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Cap questions

Discussion in 'Effects [BG]' started by Droog, May 20, 2004.


  1. Droog

    Droog

    Aug 14, 2003
    PDX
    On the board of this pedal I am going to mod, I come across two 10 uf and one 220 uf capacitors. It seems odd that there would be two 10 micro farad and a 220 in a fuzz box, those values seem really high. Am I wrong? I was going to replace the input and output caps with ones with greater values, but these already seem to be pretty high. Is there a decimal in there that I am just not seeing? .10 uf seems more reasonable. Thanks to anybody who knows more than me (which is a lot of you).
     
  2. tplyons

    tplyons

    Apr 6, 2003
    Madison, NJ
    The 10uF seems right, just a bit on the high side maybe, but OTOH, are you sure the 220 isn't picofarads? 220pF is .22uF I believe.
     
  3. Droog

    Droog

    Aug 14, 2003
    PDX
    O.K. I believe I was wrong as to what Caps I was looking at. I'm right about the values but the one cap that I was kinda ignoring turns out to be to be the input cap. It says 2A224K, which an electrician I know just told me is 224 picofarads, so thats like .224 uF right? So maybey I should stick a .10 uF in there?

    Still not shure what the 10 uF and 220 uF are for but they are not input or output caps as near as I can tell.

    Oh yeah and the manufacturer filed off the IC number, is that common?
     
  4. tplyons

    tplyons

    Apr 6, 2003
    Madison, NJ
    Hmm, thinking...

    Since 4700pF = .0047uF, then 224pF = .000224uF right? Never heard of one; but remember the higher the capacitance, the greater the bass response. What unit exactly are you looking at?

    Yep. Easiest way to keep someone from copying your circuit. Other people rebrand (put another part number on it) and sometimes companies go as far as to put non-working or dummy parts in a circuit to confuse copiers.
     
  5. nonsqtr

    nonsqtr The emperor has no clothes!

    Aug 29, 2003
    Burbank CA USA

    224K means 22 followed by four zeros, in pF. Which translates to .22 uF (and that's a standard value). The two 10 uF caps are most likely filter caps.

    I'm not entirely sure why you want to do this, I'm guessing that because it's a fuzzbox, it was meant for a guitar and you're trying to let more bass through the circuit so you can use it with your bass?

    If that's the case, increasing the coupling cap values may or may not give you the desired result (and changing the filter caps won't do anything, so if they really are filter caps you can just ignore them). It's usually a bad thing to let too much bass through a fuzzbox. You end up with this bumblebee-like sound that's not at all pleasing to the ear.

    Some people use multi-band circuits for bass, kind of like a multi-band compressor, except what you're doing is applying different amounts of "fuzz" at different frequencies. I've heard some excellent sounding bass fuzzboxes that use this approach.

    No it's not common for the manufacturer to file off the IC number. It's probably a 741 type op amp (or equivalent, like a 748, or a TL072, or maybe even a 5532 if you're lucky). If you can post pics of the top and bottom of the circuit board I can probably figure it out for you. Or a schematic would do the trick too.
     
  6. tplyons

    tplyons

    Apr 6, 2003
    Madison, NJ
    Good call, brain isn't working too well tonight.

    Not so much in effects, but in other circuits it's more common. Lots use proprietary part numbers (Boeing and Grumann were notorius for this -- I used to work in semiconductor sales and delt with many customers like this). It's more to prevent quick schem drawings, but anyone with decent electronic knowledge should be able to reverse engineer it.
     
  7. whats a good cap value to replace the input and output caps with in a distortion pedal?
     
  8. Droog

    Droog

    Aug 14, 2003
    PDX
    So yeah this little experiment may sound like ass, but oh well. I learn by doing. Its a Fuzz Buzz from Snarling Dogs. Its deffinately a .22 uF. Would a 1.0 uF be a terrible cap to try? If replacing the caps with ones of greater values gives me the bumble bee sound what would be the correct thing to do? Your talking about a novice here so I imagine no matter what I do the results may be, well, questionable:) Thanks guys.