Misc Hacks

4178 Articles

Machining Custom Robot Parts

December 18, 2008 by 14 Comments

cncrobotparts

Robot Magazine has a great article about how to machine custom robot parts. In this article [Matt Bauer] shows the basics of making custom robot parts and skeletal brackets for his humanoid robot creations using a CNC mini-mill. He uses a custom jig overlay designed to make cutting thin sheet stock much easier and to protect his equipment. This template concept creates a platform for many other custom parts going forward. [Matt] includes the .nc g-code files as well as a “how-to” PDF  in a ZIP file.

900,000 Volts At Your Fingertips

December 17, 2008 by 14 Comments

[Nickademuss] has put together these great instructions on how to build a 900,000 volt Van De Graaff generator. For those unfamiliar, Van De Graaff generators produce massive amounts of static electricity. They are usually the things you see in science centers that make people’s hair stand on end. [Nickademuss] put a lot of effort into this, he created 3D models and diagrams for many of the steps and gave a very detailed step by step breakdown.

A ShiftBrite Christmas

December 13, 2008 by 11 Comments

[youtube=http://www.youtube.com/watch?v=8PVC5jABuB8]

[Garrett] took 30 of his ShiftBrite modules and mounted them to his front fence for Christmas. The ShiftBrite is a serially addressable high output RGB LED. The individual modules are quite adept at applications like this where you’re stringing multiple lights together. They have identical buses on either side, specifically for daisychaining. The installation above looks great.

How-to: Programmable Logic Devices (CPLD)

December 11, 2008 by 57 Comments

Complex programmable logic devices (CPLDs) contain the building blocks for hundreds of 7400-serries logic ICs. Complete circuits can be designed on a PC and then uploaded to a CPLD for instant implementation. A microcontroller connected to a CPLD is like a microcontroller paired with a reprogrammable circuit board and a fully stocked electronics store.

At first we weren’t sure of the wide appeal and application of CPLDs in hobbyist projects, but we’ve been convinced. A custom logic device can eliminate days of reading datasheets, finding the ideal logic IC combination, and then waiting for chips to arrive. Circuit boards are simpler with CPLDs because a single chip with programmable pin placement can replace 100s of individual logic ICs. Circuit mistakes can be corrected by uploading a new design, rather than etching and stuffing a new circuit board. CPLDs are fast, with reaction times starting at 100MHz. Despite their extreme versatility, CPLDs are a mature technology with chips starting at $1.

We’ve got a home-etchable, self programming development board to get you started. Don’t worry, this board has a serial port interface for working with the CPLD, and doesn’t require a separate (usually parallel port) JTAG programmer.

Continue reading “How-to: Programmable Logic Devices (CPLD)” →

Simulated Annealing

December 10, 2008 by 24 Comments

annealing

Here’s an update on our earlier post about genetic programming. Altered Qualia has posted a new implementation of [Ron Alsing]’s idea. It starts with 50 polygons and then randomly changes one parameter with each optimization step. If the the change results in fewer differences from the target image, it’s kept as the new best DNA. This search method is similar to simulated annealing. The image above is the result of 1500 good mutations out of 35900 possible. The implementation lets you choose any image, but smaller means the fitness calculation is faster. It’s written in JavaScript using the <canvas> environment. You’ll definitely get better performance using newer browser builds.

[Original image by R Stevens]

[via Waxy]

WordPress 2.7 Upgrade In One Line

December 10, 2008 by 43 Comments

wordpress

BadPoetry WordPress 2.7 has just been released and features a complete interface overhaul. Hack a Day runs on WordPress MU hosted by WordPress.com, so we got this update last week. We run standard WordPress.org on all of our personal blogs though. We recommend it because it’s free, has a massive userbase, and if you host it yourself, you can do whatever you want with it.

To make the upgrade process as simple as possible (and for the sheer rush of ‘rm -rf’), we use a one line command.

$ curl http://wordpress.org/latest.zip -o "wp.zip" && unzip wp.zip && rm -rf ./wordpress/wp-content/ && cp -r ./wordpress/* ~/www/

curl downloads the latest version from wordpress. unzip unpacks all of the files into a directory called ‘wordpress’. rm -rf removes everything in the ‘wp-content’ directory. Otherwise, you will overwrite your images, themes, and plugins. cp -r copies everything to your http document root, overwriting the previous install.

Naturally, you should back up your current install and database beforehand. We tend to use the one-liner with reckless abandon. If you’re wondering about the terseness, it was designed to fit inside the 140 character limit of Twitter.

[Thanks, Chris Finke]