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Capacitor values for opamp circuit and adjustable gain

Discussion in 'General Electronics Discussion' started by legoman, Jan 26, 2012.

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  1. legoman

    legoman

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    Oct 14, 2011
    Hi all,

    Attached is a schematic of an audio op amp preamp I wish to build. http://www.rason.org/Projects/opamps/opamps.htm I will use a NJM2068 opamp enstead of the TL082. I don't have the exact capacitors that the schematic shows. Would there be a significant impact in the circuit performance if I substituted the caps with values say 10x higher (1uF in place of 0.1uF or 100uF in place of 10uF)?

    Also this schematic shows adjustable gain by using a resistor on the output. Would it not be more desirable to put the adjustable gain on the feedback resistor?

    Thanks
     

    Attached Files:

  2. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    No, these are not critical. Increasing the input and output capacitors would increase the low frequency response. The one on the + input is to stabilize the voltage divider and a higher value would not change anything.

    Bob
     
  3. jackorocko

    jackorocko

    1,284
    1
    Apr 4, 2010
    Reason for the pot on the output is to act like volume control. I have seen it on the input and output but never in the feedback loop before. Though I can't give you a specific reason for it.

    I have an opinion on the caps, but I don't want to steer you wrong as I really don't know how it will effect the circuit performance. I just know what they are there for. :)
     
  4. jackorocko

    jackorocko

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    Apr 4, 2010
    bobk is a sniper in his day job I presume. :D
     
  5. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    Navy Seals Team 6!

    Bob
     
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