Single LED Ultraviolet Exposure Box

November 30, 2010 by Mike Szczys 40 Comments

[Jacques Lebrac] built a UV exposure box for printed circuit boards using just one LED. He usually makes boards that are just a few square inches and didn’t think building a box that had upwards of 80 LEDs was worth his time. He passed by the low power LEDs for a single 5W unit. Pumping 1.5A through this LED makes for some quick exposures, but causes heat issues. To solve this, an aluminum arm was used to mount the LED, acting as mechanical support and heat sink at the same time. The voltage regulator was glued directly to the chassis, providing at least some heat dissipation.

[Jacques] came up with an eloquent solution for holding the transparency and copper clad in place. A piece of acrylic is hinged on the back using a piece of aluminum tubing. The front has a magnet glued to it, with another one in the base to hold the cover tight to the work surface during operation.

Hacker Classifieds Featured Find: Thin Clients On The Cheap

November 30, 2010 by Caleb Kraft 40 Comments

[Bissinblob] has about 70 of these WYSE 3125SE thin clients and is offering them up at $15 a piece plus shipping. That’s quite a steal!

The specs are as follows:

NS Geode GX1 core (SC2200)266Mhz
Flash 32MB
RAM 64MB
Video 1280×1024(at 8-bit color), 1024×768 (at 16-bit)
10/100 network
3x usb
1x serial
1x parallel
2x PS/2

Be sure to let us know what you’re doing with them if you happen to get one. If you have something lying around that needs to go, feel free to post it on our classifieds.

Time-lapse Camera Dolly

November 30, 2010 by Mike Szczys 21 Comments

[Brian Grabski] was asked by a friend to design and build a dolly that would move a camera during a time-lapse sequence. Above you can see the product of his toils, and the videos after the break show off the parts that went into the design and showcase effectiveness of the build.

The dolly is designed to ride on a pair of tubular rails. These can be bent to match any desired path and the dolly will have no problem following it thanks to two features. First, the triad of skateboard wheels on each of the three corners are mounted on a swivel bearing that allows them to rotate without binding. The other piece of the puzzle is a set of drawer slides that let the third support move perpendicular to the other two sets of rollers. A motor drives a geared wheel to move the dolly along the track with speed adjustments courtesy of the motor controller. There’s also a failsafe that will shut the system down when it runs out of track, protecting that fancy piece of hardware taking the pictures.

We’ve seen timelapse equipment that moves the camera in the past, but those hacks usually involve rotating the camera along and axis. This track-based setup is a well executed tool useful at all levels of photography. We can’t wait to see the arch-based dolly that is teased at the end of the demo video.

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Pencil Balancer A Bit Noisy For Desk Use

November 30, 2010 by Mike Szczys 22 Comments

Who wouldn’t want to install this little bot as your newest pencil holder? Place a pencil tip-down and it will keep it from falling using two motors. There is a Dynamic Vision Sensor for each axis that provides feedback, but it’s not the same as using a camera. These sensors pick up changes in pixel contrast, outputting a positive or negative number based on the direction the pencil is beginning to fall. An NXP2103 running at 64 MHz reads in the values and drives the pair of servo motors accordingly.

If you’re interested in the nitty-gritty the full paper is available from the page linked above. It goes into great detail about the algorithm used, and includes plots and histograms showing the data capture during a balancing session. Or you can skip the eggheaded exercises and watch the video after the break.

Continue reading “Pencil Balancer A Bit Noisy For Desk Use” →

Unlocking RS232 Serial Comm On A Multimeter

November 30, 2010 by Mike Szczys 20 Comments

[Craig] cracked open a multimeter to unlock RS232 serial communications that can be used for data logging. There’s a couple of things that make this possible. First of all, the multimeter’s processor is not covered in a black epoxy blob, leaving the pins exposed for hacking. Second, the chip model is known and [Craig] was able to get his hands on the datasheet. One of the pins enables serial output when pulsed low. Touching it to V- even turns on an RS232 icon on the display, as seen above. To make this accessible without opening the case a momentary push button can be added, as well as connector for signal output, and a bit of parsing on the PC side to handle incoming data.