Any of you familiar with LED traffic signal design? The "bulbs" are powered from 120VAC so they must have some sort of DC power supply built into the package. Any idea of how much variation in AC input voltage can be tolerated?
80Vac to 135 Vac input, 50/60HZ, 20 watts, PFC. All done with one stage. cheers, Harry
Whatever they use it seems to sometimes take a noticeable number of milliseconds to light the LEDs. I'd guess several hundred milliseconds in some cases.
What's this phrase, "snow" ?:-)
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
powered
Not your answer, but I have noticed that the LED traffic lights around here sometimes get covered in snow and stay that way - the old-fashioned ones must be warm enough to melt snow...
Or, perhaps more critically, things like HID headlamps. The plastic fronts on most headlights these days don't get as warm so they don't tend to create as much of that dry crust that you get from driving with lights on in the right conditions (the same conditions that can cause you to go through a container of washer fluid in a single trip)**, so they are actually better in those conditions, but I'd imagine they might be worse where ice was building up.
** Typically, when the road is wet, in the winter after sand/salt has been distributed, and in heavy, but fast traffic conditions on a big expressway. The dirty water on the road is flung up into the air by all those tires front, back and across 16 lanes of high-speed road, and it comes down all over your windshield and dries there. It only occurs a few days in a given year IME.Of course if you have a Volvo or MB, you just turn on the little headlamp wipers/washers. ;-)
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
lights.
I drove a car in a sort of snow/rain/freezing rain mix once; the stuff would stick to the front glass of the light, melt and slide to the outside edge, where it would freeze again. After about 4 hours there was a vertical sheet of ice the height of the lens and about 5 inches wide attached to the outside edge. The lights were in a pop-up module so the airflow and room available helped this to happen, I'm sure.
Look outside. Oh, wait. Nevermind! ;-)
-- Keith
Cool! One more situation to add to the Unexpected Consequences list.
Replace incandescents with LEDs => conserve power and decrease maint. Snow comes along. OOPS! OK, add a heater. => Conserve less power than expected .... and decrease maint.
I wonder how much of a problem snow and slush are to LED automotive tail lights.
I think they are all making up stories about this mythical "snow." I just went outside to get the newspaper and it's about 65 degrees F (pre-dawn) here in Los Angeles outside, and the high today will be around 85. Snow is a myth.
Earthquakes, mudslides and wildfires; *those* are real!
It's now 2:45PM and I'm looking out at a foot or so of 14F and blowing myth (mythed yesterday, cold and blowing myth today).
I remember an earthquake. A 6.0 IIRC on the other side of the lake. Woke me up, but that and a few roads at the epicenter were about the extent of the damage.
A mudslide is vodka, Kaluha, and Bailey's, no?
-- Keith
Sorry, but I've seen it snow about 30 miles north of Orlando, Florida. On the other hand, go to Alaska in the wintertime and you'll see it for months.
-- ? Michael A. Terrell Central Florida
Not to mention 3 times our yearly allocation of *RAIN*
Bob
My whole hillside is populated with yellow flowers.
Makes for a bad fire season, particularly in California.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona Voice:(480)460-2350 | |
| E-mail Address at Website Fax:(480)460-2142 | Brass Rat |
| http://www.analog-innovations.com | 1962 |
I love to cook with wine. Sometimes I even put it in the food.
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