I'll get this out of the way now: I'm a brand spanking newbie when it comes to this. I've only ever read about Arduino, and while I've been quite interested, I've never had an urge to go build anything. The time has come, though, as a rash of B&E's in my complex have made me start looking for an alarm system. Trouble is, professional systems are far too much (and I doubt the complex would allow them) and the cheapo solutions just make noise, are easy to turn off, and don't really help when nobody's home.
I have this idea of a component that will do these functions:
Detect when the door opens - I feel the best way for this is a slim magnet on the inside of the door frame and the corresponding edge of the door itself. The function would be to detect when the magnets cease contact (ie, the door opens).
Do something about it - Making a noise would be ok, but we have the issue of me not knowing if it happens when I'm not home. To this end, I'd want to set it up to send a signal to a device connected to my network (wireless, ideally, but ethernet is possible), and I'd code some software to handle it and text/email me or something.
My question is, what components would I need for a setup like this, and are there any existing setups I could base this design off of? Right off the bat, I see two magnets, a board with a wireless/ethernet/maybe Bluetooth capabilities, something to detect the magnets, something to buffer the signals sent so it doesn't send out 50 signals when the magnetic field hovers between the connected/disconnected range (this may have to be software-based on my end, not sure), and a power source.
Do something about it - Making a noise would be ok, but we have the issue of me not knowing if it happens when I'm not home. To this end, I'd want to set it up to send a signal to a device connected to my network (wireless, ideally, but ethernet is possible), and I'd code some software to handle it and text/email me or something.
Two questions. First, how will you get into the house/apartment without setting off the alarm?
Second, suppose you are enjoying a nice holiday on the coast, and someone enters your house/apartment while you are gone. The alarm posts a message on your web site. What are you going to do about it?
Third, (OK I lied about the two bit) will other people have legitimate need to access your house/apartment while you are not there? If there is a fire or a water leak, what happens?
There is a reason (besides greed) that commercial alarm systems are costly.
PaulS:
Two questions. First, how will you get into the house/apartment without setting off the alarm?
To handle that, I'd add some sort of switch to it, so I could turn it off. I don't exactly want it blaring noise, which is why I'm going for the "notify me by email/text." I don't mind the unnecessary notification for a first-time entry, and I'll just switch it off once I'm in.
Second, suppose you are enjoying a nice holiday on the coast, and someone enters your house/apartment while you are gone. The alarm posts a message on your web site. What are you going to do about it?
I have friends in the complex, so first bet would be to ask them to give a casual inspection, see if anything's out of place. If so, they'd call the police. If they're not around, I'd either phone the complex's management staff or drive over to check it out myself if I wasn't far.
Third, (OK I lied about the two bit) will other people have legitimate need to access your house/apartment while you are not there? If there is a fire or a water leak, what happens?
There's nobody else with a key (besides maintenance, but they only go in with prior approval). If there's an emergency of some sort, I imagine someone will bust down the door to take care of it, which in turn would set the alarm off, where I'd resort to my second answer.
I'm less concerned about when and how it'd be used, and more concerned about how to actually make it.
Bummer. Well thanks anyways for the video and the link, it'll give me something to go off of.
I don't suppose you'd have any advice about the magnet part, as to what I could use to detect that the magnets were within close range/touching to generate a field?
Good idea with the reed sensor. In my searches for tips, I came across the video you had linked on youtube, and there were some instructions, enough for me to have a clear picture of what I can do. Thanks, everyone, for your help. I'll stumble on back if I need more help.