Salvaging Working LEDs From “Dead” Light Bulbs

Sure the box said they would last for years or even decades, but anyone who’s picked up some bargain LED bulbs knows the reality is a bit more complicated. Sometimes a few LEDs in the array pop, reducing the overall light output. More commonly, the power supply starts to fail and the bulb begins to flicker or hum. In either event, you end up pulling the bulb and replacing it.

But [Bifferos] thinks we can do a bit better than that. Rather than just chalking it up to poor QA and tossing the bulb, why not do a little exploratory surgery to identify salvageable LEDs in an otherwise “dead” bulb? After pulling apart a couple of burned out bulbs (name brand and otherwise), he was able to pull out an impressive number of handy LED panels that could be easily repurposed. Naturally, with a little more coaxing, the individual SMD LEDs could be liberated and pushed into service as well.

Separate PCBs with banks of LEDs are ideal for reuse.

As you might expect, there are far too many different LED bulbs out there to create a comprehensive teardown guide, but [Bifferos] does provide some tricks to help get the bulb open without hurting yourself or destroying the thing in the process. Once inside, the design of the bulb will dictate what happens next. Bulbs with multiple arrays of LEDs on their own PCBs can be easily broken down, but if there’s just the single board, you may want to pull the LEDs off individually. To that end, the write-up demonstrates efficient methods of stripping the LEDs using either hot air or a pair of soldering irons.

We’ve talked previously about the rather underwhelming performance of modern LED bulbs compared to the manufacturer’s lofty claims. We’d rather see these bulbs designed well enough that they actually live up to their full potential, but the ability to salvage useful components from the failed luminaries at least softens the blow of having to toss them early. Though that’s not the only reason you should disassemble your LED bulbs before you put them in the trash.

Small sensor built into audio jack, held in tweezers

Measuring LED Flicker, With Phototransistor And Audio App

No one likes a flickering light source, but lighting is often dependent on the quality of a building’s main AC power. Light intensity has a close relation to the supply voltage, but bulb type plays a role as well. Incandescent and fluorescent bulbs do not instantly cease emitting the instant power is removed, allowing their output to “coast” somewhat to mask power supply inconsistencies, but LED bulbs can be a different story. LED light output has very little inertia to it, and the quality of both the main AC supply and the bulb’s AC rectifier and filtering will play a big role in the stability of an LED bulb’s output.

Mobile phone spectrum analyzer pointed at light source
The DIY photosensor takes the place of the microphone input.

[Tweepy] wanted to measure and quantify this effect, and found a way to do so with an NPN phototransistor, a resistor, and a 3.5 mm audio plug. The phototransistor and resistor take the place of a microphone plugged into the audio jack of an Android mobile phone, which is running an audio oscilloscope and spectrum analyzer app. The app is meant to work with an audio signal, but it works just as well with [Tweepy]’s DIY photosensor.

Results are simple to interpret; the smoother and fewer the peaks, the better. [Tweepy] did some testing with different lighting solutions and found that the best performer was, perhaps unsurprisingly, a lighting panel intended for photography. The worst performer was an ultra-cheap LED bulb. Not bad for a simple DIY sensor and an existing mobile phone app intended for audio.

Want a closer look at what goes into different LED bulbs and how they tick? We have you covered. Not all LED bulbs are the same, either. Some are stripped to the bone and others are stuffed with unexpected goodness.

Light Bulb Plant Propagation Station Is A Bright Idea

We’ve always enjoyed having a few indoor plants around the Hackaday dungeon because they just make the days more cheerful. Apparently there’s a big craze for them right now, which has led to price increases of things like propagation stations — places where cuttings from mature plants go to grow a root system before getting planted in dirt. Many plants will root readily in water, and it’s better for them to start out this way because soil can come with a bunch of problems.

This goes really well with the older craze of Edison-style light bulbs. We’re glad we never bothered with those because [JGJMatt] says they don’t last long at all. The bulbs themselves are really nice looking, so [JGJMatt] decided to turn a few of them into hanging water propagation stations. After cleaning out the bulb and embiggening the opening, [JGJMatt] formed a holder by applying a torch to brass rod. This dulls the brass, so they shined it up with steel wool and some automotive polishing compound. Then it’s time for some simple macrame to hang it with, because it will soon be full of water.

Does the handle sound familiar? It ought to — [JGJMatt]’s elegant builds have graced these pages a few times before.

Retrotechtacular: The Secret Life Of The Electric Light

Normally, when we pick out something to carry the “Retrotechtacular” banner, it’s a film from the good old days when technology was young and fresh, and filmmakers were paid by one corporate giant or another to produce a film extolling the benefits of their products or services, often with a not-so-subtle “celebrate the march of progress” undertone.

So when we spied this remastered version of The Secret Life of the Electric Light an episode from [Tim Hunkin]’s fabulous educational The Secret Life of Machines TV series, we didn’t really think it would be good Retrotechtacular fodder. But just watching a few minutes reminded us of why the series was must-see TV back in the 1990s (when it first aired widely here in the States), especially for the budding geek. When viewed with eyes more used to CGI animations and high production values, what [Tim] and his collaborator, the late [Rex Garrod], accomplished with each of these programs is truly astounding. Almost every bit of the material, as well as the delivery, has an off-the-cuff quality to it that belies what must have taken an enormous amount of planning and organization to pull off. [Tim] and [Rex] obviously went to a lot of trouble to make it look like they didn’t go to a lot of trouble, and the result is films that home in on the essentials of technology in a way few programs have ever managed, and none since. And the set-piece at the end of each episode — often meeting its pyrotechnic destruction — always were real crowd-pleasers. They still are.

We have to say the remastered versions of The Secret Life episodes, all of which appear to be posted at [Tim]’s YouTube channel, look just great, and the retrospectives at the end of each episode where he talks about the travails of production are priceless. Also posted are his more recent The Secret Life of Components, which is a treasure trove of practical tips for makers and backyard engineers that’s well worth watching too.

Continue reading “Retrotechtacular: The Secret Life Of The Electric Light”

Lewis Latimer Drafted The Future Of Electric Light

These days, we have LED light bulbs that will last a decade. But it wasn’t so long ago that incandescent lamps were all we had, and they burned out after several months. Thomas Edison’s early light bulbs used bamboo filaments that burned out very quickly. An inventor and draftsman named Lewis Latimer improved Edison’s filament by encasing it in cardboard, earning himself a patent the process.

Lewis had a hard early life, but he succeeded in spite of the odds and his lack of formal education. He was a respected draftsman who earned several patents and worked directly with Alexander Graham Bell and Thomas Edison. Although Lewis didn’t invent the light bulb, he definitely made it better and longer-lasting. Continue reading “Lewis Latimer Drafted The Future Of Electric Light”

Bask In The Warm Glow Of DIY Incandescent Bulbs

With most of the apparatus and instruments we now take for granted yet to be developed, the early pioneers of the Electric Age had to bring a lot to the lab besides electrical skills. Machining, chemistry, and metallurgy were all basic skills that the inventor either had to have or hire in. Most of these skills still have currency of course, but one that was once crucial – glassblowing – has sadly fallen into relative obscurity.

There are still practitioners of course, like [2SC1815] who is learning how to make homemade incandescent light bulbs. The Instructable is in both English and Japanese, and the process is explained in some detail. Basic supplies include soda-lime glass tubing and pre-coiled tungsten filaments. Support wires are made from Dumet, an alloy of iron, nickel, and cobalt with an oxidized copper cladding which forms a vacuum-tight seal with molten glass. The filament is crimped to the Dumet leads and pinched into a stem of glass tubing. A bulb is blown in another piece of tubing and the two are welded together, evacuated with a vacuum pump, and sealed. The bulbs are baked after sealing to drive off any remaining water vapor. The resulting bulbs have a cheery glow and a rustic look that we really like.

Of course, it’s not a huge leap from DIY light bulbs to making your own vacuum tubes. That’s how [Dalibor Farny] got started on his handmade Nixie business, after all.

An Artsy And Functional LED Filament Lamp

Some projects end up being more objet d’art than objet d’utile, and we’re fine with that — hacks can be beautiful too. Some hacks manage both, though, like this study in silicon and gallium under glass that serves as a bright and beautiful desk lamp.

There’s no accounting for taste, of course, but we really like the way [commanderkull]’s LED filament lamp turned out, and it’s obvious that a fair amount of work went into it. Five COB filament strips were suspended from a lacy frame made of wire, which also supports the custom boost converter needed to raise the 12-volt input to the 60 volts needed by the filaments. The boost converter is based on the venerable 555 timer chip, which sits in the middle of the frame suspended by its splayed-out legs and support components. The wooden base sports a few big electrolytics and some hand-wound toroidal inductors, as well as the pot for adjusting the lamp’s brightness. The whole thing sits under a glass bell jar, which catches the light from the filaments and plays with it in a most appealing way.

There’s just something about that dead bug building technique that we love. We’ve seen it before — this potentially dangerous single-tube Nixie clock comes to mind — but we’d love to see it done more.

[via r/electronics]