Help Door Knob Alarm

Discussion in 'General Electronics Chat' started by Grizzly09, May 23, 2018.

  1. Grizzly09

    Thread Starter New Member

    Oct 24, 2017
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    0
    Hello everyone
    I need some help on this circuit
    Piezo in this circuit is not alarming loud enough
    I tested it on Proteus
    Can anyone help me
     
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
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    725
    Since u r unable to formulate observations and requirements, I will offer some suggestions that might or might not work:
    - reduce r1
    - increase b1
    - instead of buzzer use amplifier and attach louder sound device (buzze, speaker, whatever) to the amplifier.
     
  3. ian field

    AAC Fanatic!

    Oct 27, 2012
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    Many commercial products have a peaking inductor in parallel with the piezo sounder.

    Step up autotransformers aren't exactly rare in CO alarms that need to be loud.
     
  4. Grizzly09

    Thread Starter New Member

    Oct 24, 2017
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    Actually it's almost like a silent.And as you can see i should have used touch palette but i replaced it with a button.Clicking button doesnt make any noticeable change in sound.
    Thanks for the reply
     
  5. ian field

    AAC Fanatic!

    Oct 27, 2012
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    Piezos need a fair bit of voltage - they're also capacitive and resonant. you'd probably hear it if you drive it at the right frequency, but most commercial products have some form of peaking inductor.
     
  6. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    I'm not surprised. The pull-up resistor R8 is probably effectively clamping the oscillator output to the positive rail, and pressing the button clamps the output to the negative rail. Both situations result in Q3 turning off and the sounder being actuated.
     
  7. Grizzly09

    Thread Starter New Member

    Oct 24, 2017
    10
    0
    Any tips or answers will be very appreciated.
     
  8. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    Try removing R8.
     
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