Hackaday links: October 17, 2010

Cards you should crank

These greeting cards must be the product of a mechanical engineer run amok. They come with a crank and are designed to entertain with their simple, yet elegant movements. [Thanks Phil]

Magnetic card stripe reader

[JP] built an Arduino based magnetic card reader. It uses off-the-shelf parts but if you don’t mind buying the components this will get you up and running in no time. If you want more info there’s also this Teensy based version.

Homemade Airsoft sentry gun

This sentry gun has an amazingly fast firing rate that can continue for quite a while, thanks to the big flashlight housing that is holds a lot of ammo. [Thanks David]

Scanner easter egg

The engineers over at HP had a little fun building an easter egg into this scanner. If you know what you’re doing you can get it to play the Ode to Joy. It needs to join the old-hardware band from our Links post earlier in the month. [Thanks Googfan]

Cheap(er) biometric gun safe

[Greg] sent in his biometric pistol safe lock. He keeps his guide light on details so not every Joe can crack the system (there is a thread to sift through if you really wanted to), but the idea runs fairly simple anyway. [Greg] took an old garage door opening fingerprint scanner and wired it into a half broken keypad based pistol safe. While he did have some issues finding a signal that only fired when the correct fingerprint is scanned, a little magic with a CMOS HEX inverter fixed that problem quick.

This does bring one question to our minds, are fingerprint scanners as easy to crack as fingerprint readers?

Ditch the LPs and build your own 3D scanner

Find yourself an old record player, a laser level, and a digital scanner and you can build a 3D scanner. That’s what [Rob] did. The camera and laser level are mounted on the turntable for steady rotation. The camera captures the vertical laser line traveling around the room by recording 30 fps at a resolution of 640×480. This data is then translated into a Blender 3D file via a Python script and the Python Image Library. You can scan a whole room or just a small object. The face above is the result of this image capture after a bit of processing. [Rob] found this worked best in the dark and when scanning surfaces that are not reflective.

Make sure you also check out the camera-and-projector scanning method.

Update: Realtime 3D for you too!

[Kyle McDonald] has kept himself busy working on 3D scanning in realtime. He’s posted a writeup that takes us through the concepts, tools, and assembly of a DIY 3d scanning camera. You should remember a preview of this method posted earlier this month, but now it’s time to build your own. You’ll need a camera, a projector, and some open source software to process the image data. Using these simple tools, [Kyle] turned out much better video than before. Take a look after the break to see his results from scanning at 60 fps using a PS3 Eye. The trick to this setup is getting the correct synchronization between the projector and the camera, something that could be improved with a bit of extra hacking.

Does [Kyle's] name sound familiar? It should, he’s got a long history of quality hacks that we’ve featured over the years. If you’re looking to use a scanner as a multitouch, add some music to tea time, or play with your skittles his work will give you a shove in the right direction.

[Read more...]

Panoramic scanner camera

[Photodesaster] put together a panoramic digital camera using a scanner and some miscellaneous parts. You may remember seeing something like this about six months ago and originally about five years back. The parts used here work together nicely. The sensor board from the scanner is mounted to a metal plate along with a 50mm lens. The plate is mounted to a hard drive platter that is turned via belts connected to the original scanner motor. This way, when you tell the computer to scan an image, the lens is rotated to capture the panorama. The use of an 18V tool battery is a nice portability hack for the scanner circuitry.

Judging from this 71MP image he has achieved some remarkable results.

[Thanks Stefan]

LEGO book scanner

Here’s a good one from a few years back. [Muranushi] built a scanner to automatically scan an entire book. LEGO is used as the primary building material. A book is placed on a LEGO balance (inset photo) with a counterweight that eases the work of raising and lower the book. The book is lowered, a LEGO carriage moves across the book to turn the page, the book is raised to the glass of an upside-down scanner and scanned into a laptop.

It seems LEGO and imaging devices are a great match. Most of the parts used here are from LEGO Technical set 8485, a set that comes with motors and a motor controller seen above, on the floor behind the computer. We’ve embedded some video after the break of a book in the midst of the scanning process. [Read more...]

Slide digitizer

Remember slide shows? The ones that used a carousel projector and real slides? [Brian] wanted to bring his slides into the digital age but was spending far too much time scanning in the 35mm relics. He set to work and built a rapid slide digitizer using a projector, a DSLR, and a microcontroller.

His system centers around an AVR microprocessor, the ATtiny2313. Some DIP switches are used to set the number of slides to be scanned, and the timing for synchronizing the projector and the camera. Using two relays, the cable release for the DSLR and the remote advance pins on the slide projector are connected to the AVR. [Brian] used a macro lens and sets the focus, exposure, and f-stop manual. Once everything looks good the touch of a button quickly steps through the entire carousel at about 1 slide per second. A small video of the process is embedded after the break and his writeup has some comparison photos between a slide scanner and this setup.

[Read more...]