Breaking Up an Audiobook to Learn Spanish


I have been studying Spanish nearly every day for the last few months. My goal is to be able to hold a conversation in one year. I use a variety of tools to learn (podcasts, duolingo, workbooks, audio lessions).

I am starting to work on my listening skills and have downloaded a couple of audiobooks to listen to. My Spanish is not strong enough to listen to a book straight-through and comprehend very much. I’ve found that I can listen to about a minute of audio at a time and work to translate it into English.

I wrote a Matlab script which breaks up an audiobook into ~1 minute chunks so that I can load them onto my phone and easily listen to a small segment at a time. It would be distracting if these pieces were split mid-word, so I added a simple way to detect silence and only split files during silence. I also added a 1 second pad to the beginning and end of each file and feathered the audio on and off slightly for smooth sound.

I am including the Matlab code and a couple of example clips.


Garden Sunlight Tracking


I am doing a lot of gardening this year (tomatoes, peppers, hops, and a few other veggies). Different plants require different amounts of sunlight. In order to place my plants optimally, I wrote a Matlab script that calculates the amount of sunlight that will reach each area of my yard on a daily basis. Its pretty interesting to see how the sunlight varies throughout the year.

April Sunlight Chart

June Sunlight Chart

September Sunlight Chart

Ferminator 2000


I’ve been brewing a lot of beer lately. One thing I’ve learned is that its important to be able to control the temperature of the beer during the fermentation process. To that end, I’ve designed and built the “Ferminator 2000”:

Ferm 2000

It has the following features:

– Two FET’s to control heater/cooler
– Three inputs: two thermistor inputs and a thermocouple input (Type K)
– SD card for config storage and logging
– Onboard FTDI for usb->serial comms
– DC/DC converter so that the uC power can be pulled from the drive voltage of the heater
– Accurate RTC for time-keeping (added to the second revision).

You can find the board files and the software (still in development) at

It can be used to drive almost any kind of heating/cooling element. I used some flexible heaters that are normally used for heating the beds of 3D printers. By wiring three of the heaters in series (24V), they draw about 60W. This is enough power to heat up a 5 gallon carboy of beer by 5 degrees Fahrenheit per hour.

2012-11-01 13.17.38

I’m still (slowly) working on the Software. Each of the blocks appears to be functional, but I need to setup the whole thing with a gallon of water before I risk it on any beer. :)

Reprap Build Log Part One: Components and Materials


I have used printed parts from rapid prototyping machines for a few projects in the past and they have always made my life a lot easier. This winter I decided to build a 3D printer of my own. I have been following the progress of the RepRap project for a few years now – a RepRap is a 3D printer capable of creating the plastic parts needed to create a copy of itself. The latest version, the Prusa Mendel, strikes a good balance between print quality, cost, and ease of assembly so I figure its finally time for me to jump on the bandwagon!

I did a lot of research before starting the build. The first thing I did was create a Bill of Materials including any modifications I would be making to the basic Prusa Mendel design. I tried to strike a balance between saving cost and keeping my life simple. For example, I soldered together the electronics myself, but I didn’t buy a bare PCB and the components separately, I got the DIY kit from

X ends printed by elderfarrer2hy7 Z Axis Stabilizers

I got my RP parts from ebay user elderfarrer2hy7. The parts arrived in good condition and they all worked well. It looked like they came straight off the printer, but it only took me about half an hour to clean them up with a sharp knife. I bought a kit with SAE RP parts, lm8uu bearings, nuts, bolts, timing belt, and a laser-cut acrylic Y-carriage/bed (I ended up replacing the bed with MDF). Elderfarrer2hy7 was even nice enough to print me some z-axis stabilizers at no extra cost. Overall I would recommend buying parts from this seller.

Aluminum Helical Coupler

It seems like many people have problems with the default Prusa z-couplers. The two alternatives I have seen are Nopheads improved z-axis couplers and some aluminum helical couplers. I bought two aluminum couplers on Ebay from NRG24Seven which have worked very well.

I am confident that the printed gears in the kit would have worked well, but I still decided to invest in some nicer GT2 belts and pulleys. There is a great article here ( that explains why GT2 belts are preferable to the T5 and T2.5 belts often used on RepRaps. On the Y-Axis stepper I used the 42-tooth pulley recommended in that guide. For the X-axis I used one of the metal pulleys that came installed on the stepper motors I bought on Ebay (lucky break!). The 42-tooth pulley would have been too wide for the x motor mount design.

Eckertech Hobbed Bolt

I also opted to pay a little extra to buy a hobbed bolt from Eckertech for my Wade’s geared extruder. I probably could have hobbed it myself just fine, but it is such a critical component I felt the extra money was worth the time I might have otherwise spent troubleshooting extruder problems. So far it has worked great. I have never had to dismantle my extruder to clean the bolt and any problems I’ve had extruding have been my own fault (more on this later).

Heated Build Platform

I payed the money for a MKI heated build platform (HBP). It seems to work well for me hooked straight up to my Ramps board for power. One (minor) annoyance is that the MKI pcb has very small surface mount pads to solder the power wires too. I think they’ll hold, but I used a few strips of Kapton tape to try help hold it in place. I would prefer plated through-holes for the power connectors or at the very least some holes in the PCB to tuck the wires through for strain relief.

Ramps 1.4 PCB Ramps 1.4 Parts

I bought a DIY Ramps 1.4 kit for the electronics. The kit comes with a Ramps 1.4 PCB, an Arduino Mega 2560, all the components for the PCB, and 3 end stops. I bought the optical endstops since I already had some mechanical endstop switches at home. I ended up using a mechanical endstop for the Z-axis and optical endstops for X and Y. I think mechanical endstops are easier to setup and more than reliable enough for the reprap. The kit offers both types at the same price, so buying the opto-endstops is probably a better value.

J-Head mk IV 0.35mm hot end

I bought a J-Head Mk. IV hot end with a 0.35mm nozzle. It has worked extremely well. I have absolutely no complaints. Using PID control in the firmware I am always within 0.2C of my target temperature. I didn’t use any cement to hold the power resistor in place because I know the resistor might fail sometime down the road and I don’t want to have to clean it up. The fit is already pretty tight. The hot end has been one of the most reliable parts of my printer.

I bought my threaded rod at a local Ace hardware store. I bought three of the 6ft 5/16”threaded steel rods for the frame, and a 3ft 5/16” threaded stainless rod for the z-axis drive screw. I bought 8mm precision ground rod at McMaster, part #88625K67. It is important that the smooth rod be 8mm rather than 5/16” if want to get the most out of your lm8uu bearings. All the other parts can be SAE. Since 8mm and 5/16” are so similar, the 8mm rods will fit into any plastic parts designed for SAE rod.

Assembled Reprap - powered by computer PSU

I used an old computer power supply to power the printer.

In Part 2 I’ll describe the construction of the printer, the problems I had (very minor), and I’ll post some closeup pictures of the build.

Suppliers I bought product from:

McMaster-Carr (also a good source for filament)


Automatic Christmas Train


Now that finals are over, I finally have some time to work on the projects I’ve been putting aside over the last few months. The first thing I checked off my list is something I’ve been promising my mother for a couple of weeks.

Christmas Train

We decided to put our Christmas tree outside on the front porch this year. My mom had the idea of setting up the train under the tree and having it automatically move around the track whenever someone came up to the front door. She setup the tree and the train, my task was to make it move.

Generating High Voltage



Note: This project deals with high voltage and is inherently dangerous. I’ve built everything I describe on this page – and it works well for me – but I take no responsibility for your actions. If you decide you are interested in high voltage experiments PLEASE be careful and do so at your own risk.

This is part one of a two part article. On this page I am going to show you how to build a simple flyback transformer driver to generate very high voltages. I had to experiment a lot when I first tried this, so I hope to provide enough detail that anyone reading this can successfully generate a high voltage arc on their first try.