Steps:
* Redraw the echo hello-world board
* Add a button and a LED
* Make it

Redraw the echo hello-world board + add a button and a LED

I used Eagle to redraw the board. I just downloaded a few libraries: the Fab and adafruit. Federico Vanzati (our FabLab instructor) gave us a quick electronic’s introduction and show us how Eagle works. I watched also two video tutorials (Tutorial 1, Tutorial 2) that explain the basics of schematic and board design.
We made a schematic sketch together

I choose a bright withe led, so I check the led's data sheet on internet and I calculate the right resistor using the Ohm law: R=V/I --> V white led=3.3V --> V=5V-3.3V --> R= 1.7V / 0.01A = 170 Ohm.
Than I did the Elettrical Rule Check

0 Errors, 7 Warnings. I just forgot to put junction (using junction botton).
So I opened the Board's window and I started to place the different component in the better positions.
As I did two weeks ago, I use a polygon to make the GND.

I use the autorouter's button, just to start and than I fixed the problems. A useful button for organize the routs is the eye, that highlights the way of the current. Look often at the schematic helps a lot.

Finally I found a good components' disposition and I create an optimized shape.

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Make it

I milled the board and I start soldering as I did two week ago.

The female 6pin input that I used where a trowholes component, so I decided to blend 5 pin to one side and the GND to the other, in order to give him a sort of stability.

Using the Ohm law, I calculated the white led's resistor: R=170 Ohm, but I didn't had a 170 one.
So I choose a 150 Ohm one: brighter, but my led will die younger then a led with a 170 Ohm resistor. Doesen,'t matter, I'll not use every day my Eco Hello-world board. To be sure, I check the amperage reversing the equation: I=V/R --> I=1,7V/150=0,011333A. In the data sheet the I max was 0,02A, so I'm sure that my combo will work.

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While I was soldering components I found 2 CRITICAL ERRORS:
I divided the routes with a cutter and I try my best to sold the Resonator, but was not enough.

I isolated each error and I try to understand: when I finished the eatching file was late and I didn't saw that two routes were too close.

Eatching, the cone of the milling tool works too deep and take off too much material. Or maybe I choose a wrong dimension's component.
I draw some offset routes in order to help my soldering task and I milled again.

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