I want to create a "buzz" noise when someone sits on a chair. Essentially, if such a sensor exists, I would like to embed it into the seat cover and when it detects weight then it would trigger.
I dont need to actually measure the weight, just know that there is weight.
music_connector:
Yep, you're right. I was thinking along the lines of this: https://www.sparkfun.com/products/8712 -- flexiforce pressure sensor -- one or two would be enough, and very easy to implement.
IMO, that wouldn't make a good sensor to embed in a seat cushion. That sensor would be better at detecting pressure over a small area not a large area like a seat cushion.
The datasheet shows how to use the sensor. The example circuit includes an op amp.
There are lots of DIY pressure sensor examples on the net. I think you could make a sensor for much less than $22.
Henry_Best:
Then he will have to measure the weight (to see if it's over the threshold and not the cat).
What he doesn't need to do is to record the weight.
We once had a cat that weighed 18lbs. You sure noticed if he jumped on your lap!
Ha ha. Like my fat old dog. (Long gone now.)
And you're quite right, of course. You have to work out just what threshold to set.