On the Bench: LED Traffic Signal Light
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Many cities are switching to LEDs for their traffic signals, and is it any wonder? The energy savings are tremendous, never mind not having to change burnt-out bulbs all the time. Luckily for us, LED traffic signals are finally ubiquitous enough to show up at the surplus stores. Our local junk shop had a couple of big barrels of LED stoplights and turn signals of various sizes. We picked one out that still had the connector attached for screwing it into a regular light bulb socket.
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| Of course, after we made sure it worked, we promptly took it apart. It is a fabulous object, designed to be used, abused, taken apart, and maybe even fixed, though there is not much to go wrong. Click through for more gory photos and delightful design details. |
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Of course, the first thing we did was screw it into a lamp to see how bright it was. Since it is only a 14 watt device it can be used in just about any fixture. It is very strange to see a couple of wires coming out of a lamp, but it is even stranger to turn the lamp on and see the light come from elsewhere. So how bright is it? So bright it is hard to look at, and everything seemed extremely green for a long time after we turned it off. Okay, so that's a pretty subjective measurement, but it really is extremely bright. My eyes hurt thinking about it.
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From the back you can see five screws just under the edge of a rubber gasket. The gasket pops off, and the phillips head screws are easily accessible. Interestingly, there are ten holes, and there is also a handy reference arrow to help you determine which way is up.
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With the first set of screws out, the red plastic cover comes off and you can see the sheet of lenses which is fixed over the LEDs. This also has a reference arrow, which was helpful during reassembly. There is another set of screws going through the legs for the lenses to the back cover.
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Once that set is unscrewed, the back cover can be pulled away, and the array of LED leads can be seen. Fascinatingly, the LEDs are not soldered to a circuit board, but are placed in a plastic grid. They are not soldered together, but are instead joined mechanically in series by twisting the leads together. After twisting, the leads are bent over.
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A couple more screws allow removal of a small plastic panel protecting the circuit board from the LED leads.
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Removing the screw holding the circuit board to the back panel is the last step. From there you can see the meat of the board. I love that since this is a Canadian light, the board is printed in French. I also like that they use the same board for both the red and green lights, just changing which resistors are placed for the different LED colors. I really dig the high-power zero-ohm jumpers. We use zerohms all the time; they are the handiest little guys to have around, but the blue ones are much prettier than our little brown ones.
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The LEDs are not quite your standard 5 mm package; they have a slightly different lens than we are used to seeing. The placement in the plastic grid allows them to be precisely located under the sheet of lenses, which has several feet resting on the plastic and a couple of feet protruding through and secured in place on the back.
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Unlike the pedometer we recently took apart, all of the screws were the same, making reassembly easy. Everything went back together smoothly (thanks to those reference arrows) and we once again have a surplus of red light.
One of these would make an excellent party light. Recommended installation: flush against the ceiling with a disco ball suspended beneath. | |
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