What kind of Amplifier should I use?

Discussion in 'The Projects Forum' started by Mussawar, Aug 30, 2013.

  1. Mussawar

    Thread Starter Member

    Oct 17, 2011
    68
    3
    Hi!
    I’m using a sensor which gives analog output in the range from 0 to 1V dc. I need to convert it in the range of 0 to 5v dc(or might be from 0 to 9V). Please suggest me what kind of amplifier should I use? or is there any other way to do this? Please give an idea. I need precision, linearity and stability. I’m using 9V regulated single power supply for the project. (Excuse me for bad English).:) Thanks.
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,126
    3,048
    A simple, ground-senseing op-amp such as LM358 should work fine. Set gain to 5 or 9 as needed.

    Pay attention, though, to your max voltage available at the output of your chosen op-amp. For example on a 9V supply, your amp might only go to 7.5V (like the LM358). Other amps support rail-to-rail output, which you'll need if you want 9V out of it.
     
  3. crutschow

    Expert

    Mar 14, 2008
    13,014
    3,234
    A low offset, rail-rail op amp such as the LT1637 should work. If you want the signal to not be inverted, use the amp in a non-inverting configuration with the desired gain.
     
  4. DickCappels

    Moderator

    Aug 21, 2008
    2,653
    632
    The linear technology part is a beautiful amplifier, and much better than the LM358, but the datasheet only shows it going down to 10 mv. The LM358, which crutschow, in another thread noted can go almost all the way down to zero volts will do so if it doesn't have to sink very much current (more and 50 microamps). So if that last few millivolts is more important than the improved offset voltage of the Linear Technology part, you might consider the old '358. (Admittedly, nobody has ever measured zero volts with sufficient resolution to prove that it is actually zero :)

    crutschow [​IMG]
    Senior Member
     
  5. Mussawar

    Thread Starter Member

    Oct 17, 2011
    68
    3
    Thanks to all for a good response. Well I have come to the end that I should use OP-Amp. I'm thinking about uA741 and LM 324; since these are easily available to me. What is your openion about 741 and 324? Actually I need 4 sets of such amplifiers to work with four different sensors in the same fashion.
     
  6. Shafquat

    New Member

    Aug 31, 2013
    10
    0
    other way to increase votage by voltage doubler circuit. it's a simple circuit consist only diode and capacitor.
    if 2v input, then output is 4v.
     
  7. wayneh

    Expert

    Sep 9, 2010
    12,126
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    Then why did you waste our time asking for options when there was only a choice of 2?

    Of those 2, the LM324 is the (far) better choice.
     
  8. crutschow

    Expert

    Mar 14, 2008
    13,014
    3,234
    That only works for a bipolar AC sinewave signal and not well at all for a 1V signal due to the diode drop. The OPs signal is unipolar. And you need more than 1 diode and 1 capacitor for a doubler.
     
  9. crutschow

    Expert

    Mar 14, 2008
    13,014
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    You stated you wanted precision so neither is particularly good unless you can tolerate their input offset. The LM324 is the better unit but still has 3mV max. of offset. That would give an offset at the output of 27mV with a non-inverting gain of 9 or 15mV with a NI gain of 5. Is that acceptable?

    Incidentally to get an output voltage of 9V with the LM324 you would need a 12V supply voltage. With 9V supply you'd be limited to about 6V maximum output.
     
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  10. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    You might also see if the device that you're feeding the signal to (presumably some kind of A/D converter) has a calibration and offset function. If that's the case, you won't need to add any hardware.

    Eric
     
  11. Mussawar

    Thread Starter Member

    Oct 17, 2011
    68
    3
    This is not just the choice of 2. I would have to use only one at last. I started this post to get suggestions about what kind of amplifier should I use? Here come suggestions pointing to Op-Amp would be a good choice. By putting these two in the front, I meant that if I should use an Op-Amp then what about these two? I did not use them yet until I get some recommendations. :cool:
     
  12. Mussawar

    Thread Starter Member

    Oct 17, 2011
    68
    3
    Thanks! I’m intended to send it at a comparator. Ref will come from a D/A converter.
     
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