Archive for the 'Tech' category

Let me tell you first off, I want one!

It can seem difficult to believe (at first, I thought it was fake!) but it is possible to make music with a Tesla coil!

To prove it to you, watch and listen this video of two coils playing the Super Mario Bros. Theme song:



or if you’re more inclined to like classical music the 1812 Overture of Tchaikovski:




Cool, eh?

You’re still skeptical? Do you want a rational explanation of how it works?

That’s what I thought. So for the neophytes, I’ll put my physics teacher’s hat on (I started my masters in electrical engineering after all!) and will attempt to explain the principle in simple words (not so easy!):

Firstly, a Tesla coil is an electrical transformer, so it transforms a low voltage current to a very high voltage current, in our case. The high voltage part of the contraption emits violet sparks and lightnings that travels to the nearest metal rod to discharge the accumulated charge.

The principle invented by Nikola Tesla consists of two or more electrical resonance circuits. Basically, by choosing the right value for a coil and a capacitor we can make an electrical circuit resonate. I actually experimented with that in university and it actually creates a buzz. The pitch of this buzz depends of the choice of the capacitor and coil value. So each Tesla coil has a fixed resonance frequency, and in the case of the Tesla coils in the videos above, it is higher than the audible frequencies.

So how can we hear a sound then?

Well, the clever trick is to turn the device on and off very fast! The frequency (number of swtich on/off per second) at which the switch is turned on and off determines the pitch of the sound. So what we hear is thus the frequency modulated fixed signal of the Tesla coil!

Open parenthesis, the frequency modulation is exactly what an FM radio does. It emits on a fixed carrier wave frequency (the no. of the station, e.g. 90.3) the modulated audio signal, close parenthesis.

So from here on, all that is left to do is to link this wonderful device to a digital controller and to either a computer or a musical instrument to be able to play it. :).

For further explanations on how it works, check this video out.

Unfortunatly, this new musical instrument, called the Zeusaphone by the inventors, will not be available for purchase until 2008.

brem, flabergasted.

After Honda’s Asimo who can walk and climb stairs, here comes Toyota with their own robot.

This time, it’s a robot who not only can walk, but also keep the beat with his feet and best of all, play trumpet!

It never misses a note and has a perfect pitch, fingering and tonguing. Although guys, you could not replace me with this thing yet because I don’t think it’s able to adapt to live performances where our patterns keep changing according to what we feel like at the moment. And for improvised solos, it’s yet to be heard.

Still, it’s technologically incredible. This robot plays better than most trumpeters. Ahem.

brem

Reality once again met fiction.

It seemed improbable in 1977 that the Princess Leia hologram projected by R2D2 the droid would become a technology of the future.

We were hopeful it would one day exist, but we couldn’t possible hope that the movie would only be 30 years in advance!

Indeed, the USC Institute for Creative Technologies developpped a holographic 3D display!

From what I gathered, it’s a girating mirror rotating around its vertical axis at high speed with a projector positioned above it. With a good synchonisation of the projected images and using the fact that the mirror rotates at high speed, it becomes possible to obtain a moving image from any point of view on a 360 degrees sphere.

Awesome!

Watch the demo video.

No need to mention I want one!

brem


via Neatorama

These past years, we’ve seen a lot of bridges collapse. What comes immediatly in my mind is of course the bridge in Minnesota that fell and that one in China this year, also the “de la Concorde” overpass in Laval, and I forget some.

It happens more often than we tend to remember, and everytime it’s a tragedy. Especially when the bridge is on construction, because more often than not, workers die. Exactly 100 years ago, August 29 1907, it was the case of the Quebec Bridge.

Since we have to celebrate commemorate that and learn of our mistakes, I though it would be appropriate to write this article.

After four years of construction, the south part of the bridge fell apart and plunged in the Saint-Lawrence river in less than 15 seconds, and less than 20 minutes before the end of the work day, at 17h37. Of the 100 working on the structure, 76 died.

An inquiry revealed that a bad evaluation of the actual weight of components of the structure, an arrogant engineer and inadequate communication contributed to the catastrophe.

By lenghting the cantilever span by 60 meters from the original plans without taking into account the heavier than expected weight of the steel , the engineer Theodore Cooper unknowingly created a structural problem. The bridge was going from 490 m to 550 m.

The official reason: to allow the pillars to be in more shallow waters. The more probable reason: break the record for the longest cantilever bridge currently held by the Forth Rail Bridge, a Scottish bridge, built a few years before whose cantilever span measures mesure 520 m.

In 1906, a judgement error by Cooper scealed the tragic destiny of the bridge. He had received a report mentionning that the steel used for the construction, of lesser quality than what was originally planned, was 33% too heavy. The only logical option to fix this problem while keeping on the original plan would have been to stop te construction, demolish the structure and start over again. It was of course out of the question.

In June 1907, the workers noticed a worrisome problem: the holes for the studs were not aligned properly with the steel parts in place. In the morning of Tuesday August 27, they noticed a deformation of a few centimeter of the bridge frame. The foreman in charge of the construction site immediatly went to New York to inform his boss that the bridge could collapse any time now. A telagram was thus sent, demanding an immediate stop to the construction, but this telegram was sent to the headquarters of the company, in Phoenixville instead of Quebec City.

It seems we have a special gift to hire incompetent engineers for big projects in Quebec, don’t you find? The tradition continues.

When we take a look at the images of the original plan of the bridge, we notice that the frame of the cantilever arms was different than the ones currently in place. Indeed, they were more curved.

It took more than two years to remove the 9000 tons of metal, of which some remains are still visible at low tide.

This first failure wasn’t enough to end the project since the economical impact to building the bridge were too important.

In 1916, the reconstruction of both cantilever arms was completed and all that was left to complete the bridge was the middle span. When it was finished, it was transported to the bridge using barges. It never reached its final intented destination however.

On September 11, 1916, it plunged in the waters of the St-Lawrence river, taking the lives of 13 workers. After the investigation, it was determined that the accident was due to a broken part of the lifting device.

The bridge as we know it nowadays was completed in 1917 and inaugurated by Edward VIII of the United Kingdom (then Prince of Wals) in 1919. Here’s a picture of Edward VIII taken during his visit to Canada 1919.

It is still the longest cantilever bridge in the world.

Further readings:

- Wikipedia article
- Mysteries of Canada
- Canadian Encyclopedia

Some nifty cool pictures of the new iPhone concept by Apple from the Macworld conference.

Is it just me or is it just a smaller Newton?

Cingular Wireless, owned by AT&T Inc., is to provide cellphone service to go with the iPhone.

Update: Watch an online demo of how it works on Apple’s iPhone page.

brem