Breadboarded an Earth Sound Research graphic fuzz.

Rambozo96

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A weird rather broken distortion circuit from the mid 70’s from a very short lived company this is a wordy post with technical detail so scroll to the bottom for the demo video and shortened explanation. The pedal originally had a weird floating +4.5/-4.5 power supply from a 9v battery that would make it impossible to daisy chain without proper modifications. Which is what I did on a breadboard modding the voltage divider side to make a 4.5v virtual ground to hook to pin 3 of the 741 opamp, added decoupling caps to make it work with this virtual ground set up and made an accidental discovery as to tame the infamous whine of this circuits filter.

The TLDR short of it: The links provided is a schematic drawn up by a former Earth Sound Research employee which I then further modded for the modern day and to be less broken sounding.

CAUTION THIS VERSION OF THE BREADBOARD MAKES A HORRIBLE WHINING TONE! Listen at low volume and adjust accordingly or click on the second link for the non noisy version

Modified version with no terrible high pitched whistle:
 

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Rocky

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The guitar and the feedback both go to the inverting input?
 

Rambozo96

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Oh fun! I have a couple of Sola Tonebender kits on the way. Should easy peasy.
I have a Burns Buzzaround on a veroboard I seriously need to hurry up and finish. The MKIV is pretty close to that Burns circuit
 
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