hudson

I like to take things apart. Sometimes they work when I'm done. I've been a member of NYC Resistor since 2010 and you can see more of my projects at trmm.net.

SparkSign

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Mar 152015
 

Spark Sign at NYCR
Next time you visit NYC Resistor, you might notice a new LED clock above the laser room door. It’s built with a surplus AMD1026 one-line LED display that has been re-brained with a SparkCore. Eventually we might take advantage of it being online to interface with the laser reservation system. For more details on interfacing with the hardware and the source code, check out trmm.net/SparkSign.

Feb 022015
 

NYCR Nail art makealong

NYC Resistor members Colleen AF and Shelby recently led a workshop on nail art during the first of their 2015 Make-Along Craft class series. Many of the participants opted for laser cut stencils to jazz up their nails — it is totally safe and doesn’t involve putting your hand in the laser.

PCB Nail art

I wrote a quick Nail Art HOWTO if you’re curious how the process works. It is very surprising how much fine detail you can transfer with the right nail polish and some practice with the technique. Those traces would work for 0603 SMD parts without too much difficulty if we could find the right conductive paint and power supply.

Jan 262015
 

Wireframed dodecahedron

Sometimes I want to fabricate things that are larger than the build volume on my 3D printer or to make things that are hollow and can be covered with fabric to diffuse LEDs inside. To help out with that, I’ve written a program that will generate 3D printable versions of just the vertices — the resulting object looks like a real-world wireframe of the STL file. This also lets you use other materials for the edges, like wooden dowels, laser-cut acrylic or aluminum extrusion, and makes it easy to cover with stretchy fabric.

Wireframed dodecahedron

The wireframe program parses the STL file, finds all of the unique vertices, eliminates coplanar edges and generates connectors for the ones that remain. It isn’t very smart about some of the intersections of very acute angles, and the output OpenSCAD file needs some cleaning up before it is ready for printing, but simple low-poly shapes can be fabricated without too much effort.

Dodecahedron Connectors

More info is at trmm.net/Wireframe and the source is available. I’ve also posted the dodecahedron that you can make with regular unsharpened pencils from the office supply closet: thing:653464 on thingiverse. I hope you have fun making large-scale things!

Jan 112015
 

We’ve added a new information screen at NYC Resistor on the new wall that we built next to the new laser cutter. It has a Raspberry Pi connected to the local ethernet and boots into a full-screen kiosk display based on the instructions. To do this we modified the /etc/rc.local to invoke Chromium in “application” mode, which has no GUI chrome or user-interface elements:

 chromium --app="$URL"

Right now it shows us current tweets about @nycresistor, although the plan is to add video feeds for a front-door camera, Laser-vision and other stats about the space. Have any idea how to make this display more awesome? Let us know!

Dec 022014
 

Want to drive more LEDs with fewer IO pins? Then you might be interested in the Charlieplexing technique. I’ve written an example sketch can drive six LEDs each with 8-bit PWM using the three IO pins on the Adafruit GEMA microcontroller and is a fairly easy sewable LED sequin project since there are no crossed wires when it is stitched with conductive thread. Enjoy the short video of it in action below and read on for more details…

Nov 162014
 

Are you worried that you’re not paranoid enough about your communications security and want to improve your OpSec? Edward Snowden says to trust in encryption, but you still need to worry about the systems that run it:

Encryption works. Properly implemented strong crypto systems are one of the few things that you can rely on. Unfortunately, endpoint security is so terrifically weak that NSA can frequently find ways around it.

One step towards going “Full-Snowden” is with hardware storage of your PGP secret keys! The Yubikey Neo and Neo-N USB tokens are a neat (and not too expensive) way to keep the secret part of your RSA2048 keys locked in a hardware device rather than stored as a file on your harddrive. The hardware tokens are compatible with the OpenPGP card protocol, which recent versions of gnupg support out-of-the-box. All of the public-key cryptography happens inside the tamper-proof device, so your secret key is never decrypted in the memory nor stored on disk of your machine.

Since setting up the key pairs and transferring the secret ones to the device can be tricky the first time, I wrote a brief guide to configuring Yubikeys as OpenPGP crypto-hardware tokens. They integrate nicely with Apple’s Mail.app (or mutt with gpg-agent), so there is one less excuse for not protecting your email.

Hack Holyoke

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Nov 102014
 

Hardware checkout at Hack Holyoke
Last Friday was the Hack Holyoke 24-hour embedded systems hackathon, held at Mt Holyoke College. Of the 200 participants, well over half were women from the Seven Sisters schools and many were attending their first hackathon.

Hack Holyoke dance party
One of the distinguishing features of this hackathon was a 2am dance party! Every event should include one.

You can read @HackHolyoke twitter stream and read on for some photos of a few of the teams.

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