Bass guitar compressor-Sustain sustain control

Discussion in 'The Projects Forum' started by Bigbizkit, Dec 14, 2015.

  1. Bigbizkit

    Thread Starter Member

    Oct 29, 2015
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    1
    hi, i made an orange squeezer comp by tonepad
    when i adjust the SUSTAIN knob to low or below 50% the volume also go down, as in zero output sound. its like the sustain knob has become a gain control..
    ya think thats normal?
    I used 2n5486 as a replacement for the original 2n5457 fet transistor(availability issue)
    1n270 for 1n34a
    Did some mods too
    Output cap 4.7uf to 1uf
    Bleeder cap 4.7uf to 10uf
    Feedback resistor 220k to 200k
    Mods on the tonepad site.
    Thank you in advance guys.
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,031
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    @Bigbizkit
    How did you wire the circuit around Q2? There appears to be something missing there. I see an arrow that is normally associated with a pot but no resistor portion of the pot. The connections between source and gate on Q2 seems odd as well.
     
  3. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
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    Q2 looks like a current source connected to Vcc.
     
  4. Bigbizkit

    Thread Starter Member

    Oct 29, 2015
    44
    1
    Screenshot_2015-12-14-20-55-53.png here is the parts placement guys. Thank you...
     
  5. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    Q2 is used as a constant current source, to charge up the 4.7uf cap.
     
  6. ian field

    Distinguished Member

    Oct 27, 2012
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    Q2 looks OK to me - its wired as a current source, the source current develops a voltage across its resistor and the gate to the bottom of that resistor ends up negative WRT the source. If you just shorted the gate and source together, it would still be a current source at the IDss stated on the datasheet.
     
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