LM3915/LM741 amplifier

Discussion in 'General Electronics Chat' started by AR_BO1021, Jun 17, 2016.

  1. AR_BO1021

    Thread Starter New Member

    Nov 28, 2015
    4
    0
    Hi

    I have built a vu meter with the LM3915 IC and i want to amplify my audio signal because its to low from my mp3 which is 300mV.
    To how much should i amplify the voltage and why?
    Is lm741 a good amplifier to use?
    Is there any difference between using ±12v or 0v and 24v to supply the lm741 amplifier?

    Thanks,
     
  2. Lestraveled

    Well-Known Member

    May 19, 2014
    1,957
    1,215
    Hi
    First, what did you set the reference voltage to? Now is a good time to post a schematic.
     
  3. dl324

    Distinguished Member

    Mar 30, 2015
    3,243
    620
    Probably not a good choice for your application.
    Yes. LM741 is spec'ed to have a common mode input range to about 3V from the rails. If you use a single supply, the input couldn't go below around 3V. With dual supplies, oV would be supported. If you don't already have a negative supply, I'd use something else.

    As mentioned, you should post a schematic so we don't have to guess about your circuit.
     
  4. AR_BO1021

    Thread Starter New Member

    Nov 28, 2015
    4
    0
    Vref is set to 10v
     
  5. benta

    Member

    Dec 7, 2015
    101
    24
    1: no need to amplify anything, just insert a voltage divider between REF-OUT and R-HI.
    2: The LM741 is NOT a good amp to use in ANY situation. Send it to its grave and RIP.
    3: not relevant.

    Benta.
     
  6. dl324

    Distinguished Member

    Mar 30, 2015
    3,243
    620
    It will work fine for many applications. I have dozens in my parts bins and find them still quite useful.
     
  7. Lestraveled

    Well-Known Member

    May 19, 2014
    1,957
    1,215
    You don't need an amplifier. Just change your reference to 1.2 volts.
     
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