The Basics Of Building A Multitouch Table

April 16, 2011 by Mike Szczys 15 Comments

Here is a bare-bones multitouch table setup. We looked in on [Seth Sandler’s] multitouch work a few years ago when he completed the MTmini build. He’s scaling up the size a bit with the MTbiggie, and showing you how easy it is to put together. The demo rig seen above is just a couple of chairs, a sheet of acrylic, a mirror, a projector, a computer, and a diy infrared webcam.

The rig uses ambient infrared light to detect the outlines of your fingers when they touch the acrylic surface. A webcam with an exposed camera film filter feeds an image of the infrared light received below the surface to the computer. The incoming video is processed using Community Core Vision, where each individual point is isolated and mapped. Once the data is available the sky’s the limit on what you can develop. [Seth’s] demo packages include a mouse driver, some physics applications, an Angry Birds implementation, and a few others. See for yourself in the video after the break.

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Pidato Box Adds Vibrato Effect To Digital Pianos

April 16, 2011 by Mike Nathan 9 Comments

piano_vibrato_box

[Joren] likes his digital piano, but it was missing one key component that he wanted to use: the ability to produce vibrato while playing. Vibrato can be done in several different ways on regular pianos, but it seemed as if there was not a lot of consideration given to the effect when designing digital pianos.

He enjoys playing all sorts of music, including solos from Franz Liszt which suggest using vibrato at times, so he decided to build himself a vibrato box. Constructed with a bit of assistance from the friendly folks at Hackerspace Ghent, his “Pidato” incorporates an Arduino and three-axis accelerometer to get the job done.

The Arduino is connected to both the MIDI output of the piano as well as to the accelerometer, which he has mounted on his wrist. While playing, all he needs to do is simply move his hand rapidly to produce the vibrato sound as you can see in the video below. The Arduino code filters out any other sorts of movements to ensure that he does not accidentally trigger the effect when it is not desired.

Check out the video below for a quick demonstration of the Pidato box.

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Pinewood Derby Cars Have Come A Long Way

April 16, 2011 by Jesse Congdon 20 Comments

Get your graphite and hike a wheel, [Aron Hoekstra] writes in to completely embarrass us with some excellent pinewood derby cars. In the pursuit of that extra something [Aron] consulted with his sons who came up with some cool ideas for cars, one Tron themed and the other basically a Wiimote with wheels! The official Pinewood derby rules say nothing about electronics, so as long as nothing helps the block-o-wood travel down the track faster, anything goes. This means you are free to load up whatever cool lights you want, but will have to earn your robotics merit badge some other way.

[Aron] Starts the builds by carving out the shape of the cars, each feature a hollowed out cavity underneath to accommodate the batteries and electronics. For the Tron Light Runner car, one continuous EL strip weaves in and out of the derby car’s body, and a single AAA battery runs the driver. [Aron] notes that it took around five feet of EL wire to cover the little car, which is two more than the driver is rated for. Fortunately the extra little bit of additional wire had little effect on its brightness.

The Wiimote car has detailed 3d buttons, a breadboard with a linear regulator, and PIC 16F628 driving blue LEDs. For the majority of the time the PIC simply runs a chase routine for the four LEDs, but [Aron] went through the trouble to program in the Wiimote’s start-up sequence!

Shown above the [Hokestra]’s work is my older brother’s pinewood derby car (top left) and my… potato rocket… thing… (top right) from many many years ago. I now seriously regret not considering LEDs! Although I think all that existed then was red, green and IR.

Check out videos of the [Hoekstra] bros’ cars after the jump!

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Creating NES Cartridge Clones From ROM Dumps

April 16, 2011 by Mike Nathan 25 Comments

Sometimes emulators just don’t cut it when you want to play a vintage game. Like it or not, some people enjoy the nostalgia of playing old games on the actual hardware for which it was designed.

[Callan] wrote in to share a method he has been using to make some of his own NES game cartridges from ROM dumps in order to play them on an honest to goodness NES console.

He starts out with a 190 in 1 game cartridge, where he found a neat Famicom game never released in the US. He decided he would patch the ROM he found on the multicart in order to have an English menu, and then create his very own cartridge from the image. He discusses how to identify which EPROM chips you will need in order to construct your cartridge, as well as some helpful ways of finding a donor cart that has a similar enough board to house your components.

[Callan] also provides a quick walkthrough of erasing and burning your new EPROM chips, before discussing some post-soldering troubleshooting steps you might need to take before your game will work properly.

While we can’t comment on the legality of these game clones, we still think it’s pretty awesome.

Be sure to check out his site for a far more in-depth discussion of the process if this is something that interests you.

Long-range Bluetooth Wardriving Rig

April 15, 2011 by Mike Nathan 56 Comments

bluetooth_wardriving

[Kyle] was digging through a box of junk he had lying around when he came across an old USB Bluetooth dongle. He stopped using it ages ago because he was unsatisfied with the limited range of Bluetooth communications.

He was going to toss it back into the box when an idea struck him – he had always been a fan of WiFi wardriving, why not try doing the same thing with Bluetooth? Obviously the range issue comes into play yet again, so he started searching around for ways to boost his Bluetooth receiver’s range.

He dismantled the dongle and found that the internal antenna was a simple metal strip. He didn’t think there would be any harm in trying to extend the antenna, so he soldered an alligator clip to the wire and connected the CB antenna in his truck. His laptop sprung to life instantly, picking up his phone located about 100 feet away in his house. He took the show on the road and was able to pick up 27 different phones set in discoverable mode while sitting in the parking lot of a fast food chain.

While it does work, we’re pretty sure that the CB antenna isn’t the most ideal extension of the Bluetooth radio. We would love to see what kind of range he would get with a properly tuned antenna.

Keep reading to see a quick demonstration of his improvised long-range Bluetooth antenna.

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Drag And Drop Programming Gets Kids Started Early

April 15, 2011 by Mike Nathan 49 Comments

While programming an Arduino is a piece of cake for EEs who have been around the block a few times, there are some groups who would still find it difficult to get started with the IDE. It is touted for its ease of use, but there is a steep learning curve if say, you are 5 or 6 years old. [Julián da Silva] has been hard at work for a while now, to make the Arduino more accessible than ever.

Earlier today, we posted a story about moldable putty which can be used by children to build rudimentary circuits, enabling them to enter the fun world of hobby electronics at a young age. [Julián’s] project “Minibloq” aims to do the same thing with the Arduino. A work in progress, Minibloq uses a graphical interface to “build” Arduino code a block at a time. The code components are dragged and dropped into place on one side of the screen, while the source code is generated on the other half. This helps gently introduce those people new to the Arduino how to write actual code, a little bit at a time.

[Julián] is working hard to ensure that his application works well on OLPC and other classroom-oriented computers to ensure it can reach as wide an audience as possible. We think this would be a great introduction to the world of micro controllers for children as well as those who have never tinkered with electronics at any point in their lives.

Keep reading to see a quick demo of the software in action.

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Aquarium Overflow Sensor Saves Your Fish And Your Floors

April 15, 2011 by Mike Nathan 31 Comments

If you’ve ever had a water leak in your home, you know the sinking feeling that comes over you as you walk through the door to the sound of running water. [Greg] knows this feeling quite well, having returned home to a sopping wet floor and an overflowing reef aquarium on more than one occasion.

Both of the overflows he experienced were due to a clogged drain in his display, but there was little he could do as far as walling off the drain from potential blockages. With all of the delicate creatures living in the tank, the only possible solution that came to mind was monitoring the aquarium’s water level.

Unfortunately he had no idea how to get this done aside from using probes (which would rust in the salt water) or expensive off the shelf systems. [erich_7719] from the All About Circuits forums helped [Greg] out and designed a circuit for him which would monitor the water level using an IR sensor. The circuit simply shuts off the pump if the water level gets precariously high. As you can see in the video below it works quite well, and as a safety measure, requires a manual restart of the pump once the high water sensor has been tripped.

If you have a need for the same sort of setup, swing by his site for a detailed schematic as well as a bill of materials.

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