Should these piezo cap sensors be replaced?

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  • gomavs123
    New Member
    • Apr 2013
    • 1
    • USA

    #1

    Should these piezo cap sensors be replaced?

    Hello all, first time poster.

    I have a set of 10 piezoelectric sensors that I measured before going through with a test. Usually, when measuring the capacitance I get around 3nF. However, I noticed that for about 30% of them that I had (~3 out of 10 that I had), the capacitance meter, will spike up to a value much higher, like 100nF or so and keep on ramping down to about 15nF or so. It will slowly retreat down, but to about 5nF or so. Some of them will just go up to 10 nF and go back down, but one way or the other won't reach the value of 2.

    Usually when the capacitor is bad, or broken, this particular type of capacitive sensor gave a very low value, such as .167nF or so. However, these are not doing that.

    I tried it with a different capacitance meter (different brand), and noticed this same issue with this particular batch.

    What is the explanation of this? Should I replace them? Have you guys seen this pattern for regular caps before?

    Thanks in advance for your help.
  • cheapie
    null
    • Jul 2010
    • 849
    • USA

    #2
    Re: Should these piezo cap sensors be replaced?

    High leakage current (partial short) can confuse a cap meter like that.

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