A Personal Alarm System

Lets make an alarm to prevent an authorised entry into the room!

Materials Required

• 9-Volt Battery with a battery clip
• An electricity conducting paper clip
• A small bulb and a bulb socket
• 2 Upholstery Tacks
• Tape
• Scissors & Hammer
• Wire with stripped ends
• A spool of thread

Instructions

1. Hammer the tacks into the wall close to the door, make sure the lower tack is a closer to the upper one relatively but the perpendicular distance between the two must be close. (See Picture)



Use Picture for Reference. Picture NOT TO SCALE

2. Push the bulb firmly into the socket and attach the battery clip to the 9-Volt battery. Twist the red battery together with one of the light socket wires. Twist the black battery clip wire tightly around the bottom tack. Twist the remaining light socket wire tightly around the top tack. Tape the wires to the wall as shown.

1. Securely tape a paper clip to the opposite door frame. Place the spool of thread on the floor. Poke the thread through the paper clip. Pull the thread across the closed door, towards the tacks
2. Tie one end of the thread to the other paper clip. Poke the paper clip under the black battery clip wire. Let it hang down so it doesn't touch the bottom tack as long the door is closed.

What Happens???

When the door is pulled the paper clip is pulled to the bottom tack causing the circuit to be completed, and hence the electricity flows causing the light to glow.