LED grid Part 2 – First hardware tests

This is part 2 of the led grid project, a joint project of engunneer.com and ericagunn.com. In the last post, the boards had just arrived, and the rest of the parts were on order. A few days later, everything was here! Because resistors are so cheap when you get 100 or 500, it was worth getting a few extra values to allow for testing the IR receivers. Just before assembly, I realized why DirtyPCBs are so cheap, and why they do electrical tests on all boards: Yes, that’s blue sharpie on top of a hand repaired trace. About 30% of the boards had some kind of repair like this. I soldered one board up and started testing. Getting the color LEDs working wasn’t a big deal, but I had problems with the IR power supply (which is also duplicated for the shift registers). It just wasn’t regulating voltage and had […]

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Game Clicker PCB design

My brother had an idea for a project, and asked me to design and produce a PCB and case. If you have a circuitmaker login, you can look at it here. The basic design is a combination of the following products all in to one PCB, with additional buttons and LEDs to do the job he wants: LiPo charging and power conversion: (http://www.sparkfun.com/products/11231) Arduino Micro compatible CPU (http://www.sparkfun.com/products/12640) 7-Segment displays (similar to http://www.sparkfun.com/products/11442) I did run the 7 segment displays off of a shift register instead of the ATMega328 sparkfun used, which helped keep my I/O to a minimum. For power, the unit will use a LiPo battery, but I haven’t yet picked the exact model that will fit in the case and also last all day. I still have a few power measurements to make. Layout on GerbLook Schematics: Game Clicker (pdf) Early renderings (there are a few updates […]

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Led grid part 1 – Design Process

This is a copy of a guest post I wrote for my wife’s blog, about building an LED Grid for our collaborative design project The hardware for the LED grid project consists of two major elements: The LED lights, and the IR touch system. The first idea for the board had the main LEDs spaced out in a 10mm grid. I prototyped this on some surface mount prototyping board to see if I could fit everything needed into the space available. It was a bit of a tight fit, and the nature of how I made it makes it not very pretty. Because the LED cells were so close together, I had to alternate the IR touch transmitters and receivers in each column to keep them from interfering with each other. This was enough to prove out the concept and get initial values for the resistors for the touch system. […]

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Z axis upgrade

3D printing as a hobby brings with it plenty of tinkering. I noticed an effect in my printed parts that looks like z wobble from my old cupcake, but the openbeam printer should be better constrained in the xy axes to prevent that. Basically there are 8mm guide shafts that keep everything aligned and a pair of z motors with misalignment couplings and a threaded rod and M8 nut to actually impart the force in the z direction with minimal x and you components. I had used some spare M8 threaded rods that I bought from makerbot when they were clearing out old cupcake parts. What I noticed was that the ridges on my parts changed size as a function of layer height. This meant that some layers were being squished more than others. The pattern was the exact same pitch as the threaded rod, which meant the z didn’t […]

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DLNA Adventures

It’s 2014. There really ought to be a good way to handle mp3 files and be able to organize and listen to music in some kind of sensible manner. I was a college kid in the early 2000s, so I had a haphazard collection of mp3s ripped from CDs and shared around campus. I attempted to organize it at least a half dozen times since then, and it has become so scattered that it just became unmanageable over the years and the new computers, external drives, backing everything up to CD and DVD, etc. The current solution: It looks like a decade of procrastination has allowed other people to nearly solve the problems of managing a media library. The current solution looks to be DLNA, which strikes me as the OPC-UA equivalent to the media space. Without boring you with the details of arriving at this solution, here is my […]

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Hacked!

Disclaimer: I am NOT a web programmer, nor am I a PHP expert. In preparation for FRC season, I decided to do some maintenance of the quiz website where I have hosted FRC rules quizzes for the past two years. Apparently Webtester has two(or more) major security holes. I discovered at least 12 different malicious files uploaded, and at least two other major problems on my site. I’m going to document here what I did to fix my copy of Webtester (version 5.1.20101016), since I haven’t really found a better tool for the way I want to host quizzes. I’m taking two approaches to this: Closing known holes (Google for “WebTester 5.x Multiple Vulnerabilities” to see a few detailed reports), and obfuscating obvious things. At least one of the attacks made an attempt at getting the details of any blog software I use, but I think the randomized table prefix […]

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First long unattended print on openbeam printer

In preparation for 3d printerfest at Einsteins workshop in Burlington, I attempted a 6+ hour print, which is by far the longest I have done, unattended or otherwise. My previous printer simply wasn’t large or reliable enough to print for 6 hours. This print is a 150 mm diameter herringbone gear bearing. I came home from work expecting a big mess and actually was surprised it worked. It’s a bit thin in spots and didn’t break free, but it’s pretty close. I think I just need to make the cold end of the extruder a tad more reliable. I’m pretty excited about my new larger build area, and think I can get quite a bit better results than the previous printer. Next up, upgrading this to octopi as well.

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Office organization

There was a discussion on the askelectronics subreddit about part storage, which reminded me that I’ve been meaning to post about the latest office arrangement. For the video tour, see this post. Since the main question is about components, I’ll start there. Since the organization has grown over a decade or so, there is some duplication and some things that could be grouped better, which is an ongoing process. This is the main electronics workbench in my office: From top row, left to bottom row right: Grey bins – the oldest bins. Contains US machine screws, wood screws, nails, etc. Teal bins – until recently this was metric hardware and rivets, but most of that has moved to primary storage (covered below) – now mostly empty Partitioned containers. These are $10 from the container store. There are 5 in use here and 3 more emptys in primary storage. This is […]

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