Smoke Alarm Help

Discussion in 'The Projects Forum' started by Chris15, Sep 14, 2009.

  1. Chris15

    Thread Starter Active Member

    Apr 15, 2009
    252
    0
    Hi
    i am working on yet another motion security unit that uses a smoke alarm beeper, however i did a stupid thing and threw the smoke alarm circuit away thinking i only needed the beeper (i was scared to keep the radioactive unit) i know they cant penetrate your skin but i was just cautious, anyway dose anyone know how much Voltage and Current they need to operate, i figured maybe 9V but i put a 9V battery on the +red and -black pos neg and it made a quick short "tik" then i take it off and put it back on and same thing.

    Please help

    Thanks, Chris
     
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
    That's not a "beeper", it's most likely a piezo "speaker". You will need to drive it with an oscillator circuit.

    Ken
     
  3. Chris15

    Thread Starter Active Member

    Apr 15, 2009
    252
    0
    Oh sorry i know it is a piezio electric sound generator and i may have thought it would need an oscillator, could you explain in more detail what kind, a 555 Timer, but with what time constant resistance X Capacitance

    Thanks Chris
     
  4. KMoffett

    AAC Fanatic!

    Dec 19, 2007
    2,574
    230
  5. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    A piezo transducer (speaker) has a sharp resonant frequency that is affected by the size of the cavity of its enclosure. The oscillator must be tuned to the peak of the resonant frequency for the loudest sound or the most sensitive microphone.
     
  6. Chris15

    Thread Starter Active Member

    Apr 15, 2009
    252
    0
    OK Thanks heaps both of u now i dont only know how to use it i also know what it is, will try that circuit

    Chris
     
Loading...