LED Lights and Garage Door Opener???
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From: krw on 15 Apr 2010 19:09 On Thu, 15 Apr 2010 11:06:39 -0400, Spehro Pefhany <speffSNIP(a)interlogDOTyou.knowwhat> wrote: >On Thu, 15 Apr 2010 14:12:23 +0200, "PovTruffe" ><PovTache(a)gaga.invalid> wrote: > >>Just one thought: why did not they design traffic lights with RGB LEDs ? >>They should be much cheaper with a single lamp. >>However we are all so used to 3 lamp traffic lights... >> > >For people that can't distinguish colors it's certainly better.. since >they seem to be standardized in most places in North America with red >at the top and green at the bottom. > >Of course some of the outlying settlements, such as Britain and >Quebec, have their own quaint customs: > >http://en.wikipedia.org/wiki/File:Modern_British_LED_Traffic_Light.jpg >http://photos-e.ak.facebook.com/photos-ak-sf2p/v323/26/109/517132740/n517132740_1211892_8628.jpg > >I'm old enough to remember driving in NYC with the two-color lights >(red and green on simultaneously rather than amber), which always >struck me as being more efficient. The ones I liked, also in NY, were standard three-color lights but the yellow lit during the final part of the green cycle, warning that the light was about to change to yellow. It seems they replaced that with a delay after red, before green the opposite direction.
From: krw on 15 Apr 2010 19:11 On Thu, 15 Apr 2010 13:45:29 -0400, "Michael A. Terrell" <mike.terrell(a)earthlink.net> wrote: > >PovTruffe wrote: >> >> Just one thought: why did not they design traffic lights with RGB LEDs ? >> They should be much cheaper with a single lamp. >> However we are all so used to 3 lamp traffic lights... > > > They didn't. The LED lamps are retrofitted. They did the red first, >in my area. Red lights were often higher power and burned out faster. LEDs made more sense, initially, for the red (and were cheaper).
From: JosephKK on 20 Apr 2010 00:19 On Thu, 15 Apr 2010 18:09:51 -0500, "krw(a)att.bizzzzzzzzzzzz" <krw(a)att.bizzzzzzzzzzzz> wrote: >On Thu, 15 Apr 2010 11:06:39 -0400, Spehro Pefhany ><speffSNIP(a)interlogDOTyou.knowwhat> wrote: > >>On Thu, 15 Apr 2010 14:12:23 +0200, "PovTruffe" >><PovTache(a)gaga.invalid> wrote: >> >>>Just one thought: why did not they design traffic lights with RGB LEDs ? >>>They should be much cheaper with a single lamp. >>>However we are all so used to 3 lamp traffic lights... >>> >> >>For people that can't distinguish colors it's certainly better.. since >>they seem to be standardized in most places in North America with red >>at the top and green at the bottom. >> >>Of course some of the outlying settlements, such as Britain and >>Quebec, have their own quaint customs: >> >>http://en.wikipedia.org/wiki/File:Modern_British_LED_Traffic_Light.jpg >>http://photos-e.ak.facebook.com/photos-ak-sf2p/v323/26/109/517132740/n517132740_1211892_8628.jpg >> >>I'm old enough to remember driving in NYC with the two-color lights >>(red and green on simultaneously rather than amber), which always >>struck me as being more efficient. > >The ones I liked, also in NY, were standard three-color lights but the yellow >lit during the final part of the green cycle, warning that the light was about >to change to yellow. It seems they replaced that with a delay after red, >before green the opposite direction. Thanks for this bit of minutia. It explains some of the dumber design decisions i have seen in traffic signal timing. And i think that the yellow overlap is a really good idea. Though not as good as all red intervals.
From: JosephKK on 20 Apr 2010 00:24 On Thu, 15 Apr 2010 10:57:03 -0700, "Joel Koltner" <zapwireDASHgroups(a)yahoo.com> wrote: >"Michael A. Terrell" <mike.terrell(a)earthlink.net> wrote in message >news:4BC750B9.C003B50D(a)earthlink.net... >> They didn't. The LED lamps are retrofitted. They did the red first, >> in my area. > >Hmm... I wonder why red? Spends the most time on? If one color is going to >fail, presumably people will just stop anyway, so why not make it the red one >that'll fail anyway? It was more a technology choice, not only are they on the most they were the easiest, and least expensive to start with, back 20+ years ago. In many places they were financed by giving an investor a piece of the energy savings for years to pay for the modules and installation.
From: JosephKK on 20 Apr 2010 00:29
On Thu, 15 Apr 2010 11:11:17 -0700, Charlie E. <edmondson(a)ieee.org> wrote: >On Thu, 15 Apr 2010 10:57:03 -0700, "Joel Koltner" ><zapwireDASHgroups(a)yahoo.com> wrote: > >>"Michael A. Terrell" <mike.terrell(a)earthlink.net> wrote in message >>news:4BC750B9.C003B50D(a)earthlink.net... >>> They didn't. The LED lamps are retrofitted. They did the red first, >>> in my area. >> >>Hmm... I wonder why red? Spends the most time on? If one color is going to >>fail, presumably people will just stop anyway, so why not make it the red one >>that'll fail anyway? > >First, red LEDs are the cheapest, and easiest to drive, so they were >the first to come out. Also, the red filter means a lot of heat insde >for the old incandescents. > >Next came green. which was a little harder to drive, and didn't last >as long initially. After those problems were solved, they were in >use. > >The yellows came last, mainly because the yellow incandescent is on >with so little duty cycle that they last forever anyway! > >Charlie No. The yellow and green indications were normally replaced together, the issue being maintenance cycle. Very much from the required lane closures and attendant traffic control issues. |