Hacking A Non-Dimmable LED Fixture

February 24, 2021 by Dan Maloney 22 Comments

For most of us, the solution to having a non-dimmable LED light bulb but needing a dimmable one is a simple as a drive to the store to get the right kind of bulb. But that seems downright boring, not to mention wasteful, so when [Leo Fernekes] was faced with this problem, he looked for a way to make a non-dimmable bulb dimmable.

To be fair, there was a financial aspect to this hack, too. [Leo] had a bunch of cheap non-dimmable light fixtures he wanted to put to use. He started with a teardown and reverse-engineering of a light strip, which contains little more than LEDs and a small buck converter. His analysis of the circuit led him to a solution for dimming the light: inserting a MOSFET as a shunt around the LEDs. That and the addition of a diode to isolate the LEDs from the current regulator would allow for simple PWM-control of the lights via a microcontroller.

As is typical with these things, there were complications. [Leo] found that a timing problem resulted in flickering LEDs; the fix came from adding a sync circuit that cleverly leveraged a flip-flop inside the PIC16 microcontroller he chose for the circuit. His prototype incorporates these modifications, plus an interface that supports the DALI protocol for architectural lighting control. As always, [Leo] is quick to point out that mixing line voltage into your projects is not without risks, which he takes pains to mitigate. And as is also typical for his projects, [Leo] gives just the right amount of detail to understand the theory behind his design.

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“Artificial Sun” Lighting Via Old Satellite Dishes

November 13, 2020 by Lewin Day 53 Comments

Real sunlight is a beautiful thing, but due to the vagaries of Earth’s orbit and local weather systems, it’s not available all the time. [Matt] decided this wasn’t good enough, and set about building a rig to replicate the sun’s rays as closely as possible.

Rayleigh scattering is emulated by passing the light through a glass chamber filled with soapy water – taking advantage of the Tyndall effect.

The great distance between the Sun and the Earth means that the sun’s rays are essentially parallel from our local vantage point. Replicating this, and the soothing nature of a blue sky, were [Matt]’s primary goals with the project. To achieve this, an old satellite dish was pressed into service as a parabolic reflector, coated with mirror-finish vinyl strips. A 500W white LED with a good color rendering index was fitted at the focal point, outfitted with a water cooling system to shed heat. With a point source at its focal point, the parabolic reflector bounces the light such that it the rays are parallel, giving the sense that the light source is coming from an effectivelyl infinite distance away. To then achieve the blue sky effect, the light was then passed through a glass chamber filled with soapy water, which scatters the light using the Tyndall effect. This mimics the Rayleigh scattering in Earth’s atmosphere.

The final result is amazing, with [Matt] shooting footage that appears to be filmed in genuine daylight – despite being shot at night or on rainy days. He also features a cutdown build that can be achieved in a far cheaper and compact form, using Fresnel lenses and blue film. We’ve featured [Matt]’s daylight experiments before, though we’re amazed at the new level reached. Video after the break.

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Oh, Holey Light

September 30, 2020 by Brian McEvoy 18 Comments

We consider ourselves well-versed when it comes to the technical literature plastered on hardware store parts. Acronyms don’t frighten us, and our Google-fu is strong enough to overcome most mysteries. One bit of dark magic we didn’t understand was the gobbledygook on LED lamps. Wattage is easy and color temperature made sense because it corresponds with warm and cool colors, but Color Rendering Index (CRI) sounds like deep magic. Of course, some folks understand these terms so thoroughly that they can teach the rest of us, like [Jon] and [Kevin], who are building a light controller that corrects inadequacies in cheap lamps by installing several lamps into one unit.

We learned a lot by reading their logs, which are like the Cliff Notes from a lighting engineer’s textbook, but we’ll leave it as an exercise for the students to read through. Their project uses precise light sensors to measure the “flavor” of light coming off cheap lamps so you can mix up a pleasing ratio. In some ways, they are copying the effects of incandescent bulbs, which emit light relatively evenly across the visible light spectrum, right into the infrared. Unfortunately, cheap LEDs have holes in their spectrum coverage, and a Warm White unit has different gaps compared with Daylight, but combining them just right gives a rich output, without breaking the bank.

Reviving A DOA Smart Bulb With Custom Firmware For Its ESP8266

July 5, 2020 by Tom Nardi 14 Comments

There are some incredibly cheap WiFi smart bulbs on the market these days, but as is often the case, you tend to get what you pay for. When [Viktor] took delivery of his latest bargain basement bulb, the thing didn’t even work. So much for Quality Assurance. On the plus side, it was a great excuse to pop it open and replace the firmware.

For anyone wondering, [Viktor] never actually figured out why the bulb didn’t work. Its ESP8266-based control board was getting power, and data was getting spit out of the serial port when he connected it to the computer (although he never got the communications settings right to actually see what it was saying). But he also didn’t care much; once he confirmed that the hardware was good, he just uploaded the custom firmware he’d previously developed for another ESP8266 bulb.

Of course, it wasn’t quite that easy. The chances that both bulbs would have used the same GPIO pins to control the red, green, blue, and white LEDs were pretty slim. But after some testing and modifications to the code, he was able to fire them up. The other issue was a bit trickier, as it turned out the bulb’s flash chip was too small to hold his firmware’s web configuration pages. So he had to break out the hot air gun and replace the SPI flash chip with something a bit roomier. We suppose he could have just made smaller web pages… but where’s the fun in that?

Even with the chip swap, this looks a lot easier than building your own smart bulbs from scratch. With so many cheap ESP8266 bulbs on the market, it seems there’s never been a better time to code your own home lighting solution.

Dim Hallway Gets Lighting Upgrade

May 27, 2020 by Lewin Day 13 Comments

There’s nothing worse than a lightswitch that’s nowhere near where it should be, leaving you fumbling around in the dark. [supersquirrel72] had just this problem, and decided to put an Arduino to work instead.

Rather than using the original mains lighting that was poorly positioned and not enough to light the hall, instead 2 meters of white LED strip was chosen. The form factor is perfect for lighting a long, thin space – far better than running a series of seperate bulbs. The strip was rigged up to an Arduino Uno, that triggers the lights when movement is detected with a simple PIR motion sensor. After some feedback from the other occupants of the house, it was decided to tweak things further. An RTC was implemented to allow the Arduino to keep things dimmer after 9PM, so as to not wake others when making a trip to the kitchen for a midnight snack.

It’s a simple solution which brightens up the hallway nicely. We imagine this could just be the first step to a yet-more-integrated lighting solution in [supersquirrel72]’s house. Whether it’s IOT lights or something more festive, we can’t wait to see what’s next.

It’s Not An Arc Lamp, It’s A Lamp Arc

March 26, 2020 by Jenny List 17 Comments

One wouldn’t expect there to be much to cause envy in the world of desk lamps, after all whether it’s a classic Anglepoise or a dollar store LED affair if it does its job of casting the requisite quantity of light where it’s needed, most of us are happy. But then we saw [Ronny Ziss]’s LED arc desk lamp, and suddenly all other lamps simply aren’t good enough any more. If it’s not a wall-to-wall arc of LEDs spanning the length of the desk, it quite simply no longer cuts the mustard. We’ve entered the world of lamp envy, folks, and it’s a poorly-illuminated place to be.

As you can see in the video below the break both the hardware and the software of this lamp are impressive in their own right, the structure being an aluminium extrusion carrying an addressable white LED strip fitted into an arc between two custom plywood blocks on the walls either side of the desk. The software is controlled through a rotary encoder, and allows command of the position, width, and brightness of the illuminated portion, as well as having a hidden Pong game. Sadly he doesn’t reveal the software or the microcontroller in question, however the task is not an onerous one and it’s likely most Hackaday readers could put it together using their board or processor of choice.

In years of lamp projects on Hackaday, we can’t find another quite like this one. Conventional lamp projects can still be stylish though.

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It’s An LED Cube, But Maybe Not Quite What You Were Expecting

January 27, 2020 by Jenny List 11 Comments

LED cubes are a pleasing ornament and still something of a talking point, but now they have reached the point of being available as inexpensive kits from China. The simpler ones don’t have quite the cachet they used to. It’s still a project that can deliver a few surprises though, as [Moritz v. Sivers] shows us very well with his glass LED cube. Instead of the usual wire frame construction he’s employed a novel technique of applying each layer of WS2812 LEDs to its own glass PCB.

The PCBs are created with self-adhesive copper foil, cut out with a CNC cutter and painstakingly transferred to the glass substrate with the help of a piece of transfer paper. The LEDs are soldered on, and once each board has been tested they are mounted in the manner of a toast rack to laser cut acrylic corner pieces. There are four layers of 16 LEDs each, which might not make for the largest cube, but still makes for a respectable show. The addressable LEDs take it a level above the 3D matrix type of cube with which you might already be familiar, and the extra time required to load each value into them doesn’t seem to slow the display down.

There are a couple of videos we’ve placed below the break, one showing it in action and the other taking us through the build process. This last one should provide plenty of inspiration for anyone with an interest in creating this type of PCB on glass or any other unusual substrate. Continue reading “It’s An LED Cube, But Maybe Not Quite What You Were Expecting” →