All right this is an easy one, it is just a switch, with a resistor, just like the previous sensor blog, except this one is activated by someone or something pushing it. What about that Magnetic Hall effect transistor lab, well, that sensor looks like another sensor, and the output is odd, might be that the transistor is the problem, or not. Going to go by Radio Shack and lay some small change an buy a separate, or discrete, Hall Effect Transistor and hook it up later.
But the switch is kind of cool, the circuit is simple, you should draw it out like I have, normally I would use Fritz or something similar, but the Fritz didn’t have the Keyes Sensors or if it does then I couldn’t find them. So I just used Paint, the resistor is shown using the non-US rectangle.
I used the code directly from the Arduino site, which you should be careful and make sure that the baud rate set in the program is the same as the setting for the serial port. (Baud rate is the number like 9600, 15200, and so forth.) Make sure to watch the serial read out on your screen carefully, if you don’t.
Find the code and better explanation than mine at: http://arduino.cc/en/Tutorial/DigitalReadSerial, this can be done using the Netduino, you just need to change the code of course. This is the basis for many sensor applications. For fun you could create a simple display or similar in Windows.