Monday, May 6, 2013

KNSU Rocket Motor Test with 3D Printed Nozzle Mold

I successfully fired a static test of a KNSU propellant motor. I had it set up to measure the resulting thrust with a load cell and FubarinoSD.

Sunday, May 5, 2013

3D Printed Rocket Nozzle Mold

I have tinkered with small PVC rocket motors using sugar fuels in years past thanks to information posted by Richard Nakka, Dan Pollino, and Jacob's Rocketry. The frustrating part of the build, particularly for smaller diameters, was the nozzle. After building a 3D printer, it was time to print my own nozzle molds.

Nozzle molds on print bed.

Monday, March 25, 2013

BasicSDAudio Alpha Release and Demo

I have posted an alpha release of the BasicSDAudio library on GitHub! Check it out here. It is capable of 78125Hz stereo PWM audio outputs read from an uncompressed RAW file on an SD card. Psuedo 16bit playback should also be possible.

Also, here is a quick demo of the library running with my BabyBOOMER amplifier/buffer/filter prototype at 78125Hz, 8bit, mono output:

Testers and collaborators are welcome. Future improvements to the library include:
  1. test stereo pseudo 16 bit playback
  2. test higher output frequencies
  3. auto called worker routine
  4. efficiency improvements
  5. multiple simultaneous file playback?

Monday, March 18, 2013

RAMPS 1.4 Now Available for $65!

Head on over to the Store and order one today. Any questions? Ask them in the comments section here. 

Note that we can only ship to US customers at this time.

Sunday, March 10, 2013

Wine Bottle Hydroponic Planter Tutorial

For Christmas every year, we pick a hand-crafted gift to give to, friends, coworkers, the ladies at the sandwich shop...everyone.

Our Yuletide production line was cranking out a fun one this past year, Wine Bottle Hydroponic Planters. Follow these instructions to make your own!

Monday, February 25, 2013

BabyBOOMER Audio Amplifier and Filter Prototype for Arduino/ChipKit

Here is a prototype of one of my circuit boards for the planned BOOMstick Audio board family. This series was introduced in my previous post. It is intended for use with Lutz Lisseck's SimpleSDAudio Arduino library and my port of that library to ChipKit, BasicSDAudio. Really, it should work for any PWM-based audio system, including the Tone library.

Top side of the BabyBOOMER Audio board prototype
Here are the goals I was trying to meet with this board:

  • small (only 0.56 sqin)
  • breadboard friendly (basic 0.1" headers)
  • at least 1W speaker output using 8ohm speaker (efficient class D amplifier)
  • easily accessible volume control (right out on top)
  • lower PWM noise including buffers, filters, and a pseudo 16-bit mode

Bottom side of the BabyBOOMER Audio board prototype
I did a preliminary test just running the ToneMelody Arduino example sketch with a 4ohm speaker. It was *very* loud for such a small board. I had to run off a battery since my wimpy USB cable cannot reliably supply 5V with the estimated 2W output using a 4ohm load.

Time for some real testing!

Sunday, February 24, 2013

$65 RAMPS 1.4 Boards Available Soon!

I will soon have RAMPS 1.4 fully assembled circuit boards available for sale on my Store page. 

The price will be $65 USD with free shipping!

RAMPS 1.4 with only SMT components mounted. $65 price is for the fully assembled board.
This board is used along with an Arduino Mega (or compatable) and Pololu Stepper drivers to create the most common 3D printer controller.

I expect to start sales in the next couple weeks, so stay tuned.

At least for now, I am only prepared to make sales to US customers. If you are outside the US and interested in this board, please vocalize your desire in the comments section.

*Assembled in USA*

Saturday, February 23, 2013

Prototyping with OSH Park

Thanks to a tip from an awesome open source project (FreeIMU) a few years ago, I started using DorkbotPDX for circuit board prototypes. Since then, Dorkbot consolodated its PCB fabrication service onto a dedicated site,

For a flat area rate and free shipping, you can get professional grade circuit boards that not only look good, but are easier to assemble than homebrewed options such as etching or routing. You pay $5 per square inch for 3 copies of a two layer board and $10 per square inch for 3 copies of a four layer board.

I wanted to test some mosfets that I found on Digikey for use with an outdoor laser tag system I am working on. I drew up the circuit and layed it out in Eagle, exported the gerbers and uploaded them to OSH Park.

OSH Park Order Page
$1.20 and two weeks later, I had 3 boards in hand, ready to solder.

My MOSFET_breakout board ready for breadboard testing 
OSH Park can deliver such great rates for prototype PCBs because it is a panelizer. It collects dozens of different PCB designs in order to fill a much larger panel. This mosaic panel is what is sent to the PCB fabricator. When the panel comes back from the fabricator, it is broken up and sent to the correct addresses. This effectively gives everyone on the panel a quantity discount, even if their order was only a few square inches.

The quality of the boards is superb. If you are looking for prototype PCB service, use OSH Park!

Wednesday, January 23, 2013

3D Printing from Thingiverse!

So you've got a 3D printer and want to get started printing right away without designing anything? Visit You can always find something useful or at least interesting to print. Check out some of my early prints on my modified MendelMax 3D printer.
My print of chopmeisters "Roundom Vase"

My print of  Landru's "Rocket Shot Glass"
Also, take a look and follow my thingiverse page (cobra18t on Thingiverse) to stay up to date on my "things" that I post.

Happy printing!


Tuesday, January 8, 2013

BOOMStick Audio Modules

The SnakeEyes V0.02 board has most everything I want but still needs some tweaking. I did not like the 0402 components, so I am going back to 0603. Additionally, I think people are interested in having exactly what they need and not much else in order to save costs. With that in mind, my next iteration of the audio board will actually be a small collection of breadboard-friendly modules:

Closest derivative to the V0.02 but only mono output. This will have a buffered SD Card, buffered PWM, improved 1W class D audio amplifier, headphone jack, and volume control.

Pared down version that scraps the headphone jack and SD card support. This can be paired with the BOOMStick for stereo output. Or, two BabyBOOMERS can be used with a SD-enabled microcontroller, such as the Fubarino SD, for an even more streamlined stereo output with 1W output per channel when using 8ohm speakers.

BabyBOOMER prototype

These will be small breadboard friendly speakers with current limiting resistors

Stay tuned for more development...


Monday, January 7, 2013

SnakeEyes Audio Boards

A few months ago, I started work on an audio board for Arduino and Chipkit microcontrollers. I wanted something that could play good quality sound effects and music with a small form factor.

SnakeEyes V0.01

My first attempt was a mash up of an Arduino Pro Mini and the same functional structure of the Adafruit Wave Shield. I wanted something that could play all by itself when given a few commands. The host processor would then be free from the low-level audio generation. Small speakers were to be soldered directly to the board in the space above the SD card. This was not a good design from a manufacturing standpoint and frankly, I am not a huge fan of Atmel microcontrollers. I abandoned the project for a while since I was discontent with the results with this board.

SnakeEyes V0.01 Audio Board (front and back)

SnakeEyes V0.02

As noted in some of my previous posts, I found Lutz Lisseck's SimpleSDAudio library for Arduino that used high speed PWM to generate audio from a streamlined SD library. I have a working port of the library to the Microchip-based PIC32 Chipkit processors. The library is very simple and requires very little hardware to get basic functionality. To get higher quality sound, however, more circuitry is necessary.

V0.02 of the SnakeEyes Audio board was born. This used a completely different form factor and used SimpleSDAudio type hardware rather than Wave Shield inspired hardware. It sports Stereo 16-bit 78.125kHz buffered PWM audio generation when using a Chipkit board. The host processor handles all audio generation. It has a headphone jack and thumb wheel volume control as well as two small speakers. There is also the option to use external speakers.

SnakeEyes V0.02 Audio Board

Check for the next post about future audio boards.