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I am designing a vibration sensor in enclosure to be placed on vertical surfaces, like windows, doors, etc.

My first try was with ready made sw420 module, but looks like it is to sensitive for my purposes (when adjusted to lower sensitivity, it reacts to light knocking, when i need it to detect "slamming").

Then i decided to try Piezo Disks. I found nice article about it. It looks promising.

The one thing is worrying me is positioning of disk. In article it is placed horizontally and there is some "weight" on it (as explained - to increase sensitivity). In my case it will be positioned vertically in plastic enclosure. So i cannot use any "weight".

enter image description here

Should it works if i just stick disk to enclosure with epoxy.

I will redesign extension/tamper board (right one in top enclosure) to fit op-amp and other components. So i was thinking, maybe i can solder bottom part of disk to bottom layer of board, and top(ceramic) with wire to the pad on top. Basically disk will be floating in air soldered to left side of board.

So in which case the element will be more sensitive? Fixed to enclosure or floating with board? Or may be other solutions (combined)? (i can redesign board and enclosure).

Currently i don't have components and pcb to experiment. And i want to gather more information before ordering new board.

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  • \$\begingroup\$ You will need to experiment. And be aware of lot-to-lot variation in piezo sensitivity. Friend of mine sees at least 5:1 variation, lot-to-lot. \$\endgroup\$ – analogsystemsrf May 13 at 13:16
  • \$\begingroup\$ @analogsystemsrf As i understand, i will be able to adjust sensitivity with op-amp and comparator. Do I? \$\endgroup\$ – Y Borys May 13 at 14:47

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