It all started when [Damien Walsh] got his hands on some surplus LED boards. Each panel contained 100 mini-PCBs hosting a single bright LED that were meant to be to be snapped apart as needed. [Damien] had a much better idea: leave them in their 20×5 array and design a driver allowing each LED to be controlled over WiFi. He was successful (a brief demo video is embedded down below after the break) and had a few interesting tips to share about the process of making it from scratch.
The first hurdle he ran into was something most of us can relate to; it’s difficult to research something when one doesn’t know the correct terms. In [Damien]’s case, his searches led him to a cornucopia of LED drivers intended to be used for room lighting or backlights. These devices make a large array of smaller LEDs act like a single larger light source, but he wanted to be able to individually address each LED.
Eventually he came across the IS32FL3738 6×8 Dot Matrix LED Driver IC from ISSI which hit all the right bases. Three of these would be enough to control the 100-LED panel; it offered I2C control and even had the ability to synchronize the PWM of the LEDs across multiple chips, so there would be no mismatched flicker between LEDs on different drivers. As for micontroller and WiFi connectivity, we all have our favorites and [Damien] is a big fan of Espressif’s ESP32 series, and used the ESP32-WROOM to head it all up.
The other issue that needed attention was wiring. Each of the LEDs is on its own little PCB with handy exposed soldering pads, but soldering up 100 LEDs is the kind of job where a little planning goes a long way. [Damien] settled on a clever system of using strips of copper tape, insulated by Kapton (a super handy material with a sadly tragic history.) One tip [Damien] has for soldering to copper tape: make sure to have a fume extractor fan running because it’s a much smokier process than soldering to wires.
A 3D-printed baffle using tracing paper to diffuse the light rounds out the device, yielding a 20 x 5 matrix of individually-controlled rectangles that light up smoothly and evenly. The end result looks fantastic, and you can see it in action in the short video embedded below.
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.
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.
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.
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.
[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.
[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.
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.