Motion or vibration sensor

[Butt3rz]

I have two cats that are always up to no good. I have read several places where they do not like loud noises. My Fiance and I both work so we can not be home all the time to clap or snap or do something to keep them from doing things or being on things they are not supposed to be doing or on. So I did some searching and found something called a tattle tale alarm. It is triggered by vibrations. So I thought of trying to build one but I have had no luck in finding a schematic or anything others have done that might work the way that I would like. I am thinking of using either vibration or even light where if the jump up on the couch it will sense the vibration and sound an alarm maybe 1 or 2 seconds and then reset. Or light sensing where if they jump in front of it, it will sound until they move away. If anyone has any ideas I would be very greatful because I want to build a few of them since the one online is $25 and I am not going to spend $50 - $100 to have several of them around the house. Here is the url to get a general idea of what I am talking about. http://www.drsfostersmith.com/product/prod_display.cfm?c=3261+1894+3453&pcatid=3453

 

[(*steve*)]

I was looking at that and thinking...

If you need a sensitive vibration sensor then you might be able to use a small speaker with a weight attached to the centre of the cone.

The weight will tend to remain stationary as the rest of the device vibrates up and down around it.

You may be able to use an op-amp to amplify the signal, and if you detect a large enough peak, sound an alarm.

 

[Butt3rz]

I am not sure that is quite what I am looking for. Can something like that be put on a flat surface to pick up if say a cat jumps up on a couch?

 

[KMoffett]

Maybe a large, cantilevered, peizo speaker element, one end fixed inside a box and a small weight on the other. Poor man's accelerometer. Feed that to an opamp to drive a buzzer...maybe with a monostable to extend the buzz.

ken