Recently I had the opportunity to do a teardown of a battery-backed LED bulb, and found some interesting details on how the device operated. Essentially, the bulb contained a low voltage DC uninterruptible power supply that would automatically switch between AC power and internal battery as needed. The implications of this seemed pretty exciting. For around $12 at big box retailers, this little bulb could be a cheap and convenient solution for providing fault tolerant power to microcontrollers and other low-power devices.
The teardown was a runaway success, with quite a bit of discussion of the UPS idea specifically. Some people hated it, others loved it. But as we’ve come to expect from Hackaday readers, the comments from both sides of the aisle contained keen observations and invaluable real-world experience. From the safety of the device to the accuracy of the manufacturer’s claims, it seems like every element of the product was addressed.
I had ended the teardown with a promise that I’d continue experimenting with the tiny salvaged UPS, but even if I hadn’t, with so much feedback it seemed revisiting the subject was all but a necessity. It this little UPS really viable? Is it too dangerous to safely implement in your project? Will the thing just blow up?
So with your comments as a guide, and free of the somewhat restrictive teardown format, I set out to conduct a more thorough investigation of this little circuit that caused so much debate last month. It’s not all good news, but it’s not in the trash either. Not yet, anyway.
At a glance, little Mr. Rise and Shine can see if it’s time to spread cheer, or if he has to stay in his room and play a bit longer. At 6:00AM, the light powers on and glows red. At 6:50, it turns yellow for 10 minutes. At the first reasonable hour of the day, 7:00AM, it finally turns green. In reading the code, we noticed that it also goes red at 8:00PM for 45 minutes, which tells us it also functions as a go-to-sleep indicator.
[Nate] has made snowboarding cool with his Bluetooth connected board. Using 202 WS2812 LEDs carefully wrapped around the edge of the board and sealed with a conformal coating, it’s bright and waterproof. It’s controlled with an Arduino Nano and a Bluetooth classic board, as well as a large swappable USB battery bank; he can get roughly four hours of life at full brightness on his toy.
Where it gets even cooler is with a six-axis gyro connected to the Nano, which tracks the board movement, and the lights respond accordingly, creating cool patterns based on his speed, angles, and other factors. The app used to control this intense ice-rider is a custom app written using MIT App Inventor, which has the ability to work with Bluetooth classic as well as BLE. This came in handy when he made the 100-LED skateboard, which is based on a Feather with BLE and a large LiPo battery. The challenging part with the skateboard was making the enclosure rugged enough (yet 3D printed) to withstand terrain that is a lot less fluffy than snow.
Who has the fastest thumbs at Maker Faire UK? That’s the question [wellsey1972] sought to answer when he created this simple game using little more than two NeoPixel rings, two chunky arcade buttons, and a Trinket.
The idea is simple: each button push lights up one NeoPixel. The first one to fill up their ring is the winner, and is treated to a ring of flashing green lights. The loser, of course, gets flashing red. Both controllers are hard-wired to a box containing a Trinket, a custom PCB with pull-up resistors, and two sets of solderless terminals. [wellsey1972] smartly re-purposed a cat 5 cable for sleeker wiring.
He has a few ideas for the future, like going wireless, printing smaller controllers, and making winning more difficult via potentiometer. We humbly suggest that the loser be taunted by the cry of a sad tuba. Mash past the break for a brief demo.
Regular Hackaday readers will be familiar with the work of Boldport’s [Saar Drimer] in creating beauty in printed circuit board design. A recent work of his is the Widlar, a tribute to the legendary integrated circuit designer [Bob Widlar] in the form of a development board for his μA723 voltage regulator chip.
The μA723 is a kit of parts from which almost any regulator configuration can be made, but for [tardate] it represented a challenge. The μA723 is so versatile that what you can create is only limited by the imagination of the builder. Having done the ordinary before, [tardate] looked toward something unconventional.
The result is modest, a simple LED flasher using the error amplifier as a not-very-good op-amp, building an oscillator at a frequency of about 2 Hz. This is pretty neat and if you are used to the NE555 as the universal integrated circuit, perhaps it’s time to set it aside for the obviously far-more-useful μA723.
It’s built around an 8-pin PIC16F18313 microcontroller, uses a joystick for input, and nine WS2812 LEDs to display the player and the surrounding maze walls. His inspiration was [David Johnson-Davies’] minimalist secret maze game built around the 8-pin ATTiny85. In that one, [David] cleverly used charlieplexing to get four pins to control four LEDs and four pushbuttons. [Vegipete’s] use of the WS2812 LEDs allowed him to control the LEDs with just one pin, and also get color while using three pins for the joystick and its button. He may use another pin in the future for sound and vibration.
He goes into some detail on the WS2812 protocol, how communication is done with the LEDs using just one pin and different pulse-lengths to represent 0 and 1. We’ll leave you to see his post for more depth but basically, he introduces a module on the PIC called the Configurable Logic Cell (CLC) which makes this easy and frees up processor cycles for the user’s code to do other things.
His source code is available on request but he does detail a neat software trick he uses for rotating the view. It may be confusing for some but as you move through the maze, your viewpoint rotates so that up is always the direction you’re facing. Luckily, the walls surrounding the user can be represented using 8-bits, four for east, west, north, and south, and four more for the corners. The maze is stored as a bitmap and from it, 8-bit values are extracted for the current position, each bit representing a wall around the position. To rotate the walls to match the user’s current orientation, the bits are simply shifted as needed. Then they’re shifted out to set each LED. Check it out in the video below.
It works very well despite the minimal interface and part count.
Got a broken laptop screen sitting around? If you haven’t already pilfered the LEDs and used the polarizing sheets for screen privacy filters, why not turn it into a unique table lamp? See if you can use more parts of the screen than [alexmaree-ross] did.
This is a simple idea with great-looking results, but the process is a bit fiddly. After all the layers are separated and the LEDs extracted, there’s still the matter of figuring out how they’re wired up. [alexmaree] tested them in pairs to see how they’re grouped together and ultimately powered them with a transformer from an old printer. To build the case, [alexmaree] carefully scored and snapped the pieces from the plastic layer and carefully glued pieces of the polarizing layer on top to give it that underwater infinity mirror look. The finishing touch comes from edging the shade with thin metal from the bezel.
The case could be in any shape you want, but we think the prism is quite appropriate considering the polarizing effects. And it looks really cool when you walk around it, which you can do vicariously after the break.