Random Projects

QR Code Resume

Mon, 15 Aug 2011 20:50:12 -0500

I’ve been fascinated by the versatility of QR codes for a while, but I have been unimpressed by their complete lack of human-readable information. The recipient rarely has a good indication of where a QR code will take them, so I am generally reluctant to scan any random code I see.

After reading this post on Hack a Day about putting logos into QR codes, I decided to make job-hunting tools out of QR codes modified to be human readable. The trick is that QR codes contain a lot of redundant data for error correction, up to 30% of the code’s area can be covered up and it will still remain a readable code. That allows you to provide some human readable information, a logo, or other fun graphic element.

I decided to create two job hunting tools: a QR code resume card and a QR code business card.

My business card uses the bubbly erlenmeyer flask logo from my chemhacker project as a personal logo. When scanned, the business card (printed at standard US business card size) adds a vCard with my contact information and a link to simple switch labs to the recipient’s contact list.

When scanned, my resume card (printed on a standard 3x5 card) takes the user to a special URL I’ve created that contains my contact info and a PDF version of my resume. The resume card uses a paper-and-star icon which is also used in the special contact info URL, for consistency.

To create these documents, I used this excellent QR code generating website to create scaled vector graphics, and then I created the business and resume card layouts and logos in Inkscape.

Note: no, that’s not a mistake-- all the QR codes photographed in this post point to the same place: simpleswitchlabs.com, to protect my personal information.

Prusa MDF Verticies

Mon, 4 Jul 2011 23:54:15 -0500

While in the process of attempting a build of a RepRap Prusa from cast parts, I discovered a problem: since the verticies weren’t drilled exactly in line, my printer was impossible to make square and level.

I also discovered that printing a new set of six verticies would take about 6 hours because the verticies are the most massive portions of the printer.

I came up with a solution to both problems: make verticies out of 3/4” MDF, but cut and drill them in a way that all the holes are automatically straight and level.

Here is the pdf template with instructions.

Thanks to Steve Finkleman, Tim Saylor, and Dan Meyer for coming up with this idea with me.

French Press Crema Hack

Fri, 24 Jun 2011 16:31:18 -0500

I make my daily coffee in a French Press (aka: a press pot) - a lovely, inexpensive, fast, and easy way to make a great cup of coffee. I have a fairly common Bodum glass, metal, and plastic press pot, and I use medium-ground coffee (a barista friend tells me that this is actually best for press pots, but other people disagree).

I noticed that when I actually press the coffee, there is some lovely crema (foamy coffee, for normal folk out there - it helps enhance the flavor of the coffee like the head on a beer) on top of the coffee, but when I pour the cup out, most of that beautiful crema is sadly left behind.

The culprit is the safety lid! That filter isn't doing anything useful except for filtering out the crema.

Most press pots have the following parts:
Beaker Assembly:
• Beaker (usually glass, mine is ) - where the actual liquid and coffee grounds reside.
• Carrying handle (metal, plastic, wood) - supports and protects the beaker, insulates your hand from the hot liquids
• The beaker assembly is usually separable for cleaning.

Plunger Assembly (bottom to top):
• Lower filter support (metal) - attaches the filter to the plunger handle, contains threads for the plunger handle. Spin counter-clockwise to remove.
• Filter (nylon or wire mesh) - performs the actual coffee filtration. Comes off with the lower support.
• Upper filter support (metal) - presses the filter firmly against the glass surface, attaches the filter to the plunger handle. Comes off with lower support.
• Plunger nut (metal) keeps the filter and supports together. Spin counter-clockwise to remove.
• Lid (metal or plastic) - prevents spilling, keeps the plunger aligned properly when pressing. Pulls off after the Plunger nut is removed.
• Plunger handle (metal threaded rod with plastic handle) - holds the assembly together and transmits force to the filter

Take everything apart and wash all the parts thoroughly. If you're anything like me, this will be the first time you've done this messy task.

If you learn nothing else from these instructions, I hope you learn how to disassemble your filter and clean it (it'll be disturbingly gross - mine certainly was).

Using a Dremel (or other rotary tool), gently cut away the lid opposite of the filter opening (I used the Bodum logo as a convenient guide), leaving a clean hole for coffee to flow through unimpeded. Try to clean the edges nicely (you may want to use a file or a little sandpaper).

Wash the lid thoroughly before your next use, reassemble (assembly is just the reverse of disassembly), and pour yourself some coffee with crema intact.

Transmissometer

Sat, 30 Apr 2011 18:11:56 -0500

Built a device I dubbed a Transmissometer - it measures the ability of laser light to pass through a sample, and I can use that to calculate the concentration of an ingredient in my sample.

This project was in support of my ruggedscents project.

There are lots more details, including photos, schematics, theory, and source code here.

Update: All project details moved to my chemhacker website instead.

Circuit Board Guitar Picks

Sat, 5 Feb 2011 23:49:33 -0600

I’ve wanted to attempt this for a while, and a few ancient Dell laptops were recently donated to PS1, so I removed a few circuit boards and got working.

Ingredients:
• An old circuit board you don’t need anymore (boards with surface mounted components are easier, but anything works)
• Clear coat or polyurethane spray.
• Heat gun (soldering irons work too, but heat guns are faster)
• Leather or heatproof gloves
• Scroll saw, band saw, or hacksaw
• A guitar pick (a template)
• A flat head screwdriver, needle nose pliers, or other tool for removing the components.
• File, sand paper, anything to do final shaping and cleanup.
• Eye and breathing protection (circuit boards are made from fiberglass, don’t inhale fiberglass dust)

Directions:
Step 1: put on gloves and use the heat gun to desolder the components - take them off with pliers or a screwdriver if you need to.

Step 2: trace your template and cut out the rough shape of the pick. Use eye and breathing protection on this step.

Step 3: sand or file the edges to achieve your final shape and round all corners. Use breathing protection on this step.

Step 4. Clean the pick and spray with a light coating of polyurethane. Use breathing protection on this step (or do it with lots of ventilation).

Step 5. Play some Stairway.

Update:
Now that I’ve had a chance to play with this pick for a while, I have a few notes:
First, it’s got some nice texture, so it’s easier to hold than your average plastic pick.
It’s also pretty rigid - definitely a heavy pick, which is good if you really want control.
Finally, due to the texture, it has a bright sound: it grabs the strings a bit when you strum, and it’s a pretty efficient transfer of strum into sound.

Update 2:
I’ve made a new set of these picks using a new technique: I’m cutting the circuit boards with tin snips instead of a scroll saw - this gives me better control and a much nicer end result. I’ve also finished the pics with a coating of spray lacquer.

This set were made from memory and motherboards:
This set were made from a laptop’s touchpad (the center one has the synaptics logo):
These new picks are still on the heavy end, but the smoother lacquered surface doesn’t grip the strings and play as brightly - they now sound like normal heavyweight picks.