Member Since: May 20, 2010

Country: United States



Rocket Scientist

Spoken Languages

English, Klingon

Programming Languages

Whatever best gets the job done, usually C. My favorite language was Modula-2 (look it up).


WPI, CU Boulder. Degrees in aerospace engineering and computer science.


Spacecraft systems engineering, embedded systems engineering, low-level firmware, 3D graphics and animation, and troubleshooting (but real trouble shoots back).


Hacking (the good kind), scuba diving, dumpster-diving for obsolete hardware, anything that flies (from bees to the Space Shuttle), birdwatching, sending stuff into orbit and beyond.



Sweeping legal changes are afoot that could change the hobbyist airspace for years to come. Your input can make a difference.

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CubeSats will soon be traveling beyond LEO, and are available in a new compact size. We check in with the people pushing the limits.

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On April 5th, teams from around Colorado will try out their miniature Mars rovers in the Great Sand Dunes.

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How to handle the child for whom disassembling their toys is more fun than actually playing with them.

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SparkFun returns to the AIAA Small Satellite Conference with more people, more stuff, and export-controlled sombreros.

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What did you do on your summer vacation? These students are launching experiments on government sounding rockets.

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You've just finished your new project. Before you apply power, here are a few tips to keep the smoke in.

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Mike and Pete take a road trip to an innovative aerospace conference to find out more about the final frontier for amateur spacecraft makers

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Rock-climbing researchers use clever dataloggers to solve a migration mystery and help save a species.

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Your Personal Black Box

Inexpensive sensors and storage are giving us the ability to record our lives, revisit the past, and sometimes solve mysteries.

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Sam Berrada dropped by to show off the sign language to speech system he designed. Did we mention he's in the 8th grade?

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Cackling Apple Head Witch

October 30, 2014

Make your own cackling apple head witch to scare all of the trick or treaters this Halloween!

LTC4150 Coulomb Counter Hookup Guide

September 18, 2014

A "Coulomb Counter" is like a gas gauge for your battery. Here's how to use it.

BMP180 Barometric Pressure Sensor Hookup

January 9, 2014

The BMP180 is a barometric pressure sensor, this tutorial tells you how to use it.

TSL2561 Luminosity Sensor Hookup Guide

December 27, 2013

The TSL2561 is an light sensor that's very inexpensive for the accuracy it provides. Here's how to use it.

Getting Started with the LilyPad MP3 Player

May 8, 2013

The LilyPad MP3 Player is an amazing little board that contains almost everything you need to play audio files. You can use it to create all kinds of noisy projects, from MP3 hoodies to talking teddy bears. Your imagination is the only limit! This tutorial will help you get started.

What is a Circuit?

February 6, 2013

Every electrical project starts with a circuit. Don't know what a circuit is? We're here to help.

Serial Peripheral Interface (SPI)

January 14, 2013

SPI is commonly used to connect microcontrollers to peripherals such as sensors, shift registers, and SD cards.
  • Sorry for the late reply, this sounds similar to an issue we ran into with the SHT15. As it’s not a true I2C device, it wasn’t playing well with other devices on the bus, and locking everything up as you describe. Take a look at the older USB_Weather_Board code. In particular, we added a “connectionReset()” function to the SHT1x library, and in the main Weaher_Board_3.ino code we turn the I2C peripheral off when accessing the humidity sensor and back on when we’re done with it. This solved our bus lockup issues. Note that this code is for the SHT15 not the HTU21D, but they appear quite similar to each other so it may help here as well. Good luck!

  • If you’re using Sparkfun’s 12V inverter, make sure that the switch is in the fully-on position. There’s a middle position that blinks the output.

  • I’m not sure what the first line is (OpenLog diagnostic information?), but the following lines starting with $ are correct NMEA data from the Venus. Seeing lots of zeros means that the GPS hasn’t calculated a proper fix yet. This usually takes several minutes from a cold start, and you’ll know when it happens as the NAV LED on the Venus will change from solid to blinking and the above zeros will fill in with valid data. If the light is still solid after a few minutes, ensure that the antenna is firmly connected and that you’re outdoors with a good view of the sky. If that still doesn’t work, let us know and we’ll keep working on it, but your setup sounds correct from here. Good luck!

  • The Venus and OpenLog work very well together. For the default 9600 baud rate on both devices, just connect them together (connect the Venus' TX line to the OpenLog’s RX line, and GND to GND) and go. If you configure the Venus to use a higher data rate, configure the OpenLog to match (see the tutorial on the OpenLog product page for details).

  • Yes, there is that much energy savings! When using an AB amplifier, you’re actually putting more power into heat than into the speaker (see the power dissipation graphs in the AB datasheet). The class D amplifier runs cold under the same conditions, meaning your battery will last twice as long. The tradeoff is that the THD will be lower (higher audio quality) for an AB amplifier, but unless you need absolute top-quality audio (and have the power to support it), the class D chips are a pretty good choice.

    Sorry about a lack of ruler in the pictures, I’ll see if I can’t get it into the queue for a reshoot. Also sorry about the units; as engineers we’re disappointed that we still haven’t switched to SI (and likely won’t in the foreseeable future).

    Also, if you’re looking for a more powerful AB amplifier, check out our Amplifier Kit.

  • If you’re programming using the Arduino IDE, check that your board selection has the same crystal frequency as your homemade board. There’s a frequency variable in the board definition file that the compiler uses to select the right dividers for baud rate, etc. If that doesn’t match the actual crystal, the timing won’t be right.

  • The EL Escudo uses Arduino pins D2 through D9 to control the eight output channels, and wants power on VIN and GND. If you don’t need all eight channels you can just connect the control lines you do need.

  • You said “non command line” but if you ever need to upload hex to an AVR with the Uno bootloader on it, you can use something like:

    avrdude -F -V -c arduino -p atmega328p -P COM5 -b 115200 -U flash:w:blink.hex

    It’s pretty easy to stick this into a makefile, batch file, shell script, or menu item if your IDE is flexible enough.

  • Sort of. You do have control over the pitch and inflection of the allophones, and can play with those values to emulate a female voice. But note that it will always sound somewhat robotic - think Steven Hawking’s voice synthesizer. Good luck!

  • This amp shouldn’t have a problem driving either speaker (or even much larger ones). Is it very quiet or is there no sound at all? In case your 2" speaker is defective, can you try a different one or measure any resistance across it? Contact our tech support department, they’ll be happy to help you out.