audio amp connection problem

Discussion in 'General Electronics Chat' started by bean, Sep 24, 2012.

  1. bean

    Thread Starter New Member

    Aug 10, 2008
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    0
    i found this nice circuit which works nicely,but the only problem it's to quite.
    http://www.electronics-project-design.com/DoorBellChime.html

    so i was thinking to connect an audio amp like LM386 to its output signal.

    and this is where the problem comes.
    in the circuit the output leg is connected to the power supply
    so basically the power supply of both circuits and audio signal are one leg.

    how to connect the audio amp circuit (lm386 in ,out, power) to the first circuit

    thanks
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
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  3. THE_RB

    AAC Fanatic!

    Feb 11, 2008
    5,435
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    That chime circuit uses a 555 timer IC pin3 (IC output) to drive the speaker. Just remove the speaker and electro cap, and connect pin3 into the input of your LM386 amp circuit (which probably includes its own input cap).

    It is wise to include a volume pot between the 555 pin3 output and the amp input. :)

    (edit) whoops I was gazumped by Dodgydave! :D
     
  4. Audioguru

    New Member

    Dec 20, 2007
    9,411
    896
    Don't use C2 when the input signal is ENORMOUS from the 555.

    The LM386 with a 9V supply produces only 0.5W into 8 ohms. Not loud but louder than the first circuit.

    That chime will not sound like a chime because the output from the 555 is a square-wave that sounds like a buzzer.
     
  5. bean

    Thread Starter New Member

    Aug 10, 2008
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    thanks guys :)

    the first leg of speaker goes to the output of lm386 circuit
    but to where i connect the second leg of the speaker?
     
  6. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Read the LM386 datasheet, it shows how to connect the speaker to the LM386.
     
  7. bean

    Thread Starter New Member

    Aug 10, 2008
    5
    0
    i know where the leg will go in an lm386 circuit- the ground
    but in the first circuit(doorbell) speaker one leg goes for power source and the other goes to pin 3.
    very confusing when you have to switch the power source leg for the ground.
     
  8. lawncegary

    New Member

    Sep 27, 2012
    6
    1
    Just remove the speaker and electro cap[​IMG]
     
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