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So I have a bunch of capacitive buttons sitting behind a large 50x50cm acrylic sheet and whenever I place there acrylic sheet over the buttons, they start triggering all by themselves. I can't figure out how to stop this. Any ideas?

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  • \$\begingroup\$ What's sensing the capacitive buttons? Is there a way to decrease the sensitivity? \$\endgroup\$ – 0xDBFB7 Nov 9 '16 at 19:27
  • \$\begingroup\$ Yes. Just one. The dielectric constant of acrylic is about 2-3 depending on exactly what it is and how its made. Just as a guess, I'd assume there could be problems here. You might consider trying different capactive buttons by different manufacturers to see if the problem can be resolved. Or else use a material other than acrylic that has a constant closer to 1 and the other features you're looking for. \$\endgroup\$ – jonk Nov 9 '16 at 19:33
  • \$\begingroup\$ Is it only a problem immediately after placing the acrylic sheet over the buttons? There are anti-static spray-on coatings which as a bonus would add some scratch-resistance; I haven't tried any. \$\endgroup\$ – Andrew Morton Nov 9 '16 at 19:42
  • \$\begingroup\$ I probably should add that if you designed a capacitive system to incorporate the dielectric constant of acrylic (or glass, for that matter), then things might work well. I've never attempted such a design though. Hopefully, someone who has may be able to provide some specific guidance. \$\endgroup\$ – jonk Nov 9 '16 at 22:19
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    \$\begingroup\$ No, not really. I wish I had specific experiences to share. But on this, I don't. I have used the MSP430's capacitive switch module and it works very well. But I didn't design it, just used it. And I don't know what it would do if I put acrylic in front of it. I could try and see, I suppose. I know theory, broadly speaking, but not the practice. And I think you need more of that. If something crosses my mind, I'll toss a note. \$\endgroup\$ – jonk Nov 10 '16 at 6:42

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