op amp formula symbol identification

Discussion in 'General Electronics Chat' started by minkey01, Oct 9, 2016.

  1. minkey01

    Thread Starter Member

    Jul 23, 2014
    176
    0
    hello.

    does anyone know what these double lines are in this formula: || ?

    and how to calculate with them?

    R1||R2||R3

    Thanks!

    op amp formula.jpg
     
  2. SLK001

    Well-Known Member

    Nov 29, 2011
    820
    229
    In parallel with...
     
  3. MrChips

    Moderator

    Oct 2, 2009
    12,447
    3,362
    Double lines mean "in parallel with".

    R1||R2 means that you add the conductance of R1 with the conductance of R2.
    The total conductance of R1||R2 is 1/R1 + 1/R2.
     
  4. minkey01

    Thread Starter Member

    Jul 23, 2014
    176
    0
    ahhh... so that part of the formula would be 1/R1 + 1/R2 + 1/R3

    thanks for the answers!
     
  5. minkey01

    Thread Starter Member

    Jul 23, 2014
    176
    0
    oh but then invert it :

    1/Rsum = 1/R1 + 1/R2 + 1/R3
     
  6. MrChips

    Moderator

    Oct 2, 2009
    12,447
    3,362
    You got it!
     
  7. crutschow

    Expert

    Mar 14, 2008
    13,023
    3,236
    Written as Rp = 1 / (1/R1 +1/R2 + 1/R3)
     
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