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Noisy buzzer on PIC output

Discussion in 'Electronic Basics' started by Bill, Mar 25, 2007.

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  1. Bill

    Bill Guest

    I am driving a piezo buzzer (RS 273-074 3-16v DC) from one of the outputs
    of a PIC16F88. I am getting a very faint buzz from the buzzer even when the
    PIC output is low (almost like I am picking up the clock oscillations).

    I have tried .01uf caps both in parallel and series with the buzzer. I have
    also tried .01uf on the power supply leads of the PIC. I have also tried
    pulling the buzzer H and L with 10K resistors.

    Any ideas how I can supress the noise.

    Thanks
     
  2. John Fields

    John Fields Guest

     
  3. jasen

    jasen Guest

    try a pair of anti-parallel 1n914 diodes in series with the piezo.
    a pull-down resistor on the pic output may help too.

    Jasen
     
  4. What does the other side of the piezo connect to?
    Is the supply for the PIC bypassed?
    What else is running on that supply?
     
  5. That's what I was wondering, hopefully not a car battery. :-O I assume he
    only needs DC applied and not a pulse train. Given that, I'm thinking that
    the other end is connected to a voltage slightly higher than the PIC Vcc or
    lower than it's Vss allowing current to flow thru the protection diodes. If
    so, it'll probably take care of itself when it burns out that diode. ;-)
    I'm betting on your first question. JF's idea should work fine too, but I
    think the OP should find out what the real problem is. It's most likely not
    the PIC, unless the output port is somehow damaged.
     
  6. I am driving a piezo buzzer (RS 273-074 3-16v DC) from one of the
    outputs
    Thanks,

    The diodes did the trick :)
     
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