A Year-Long Experiment In OLED Burn-In

If you need to add a small display to your project, you’re not going to do much better than a tiny OLED display. These tiny display are black and white, usually found in resolutions of 128×64 or some other divisible-by-two value, they’re driven over I2C, the libraries are readily available, and they’re cheap. You can’t do much better for displaying a few numbers and text than an I2C OLED. There’s a problem, though: OLEDs burn out, or burn in, depending on how you define it. What’s the lifetime of these OLEDs? That’s exactly what [Electronics In Focus] is testing (YouTube, in Russian, so click the closed captioning button).

The experimental setup for this is eleven OLED displays with 128×64 pixels with an SSD1306 controller, all driven by an STM32 over I2C. Everything’s on a breadboard, and the actual display is sixteen blocks, each lit one after another with a one-second display in between. This is to test gradually increasing levels of burnout, and from a surface-level analysis, this is a pretty good way to see if OLED pixels burn out.

After 378 days of testing, this test was stopped after there were no failed displays. This comes with a caveat: after a year of endurance testing, there were a few burnt out pixels. correlating with how often these pixels were on. The solution to this problem would be to occasionally ‘jiggle’ the displayed text around the screen, turn the display off when no one is looking at it, or alternatively write a screen saver for OLEDs. That last bit has already been done, and here are the flying toasters to prove it. This is an interesting experiment, and although that weird project you’re working on probably won’t ping an OLED for a year of continuous operation, it’s still something to think about. Video below.

Continue reading “A Year-Long Experiment In OLED Burn-In”

Improving Depth Of Field With Only 5 Phones

The hottest new trend in photography is manipulating Depth of Field, or DOF. It’s how you get those wonderful portraits with the subject in focus and the background ever so artfully blurred out. In years past, it was achieved with intelligent use of lenses and settings on an SLR film camera, but now, it’s all in the software.

The franken-camera rig, consisting of five Pixel 3 smartphones. The cameras are synchronised over WiFi.

For the Pixel 2 smartphone, Google had used some tricky phase-detection autofocus (PDAF) tricks to compute depth data in images, and used this to decide which parts of images to blur. Distant areas would be blurred more, while the subject in the foreground would be left sharp.

This was good, but for the Pixel 3, further development was in order. A 3D-printed phone case was developed to hold five phones in one giant brick. The idea was to take five photos of the same scene at the same time, from slightly different perspectives. This was then used to generate depth data which was fed into a neural network. This neural network was trained on how the individual photos relate to the real-world depth of the scene.

With a trained neural network, this could then be used to generate more realistic depth data from photos taken with a single camera. Now, machine learning is being used to help your phone decide which parts of an image to blur to make your beautiful subjects pop out from the background.

Comparison images show significant improvement of the “learned” depth data versus just the stereo-PDAF generated depth data. It’s yet another shot fired in the smartphone camera arms race, that shows no signs of abating. We just wonder when the Geiger counter mods are going to ship from factory.

[via AndroidPolice]

Adventures In Gas Filled Tube Arrays

Vacuum tubes are awesome, and Nixies are even better. Numitrons are the new hotness, but there’s one type of tube out there that’s better than all the rest. It’s the ИГГ1-64/64M. This is a panel of tubes in a 64 by 64 grid, some with just green dots, some with green and orange, and even a red, green, blue 64 by 64 pixel matrix. They’re either phosphors or gas-filled tubes, but this is the king of all tube-based displays. Not even the RGB CRTs in a Jumbotron can match the absurdity of this tube array.

[Muth] got his hands on a few of these panels, and finally he’s displaying images on them. It’s an amazing project that involved finding the documentation, translating it, driving the tubes with 360 Volts, and figuring out a way to drive 128 inputs from just a few microcontroller pins.

First, the power supply. These panels require about 360 Volts to light up. This is significantly higher than what would usually be found in a Nixie clock or other normal tube-based display. That’s no problem, because a careful reading of the datasheet revealed a circuit that brings a normal-ish 180 Volt Nixie power supply up to the proper voltage. To drive these pixels, [Muth] settled on a rather large PIC18F microcontroller with eight tri-state buffers. The microcontroller takes data over a serial port and scans through the entire framebuffer. All in all, there are eight driver boards, 736 components, and 160 wires connecting everything together. It’s a lot of work, but now [Muth] has a 64×64 display that’s green and orange.

You can check out a ‘pixel dust’ demo of this display in action below.

Continue reading “Adventures In Gas Filled Tube Arrays”

Marquee Display Uses Six Dozen Surplus VFD Tubes to Great Effect

The quest to repurpose surplus parts into new and interesting displays never ends, it seems. And the bigger the display, the better, with extra points for using some really obscure part, like these surplus Russian vacuum-fluorescent tubes turned into a marquee display.

As [tonyp7] freely admits, this is a pet project that’s just for the fun of it, made possible by the flood of surplus parts on the market these days. The VFD tubes are IV-25s, Russian tubes that can be had by the fistful for a song from the usual sources. The seven small elements in the tube were intended to make bar graph displays like VU meters, but [tonyp7] ganged up twelve side by side to make 84-pixel displays. The custom driver board for each matrix needs three of the old SN75518 driver chips, in 40-pin DIPs no less. A 3D-printed bracket holds the tubes and the board for each module; it looks like a clock is the goal, with six modules ganged together. But the marquee display shown below is great too, and we look forward to seeing the finished project.

From faux-Nixies made with LEDs to flip-segment displays driven by relay logic to giant seven-segment LEDs that can be 3D-printed, we really like the trend to unique displays. What are you dreaming up?

Continue reading “Marquee Display Uses Six Dozen Surplus VFD Tubes to Great Effect”

Flip-Dot Display Brought Out of Retirement by New Drivers

LED matrix displays and flat-screen monitors have largely supplanted old-school electromechanical models for public signage. We think that’s a shame, but it’s also a boon for the tinkerer, as old displays can be had for a song these days in the online markets.

Such was the case for [John Whittington] and his flip-dot display salvaged from an old bus. He wanted to put the old sign back to work, but without a decent driver, he did what one does in these situations — he tore it down and reverse engineered the thing. Like most such displays, his Hannover Display 7 x 56-pixel flip-dot sign is electromechanically interesting; each pixel is a card straddling the poles of a small electromagnet. Pulse the magnet and the card flips over, changing the pixel from black to fluorescent green. [John] used an existing driver for the sign and a logic analyzer to determine the protocol used by the internal electronics to drive the pixels, and came up with a much-improved method of sending characters and graphics. With a Raspberry Pi and power supply now resident inside the case, a web-based GUI lets him display messages easily. The video below has lots of details, and the code is freely available.

You may recall [John] from a recent edge-lit Nixie-like display. Looks like he’s got a thing for eye-catching displays, and we’re fine with that.

Continue reading “Flip-Dot Display Brought Out of Retirement by New Drivers”

Hull Pixel Bot, A Mobile Pixel

There are many designs for little two-wheeled robots available to download for constructors with an interest in simple robotics. You might even think there are so many that there could not possibly be room for another, but that has not deterred [Rob Miles]. He’s created HullPixelBot, a platform for a mobile pixel as well as for simple robotic experimentation.

So what makes HullPixelBot more than just Yet Another Arduino Powered Robot? For a start, it’s extremely well designed, and has a budget of less than £10 ($12.50). But the real reason to take notice lies in the comprehensive software, which packs in a language interpreter and MQTT endpoint for talking to an Azure IoT hub. This is much more than a simple Arduino bot on which you must craft your own sketches, instead, it is a platform for which the Arduino bot is merely the carrier.

The project has had quite a while to mature since its initial release, and now has the option of a single pixel or a ring of pixels. The eventual aim is to use swarms of networked HullPixelBots to create large autonomous moving pixel displays, containing more than a hundred individual pixels.

There is an early video of some PixelBots in action which we’ve placed below the break, but it serves more as eye candy than anything else. If you have a spare ten quid, download and print yourself a chassis, install Arduino and motors, and have a go yourself!

Continue reading “Hull Pixel Bot, A Mobile Pixel”

Raspberry Pi Software Comes To PC, Mac

The Raspberry Pi Foundation has put a lot of work into their software stack. You need only look at a few of the Allwinnner-based Pi clones for the best evidence of this, but the Pi Foundation’s dedication to a clean and smooth software setup can also be found in Noobs, their support for the Pi Hardware, and to a more limited extent, their open source GPU driver offerings.

Now the Pi Foundation is doing something a bit weird. They’re offering their default Raspberry Pi installation for the Mac and PC. Instead of Flashing an SD card, you can burn a DVD and try out the latest the Pi ecosystem has to offer.

A few months ago, PIXEL became default distribution for the Raspberry Pi. This very lightweight distribution is effectively the Knoppix of 2016 – it doesn’t take up a lot of resources, it provides enough software to do basic productivity tasks, and it’s easy to use.

Now PIXEL is available as a live CD for anything that has i386 written somewhere under the hood. The PC/Mac distribution is the same as the Pi version; Minecraft and Wolfram Mathematica aren’t included due to licensing constraints. Other than that, this is the full Pi experience running on x86 hardware.

One feature that hasn’t been overlooked by a singular decade-old laptop in the Pi Foundation is Pixel’s ability to run on really old hardware. This is, after all, a lightweight distribution for the Raspberry Pi, so you shouldn’t be surprised to see this run on a Pentium II machine. This is great for a school in need of upgrading a lab, but the most interesting thing is that we now have a new standard in Linux live CDs and Flash drives.