worked!
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Post by Chris W on Jan 24, 2018 13:21:19 GMT
Thread unlocked pending an update from flippyff
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