In this instructable I will show you how to make a simple tripwire alarm. If you have any questions please comment.
Here is a video of the first test:

Step 1: Supplies

You will need:
-an alarm/buzzer
-wire
-tinners tape
-batteries and holder
-clothes pin
-duct tape
-thread
-cardboard or a thin sturdy material
-switch
-screwdriver

Step 2: Step 1

Cut small pieces of the tinners tape and cover the end of both sides of the clothes pin. Then put the two wires on the outside of the clothes pin on the tinners tape and tape them in place.

Step 3: Step 2

Attatch the negative wire to the alarm. Then attatch the positive wire to the switch.

Step 4: Step 3

Attatch one of the wires from the clothes pin to the switch and the other to the alarm.

Step 5: Step 4

Mount the clothes pin just under knee high on the door frame. You can leave the alarm, switch, and batteries on the floor.

Step 6: Step 5

Cut out a small piece of cardboard with a small hole near one end. Tie thread to the cardboard, DO NOT CUT THE THREAD

Step 7: Step 6

Open the clothes pin and clip the cardboard into the clothespin to separate the two sides and break the circuit. Measure how long the thread has to be to reach the other side of the door. Cut the thread and tie it to something on the other side of the door, I tied it to the door stopper.