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Both Laplace results were correct May 9, 2012

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Hooray! my result was correct and it’s the first time I write a proof to someone else outside university.

From: The Wolfram|Alpha Team via RT <info@wolframalpha.com>
Date: Wed, May 9, 2012 at 5:30 PM
Subject: [W|A #302928] W|A Feedback

Dear Iker,

Both your result and the result given by Wolfram|Alpha are correct. There are various ways to write the result. Our result “alpha(laplace transform sin(3t)/t)”, and your result agree for positive s: alpha(arctan(3/s) – (pi/2 – arctan(s/3)))

Also, in the complex plane the two expressions are the same for Re(s)>0

plot3d |arctan(3/(x + i y)) – (pi/2 – arctan((x + i y)/3))|

Now, for the inverse Laplace transform one integrates along a contour
that goes parallel to the imaginary axis and is in the right-half plane:

http://www.wolframalpha.com/input/?i=define+inverse+Laplace+transform&a=*DPClash.MathWorldE.inverse+Laplace+transform-_*LaplaceTransform-

As the two functions agree there, they both give the same inverse Laplace transform:

http://www.wolframalpha.com/input/?i=inverse+Laplace+transform+arctan%283%2Fs%29+&a=*C.s-_*Variable-

inverse Laplace transform pi/2-arctan(s/3)

Please let us know if you have any other questions.

Best wishes,

Elif
The Wolfram|Alpha Team
www.wolframalpha.com

Laplace problem with wolfram alpha May 9, 2012

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I don’t know if wolfram alpha is right or not but their result is different than mine and I think I’ve done it well.

Their result is this: http://www.wolframalpha.com/input/?i=laplace+transform+sin%283t%29%2Ft

And mine is this:

DIY SOIC progamming adapter with a PCI connector April 16, 2012

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Image

The idea is simple. Grab an old/broken motherboard, unsolder the PCI connector, cut to the pin size and

cut it again  in half. Solder cables on the bottom.

Well I’m looking for a similar alternative but for  SSOP, the commercial ones cost 23+ euros.

Seen here:

http://www.swiatelka.pl/viewtopic.php?t=2178

Arduino nano Shields. March 30, 2012

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Gravitech guys are going to make arduino nano shields. This is a great idea. 

They are pin to pin compatible with standard shields but done for arduino nano size, a photo explains it better:

http://www.gravitech.us/arnaadmo.htmlImage

Educational Boards. March 29, 2012

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Before Arduino there where a lot of expensive education platforms/boards. All begun with the MIT brick. The cheapest one just before arduino was the BasicStamp. Arduino intented to be a cheaper clone of Wiring, started to sell a lot and several somewhat compatible clones where done like Pinguino but at first they lacked the best feature of arduino, a lot of shields and a lot of code already done for them. Even though the user code was similar and the languages where compatible the specific assembler code wasn’t. Arduino began to be too small to do complex projects and several ARM clones appeared. At that time Microchip saw it maybe could take on arduino market and adapted Pinguino to it’s PIC32 platform that Olimex sells. Microchip saw that at least it had to be pin to pin compatible with shields. It arrived late and cheap ARM clones where taking the high end market. Meanwhile arduino variants where done, Sanguino, Arduino Mega… but soon it became clear that ARM would dominate the high end. STM32 had a super cheap (less than 14 USD) eval board and STM32 lead to Arduino due but due to arduino.cc close relations with Atmel it’s still a ARM cortex M3 but not a STM32.

While all this was happening, far from microcontrollers, at the netbook/Pc like level there where several attemps.

The first ones where blackfin boards but they didn’t succeded because they arrived too soon and few people where willing to learn a little used chip. Then BeagleBoard was done, learning from what blackfin did well (community, documentation…) and it used an ARM Cortex8 core that everyone was using for low power high end machines so there was a huge code base and a lot of related forums.

Google intented to unite low end boards with it’s Android plattform ADK and Raspberry PI tried the aproach of reducing the price of a Beagleboard. It seems they forgot that one key factor to arduino success were it’s shields.

Lego mindstorm is the direct succesor of the original MIT brick, it also uses an ARM but it’s irrelevant for hobbyists. It’s still a good platform to learn but it’s very expensive and it’s better suited for K12 students.

 

Update: NXP used a arduino shield style board for their ek040 EVB for the internet of things

Altera FPGA board March 14, 2012

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An Altera FPGA board has arrived, similar to this one but six times cheaper and with a 2,4″ TFT instead of a char line LCD. If that’s what chinese people use that’s what I’ll use (they know how to acquire knoledge fast on a shoestring budget).

The main reason apart from the cost to buy a chinese copy board instead of the official one was that it comes with a lot of example implementations, full component datasheets and full PCB schematics. It’s as free hardware as it can be. As a plus it includes a lot of ebooks at no cost for me 😛

We’ve been in the press February 22, 2012

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The reprap workshop at Arteleku has been in the spanish press

http://tecnologia.elpais.com/tecnologia/2012/02/10/actualidad/1328877228_999295.html