Archive for April, 2009

Build Your Own Multitouch Surface Computer

Wednesday, April 29th, 2009

Touch interfaces are hardly futuristic at this point, but multi-touch hardware like the Microsoft Surface or the iPhone is just starting to become a big deal. Now it is time to learn how they work and maybe try to build our own.

maximumpc.com site has published an interesting article called “Build Your Own Multitouch Surface Computer”. The art of building DIY multi-touch surfaces isn’t exactly simple but the results shown on article stunning: multitouch surfaces with responsiveness rivaling Microsoft’s $12,000 offering, built in a garage on a shoestring budget.The article documents the whole process, from start to finish, so that you can try building one of your own, if you’re so inspired.

Build Your Own Multitouch Surface Computer article can be found at
http://www.maximumpc.com/article/features/maximum_pc_builds_a_multitouch_surface_computer

Multitouch computer screen

The screen uses FTIR (short for Frustrated Total Internal Reflection) setup. It involves three vital components: a sheet of transparent acrylic, a chain of infrared LEDs, and a camera with an IR filter. The LEDs are arranged around the outside of the sheet of acrylic so that they shine directly into the thin side surfaces. The net effect of the setup described above is a sheet of acrylic full of internally reflecting infrared light. When a finger is pressed against the acrylic, it causes some of the light to be reflected down, through the acrylic and into the cabinet, where it is detected by the webcam.

Multitouch screen technology

Posted in Computers, diy | 62 Comments »

How big shows are built

Tuesday, April 28th, 2009

Eurovision stage

Ola Melzig, Production Manager for lights, sound, video and rigging used in 2009 Eurovision Song Contest is keeping on on-line diary of the production.
The first broadcasts will be aired between May 12 and May 16 throughout Europe. Because the size of the production the project to build all needed technology and other infrastructure has started almost one month ago. The show takes place in Moscow Russia. The diary includes text, lots of good pictures and some funny notes.

The Eurovision Diary 2009 web site can be found at
http://www.m-m-pr.com/index.php/eurovision-diary
or you can find it through http://www.eurovisiondiary.com/
The http://www.eurovisiondiary.com/ includes also similar diary report on how Eurovision 2007 was built in Helsinki Finland.

Posted in Entertainment Technology | 3 Comments »

Circuitry Snacks

Tuesday, April 28th, 2009

Circuitry Snacks web site at
http://www.evilmadscientist.com/article.php/circuitsnacks gives tips how to make circuitry snacks! Those snacks look like electronics circuits.

If your two favorite things in the world are playing with electronics and playing with food, this site is well worth to visit. The page begins by gathering up appropriate snack-food building blocks and making food-based models of electronic components. From these components, you can assemble “circuitry snacks”– edible models of functioning electronic circuits.

Below is one full edible circuit example. The resistor values are 100 k (x2), and a 1 uF Nilla wafer ceramic cap. The LED load resistor is 330 ohms. (orange-orage-black-gold)

Technorati Profile

Electronics snack example

Electronics snack example

Posted in Uncategorized | No Comments »

Use an old Nokia charger to power 1W LED

Friday, April 17th, 2009

Here is one useful trick I invented when looking around the transformers/power supplies I had.

NOKIA ACP-7 Europe Standard Charger (Original) has a specification of 230 V, 50 Hz, 4.8 VA. Output 3.7 V, 355 mA. A normal 1W white LED is driven with 350 mA maximum continuous current and typically 3-3.8V voltage drop over the LED. Those are pretty close specifications.

Next task was to verify my theory that this should work well.I took the charger and a multimeter. I found out that the charger gave around 8V output when not loaded, the promised 3.7V when loaded with the 355 mA current and around 700-800 mA current when short circuited. This would indicate that the transformer has quite high output impedance. That’s quite good for this application, meaning that some changes on LED voltage drop do not change the current too much.

First I connected a 1W LED directly to the charger output. I got nice bright light output. I measured the current, and found out that the voltage drop over LED was around 3.5V and current was almost 400 mA. The current is slightly over the specifications for the LED and charger, which is not good.

The fix to the problem was to add one 1N4001 diode in series with the LED. This increased the voltage drop (LED + diode) to be always slightly higher than 3.7V. This will mean that the charger will always put out less than 350 mA to the load. This is on the safe side on the specifications of both LED and charger.

The end result is that an old Nokia charger combined with one diode and 1W LED (with suitable heat sinkl) will make a very simple and well working mains powered LED lamp.


Nokia ACP-7 charger



Posted in diy | 41 Comments »

Practical jokes around workplace – part III

Thursday, April 16th, 2009

I was recently subjected to a practical joke that nearly made me lose my nerves. Me and my dear colleague shared a common workroom in which we worked. One day he had a nice idea and he brought a remotely controllable socket and connected my display to it.

When ever he was in the room he cut off the power once in every hour. Then when he left for a couple of days’ trip, he gave remote control to our assistant, who was in the next room, and told her to do the same. This continued for two weeks, before I found the remotely controllable socket under my table…

I have to say that before the joke was unravelled, I nearly lost my nerves a couple of times. One day I even left work at 1200 because I was so furious because my display kept on shutting down every 15 minutes. If you have a colleague that will appreciate the joke it’s worthwhile to test it =)

Posted in Practical Jokes | 4 Comments »

Practical jokes around workplace – part II

Thursday, April 16th, 2009

In many offices they have some PC- and IT-magazines delivered to the coffee room. If you know that your colleague is interested in some specific magazine, wait for the next issue, and do the following…

Use the stapler to staple all the sheets of the magazine together and then write a post-it as follows: “John, really interested article in page 6. Reg Mike” and place it on the cover page on the top of the rivet and leave the magazine to your colleagues chair…

Posted in Practical Jokes | 3 Comments »