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I want to implement a capacitive sensor in my design. I'm thinking of doing this by adding two large(-ish) copper areas on my PCB design and using those as the capacitive plates. I would then bond the PCB to the project box with e.g. hot glue or some other method that eliminates the air gap. My issue is that on the same PCB circuit I have a crystal oscillator used to drive an RTC. Would the capacitive sensor/plates cause issues with the accuracy of the RTC? Obviously, the only way to really find out would be to test this, but does anyone know what the theory says about this?

David Högberg
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1 Answers1

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Maybe I'm missing your actual question, but I can't imagine why the addition of capacitive plates would cause any specific interference with the RTC.

The capacitive sensor would be switching (for the charging time measurement), but that shouldn't be deleterious to your RTC. If you're worried, just place the RTC circuit away from the plates (more than 1-2 cm) and do a copper ground pour/flood/plane around it. The accuracy should not be affected by the capacitive sensor.

Community
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Samuel
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  • I have never had an actual PCB manufactured before, let alone one with both an RTC and a capacitive sensor, so I'm just a bit worried about things that might go wrong... – David Högberg Oct 04 '13 at 17:38
  • @user29920 Understandable. If you have other concerns about the process or specific questions about aspects of the final design, ask another question, it's why we're here. – Samuel Oct 04 '13 at 17:44