Coin-Sized LED Control

EE and firmware developer [Enrico] had played with LEDs as a kid, burning out his fair share of them by applying too much current. With the benefit of his firmware chops, he set about creating a board that drives LEDs properly.

[Enrico]’s project centers around a Texas Instruments LM3405 buck controller. It accepts input voltage from anywhere from 3V to 20V and outputs up to 20V/15W to one or more LEDs. He built a ton of safety features into it like short-circuit and open-circuit immunity, temperature control, and auto-off switching when idle. He also created a LED board to test the maximum efficiency of the driver. It consists of four Luxeon Rebel ES diodes, one each RGB and W. The entire back of the LED board is copper, with a monster heat sink attached.

You can follow along with the Glighter-S project on, or you can buy one of his boards from his Tindie store.

We’ve covered LED drivers extensively in the past, with posts on a simple 10-watt LED driver and how to design your own LED driver.

Reverse Engineering A BLE Service To Control A Light Bulb

So, you buy an Internet of Things light bulb, it’s a fun toy that allows you to bathe your environment in pretty colours at the touch of an app, but eventually you want more. You start to wonder how you might do more with it, and begin to investigate its inner workings. Then to your horror you discover that far from having bought a device with a convenient API for you to use, it has an impenetrable closed protocol that defies easy access.

This was the problem facing [Ayan Pahwa] when he bought a Syska Smartlight Rainbow LED bulb, and discovered that its Bluetooth Low Energy  interface used a closed protocol. But instead of giving up, he proceeded to reverse engineer the communication between bulb and app, and his write-up makes for an interesting read that provides a basic primer on some of BLE’s workings for the uninitiated.

BLE allows a device manufacturer to define their own device service specific to their functionality alongside standard ones for common device types. Using a handy Android app from Nordic Semiconductor he was able to identify the services defined for the light bulb, but sadly they lacked any human-readable information to help him as to their purpose. He thus had to sniff BLE packets directly, and lacking dedicated hardware for this task he relied on a developer feature built into Android versions since KitKat, allowing packets to be captured and logged. By analysing the resulting packet files he was able to identify the Texas Instruments chip inside the bulb, and to deduce the sequences required to control its colours. Then he was able to use the Bluez utilities to talk directly to it, and as if by magic, his colours appeared! Take a look at the video we’ve placed below the break.

Many of us may never need to reverse engineer a BLE device. But if we are BLE novices, after reading [Ayan]’s piece we will at least have some idea of its inner workings. And that can only be a positive thing.

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Use the Force to Turn On This Lamp

Holocrons are holographic data storage devices used in the Star Wars universe by both Jedi and Sith as teaching devices or for storing valuable information. After the fall of the Jedi, they became rare and closely guarded artifacts. [DaveClarke] built one to light the room.

[DaveClarke] built the lamp around a Particle Photon – a STM32 ARM-M0 based microcontroller with a Cypress wifi chip. All [Dave] needed for the workings were an IR proximity sensor, a servo and a bunch of super-bright white LEDs. When the sensor detects something, it starts up the system. The servo rotates a gear which raises the lamp and fades in the LEDs. The next time the sensor detects something, the servo lowers the lamp and the lights begin to fade out. And since the Photon is connected to the cloud, the system can be accessed with a web interface as well.

Okay, so it’s just an IR sensor detecting reflected infrared light and not the Force that’s used to turn it on, but it’s still pretty cool. There are plenty of pictures and videos at [DaveClarke]’s site, along with a schematic, 3D printer designs, and the source code. The whole thing was designed using Autodesk Fusion 360 and 3D printed in about 30 hours and press-fits together. A very simple yet clever design. There have been some other great lamps on the site, like this blossoming flower lamp or this laser cut lamp with which also has a unique switch.

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Oak Lamp Glows Bright

Looking for a way to spruce up your place with a touch of rustic-future-deco? Why not embed LEDs somewhere they were never designed for? [Callosciurini] had a nice chunk of oak and decided to turn it into a lamp.

He was inspired by a similar lamp that retails for over $1,000, so he figured he would make his own instead (business idea people?). The oak is a solid chunk measuring 40x40x45cm and what he did was route out an angled channel across all faces of the cube. This allowed him to installed a simple LED strip inside the groove — then he filled it with an epoxy/paint mix to give it that milky glow.

To finish it off he sanded the entire thing multiple times, oiled the wood, and sanded it again with a very fine grit. The result is pretty awesome.

Now imagine what you could do design-wise if you could fold wood to make a lamp? Well with this custom wood-folding saw-blade, the sky is the limit!

[via r/DIY]

Monster 100W LED Flashlight for Under $10!

What would you do if you came across a 100W, 7500 lumen LED diode for under $10? Probably something like this.

It’s actually quite amazing how cheap LEDs are getting. [Julian Ilett] found this 2″ x 2″ LED on eBay for only £4.79 (<$10 USD). It’s rated for 32-34V with a current draw of 3000mA, which works out to about 100W. Its brightness? 7500 lumens. That’s brighter than most home theater setups.

At that price, [Julian] had to try playing with one. The problem with these higher power LEDs is that they typically need a rather expensive LED driver, due to the less common voltages they operate at — and of course, the concern of over-driving them and burning them out. Not interested in finding a suitable driver, [Julian] decided to try something a bit less conventional — wiring a pair of 18V drill batteries in series.

Continue reading “Monster 100W LED Flashlight for Under $10!”

Make Your Own LED Lightbulb!

LED lightbulb

Do you like saving electricity? Who doesn’t!

Do you have a lot of LED light strips lying around, destined for a project that you never quite got around to? We’re guilty!

Do you have an old DC power adapter? Of course you do.

Do you love soldering? Duh.

Do you have a dead fluorescent light bulb sitting around? Maybe…

If so, here’s a quick and silly guide to making your very own LED light bulb! The result is a bit ghetto we admit, but quite functional. Perhaps it could be improved by adding a glass Christmas bobble to make it look a bit more like a regular light bulb. And if you’re ambitious enough you could throw a microprocessor in there and add wireless control to it as well … but let’s be honest, smart LED light bulbs are getting quite affordable these days. But hey, you’ve got to do something for entertainment!