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opamp with 0-5v input and +/-5v output

Discussion in 'General Electronics' started by dimention11, Jun 21, 2005.

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  1. dimention11

    dimention11 Guest

    This is my first post to sci.electronics. I have no formal electronics
    training but have completed quite a few DIY projects ( Digital and Analogue)
    from the net and elsewhere.

    At the moment I am working on a Printerport (lpt) dac using the Quad 8bit
    DAC Max506.
    This chip has a rail-to-rail output voltage (0-5V) for the application I
    need +/-5v. I know (think :) an opamp is the solution. However I am still
    bamboozled by some of the tech jargon on the datasheets. If anyone knows of
    a solution off the top of their heads I would really appreciate it. if not I
    will report back with a couple of chips data sheets and ask for some

    If you need more info I can email my project so far :)

  2. Robert Baer

    Robert Baer Guest

    Certainly one can use an opamp to amplify the 5V swing to a 10V
    swing, and make that amplified signal go from -5V to +5V.
    As you can see, that is a gain of two.
    To prevent problems at the extremes, the opamp should be powered from
    +/- 10V (or better) supplies.
    I strongly suggest that you do not use any Maxim parts; the majority
    of what they advertise is "vaporware".
  3. WDino

    WDino Guest

    ANY OP amp can be configured to have a 0-5V input and a +/-5v output.

    You would need to connect it to a + 7 and - 7V (or more) power supply and bias
    the input with resistors so that the required conditions are met.

    A simplified circuit to give a gain of two, -5v out with 0v in, and +5v out with
    +5 in :

    +ve 10V supply
    | |
    \ |
    100K / |
    \ +|xx. |
    / O----------| xx|
    | |OpAmp xx --+---O
    +--------------+----| xx| |
    | | -|xx' | |
    \ | | |
    100K / ---/\/\/\--------
    \ 50K |
    / |
    | |
    -ve 10v supply

    And one to give a gain of two, +5v out with 0v in, and -5v out with +5 in :

    +ve 10V supply
    | |
    | 100K |
    \ ---/\/\/\--------
    50K / | | |
    \ 50K | _|xx. | |
    / O--/\/\/\--+----| xx| |
    | |OpAmp xx --+---O
    +-------------------| xx|
    | +|xx' |
    \ |
    100K / |
    \ |
    / |
    | |
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