The Descriptive Camera

Matt Richardson’s Descriptive Camera sends pictures to Amazon’s Mechanical Turk where a worker writes a description of the scene:

The Descriptive Camera works a lot like a regular camera—point it at subject and press the shutter button to capture the scene. However, instead of producing an image, this prototype outputs a text description of the scene.

Via Facebook.

Receiving Oregon Scientific sensors with RTL-SDR


Kevin Mehall got his RTL-SDR dongle and wasted no time in developing a decoder using GNU Radio for the 433MHz transmissions of Oregon Scientific remote temperature sensors (v1 protocol). These devices transmit on 433.9 MHz sending data packets containing the temperature data every 30 seconds. The transmitter uses On-off keying and the 32 data bits are manchester encoded. He uses the GNU Radio osmosdr block to capture signals from the dongle. This project uses GNU Radio from the command line, not the Gnuradio-Companion GUI.

You can find the source code and docs at Kevin Mehall’s GitHub page.

30x Bus Pirate v4 build workshop

Sdixon organized a group build of Bus Pirate v4 PCBs:

Yesterday we held our group build and it was a great success. About 25 people built a total of around 30 Bus Pirate V4c. All but one of them worked! The one that didn’t work resisted some pretty determined troubleshooting and rework so we are assuming there was an etch error in the PCB. We will probably do some more troubleshooting on that one just to satisfy our curiosity on what went wrong with it. But given that at least half the participants had no SMD experience, I think our success rate is pretty impressive.

We did two sessions of about 13 people each and got through the entire build, rework, program and test cycle for everyone in about 3 hours per session. I wasn’t quite sure that would be enough time but, with some careful planning and setup, we managed it.

Thanks for your support. We had a lot of fun building the BP.

Via the contact form.

O’Reilly video: Intro to Gestural Interfaces with the Microsoft Kinect


This webcast by Greg Borenstein presented by O’Reilly offers a solid introduction to building your own applications with the Microsoft Kinect. Beginners will find a wealth of information about the Kinect’s theory of operation and how to use the data it generates to work with Arduino, Processing and other frameworks. The importance of the calibration process is highlighted as well as how to access user joint positions in 3D and use this information in user interfaces and creative tools.

Greg is the author of Making Things See: 3D vision with Kinect, Processing, Arduino, and MakerBot from MAKE.

Another fantastic Free PCB Sunday: Pick your PCB from the drawer!

We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service.

This week we have a guest PCB, the SARduino 644/1284 (by Andrew Schamp).  Use your coupon to pick this PCB, or any other in the free PCB drawer.

You get unlimited free PCBs now – finish one and we’ll send you another!

Don’t forget there’s free PCBs three times every week:

  • Tweet-a-PCB Tuesday. Follow us and get boards in 144 characters or less
  • Facebook PCB Friday. Free PCBs while you wait for the weekend
  • Free PCB Sunday, right here on the blog

Continue reading “Another fantastic Free PCB Sunday: Pick your PCB from the drawer!”

App note: The effect of power supply noise on oscillator phase noise

TI on limiting phase noise from oscillators [PDF!]:

This report provides the description of local oscillator (LO) phase noise degradation due to supply noise. Brief theoretical information supported by experiments carried out to demonstrate this degradation is discussed. The importance of selecting appropriate low-noise LDO (low-dropout) linear regulators is discussed.

App note: Driving capacitive loads with op amps

How to drive capacitive loads with op amps. Operational  amplifiers that drive large capacitive loads can have problems like oscillation and peaking. This article describes how to anticipate and limit theses problems:

Other problems include: reduced bandwidth, lower output slew rate, and higher power consumption. This application note explains why these problems occur, how to modify the op amp circuit for better performance, and how to quickly compute circuit values.

What do digital radio modes sound like?


With the growing popularity of digital radio data monitoring using SDRs, the question arises “exactly what digital data protocol is being received?” It’s easy to tell the digital data from analog transmissions like SSB, FM, AM and CW, but sometimes it’s difficult to even discern radio data transmissions from RF noise. And when you recognize a digital transmission, which mode is it?

Gary Hahn, Amateur Radio Licensee KB9UKD, has amassed a comprehensive collection of audio clips of various digital modes on his Digital Modes Samples website. PSK31 is an easy one to detect aurally, but can you pick out JT65A? APCO P25? MFSK? After checking Gary’s site you’ll have a better idea of what modes you’re hearing, and be able to know what demodulation software to use. Also see his links to mystery modes and to sites with additional amateur radio mode sound files.

App note: Calculating the error budget in precision DACs

How to chose a voltage reference and digital to analog converter chips to get the precision and stability you need:

This application note focuses on Maxim’s 3-terminal voltage references and precision DACs. To design a system, one must first understand how the parts are specified and then how their performance characteristics interact. Voltage references and DACs have many specifications. Only those factors relevant to the error budget will be discussed here.

Machined acrylic case for the Bus Pirate

Vibrolax machined a case for his Bus Pirate:

It was made from a scrap piece of 0.125″ acrylic sheet. My co-worker Arpad gets credit for the smooth edges, as he machined it on a Bridgeport mill. The 4-40 standoffs provides clearance between the top sheet and the Bus Pirate. A single washer provides clearance between the Bus Pirate and the bottom sheet. We machined a shallow pocket into the bottom sheet under the main connector to provide clearance for the through-hole pins.

 

See our case video from a few weeks ago, and even more awesome DIY cases from Bus Pirate fans.

The Bus Pirate is a hacking multi-tool that can talk to many common electronic chips. Get the Bus Pirate DIY edition PCB from the PCB drawer for $3.95. Get an assembled Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.

Via the forum.

 

Olinuxino 1.2 GHz single board computer

Development board maker Olimex is brewing up a single board computer, the Olinuxino. The latest revision uses an 1 GHz ARM Cortex A8 based Allwinner A13 SoC, which by the way, comes in a very reasonable 176pin TQFP package. For reals. The new board will feature:

  • A13 Cortex A8 processor at 1000Mhz, 3D Mali400
  • 512 MB RAM
  • USB High Speed Host
  • USB OTG
  • SD-card connector for booting the Linux image
  • VGA video output
  • Video Camera interface
  • Stereo Audio Input
  • Stereo Headphones Audio Output
  • UEXT connector for connection of different peripherial modules
  • Optional low cost WiFi module
  • Optional low cost 7″ LCD with touchscreen

Via the forum. Thanks nabilt.

Super Boost 3.6A USB charger based on LM2700

Scrawny 500mA USB charger insufficient for your hunger for power? Try this 3.6 amp USB charger based on the LM2700 boost switch-mode IC.

This design is inspired by the Minty Boost but it fixes some of the issues that I had with it. The Minty Boost is limited to 600mA due to the LT1302 chip. The Super Boost uses the LM2700 which can push up to 3.6A. This will enable i-devices to draw up to there maximum of 1A which will enable a faster recharge.

This project is open source hardware, and all the design files are available.

Free PCB coupon via Facebook to 2 random commenters

Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. More PCBs via Twitter on Tuesday and the blog every Sunday.

This week we have a guest PCB, Digital Picture Frame with clock and thermometer (Erick Aubin).  Use your coupon to pick this PCB, or any other in the free PCB drawer.

Don’t forget there’s free PCBs three times a every week:

Continue reading “Free PCB coupon via Facebook to 2 random commenters”

Dongle Shootout: Funcube vs RTL SDR


Kanal von MegaOscarVideos from Germany presents a two-part video comparision of the Funcube dongle and a RTL-SDR DVB-T dongle, in this case a Hama Nano version. The two devices are connected to the same antenna and using identical test systems from a geostationary INMARSAT satellite to compare received signal to noise ratios (SNR).
Continue reading “Dongle Shootout: Funcube vs RTL SDR”

Week in (p)review April 27, 2012

Here’s a summary of major developments over the last week. Free PCB Friday is coming up soon.

Coming up:

  • A new workshop video next Thursday
  • Free PCBs via Facebook on Friday
  • App notes on the weekend
  • Free PCB Sunday
  • New 3D model on Monday
  • Free PCBs via Twitter on Tuesday
  • Weekly roundup and preview every Friday

What are you hacking this week?

XC9572XL CPLD breakout free PCB build

Schazamp built a free XC9572XL CPLD breakout board. CPLDs are programmable logic gate arrays that allow you to build custom logic devices simply by programing them.

If you build a free PCB we’ll send you another one! Blog about it, post a picture on Flicker, whatever – we’ll send you a coupon code for the free PCB drawer.

Get an assembled XC9572XL dev-board  for $15 and CoolRunner-II development board for $15.

Bus Pirate case from a mint tin

Kaeso made a Bus Pirate case from a mint tin. The Bus Pirate is a hacking multi-tool that can talk to many common electronic chips.

See our case video from a few weeks ago, and even more awesome DIY cases from Bus Pirate fans.

Get the Bus Pirate DIY edition PCB from the PCB drawer for $3.95. Get an assembled Bus Pirate for $30, including world-wide shipping. Also available from our friendly distributors.

Via the contact form.