A Guide For Driving LED Matrices

November 27, 2018 by 9 Comments

Building an LED matrix is a fun project, but it can be a bit of a pain. Usually it starts with hand-soldering individual LEDs and resistors together, then hooking them up to rows and columns so they can be driven by a microcontroller of some sort. That’s a lot of tedious work, but you can order an LED matrix pre-built to save some time and headache. You’ll still need a driver though, and while building one yourself can be rewarding there are many pitfalls and trade-offs to consider when undertaking that project as well. Or, you can consider one of a number of drivers that [deshipu] has outlined in detail.

The hangups surrounding the driver board generally revolve around the issue of getting constant brightness from LEDs regardless of how many in the row or column are illuminated at one time. Since they are typically driven one row or column at a time, the more that are on the lower the brightness each LED will have. Driver boards take different approaches to solving this problem, which usually involve a combination of high-speed scanning of the matrix or using a constant-current source in order to eliminate the need for resistors. [deshipu] outlines four popular chips that achieve these purposes, and he highlights their pros and cons to help anyone looking to build something like this.

Most of these boards will get you to an 8×8 LED matrix with no problem, with a few going a few pixels higher in either direction. That might be enough for most of our needs, but for something larger you’ll need other solutions like the one found in this 64×32 LED matrix clock. There are also even more complicated drivers if you go into extra dimensions.

Photo credit: Komatta [Public domain], from Wikimedia Commons

Treasure Trove Of Projects Provides Endless Examples

November 27, 2018 by 4 Comments

Sometimes, traveling the internet feels a little like exploring an endless cave system looking for treasure. Lots of dark passageways without light or life, some occasional glimmers as you find a stray gold doubloon or emerald scattered in a corner. If we take the metaphor too far, then finding [Paul]’s “Little Arduino Projects” repository is like turning an unremarkable corner only to discover a dragon’s hoard.

LEAP (as [Paul] also refers to the collection) is a numbered collection of what looks like more or less every electronics project he has completed over the last few years. At the time of writing there are 434 projects in the GitHub repository and tagged and indexed in a handy blog-style interface. Some are familiar, like a modification to a Boldport project. Others are one-off tests of a specific concept like driving a seven segment display (there are actually 16 similar projects if you search the index for “7-Segment”). On the other end are project builds with more detailed logs and documentation, like the LED signboard for monitoring the status of 24 in-progress projects, mounted in a guitar fret board.

LEAP reminds us of the good old days on the internet, before it felt like 50% trolling and 50% tracking cookies. Spend a few minutes checking out [Paul]’s project archive and see if you find anything interesting! We’ve just scratched the surface. And of course, send a tip if you discover something that needs a write-up!

Bill Gross On Why Your Startup Will Succeed

November 27, 2018 by 16 Comments

Bill Gross is one of the great heros when it comes to technology incubators. Twenty years ago, he founded Idealab, a business whose business plan is to create more businesses. This started out with just a handful of companies in 1996, and has since gone on to found 150 companies, that have collectively raised three and a half billion dollars. Out of these companies, more than half have either gone through successful IPOs and acquisitions, or are currently operating. That investment has generated a 13.5x return, and created more than 10,000 jobs.

Obviously, when you want to talk about what goes into a successful startup, Bill Gross is the person you want to talk to. We were happy to have him Keynote the Hackaday Superconference this year, and the lessons he shared might surprise you, especially if you’re interested in starting your own business.

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The Most-3D-Printed 3D Printer

November 27, 2018 by 46 Comments

The most awesome things about having a 3D printer is that you can create almost anything which includes parts for the 3D printer itself. Different materials give power to your imagination and allow you to go beyond the 3D printed vase. So much so that one maker has gone as far as 3D print the bearings as well as the axis screws and nuts and it works!

The RepRap project was the first project to incorporate 3D printed parts to make it self-replicating to a certain extent. The clamps and mounts could be easily printed, however, this project uses a 3D printed frame as well as two linear bearings for the y-axis and z-axis and one for the x-axis. The y-axis is a 3D printed rack-and-pinion while the z-axis is made of a 3D printed screws and nuts. So basically, the servo motors, extruder/hotend and limits switches with mounting screws are the only part that need be bought at the store.

Even though in motors are running hot causing mounts to get soft, heat-sinks are predicted to resolve the issue. This one is not designed for accuracy though it can be a great resource for budding engineers and hackers to get their feet wet with customizing 3D printers. Check out the video for a demo.

From 3D printed guitars to RC Planes, there is a lot you can do with micro-manufacturing and all we need now is a 3D printed motor to get things rolling. Continue reading “The Most-3D-Printed 3D Printer” →

Sci-Hub: Breaking Down The Paywalls

November 27, 2018 by 125 Comments

There’s a battle going on in academia between the scientific journal publishing companies that have long served as the main platform for peer review and spreading information, and scientists themselves who just want to share and have access to the work of their fellows. arxiv.org launched the first salvo, allowing researchers in physics to self-publish their own papers, and has gained some traction in mathematics and computer science. The Public Library of Science journals focus on biology and medicine and offer peer review services. There are many others, and even the big firms have been forced to recognize the importance of open science publication.

But for many, that’s still not enough. The high prestige journals, and most past works, are stuck behind paywalls. Since 2011, Sci-Hub has taken science publishing open by force, illegally obtaining papers and publishing them in violation of copyright, but at the same time facilitating scientific research and providing researchers in poorer countries with access that their rich-world colleagues take for granted. The big publishing firms naturally fought back in court and won, and with roughly $20 million of damages, drove Sci-Hub’s founder underground.

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The Electronics Of Cold War Nightmares

November 27, 2018 by 8 Comments

It is a good bet that if you look around you, you’ll be able to find at least one smoke detector in sight. If not, there’s probably one not too far away. Why not? Fires happen and you’d like to know about a fire even if you are sleeping or alert others if you are away. During the cold war, there were other things that people didn’t want to sleep through. [Msylvain59] tears down two examples: a Soviet GSP-11 nerve agent detector and a Polish RS-70 radiation alarm. You can see both videos, below.

In all fairness, the GSP-11 is clearly not meant for consumer use. It actually uses a test strip that changes colors and monitors the color change. Presumably, the people operating it were wearing breathing gear because the machine could take quite a while to provide a positive output. Inside reminded us of a film processing machine, which isn’t too far off.

The radiation monitor looks more like a miniature version of an old floor-standing radio. The case design, the thick-traced, single-sided, hand-drawn printed wiring board, and the –by today’s standards — huge parts within all contribute to making this look like a piece of radio gear from the 1970s or even earlier.

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Video Details Construction Of Transparent Wood

November 27, 2018 by 11 Comments

We’ve talked about transparent wood before. However, the process can be difficult to get just right. [NileRed] recently posted a video with very detailed instructions on how he’s doing it. Aside from the dangerous way he uses a table saw — something he realized after he watched the video — it is some great information.

This isn’t some hand-waving explanation. For nearly 36 minutes, you get an actual demonstration of the steps along with some explanations about why it works and why certain steps are done in a particular way.

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