This door alarm is a project that composes of Snap Circuits, Arduino and a 4 channel relay (low voltage). There is a green switch that will turn on the relay. When the relay is turned on it will activate the Snap Circuits, then Arduino will monitor the alarm output of the Snap Circuits alarm, so that when the door opens the Arduino will sense that there is a broken circuit there. Then the Snap Circuits takes over by sounding an alarm. But it doesn't stop there, after the door is opened the Arduino tells a screen to print out that the status of the door is open. When the door is closed the Arduino senses that the circuit is closed because of the pieces of wire that are on the contacts of the door. Finally, when you turn off the green switch the screen prints that the status is deactivated.