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Voltage Amplifier?

Discussion in 'General Electronics' started by dmt1, Jun 3, 2004.

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  1. dmt1

    dmt1 Guest


    Just wondering if there is any device that would allow me to amplify a
    voltage by 1 log unit (ie. a factor of 10). I have something that is
    outputing at approx 0.045VDC but the sensor will only detect if it is
    in the order of 0.45VDC. I don't know the reason for the descrepancy
    but i was just wondering if there is anything i can do to amplify the
    output signal?

  2. Robert Baer

    Robert Baer Guest

    A good linear solution is to use an operational amplifier, with the
    gain set to 10.
    You can have a gain of either +10 or of -10 as you wish.
    Op amp ICs are cheap as heck, resistors toset the gain are also very
    The power supply could be as meager as a single 9V battery, or a 10 to
    30V wall wart, or a special +15V / -15V supply.
  3. JeffM

    JeffM Guest

  4. Depends on the type of signal and the required precision. Your
    question lets me guess that it is low frequency and the precision is
    not critical, in this case any cheap OpAmp will do:

    -IN to +INPUT ----| \_________________OUT
    ----|1K|----| / |
    | | |/ |
    | | |
    GND | |
    If it must be adjustable
    use a trimpot here

    Most of them work with supply voltages from +/-3 to +/- 18 VDC
    For higher precision/frequency get the datasheet of the OpAmp, many of
    them have circuit examples.
  5. Ben Moss

    Ben Moss Guest

    Actually that should be a 9K ohm, not a 10K (when you use the positive
    input the gain is 1 + R2/R1). A trimpot is still a good idea,
    considering tolerances of typical resistors.

    -IN to +INPUT ----| \_________________OUT
    ----|1K|----| / |
    | | |/ |
    | | |
    GND | |
    If it must be adjustable
    use a trimpot here

  6. Of course. Thank you for pointing that out.
  7. JeffM

    JeffM Guest

    that should be a 9K ohm
    or you could specify values that are actually available
    (no matter the tolerance).

    -IN to +INPUT ----| \_________________OUT
    ---- 2K ----| / |
    | | |/ |
    | | |
    GND ---- 18K ------
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