Fail Of The Week: The Case Of The Curiously Colored Streetlights

October 9, 2024 by Dan Maloney 115 Comments

What color are the street lights in your town? While an unfortunate few still suffer under one of the awful colors offered by vapor discharge lamps, like the pink or orange of sodium or the greenish-white of mercury, most municipalities have moved to energy-saving LED streetlights, with a bright white light that’s generally superior in every way. Unless, of course, things go wrong and the lights start to mysteriously change colors.

If you’ve noticed this trend in your area, relax; [NanoPalomaki] has an in-depth and surprisingly interesting analysis of why LED streetlights are changing colors. After examining a few streetlights removed from service thanks to changing from white to purple, he discovered a simple explanation. White LEDs aren’t emitting white light directly; rather, the white light comes from phosphors coating the underlying LED, which emits a deep blue light. The defunct units all showed signs of phosphor degradation. In some cases, the phosphors seemed discolored, as if they experienced overheating or chemical changes. In other LEDs the phosphor layer was physically separated from the backing, exposing the underlying LEDs completely. The color of these damaged modules was significantly shifted toward the blue end of the spectrum, which was obviously why they were removed from service.

Now, a discolored LED here and there does not exactly constitute a streetlight emergency, but it’s happening to enough cities that people are starting to take notice. The obvious solution would be for municipalities to replace the dodgy units Even in the unlikely event that a city would get some compensation from the manufacturer, this seems like an expensive proposition. Luckily, [NanoPalomaki] tested a solution: he mixed a wideband phosphor into a UV-curable resin and painted it onto the lens of each defective LED in the fixture. Two coats seemed to do the trick.

We have to admit that we have a hard time visualizing a city employee painstakingly painting LEDs when swapping out a fixture would take an electrician a few minutes, but at least it’s an option. And, it’s something for hobbyists and homeowners faced with the problem of wonky white LEDs to keep in mind too.

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Hackaday Links: November 29, 2015

November 29, 2015 by Brian Benchoff 32 Comments

The Raspberry Pi Zero was announced this week, so you know what that means: someone is going to destroy a Game Boy Micro. If you’re interested in putting the Zero in a tiny handheld of your own design, here are the dimensions, courtesy of [Bert].

[Ahmed] – the kid with the clock – and his family are suing his school district and city for $15 Million. The family is also seeking written apologies from the city’s mayor and police chief.

There are a lot — a lot — of ‘intro to FPGA’ boards out there, and the huge variety is an example of how the ‘educational FPGA’ is a hard nut to crack. Here’s the latest one from a Kickstarter. It uses an ICE40, so an open source toolchain is available, and at only $50, it’s cheap enough to start digging around with LUTs and gates.

Over on Hackaday.io, [Joseph] is building a YAG laser. This laser will require a parabolic mirror with the YAG rod at the focus. There’s an interesting way to make one of these: cut out some acrylic and beat a copper pipe against a form. A little polish and nickel plating and you have a custom mirror for a laser.

You know those machines with wooden gears, tracks, and dozens of ball bearings? Cool, huh? Tiny magnetic balls exist, and the obvious extension to this line of thought is amazing.

[David Windestål] is awesome. Completely and totally awesome. Usually, he’s behind the controls of an RC plane or tricopter, but this time he’s behind a slo-mo camera, an RC heli, and a watermelon. That’s a 550-sized heli with carbon fiber blades spinning at 2500 RPM, shot at 1000 FPS.

How do you label your cables? Apparently, you can use a label printer with heat shrink tubing. Nothing else, even: just put heat shrink through a label maker.

How To Build Your Own Pulsed Laser Pistol

July 10, 2011 by Mike Nathan 50 Comments

build_your_own_pulsed_laser_gun

Self-declared Mad Scientist and Instructables user [Trevor Nestor] recently built a pulse laser pistol and decided to share his build process, so that you too can build a ray gun at home. The gun is made up of mostly scavenged components, save for the Neodymium:YAG laser head, which he purchased on eBay for about $100. He does say however, that you can score an SSY-1 laser from an old rangefinder, providing you hang out near a stockpile of decommissioned Abrams tanks.

[Trevor] walks you through the process of recycling old disposable cameras to get enough components for a capacitor bank, as well as how the charging circuit should be constructed. He also discusses how the laser head needs to be wired, before showing off the finished laser pistol in a cheeky video, embedded below.

While the gun lacks the finish of this laser pistol we showed you, it’s no less potent when shooting through plastics, wood, and thin metals. It’s a great starting point if you are looking to build a laser of your own, leaving room for improvements, such as a faster charging circuit.

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