| Fun science projects are those that teach you | | | | the battery holder by joining the wires together and |
| something about science and at the same time allow | | | | then wrapping insulation tape around the joins. |
| you to make something useful and fun. This is one of | | | | - To the other end attach the buzzer in much the |
| those projects! | | | | same way as you did the battery holder. To check if |
| The job of a burglar alarm is basically to tell you when | | | | all is good up till now, if you attach the battery the |
| someone who shouldn't be in your house has come in | | | | buzzer should sound. |
| - not so. And where will these nasties come in? | | | | - About half way down the wire cut one of the wires |
| Through a door or window - right? So if we can make | | | | in half, leaving the other one in tact. Strip the ends so |
| something that will tell us when a door or window has | | | | that about a centimeter of wire is exposed. |
| been opened that should not have been opened, we | | | | - Press the thumb tacks onto the inside of the opening |
| would know when someone, who shouldn't be coming | | | | end of the clothes peg. Before you push them all the |
| in, is in fact coming in - right? | | | | way in, place the end of the wire you have just |
| So how are you going to pull this off without some | | | | stripped under each of the thumb tacks and push |
| specialized equipment. | | | | them in hard so that the wire is held there. |
| Easy... | | | | - Attach the battery. If everything is attached correctly, |
| You are going to use simple circuit that when closed | | | | with the clothes peg closed, the buzzer should buzz. If |
| with a switch will set off an alarm. The switch is going | | | | it does not, you need to check your connections on |
| to be a clothes peg! | | | | the battery, buzzer and peg. |
| First up - what you are going to need: | | | | - Once everything is working, open the clothes peg |
| - Approximately a meter of flexi-wire | | | | and jam it into the gap of a door and it's frame or in a |
| - A 9V battery (the correct scientific term is a cell) | | | | slightly open window. |
| - A 9V battery (cell) holder | | | | - Alternatively, put a piece of cardboard or paper |
| - A wooden clothes peg | | | | between the thumb-tacks that has a string attached. |
| - 2 thumb tacks | | | | The other end of this string can be attached to |
| - A sharp knife | | | | anything that is going to move, with the idea that if that |
| - Electrical insulation tape | | | | object is moved the cardboard is pulled from between |
| - An small electric buzzer | | | | the thumb-tacks. |
| And here is how it is done - | | | | - Once the thumb-tacks touch - if all is in working |
| - Strip about 1cm of the plastic insulation off the one | | | | order, the buzzer will alarm you to something out of |
| end of both wires of the flexi-wire using the sharp | | | | the ordinary. |
| knife. | | | | And hey presto - a simple, but very effective burglar |
| - Attach both wires of the one end of the flexi-wire to | | | | alarm. |