Resurrecting Dead LED Lightbulbs

If you’ve gone down the lighting isle of a store recently, you’ve no doubt noticed we are firmly in the age of the LED light bulb. Incandescent bulbs are kept in small stock for those who still have the odd-ball use case, there’s usually a handful of CFL bulbs for those who don’t mind filling their house with explosive vials of hot mercury, but mostly its all LED now. Which is as it should be: LED lighting is clearly the superior choice in terms of energy efficiency, lifetime, and environmental impact.

Unfortunately, a lot of the LED bulbs you’ll see on the rack are of pretty poor quality. In an effort to drive cost down corners get cut, and bulbs which should run for decades end up blowing after a couple of months. After yet another one failed on him, [Kerry Wong] decided to do a teardown to examine the failure in detail.

The failed LED driver.

He notes that most of the LEDs seem to fail in the same way, flickering after they are switched on until they just stop lighting up entirely. This hints at an overheating issue, and [Kerry] opines that aesthetic and cost considerations have pushed heat dissipation to the back burner in terms of design. It also doesn’t help that many of these bulbs are sitting in insulated recessed fixtures in the ceiling, making it even harder to keep them cool.

Once he separates the actual LEDs from the driver circuitry, he is able to determine that the emitters themselves still work fine. Rather than toss the whole thing in the trash, it’s possible to reuse the LEDs with a new power source, which is quickly demonstrated by showing off a shop light he built from “dead” LED light bulbs.

[Kerry Wong] isn’t the only one to put his LED bulbs under the knife. We’ve covered a number of teardowns which explore the cutting edge of home lighting; for better or for worse.

Continue reading “Resurrecting Dead LED Lightbulbs”

Building your own LED-based home lighting

We see LEDs used in all kinds of projects but rarely does someone build a home lighting system from scratch with them. [Paulo Oliveira] decided to give the idea a try, included a fading power supply for the LEDs which he built himself. Here you can see the installation at full brightness, but his controller also offers a single lower setting.

We saw [Sprite_TM] use an RGB LED strip to light up his living room. [Paulo] went with individual LED modules instead, all the same color. They are Cree XM-L power LEDs so some thought needs to be put into heat dissipation. All six are mounted along an aluminum strip which serves as the heat sink. They’re wired in series and powered by an old laptop power supply. A PIC 12F683 uses PWM to dim the string via a MOSFET.

The control system for the two brightness levels uses the wall switch. When turned on, the LEDs fade in to full brightness. If you turn the switch off and back on before they are all the way on, the dimmed setting takes over. This was complicated by the capacitance of the PSU but [Paulo] solved that by adding a power resistor.

He blinded me with backup lights

When driving at night you need to be able to see where you’re going. And that goes for reversing up as well. But the stock white lights on [Ryan’s] ride didn’t provide the type of illumination he wanted, so he replaced them with two sets of super bright LED modules. These are ridiculously bright, perhaps outshining some types of headlights. And since they bring a lot of heat there’s a fair amount of work that went into mounting them.

He sourced some Cree XM-L T6 LED modules, two for each side of the car. These can put out intensity approaching 1000 Lumens each. To keep them cool he grabbed one CPU heat sink for each. These include a copper core with aluminum fins coming off like a spiral starburst. To act as a bezel he used a piece of copper clad board. This gives him a surface to mount the heat sinks, and after coating it with chrome brite it also acts as a reflector. Once mounted he fires it up and the difference is remarkable.

Arduino aquarium lights

[Kalle Hyvönen] just finished building his own aquarium lights. He used four powerful soft-white LEDs, mounting them on a pair of heat sinks to keep things cool. Now he could have just connected them to the power supply and plugged it into the wall, but instead he included is own controller. An Arduino drives the switch-mode power supply, offering dimming thanks to PWM, and the ability to automatically switch the light on and off using an RTC chip with a battery backup. The sketch includes the ability to alter the lighting schedule and other variables by sending serial commands through a USB connection. This protocol is detailed with comments in his sketch.

We’ve seen a lot of interesting aquarium light projects. This one that uses heat from the LEDs to warm the water is one of our favorites. Others are full of features like this version that includes a moonlight mode. But Arduino enthusiasts don’t have to look far to find offerings like this PAR meter build, or this aquarium light controller library which can be recreated using the ubiquitous controller board.

Lamp upgrade makes you a hot-head

[Cameron] decided to give his twenty-year-old headlamp a makeover. He uses it when he’s out for a run and wanted to have more light to see where he’s going, as well as a red tail light on the back. The stock design uses an incandescent bulb on the front of the head band, and a battery pack on the back. He managed to convert the device to output 700 lumens without major changes to the form factor of the unit.

The first change he decided on is to use a Cree XLamp which provides the 700 lumens of light by drawing about 9.5 Watts of power. Obviously the original battery pack isn’t going to do well under that kind of load, so he also sourced a 5000 mAh Lithium battery. A bit of circuit design and PCB layout gives him two driver chips for the four-element LED module, a charging circuit for the battery, and an ATtiny13 to drive the head lamp and flash the red LED tail light. See the blinky goodness in the video after the break.

That’s a lot of light, but we wonder if he experiences a warm forehead from the heat sink used to keep that LED package cool? Continue reading “Lamp upgrade makes you a hot-head”

Building a 1300 lumen bike light

[Brainiac27] isn’t going to let the absence of sun prevent him from biking. He has no trouble lighting his path with this 1300 Lumen bike light he built.

The light source is a 3-up star by Cree. It puts off a lot of light, but also generates quite a bit of heat which is the reason for that large heat sink. It is meant to be used with a CPU but works well for this purpose thanks to the adhesive thermal paste used to unite the two parts.

The mounting bracket is a custom job, bent from 1″ by 1/8″ aluminum bar. [Brainiac27] had some issues with length the first time he tried making it. For his second attempt he started with an overly long piece, made the bends from the center out, and only made cuts once the bends were all completed. The bracket makes it easy to mount to his bike, with the battery stored in a bike bottle and a remote switch (with attaches to the jack you can see on the project box above) hidden underneath one of the brake hoods.

The intensity of this light nearly doubles one of our other favorites.

ATtiny Hacks: DIY high-speed photography LED lighting rig

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[Tom] wanted to try his hand at high-speed photography and needed some equipment to get things rolling. Not wanting to spend a ton of money on a lighting rig or trigger mechanism, he decided to build his own. In a three part series on his blog, he details the construction and testing of his high-speed setup along with the improvements and lessons learned along the way.

His adventures started out with a small off-brand Cree LED clone and an ATiny15L that was collecting dust in his workshop. He built a simple circuit that would trigger the LED to light his subject, which in [Tom’s] case was a bowl of milk. Rather than using a motion or sound trigger, he opted to mount a small piezo to the bottom bowl, firing the LED any time a droplet hits the bowl’s surface.

The pictures he took were decent, but he knew he could get better results. He purchased a new, more powerful Cree LED, and wrote a small terminal program that allows him to tweak his flash parameters using his laptop. The results he gets now are far better – in fact, he has a whole gallery of pictures you can check out.

If you want to delve into high-speed photography as well, all of the schematics and code can be found on his blog.