[Ito-Brazil] pointed out N-Labs simple current limiter for stepper motors. A current limiting system will let you run stepper motors at higher speeds, with greater torque and efficiency without overheating. This particular design is meant to improve upon the common L/R and Chopper drivers. It can handle high voltages without using large resistors and is high performance without using expensive ICs.
[Mac Cody] wanted to add a digital compass to his robot. He thought the idea of the affordable Dinsmore 1490 digital compass using 4bits to transmit 3bits of data was ridiculous. He decided to build his own 16 point digital compass instead. The compass has four pairs of IRLEDs that reflect off of a gray code wheel. Each concentric track on the wheel represents 1 bit. He ran into some trouble when the compass magnets were being thrown off by the component leads. It just required a bit of tweaking to get right. Mac isn’t sure that this is the most cost effective way to gain one more bit of precision, but he did enjoy the experience and gained a greater appreciation for commercial units.
Wire wrapping is a quick and reliable way to build prototypes and one-off pieces of hardware. The multiple cold welded joints makes it even more reliable than PCBs in certain environments like high vibration. [Justin Jones] couldn’t find his favorite wire wrapping tool or anyone selling a replacement so he decided to improvise. He constructed a new tool using a pen tube, small screwdriver, and a bit of metal cut from a floppy disk. The only thing it’s really missing is a built in wire stripper.
Hack-A-Day reader [al cohen] was pretty perturbed by Staple’s Easy Button campaign since nothing in business is easy. So he decided to modify their cute button (PDF). He replaced the guts with a cheap recording circuit from RadioShack. He also added a 1/8 inch jack so you can record directly from the computer. The new button doesn’t need a separate mic either; you can record by speaking into the speaker. As a final touch Al ground off the easy, polished it and made the button evil. You can watch a video of the button declaring his distaste for Spam. You might have seen Jeff Caylor’s previous abuses of the Easy Button on Make. My roommate thought it would be funny if someone wired it to generate the “shift+delete” key sequence.
[lain]’s newest wearable project features two 21×10 dot displays (front and back). The panels are constructed from 5×7 LED modules from HP. The display is driven by an AVR ATMEGA32L. The 21×10 matrix would require 31 wires, but lain implemented a shift register so only 4 wires are needed. The hat has a microphone so it can do beat detection and VU display. It can also scroll space invaders, play pong and show text. The batteries and control board are in the ear flaps. Lain keeps referring to this as the perfect summer season hat which I can’t understand since today it’s going to hit 101degF at my house.
[don] built this RC car using two $10 cordless screwdrivers and a few parts from his bin. He cracked open the screwdrivers and relocated the switches to the outside. These micro-switches are activated using some servos and radio gear he had laying around. For as little time as it took to build, the car seems pretty serviceable. He mounted a camera to a turning servo so he could see the car’s perspective. The camera looks into the turn so it’s easier to drive the car than if it was in a fixed position.
[xander] sent in links to two machines designed to solve padlocks automatically. The first one just modified an old robot project since it already had the necessary stepper motor. The second one was built from scratch and includes a solenoid to test the lock. Both systems are just brute forcing the combination, but they do use some shortcuts. Even though locks have 60 numbers there is less than 20 actual divisions. Also, multiple final numbers can be tested without putting in the first two. With these two shortcuts there are approx. 400 passes. These machines can solve a lock in about 30 minutes. Of course we’ve shown before that any human can solve one in about 10 minutes.
