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ditital voice

Discussion in 'Beginner Electronics' started by Jeff, Jun 8, 2004.

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  1. Jeff

    Jeff Guest

    Can anybody help me design a circuit that will digitize voice and
    place the data into RAM, then read it and convert it back? The chips
    from ISD won't work for my situation because there is no access to the
    data. I want to be able to read the data in reverse to play the audio
    backwards. I am going to have to use A/D and D/A converters and a PIC
    microcontroller to do the job for me. My question is: Which is the
    best A/D and D/A converters to use for a clear voice recording? What
    should the sampling rate be? How many bits/resolution should I be
    looking for? The PIC16F872 has a 10-bit A/D converter built in but I
    am not well versed in Assembly Language and my BASIC compiler doesn't
    support this function as far as I know. So, my thought is to build a
    circuit around the PIC16F872 which will provide the address for the
    RAM and sync pulse for the A/D converter. The converter will send
    serial data to the RAM to store the recording. The PIC16F872 will
    interpret which button is pushed by the user and access the RAM either
    forwards or backwards (count up/ count down). Data will be sent to the
    D/A converter and play the audio. Any suggestions?

  2. Kirk Shirley

    Kirk Shirley Guest

    There are many PC based solutions to digitize and play your message
    Is there a reason you can't do this?
  3. Jeff

    Jeff Guest

    My project must be stand-alone. It can't rely on a PC. It should be a
    rather simple circuit. I'm just not sure if simply accessing the
    digital data in reverse will convert the original audio to play
    backwards. There are hundreds of A/D converters out there. If anybody
    has experience using them to digitize audio, I just need to know which
    one to choose.
  4. nemo

    nemo Guest

    Do a Google search on the phrase "analogue to digital converter" It will
    point you towards other chips and searching on the phrase, "analogue to
    digital conversion" might turn up the sort of info you're after.

    The ones I know about like the ZN 435 which can work both ways round BTW but
    blows up at the slightest hint of static, are rather obsolete nowadays.

    Hope this helps,

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