LED Lights and Garage Door Opener???
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From: Charlie E. on 15 Apr 2010 14:11 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
From: Martin Brown on 15 Apr 2010 14:13 Joel Koltner 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? Unfortunately not. The opposite is usually the case. People tend to plough into each other at junctions when the red light has failed. I expect red (and yellow for roadworerks please don't hit me signs) were the first to adopt because high intensity pure colour LEDs in those colours were available first at a decent price. It is only comparatively recently that true green high intensity LEDs that would pass muster for a green traffic light have become available at an affordable price. Regards, Martin Brown
From: Joel Koltner on 15 Apr 2010 16:29 Ah, thnks -- there's clearly a bit more to this that I thought.
From: Michael A. Terrell on 15 Apr 2010 18:09 Joel Koltner 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? My guess was that they were replacing more red lamps, and started the conversion to LED as they failed. -- Lead free solder is Belgium's version of 'Hold my beer and watch this!'
From: krw on 15 Apr 2010 19:06
On Thu, 15 Apr 2010 12:17:35 +0100, Martin Brown <|||newspam|||@nezumi.demon.co.uk> wrote: >Hammy wrote: >> On Thu, 15 Apr 2010 06:28:47 +0000 (UTC), don(a)manx.misty.com (Don >> Klipstein) wrote: >> >>> My experience with LED traffic signals in Philadelphia and suburbs >>> thereof is that the LED ones are showing their superiority. >>> >>> Please keep in mind that Philadelphia gets more extreme high temperatures >>> than much of Florida. I have already lived through merely a July 1995 day >>> in Philadelphia fair-chance getting hotter than Miami was ever officially >>> noted to have achieved, some chance tying Miami's record high temperature >>> in combination with dew point that is high even for Miami! >>> >>> (PHL airport or closest-to-there official weather station determined >>> that at 4 PM "local time" July 15th the temperature was 102 F [peaking >>> that day at a slightly different time at 103 F.]) >>> >>> (I have a tale or 2 to tell about atmosphere temperature at 102 F, and >>> some cause to discount much-hotter)... >>> >>> - Don Klipstein (don(a)misty.com) >> >> Municipalities in northern climates that converted to LED traffic >> lights are having to send work crews out to de-ice them. The LED's >> don't radiate enough heat to de-ice themselves. > >This seems unlikely. LED traffic lights are efficient but to that extent >there is still enough waste heat at least in the UK up to latitude 55N. >It must take exceptional conditions for snow to accumulate on them. It's not unusual at all. When I lived in Vermont it wasn't unusual at all to see snow stuck to the LED traffic lights. It wasn't often bad enough to totally obscure the lights, but it could easily become so. >In the US there is already a fairly simple piece of bent metal solution >for wind blown snow clogging up the sun visor cowling. > >http://www.ledsmagazine.com/news/7/1/4 That may work with dry snow. It's not going to do anything with a driving wet snow. |