Python Maps Mouse Movements On An LED Matrix

[Vinod Stanur] is working with a mouse input and a microcontroller driven LED matrix. The mouse cursor is tracked inside of a window by Python and the resulting coordinates on the LED grid are illuminated. He calls it an LED matrix “Paint Toy” because one of the features he’s included lets the user create pixel art like in MS Paint.

The 10×8 grid of lights is controlled by a PIC 16F877A. This display orientation is perfect for the 8-bit controller, which uses an array of ten bytes to keep track of the pixel data. A computer running his Python application (which uses the Pygame module to track the mouse movements) communicates with the display board via an RF connection. Five bytes plus a stop character make up the communication packet. The first two bytes contain the coordinates of the cursor, the other three bytes contain mouse button status.

As you can see in the demo after the break, the system is very responsive. The mouse can be moved quickly without latency issues, and if the cursor leaves the tracking window it gets picked up right away when it re-enters.

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Laser-triggered Camera Rig Update: 2011 Version

[Fotoopa] keeps churning out new iterations of his laser-triggered camera rig. This is his latest, which he calls the 2011 setup. Regular readers will remember that we just covered a different version back in November; that one was the 2010 rendition. It had two DSLR cameras offset by 90 degrees with mirrors to face forward. This time around he has gone back to the single camera setup which was what he used on the first and second versions seen way back in 2008.

Whew, that’s a lot of links to specialty DSLR hardware. Let’s bring it back to this newest model (the link at the top). The biggest improvement is the shutter delay between when the laser beam is tripped and the image is take. [Fotoopa] reports that he’s managed to reduce that time down to 3.3 milliseconds. This is thanks to an external shutter replacement which improves on the stock shutter’s 52 millisecond delay.

For those that are seeing this for the first time. [Fotoopa] uses this rig to photograph insects in motion. A laser trip wire is responsible for triggering the shutter, and it does so with stunning results!

[Grenadier] Wins The Laser Cutter For His Portable X-ray Project

The results of the Full Spectrum Laser contest over at Build Lounge have been announce. The top prize of a 40 watt deluxe laser cutter goes to [Grenadier] for the portable x-ray machine we saw at the beginning of the month. We think this is an excellent choice for top prize because, come on, this is pretty hard-core.

Taking second place was a Christmas light show choreographed to music. The open spaces of the University of Minnesota hosted the installation. We’ve embedded a video of the performance after the break.

Third prize went to the QC Co-lab Hackerspace for their light wall. It uses the ever popular GE Color Effects lights, with each bulb housed in a vacuum formed pyramid which acts as a diffuser.

There were also several honorable mentions. There’s a special place in our heart for [Jack Buffington’s] solar clock which was included in this group. We think the use of fiber optics to pipe the sunlight into a machined index ring is ingenious. And you’ve got to give him credit for developing a project that uses no electricity and almost no moving parts (there is a slider to adjust for daylight savings time).

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Replacing An Overheating Tablet Power Supply

[Dave] has an ASUS tablet PC with a little problem. The device is charged via the docking connector’s USB cable when plugged into a special wall transformer. The problem is that the wall unit tends to overheat, and is shut down by a thermister inside to avoid permanent damage. The word on the Internet is to drop it in a zipper bag and chill it in the freezer for a bit. Although this works, it’s not the permanent solution that he was looking for. Instead, he hit the parts bin and built his own power supply replacement without buying anything.

The device is simply looking for 12V on the power pin (pin 1) of the USB cable. [Dave] dug through his mountain of unused AC adapters and found one that fit the voltage and current specs of the stock unit. He also grabbed a dusty old motherboard and plucked the USB ports off of the back. A bit of protoboard makes for a good base to connect the AC adapter wires to the ports, which was then covered with one big shrink tube. The result is seen above, and demonstrated in the clip after the break.

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Tool Box Light Dimmer Helps Out A Friend, Offers Up Design Tips


[miceuz] has a friend that works as a theatre technician, and in the course of his job he often needs to jigger with various stage components while shows are in progress. As you can imagine, the lighting situation is far from ideal, so he asked [miceuz] to build him an adjustable lighting solution for his tool box.

The circuit itself is relatively straightforward, using an ATMega88 to provide the PWM required for dimming and color control. Input is taken from three different sources, a rotary encoder for color selection, a pot for brightness control, and a button to turn the light strip on and off.

[miceuz] says that while project came together pretty easily, it still presented some issues along the way which provide some useful design reminders for beginners (and some veterans) alike.

First and foremost: debounce, debounce, debounce. [miceuz] forgot this mantra and made a mad dash to add capacitors to his design after etching the PCB to ensure that his inputs were not bouncing all over the place. He also noted that one should always be sure to read the ADCL before the ADCH register when decoding ADC data. His final observation is that using thick traces is the best policy whenever possible – he ran into a lot of issues with traces detaching during assembly, which he had to rework with wire and solder.

In the end, his friend was happy with the result, and [miceuz] is a better hacker for having worked through his issues. What sorts of important/useful lessons have you learned through the course of your projects? Be sure to share them with us in the comments.

[Pythagoras], A Delta Robot For Drawing

[Pythagoras] is a delta robot built originally using RC servos. Humbly, [Aaron] “concedes” that the first version of his delta robot using hobby servos was easy to build. As anyone who has built any kind of robot knows though, there is definitely a lot of work involved in even the simplest robot. Coordinating three axes and programming it to draw a picture is a really great accomplishment.

The second version, however is currently in development and uses stepper motors instead of servos. These upgraded motors should make the robot faster, more controllable, and more accurate. This version is at least somewhat working as evidenced by the time-lapse video after the break.

Although the title page listed above is a little sparse on build details, if you dig deeper into the page, there are actually 15 articles about the ‘bot, so be sure to poke around. Continue reading “[Pythagoras], A Delta Robot For Drawing”

Building A LED Strip The Minimal Way

For his first big build with an MSP430, [Javon] decided to an RGB LED fader. Having worked with Arduinos in the past, he figured that his MSP430 would have a few PWM channels. After being proved wrong by the data sheet, [Javon] needed to figure out a way to switch a bunch of RGB LEDs with only one PWM channel on his microcontroller.

Because there was only one PWM pin on [Javon]’s micro, he needed a way to multiplex his output. He ended up using a 74HC4052 mux/demux chip to drive 20 LEDs. The LEDs were mounted onto hard board and the main part of the circuit built on a bit of perfboard. While there’s no total cost for his build, we’re guessing [Javon] didn’t spend much on his project; certainty much less than this explosion of LEDs.

[Javon] put all the build pictures up as a Google+ album and a few video demos up. Check those out after the break (009 Sound System warning, you might want to hit mute).

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