A Fifty-dollar Projection Screen You Can Be Proud Of

September 8, 2012 by Mike Szczys 31 Comments

[Lou] wrote in to share the fifty-dollar projection screen he built in his home. We’ve seen several of these projects lately. Unlike the one used at a lake cabin, or the other that fills an awkward alcove, this version doesn’t use fabric for the screen. He actually painted it right on the wall.

The key to achieving a great end product is to make sure your wall is flat. [Lou’s] instructional video (embedded after the break) shows how to patch holes in the wall, and repair high spots. Before beginning the process he uses his projector’s grid feature to map out the portion of the wall that will be used as a viewing area (that’s the grid seen on the screen above). Once the area has been marked with masking tape and carefully repaired he paints it with bright white or silver paint. You might also consider a paint additive for better results. We’ve seen sand blasting beads used for this purpose.

A frame is added to the area to make it look like a proper screen. This is nothing more than molding covered in black fabric. [Lou] stretches the fabric around the molding, using duct tape to hold it in place until it can be stapled down.

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Building The Best Homebrew Computer Ever

September 8, 2012 by Brian Benchoff 22 Comments

A few days ago when I posted a homebrew Motorola 68000 computer spectacular, I briefly mentioned a truly spectacular homebrew computer built by [Simon Ferber]. When I posted a link to a Youtube demo of his 68k board, he was working on a website to document the architecture design, hardware, and software. That website is now up (cache if you need it) and now we can all get a good look at the best homebrew computer ever built.

Built around the 68008 CPU – slightly less capable than the 68000 found in the original Macs, Amigas, and the TI-89 – [Simon]’s Kiwi computer has peripherals out the wazoo. A Yamaha V9990 Video Display Processor provides a 640×480 display with 32k colors. Two SID chips taken from a Commodore 64 provide stereo chiptune audio, and a floppy disk controller, IDE/ATA bus, and CS8900A Ethernet controller provide all the practical functionality you’d expect from an awesome computer.

On the software side of things, [Simon] is running Enhanced Basic 68k, but of course he can’t just use BASIC to fiddle around with all the cool chips on the Kiwi. With that in mind, he came up with a C-based toolchain that included porting libc to the Kiwi.

Like any good homebrew computer project, all the schematics, a bit of code, and a BOM are provided. [Simon] is currently working on (slightly) redesigning the PCB layout of the Kiwi, and we’ll be happy to see those files released. Anyone up for a Kiwi PCB group buy?

Beautifully Crafted Geiger Counter A Must If You Live In A Hot Zone

September 8, 2012 by Mike Szczys 10 Comments

Have a little class when you’re screening for radioactive particles. You can follow the example which [Moustachenator] has set with this gorgeous Geiger counter case.

The business end includes the same Geiger tube we see in all of these projects, but he took the time to solder together a tidy circuit board and housed it in an acrylic tube. it connects to the base unit using a springy telephone handset cord. The laser cut walnut enclosure offers plenty of room for the ATX power supply hidden inside. This feeds the Arduino which runs the system, and provides a powerful source for the Nixie tubes which serve as the display. The attention to detail when it came time to assemble the case is what lends an antique look to the project, even though everything was built from the ground up. Check out the video after the break to see a brief demonstration.

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Rotary And Cordless Phones Mashup

September 7, 2012 by Mike Szczys 5 Comments

This pile of hardware marries telecommunications hardware from distinctly different generations. [Andrew D. Farquharson] wanted the retro look and operation of a rotary phone, with the convenience of a modern cordless. He combined the two technologies to achieve his goal.

The first problem was to find a way to translate the rotary inputs to something he could use. There are already a bunch of projects that use rotary hardware so he didn’t have to reinvent the wheel. He followed this guide to connecting Arduino to a rotary phone.

The next step was to interface with his cordless phone. He ditched the case and soldered rainbow ribbon cable to the entire button matrix. An opto-isolator is used to protect the Arduino while making each connection. Finally, he patched into the mechanism which monitors the cradle to see if the handset has been picked up. It sounds like his code lets you enter the number on the dial, then pick up the handset to actual transmit it through the cordless phone.

Cheetah Robot Can Run Down Even The Fastest Of Us

September 7, 2012 by Mike Szczys 69 Comments

It’s a blur, but you really don’t want to seen this thing coming for you anyway. It’s the latest look at what the folks at Boston Dynamics have been working on under a DARPA contract. They call it the Cheetah robot as it’s the fastest four-legged bot ever developed. The clip after the break shows it breaking the world record over 100 meters… for a human. This isn’t really legitimate since the run is done on a treadmill and the robot is tethered. But it’s still ~~impressive~~ scary.

The Cheetah is a relative of BigDog, another Boston Dynamics robot which we’ve seen several times in the past. BigDog specializes in lifting heavy loads and traversing rough terrain. We don’t think it will be too long before both traits can be “bred” into one device. A lot of times when we feature these robots there are comments about how they invoke images from The Terminator movies. For us this is more along [Michael Bay’s] vision of robots from the Transformers series. It certainly not small enough or fast enough to be seen as an early version of the Rat Thing.

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Scratch-built RFID Reader

September 7, 2012 by Mike Szczys 11 Comments

We never bought an RFID reader because it seems too simple to be all that much fun. But [Abdullah] really caught our eye with his latest project. It’s an RFID reader built from discrete parts, and that’s an adventure we can get behind!

His write-up dives right into the theory of the device. He wrapped his own coil, which measure about one microhenry, then shares an equation used to calculate the appropriate capacitor pair for it. This is fed by a 125 kHz oscillator and works as the most basic reader. In practice this needs more components for rock-solid operation and he quickly moves to a marginally more complicated circuit which still does exactly the same thing.

He is now able to detect RFID tag data by reading this circuit with an oscilloscope. But the signal is very very weak. The rest of the post focuses on how to best utilize an OpAmp to increase signal quality and on/off time.

If you’re looking to recreate his reader [Abdullah] included a Kicad schematic and board layout.

Adding EPaper Navigation Data To A Sailboat

September 7, 2012 by Mike Szczys 27 Comments

[Mike Holden] has been on the hunt for a display that is easy to read in bright sunlight. He wants to use it to read out navigational data on his sail boat. The best option is an ePaper display. He managed to build a system that will feed updating NMEA 0183 data to a Nook Simple Touch.

NMEA 0183 is a protocol that governs data from marine navigational equipment. The most obvious is GPS, but there are a lot of possibilities like sonar, a gyrocompass, and an autopilot. To get things rolling he wrote an Arduino sketch which generates dummy packets using the standard. This let him develop and test the system without being near any of the real equipment. The heart of the build is a WiFi router. It pulls in the data over a USB port using an RS232 to USB converter cable. A Python script parses the data and generates a webpage which refreshes the data every second. This is loaded using Opera browser on the Nook

Check out the video after the break to see a demo of the system.

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