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Need Help: Grade 8 Science Project Idea

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bumbalette

New Member
Hi,

My son is doing a grade 8 science project.

My son wants to create an invention that allows it to "beep" at him when he leaves the house. He can then go over and press a button and a message will remind him of something. Since other family members leave the house, he doesn't want this device to go off - except when it is him.

He is looking for a "chip", "sensor", something that he can put into his knapsack so that it will trigger when he leaves the house (only him and not the rest of the family). This is very similar to big security systems at stores and libraries (where it tries to beep at you when you leave with an item). We have not been able to find something for home use.

He wants to add an LCD clock & tape recorder to this device.
Are there kits out there? I've gone to the various electronic stores in my area and no one has been able to help. I've also gone to a spy security store and they don't have anything . Am I looking in the wrong direction?
Any help would be appreciated. Thanks...
 

bmcculla

New Member
For easy kits try www.parallax.com one of their basic Stamps is a good place to start for a controller for the project. They also have LCDs and sound record/playback kits.

Identifying specific people as they leave is a difficult problem. The systems in stores use Those little metal tags that I beleive work by modifying the magnetic field generated by the two devices in the entryway- i dont know though. A search on google can probably get you tha answer. The system is likely to require a knowledge of circuits that will be hard for a beginner. Maxim semiconductor makes something called an iButton that is a contact device that can be used to identify people and hopefully will be interesting enough to give your son a start. The iButton should be fairly easy to interface with the Basic Stamp. www.ibutton.com should have everyting you need to get the system going.

Hope this helps
Brent
 

stevez

Active Member
If it's just an 8th grade project then it would seem that all possible problems do not need to be addressed - only the concept and an understanding of that concept needs to be addressed.

There are kits to record/playback a message so that part is covered.

It would seem that there are only a few ways to leave the house. The opening of a door or breaking of an infrared beam could momentarily turn on a low power FM or AM transmitter. Radio Shack sells the IR alarm that can be used for this. Any number of kit manufacturers sell the transmitters.

A small reciever would be carried in the knapsack - with a circuit that would activate when the door is opened. The thought is that the transmitter and reciever would have to be in close proximity to one another to limit false tripping. There are reciever kits available - or a low cost one can be purchased and modified.

The challenge would be to integrate all of the kits/devices together. This approach is far from foolproof and could not be considered reliable. The cost of the kits needs to be considered as well. There are transmitter/receiver modules or ICs however they don't address the integration problem. For someone experienced in electronics it isn't that difficult but for an 8th grader supported by someone who is less skilled in electronics it could be a formidable task.

Good luck
 
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