Dear @rjehangir and @WorkshopScience, we are pretty advanced with everything and now, we are testing our burn wire. We have a doubt about the best option for the electronic circuit and I would like to know your opinion. In the fist picture, you can see the diagram of our circuit (pretty simple, we just activate the relay with a digital pin from the Arduino):
And in the next diagram, you can see a circuit that I found surfing the Internet, and this is a burnwire used to release a GPS tied to a weather ballon:
The second diagram is more complex, it adds a diode and a transistor, but I am not sure it is critical. Any thoughts?