Radio Shack will now stock cellphones, cellphone accessories, Arduinos

A few months ago, we covered Radio Shack’s efforts to suck less, and the Radio Shack DIY team has now come back with the top ten suggestions submitted. Of course Arduinos make the list at number 1, which we somewhat expected for beginner projects.  Here’s the entire list in order:

  1. Arduino
  2. More kits and project suggestions
  3. More introduction/instructional books
  4. Larger LED selection
  5. Larger resistor selection
  6. TONS more capacitors
  7. DIY audio and speaker equipment
  8. HAM radio gear
  9. More competitive pricing
  10. Stronger sales force

Adding video out to the Open Pandora

There’s very few users out there who actually have their hands on an Open Pandora Console. But the ones who do might find this hack useful for getting TV out up and running. It’s actually not hard at all, but if you don’t want to alter the hardware on the device you’ll first have to find a cable plug that will fit the EXT jack. This proved more difficult than it needed to be, since TI carries the connector but only sells them in multiples of 2200. A group buy was organized and we’d bet you can still get in on that action.

The connector in question carries TVout1 and TVout2 conductors. These correspond to the Luminance and Chrominance signals needed for the S-video protocol. But [MarkoeZ] wanted to use a composite connection. Turns out that’s not hard either, he hooked up the ground from the plug to the ground of the RCA jack, then connected both video lines to the center conductor, making sure to add an inline 470pf capacitor on the Chrominance side. Check out the demo video embedded after the break to see the final product.

Continue reading “Adding video out to the Open Pandora”

Using Binary Code Modulation to control LED brightness

Pulse Width Modulation is definitely the preferred method of dimming an LED with a microcontroller, but we were interested in hearing about a different method called Binary Code Modulation. BCM does the same thing as PWM, it turns the LED on and off very rapidly so that your eye cannot detect a flicker. The brightness level is a result of the average amount of time the LED is on versus when it is off. This is called duty cycle and although it can be the same percentage for both PWM and BCD, there is a fundamental difference.

While PWM usually uses a cyclical on/off cycle (30% on, 70% off, repeat) BCD uses a cumulative cycle. As you can see above, each successive bit of binary code carries double significance compared to the previous bit. Now just assign a duty cycle based on your precision, and have an interrupt fire for each bit of the counter. The graph above shows some highs and some lows combining to reach the target duty cycle. An interrupt is used for each bit, and pin changes are made in the service routine.

The benefit of this system is that it is scaleable without adding overhead. You’re already running the interrupts so servicing 8 or 128 LEDs doesn’t have vastly different needs as it would with PWM. The big downside is that the more bits of precision you use, the faster your processor must run so that the eye doesn’t detect the lengthy on or off cycles of the higher bits as visible flickering.

Thank you [Yetihehe] for tipping us off about a link that [Tomas Martinsen] left when commenting about an Arduino library for up to 768 PWM outputs.

Resistor substitution box

[Vincent] on the EEVblog forums had an idea for an inexpensive resistor substitution decade box.

The build uses cheap decimal thumbwheel switches he bought on eBay. Each switch is wired up with resistors for each digit, and each switch is wired up in series. The result is a small, easy to read resistor box with a range of 1 Ω to 10 MΩ.

Continue reading “Resistor substitution box”

Beefy rover looks like tons of fun

mantis_six_wheeled_remote_control_robot

[Eric] and the crew over at The Tech Junkies, just put the finishing touches on a pretty powerful robot that they call “Mantis”.

The six wheel, chain-driven robot is pretty impressive at first glance. The robot is centered around a Netduino, which controls four 60 amp speed controllers. The speed controllers are tasked with driving four beefy CIM motors, which propel the robot along at a pretty decent tick.

For the project, the team designed their own controller application called IPGamepad, which allows the robot to be controlled by any Android device. The interface is pretty simple as you can see in the video below, making it quite easy to control the bot.

While the Mantis was not a cheap production by any means, it does look like a ton of fun to drive. The crew will be taking this robot along with 2 others out to Maker Faire Detroit, so be sure to swing by and say hello if you’re in the area.

Continue reading “Beefy rover looks like tons of fun”

Hack a Day visits LVL1 hackerspace in Louisville

We recently had the pleasure of visiting the LVL1  hackerspace in Louisville, Kentucky. Any hackers in the Louisville area who haven’t visited yet are doing themselves a big disservice.  The space recently had its one year anniversary in July, but it’s hard to tell. The space features many of the things you’d only expect in older spaces such as a laser cutter (added while we were visiting), CNC machines, extensive electronics workbenches, and even a section for those who are into music. The best part about the LVL1 hackerspace is it’s members. We’ve all heard horror stories of hacker spaces with drama or overly restricting rules, but the people at LVL1 are extremely friendly and willing to help.

The Micro Colonel (president, if you wanna go that route), [Christopher Cprek], gave us a tour of the space and its current projects. One of the most impressive is the White Star Balloon project, which aims to fly a balloon across the Atlantic. There’s also the Louisville Soundbuilders which meet at the space every other Monday at 8pm to make new instruments. Some other projects include a telepresence robot, a pony that breaths fire, and a power wheels race car for the Detroit Makerfaire. There are also things such as the Kentucky Open Source Society (KYOSS) that meets at the space. Even a few sumobots were scattered around. We were fortunate that at the same time we were visiting [Brandon Gunn], who regularly does video tours of the hackerspaces he visits, was there too; watch his video tour of the space after the break.

The space usually has an open to the public meeting every tuesday at 7:00, but be sure to check out their calendar for more.  If you’ve never been to a hackerspace before you should definitely make an effort. It’s not the tools that make a space, but the people, and LVL1 delivers.

Continue reading “Hack a Day visits LVL1 hackerspace in Louisville”