Monday, 12 August 2019

Schaller Fuzz Sustain

An old fuzztone from West Germany which was housed in a wah shell. The treadle controlled the amount of fuzz and clean signal through a dual gang pot. There was an internal 22k trimmer which controlled the amount of gain.
Built it stock which works fine but it needed some improvements like higher output level and the internal trimpot was changed to an external gain control. Increased the value to 100k for more gain. Stock units had BC413C and BC239C transistors which is fairly high gain general purpose silicon transistors so BC549C's and 2N5088's should work equally good.

Schematic.
Stock circuit

Modified circuit




7 comments:

  1. Ba07 diode, i cant find any info about em?

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    Replies
    1. I've searched for info as well and can't find anything iether...:-/
      I'm fairly certain that they are normal silicon diodes, possibly power rectifier type.
      Germanium diodes would drop the output way bellow unity in this circuit....

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    2. http://fs3oooohdzhswr4v3dozk6aqekqrvhcbhi7inn6avv7tvwlsauqvqqad.onion

      Looking at interor it seems to be a pair of BA127 by the looks of it, or what do you say?

      Ba127 seems to have 1.1vf

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    3. Yes, the schematic seems to be incorrect when it comes to diodes since the gutshots diodes in the looks like Ba127, indeed. They still seem to be avaiable at some online vendors if you want to build a 1:1 replica.

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    4. Yeah saw that! No schematic isnt inkorrekt - if you scroll in it says ba127 it just that its so small that the 12 looks like a 0. Cheers man

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    5. Cheers! Eagle eye!
      I'll change the diode lables as sson as I can.

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  2. Wonder where to find a dual 100k wah pot if wanting to build it in a wah enclousure also haha, only one i found was a old pot on reverb.

    Or if they used 220k dual gang labeled 100kb like some old but it was only ~ 100k getting affected by sweep

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