• Can letters in the kitchen posted on 01 Apr 2014

    Earlier today, my roommate texted me a picture of a sign that her work was going to throw out. When she got home, I convinced her that we should go and retrieve it!

    First, we removed the letter faces.

    With the faces free, we removed the screws that were holding the letters to their bulky mounting rail.

    Letters free from the rail.

    We were surprised to find that the letters were lit with neon. We removed the bulbs and placed them aside.

    After returning home, we cleaned the letters and lined them up to prepare for lighting.

    We then stuffed the letters with string lights.

    Letters in place above our kitchen cabinets. We were lucky they fit!

    This was a fun diversion for today, but we'll probably have to redo them with LEDs if we decide to keep them around for long.

    If you like this spontaneous bit of work, you should see what my roommate does over at Electric Trees!


  • Hotend for Metal FDM, Part 2 posted on 09 Mar 2014

    What if you could do something like SLS but with a hot tip? Take a 1200C tip and move around the work surface melting tiny metal beads. Alternatively, use a torch.

    Or perhaps metal beads could be extruded with FDM and fused later with a laser or in a kiln.


  • Hotend for Metal FDM posted on 08 Mar 2014

    Hotend & nozzle metal

    • Able to withstand 700-1100C
    • Not going to interact badly with molten aluminum, zinc, or copper
    • Hard enough that a 0.5mm hole is still 0.5mm after extruding a bunch of molten metal through it

    Hotend design

    • Thermal expansion from worst metal shouldn't cause a jam
      • worst case expansion * worst case tolerance + magic extra tolerance
    • Minimum amount of metal is molten at any given moment.

    Nozzle design

    • Metal should extrude with minimum turbulence
      • Nozzle 10x longer than diameter of extrusion?

    Coldend design

    • Thermal transfer up filament should be minimized

    Heat break design

    • Heat leakage into the coldend should be minimized
    • Filament must be supported enough that it won't bend under the pressure of extrusion
      • Ceramic sheath? Stainless tube?
    • If the heat break can't withstand the full pressure of extrusion, the hotend will need to be anchored to the coldend externally

    Extruder design

    • Filament should not be marred (eg, by a sharp gear) to minimize the risk of jamming in the cold end or damaging any components
    • Filament must be pushed with enough force to extrude
      • Need to find data on how soft metals are at various temps

    Filament research

    • Find filament of multiple metals in the same diameter & tolerance (at/near extrusion temperature after thermal expansion)


    In my mind, this hotend looks a lot like an E3d hotend made from steel or titanium, but with a directly mounted extruder and a lot more cooling (possibly water cooled?). It would be heated with a high temp heater cartridge (maybe?) and have a much heftier heat break, possibly supplemented by external thin steel wires.

    General questions

    • How will molten aluminum interact with titanium? Would it be an appropriate nozzle material? How about steel?
    • Any idea how to figure out a graph of extrusion force vs temperature for aluminum (w/ a given diameter nozzle)?
    • How horrible is it going to be to deal with thermal expansion across this entire design? If more than one metal is used, everything needs to be matched up for expansion, yes?
    • What sort of surface will be able to handle the thermal stress of being printed onto?
    • How can part adhesion to the print bed be maintained with high levels of material shrinkage?
    • Ceramics are exciting and could open a lot of opportunities, but I have no idea where to start with designing and specifying ceramic parts.
    • I know there are some additional issues I haven't mentioned here and certainly some I haven't even considered. Feel free to chime in an any of them!


  • Kinivo Bluetooth module posted on 28 Feb 2014

    Module Overview

    Kinivo BTC 450


    Audio wire colors: Left: blue, Gnd: red/copper twist, Right: green

    Power wire colors: Positive: red, Negative: copper (both are in thin plastic sheaths)


    All switches are NO with 10k pullups to 3.3v

    Has exposed SPI and UART ports

    Remote Overview

    Axxess RF remote

    Been running for almost two years on the same battery! Surprisingly, the plastic is visibly worn where it's been rubbing under my radio.

    • 8 buttons
    • Powered by a coin cell
    • uC is an rfPIC
    • Receiver uses a PIC18F2520

    I used a custom firmware to toggle test points on the receiver when buttons are pressed. I preserved all radio communications so I can still control the radio station or CD track (as if I'd ever want to).


  • Building Mono on a BeagleBone Black (Hard Float) posted on 03 Jan 2014

    I performed this on Ubuntu Saucy 13.10 from ARMhf (running from an 8Gb SD card)

    1. Launch a terminal window/ssh into your BBB
    2. sudo apt-get update
    3. sudo apt-get install mono-complete git automake libtool
    4. Wait a long time (hours)
    5. git clone git://github.com/mono/mono.git
    6. cd mono
    7. git submodule init
    8. git submodule update
    9. ./autogen.sh --prefix=/usr/local --enable-nls=no --with-sgen=yes --with-xen-opt=no --with-ikvm-native=no
    10. make
    11. Wait a long time (hours again)
    12. Ignore the errors and hope they don’t mean anything
    13. sudo make install
    14. Wait some more
    15. Ignore the errors and hope they don’t mean anything

    Post based off of: http://neildanson.wordpress.com/2013/12/10/building-mono-on-a-raspberry-pi-hard-float/


  • RAZR HD Maxx Teardown posted on 10 Oct 2013

    A friend accidentally ran over his RAZR HD Maxx, so I rescued the motherboard and tore it down!

    I wasn't too kind when removing the RF shielding, so the copper is torn off in a few places.

    View image for full resolution.


  • Why the PhoneBloks phone will never happen posted on 13 Sep 2013

    It's a physics issue. Signals in modern devices are extremely high speed; the easiest and cheapest way to combat this is to bring components closer together. For example, the wireless radios, RAM, and processor in all modern phones exist as one chip. They essentially put the CPU and wireless magic on the same silicon die (or on a separate die in the same package) and pop a RAM chip on top ("Package on Package").

    It's a communication issue. All of the ICs in a phone don't communicate over a single bus - almost every one ties directly into specific processor pins. This would restrict block size and placement.

    If we aim a little lower and try for a modular design, the interconnects needed to ensure signal integrity at high speed are still very expensive. This project would require serious economies of scale to succeed. Each high speed component - CPU, RAM, storage, modem - would need an expensive socket.

    Technically, the storage could be put on a socket pretty easily. It's not fast enough to warrant a very expensive socket, but would still add ~$2-5 to the final design. (Keep in mind, that means the consumer would be paying $4-20 extra, just to have the option to upgrade the storage.)

    It's an interoperability issue. Going a little further, even if the device could be built in some fashion - there isn't much standardization in this area. I've spent days wrestling with a display peripheral on a processor to get it to interface with a specific display or video input IC - and that's with the benefit of thousands of pages of documentation, a field application engineer on call, and a ~$15000 oscilloscope. The amount of effort in testing and debugging that would be required to ensure the compatibility of each component would be absolutely enormous.


    All of that said, I think the modular idea is excellent and could be done right - maybe not with blocks as described and - optimally - not with electrical signals. I could see it happening with optical interconnects, but we're a few years out from that. On chip optical interconnects are still in research, but there's a lot of money being put into them. Intel has demonstrated some very impressive optical tech that should come to market within the next five years. Eventually, we may be able to tie ICs together through optical traces for extreme high speed communication.

    Finally, the stated motivation for this design is to reduce electrical waste. The best way to do that in the short term is to ensure devices are more repairable. An emphasis on user-serviceable batteries would make a significant difference in how long our devices remain useful without adversely impacting their cost or limiting their design.

    It's worth noting that the smartphone market is starting to mature. Phones aren't improving by the massive leaps and bounds that they were. The technological differences are trivial - few people notice the difference between a 1GHz and 1.2GHz processor or 1GB and 2GB of RAM. Now, the main thing that separates generations of phones are millimeters of extra display space, grams of saved space, and milliamphours of extra battery life.

    One major driver of phone sales right now is software. This is where the problem lies, not in hardware. Users need the right to unlock our phone modems and bootloaders. Unlocking the modems to allow use on different carriers would give used phones a wider market. Unlocking bootloaders would let users completely replace the original software, adding improvements and features to otherwise uninteresting devices.

    We definitely have an e-waste problem - and I give this person credit for thinking outside the box - but this isn't the solution we need.


    One source, because I'm lazy: IFIXIT


  • Abandoning the EFM32G210F128 Breakout posted on 28 Aug 2013

    I'm officially abandoning my Energy Micro EFM32G210F128 breakout. The design files are all on Upverter and are released into the public domain.

    Energy Micro has microprocessors with native USB, so there's no reason for me to continue working on a design that needs an expensive USB-UART converter. This is a straightforward case of subpar research and some flawed reasoning coming to bite after the design work has been completed.


  • Personal Development posted on 13 Jul 2013

    Earlier this week, I returned from an eight day visit to Toronto, Ontario. I'm from rural New Jersey and, though there are some 'population centers' near me, there isn't anything like a three million person city.

    In some ways, the visit was scary - this was the first time I've ever heard someone get mugged. We ran outside to see what was going on, but there wasn't anyone around. We didn't know what had happened until the police stopped by later to ask questions. Yikes, that's new.

    At the same time, the visit was an amazing experience. The amount of things going on in the city is outstanding. I've never seen a spectacle quite like the Pride parade, nor have I slept in a house so close to a city block full of shops, coffeehouses and interesting people.

    Alright, so I didn't meet many people outside Upverter and friends. I plan to though! That's where my apprehension comes in - I'm a quiet, introverted guy. I stumble over my words sometimes, and I get pretty nervous when more than two people I don't know are listening to me. Giving knowledge, opinions, and speculations to others - using your voice - is one of the most profound facets of the human experience, but it scares the hell out of me.

    I can't say why. Maybe it's because my smoker voice sounds funny. Perhaps it's that I get too distracted trying to pick the right words to keep speaking. I don't really know, but I really don't care. I don't need to understand why I'm bad at socializing to become better at it. Not really.

    I'm going to become a better socializer by tour-de-force. I'm usually the type to grab a book and analyze every passage in an effort to absorb every last bit of information. Not this time - sure, I've done some reading about socializing and such, but I know enough to know I need to approach this problem from a different angle - I need to put myself right in the middle of situations I know I won't be comfortable in, because that's what it's going to take. Sure, I could read all about my problems, but no amount of reading is going to teach me to think on my feet. Nothing I read will help me remember the helpful little facts I wish I could contribute to a conversation. Nothing at all, except for braving the weather and surviving the storm.



    George Hahn.



  • Why I Want to be an Engineer posted on 08 May 2013

    Term paper for a generic Intro to Engineering class.

    Should I be an engineer? Surely this is a question every student wrestles with at some point. Many who ask it may decide not to become engineers. While it may be a tough decision for some, it's a given for me. I love designing, analyzing, building, and testing systems. I thrive on tough situations – there's nothing that gets my brain going quite like a malfunctioning circuit or a buggy piece of software.

    I embarked on the path to becoming an engineer early in life. It began with taking things apart – as a child, I would disassemble anything I was given the chance to. At eleven, I completely disassembled the old laptop my dad had given me so I could replace a noisy fan. When I put it back together, the fan had been silenced and my laptop was lighter by a couple of screws – but it still worked!

    I owe much of my inspiration in recent years to my past – and only – employer. An entrepreneur and engineer himself, he once told me that he used to have a keen interest in bird watching. Once he knew all of the birds in his area, he got bored and moved on to electronics. He hasn't gotten bored yet. I have never had an interest in bird watching, but I certainly have never gotten bored with engineering.

    My boss also taught me the importance of moving the status quo. When I started working at his company, I was given the freedom to work on a number of extremely interesting projects. As time went on, rather than working on important projects that would have an impact on our industry, my time was spent on menial projects that were barely related to my area of interest. When I proposed new projects that would move the company forward and set them up to have products to sell in ten years, they were shot down for being too ambitious, too complicated, or too expensive. When I quit four months ago, the company was scrambling to piece together a prototype that was strikingly similar to something I proposed almost two years before. They were hopelessly behind the industry and will release one or two product iterations that are painfully expensive and time consuming. Even then, they'll probably never catch up. The lesson I learned: move early. If you wait for the market to tell you what to do, you'll always be behind. Sometimes you can succeed by fulfilling a market's obvious demands, but to truly make a difference you have to be the one who reads the cards and takes the market to the next level.

    A desire to move the status quo is why I'm hoping to intern at Upverter in the coming months. They're a small Candadian startup doing work in the electronic design automation (EDA) space. While the product they're creating isn't essential yet, it has the potential to change how we design and test electronic systems. This is no easy goal, but for something that could transform the EDA market before this decade is out, it's worth the effort.

    Engineering is not for everyone, but it is everything for me. I find engineering intriguing, exciting and fulfilling. If I have changed the world by the time I die, I will rest easily. I do not ask to be remembered and I care little if my name stays around, but I want to leave the world a better place than it was when I entered it.