How to drive 1KhzTone into Telephone circuit

Discussion in 'Embedded Systems and Microcontrollers' started by prevravanth, May 2, 2007.

  1. prevravanth

    Thread Starter New Member

    Dec 29, 2006
    8
    0
    Hi,

    I am Generating 1 KHz tone in 80C51 using timer0.

    I want this 1khz tone to be fed into Telephone.

    this tone should be heared in Earpiece of telephone.

    How to drive 1 Khz requency Tone into Telephone circuit...?

    Please Help me.

    Thanks
    Prev Ravanth
     
  2. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    You'll need an impedence matching circuit. The phone line is spec'd at 600 Ohms. If you measure actual phone line impedence and match to that instead, you gan get 3 or 4 dB improvement over a 600 Ohm match.
     
  3. Arm_n_Legs

    Active Member

    Mar 7, 2007
    183
    10
    The circuit that interface the phone circuit to the line is called the DAA circuit. Google "DAA circuit".
     
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