isd4003 arll that matterr
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  1. #1

    Default isd4003 arll that matterr

    I need to record voice in an ISD4003. Using the audio input with a condenser mic isn't sensitive enough. I added a 1 transistor preamp which works well but it now has a ticking noise. Filtercaps eveyrwhere don"t help. Any suggestions? Thank you.

  2. #2
    Join Date
    Jan 2006
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    Istanbul
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    Default Re: isd4003 arll that matterr

    A circuit schematic would be useful here.
    "If the Earth were a single state, Istanbul would be its capital." Napoleon Bonaparte

  3. #3
    Join Date
    Mar 2003
    Location
    Commerce Michigan USA
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    Default Re: isd4003 arll that matterr

    I would suggest using an MAX8914 breakout board from Adafruit. Connect the microphone in single ended mode with a voltage divider and set maximum input voltage for ISD4003 for 32 Millivolts. Cap coupled of course.
    Dave Purola,
    N8NTA
    EN82fn

  4. #4

    Default Re: isd4003 arll that matterr

    Thanks guys. I am attempting to attach the schematic of what I'm doing (never did this before). Like I said, any attempt to record has a loud ticking in the back round. Shorting the 1K in the mic circuit has no effect. Disconnecting the mic has no effect, removing the 220uF has no effect. Adding disc caps in parallel to the 220uF has no effect. Reversing the ANA IN + and - has no effect. The only way to stop the ticking is to disconnect the circuit. Capacitively coupling the mic directly to the ANA IN pins works but you need to put the mic up to your lips and talk very loud. This will be a modification to an existing prototype circuit board to be mass produced. Any suggestions would be appreciated.

  5. #5

    Default Re: isd4003 arll that matterr

    That didn't work Trying to attach again PDF file.
    Attached Images Attached Images

  6. #6

    Default Re: isd4003 arll that matterr

    I forgot. There's a 10K to B+ on the collector of the transistor.

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