3-Band Equalizer Last Hurdle

Discussion in 'The Projects Forum' started by JonXp, Dec 12, 2010.

  1. JonXp

    Thread Starter New Member

    Dec 12, 2010
    Hello, I am currently making a 3-band equalizer for part of my college project and it seems ive hit a wall.

    Here is the circuit on Multisim:


    I have run a bode plotter and frequencies through the circuit and everything seems to work fine (oscilliscope + bode showing amplified frequencies from changes to potentiometers). After this i exported the circuit and printed up a circuit board.

    After populating the PCB to the circuit diagram i tried testing the circuit for real and unfortunatly it seems to do nothing now :(. when changing the potentiometers, no change can be heard what so ever to music or frequencies, although it does pass the signal through

    is there any visible or common mistakes in the circuit or that i could have made building the board ?

    Many thanks,

  2. Audioguru

    New Member

    Dec 20, 2007
    Like I said ....
    1) The value for C5 is 1000 times too big.
    2) The circuit must be fed from a very low impedance like the output of an opamp.

    Do it like this:
  3. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    You have to painstakingly verify that all the connections on your simulation were translated correctly into a PCB. The first thing I see from looking at the sim, is the crossing of lines at the op amp input. A simple mistake potentially in a PCB program because it might think two crossing wires are actually connected, and you assume it is as you intended it to be.
  4. tyblu


    Nov 29, 2010
    Does it work on a breadboard? If so, let's see the PCB.
  5. JonXp

    Thread Starter New Member

    Dec 12, 2010
    Thanks audioguru, i was looking for that one aswell. Ill try the diferent values today and if i still get nothing ill get the ultiboard and pcb

  6. JonXp

    Thread Starter New Member

    Dec 12, 2010
    Right, i tried the different values in the PCB i had originaly made and i had the same results of the sound not being proccessed as it should.

    so ive started again from the bandaxall circuit. heres how its looking:


    i know this isnt the best board layout but adjustments can be made and its all rooted as is shoulb be according to the multisim diagram.

    personally i think it looks more promising as the first was a bit of a shambles. :p
    Last edited: Dec 17, 2010