Connect with us

Piezo To Detect Sound

Discussion in 'General Electronics Discussion' started by Rajinder, Aug 14, 2016.

Scroll to continue with content
  1. Rajinder

    Rajinder

    426
    7
    Jan 30, 2016
    Hi,
    I am considering a project where i can use a piezo buzzer to detect sound rather than using a mic. I have seen different types of piezo buzzers, some with 2 wires and some with 3 wire. I think that the 3 wire has an additional feedback signal. Not sure.

    Is this a possibility? I am trying to detect vibrations as if someone is trying to smash a glass or window i.e. security for the home.

    Does anyone have any ideas on how this can be done. I was thinking piezo , with a pre-amplifier, peak detector and then comparator into a microcontroller.

    Any help would be very much appreciated.

    Best regards,
    raj
     
  2. Sunnysky

    Sunnysky

    470
    118
    Jul 15, 2016
    a buffered piezo mic = std. electret mic has the better EMI immunity. Use that instead.
     
  3. AnalogKid

    AnalogKid

    2,351
    659
    Jun 10, 2015
    Also recommend an electret mic cartridge over a piezo disc.

    And - if you talk with the people who make glass break detectors for home and commercial security systems, you lean stuff. For example, there is a large, very-low-frequency component to the sound of glass breaking, and that is the signature these detectors use so they don't false-trip on normal room sounds.

    ak
     
  4. Rajinder

    Rajinder

    426
    7
    Jan 30, 2016
    ok thanks for your assistance. so an electret mic, amplifier and comparator or similar woul ddo the trick?
     
  5. AnalogKid

    AnalogKid

    2,351
    659
    Jun 10, 2015
    That is the basic signal path to start. You probably will wind up adding filters or a rate limiter.

    ak
     
  6. Colin Mitchell

    Colin Mitchell

    1,418
    314
    Aug 31, 2014
    We use a piezo as a contact mic to hear right through glass with our wall bug transmitter. A bit tinny but as clear as a bell.
     
  7. cl10Greg

    cl10Greg

    25
    3
    Mar 20, 2014
    Usually goes mic -> filter -> amplifier -> comparator. If you have the filter after the amplifier, you also amplify the noise
     
  8. Herschel Peeler

    Herschel Peeler

    401
    65
    Feb 21, 2016
    How low a low frequency component?
     
  9. AnalogKid

    AnalogKid

    2,351
    659
    Jun 10, 2015
    1 Hz-ish
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-