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uStomp » Blog Archive » Kay Fuzztone

Kay Fuzztone

This is a great fuzz pedal. You can hear it on the opening to U2’s elevation and on Daniel Lanois’ song “Kay Fuzz”. I used a 2N5088 for Q1 and 2N3904’s for Q2-Q4. I used 1N914’s for the diodes.

Download Build Diagram
Download Etch Template
Download Schematic
Interior Photo

Kay Fuzz

12 Responses to “Kay Fuzztone”

  1. Rich Says:


    I’m interested in building one of these for myself. I had one of these pedals a while back and unfortunately sold it to fund some other equip.

    Your project seems straight forward to build and I was wondering if you’d be willing to help me by sharing your experience, parts list, etc.



  2. marcos antonio bezerra de carvalho Says:

    I make this project identic the your layout. That’s Wonderful!!! Thank you!!! I thought that transistor was critic component, however the resistance in series with 47k potenciometer that was.

  3. Aaron Says:

    Hey I’m in the process of making this, does anyone know what the RLED value would be for an Orange LED light??

  4. Jeff Says:

    Orange Led needs a voltage of 2.1 volts. You can use the resistance between 100R and 380R, depending on how bright you want it. The less resistance the brighter it will burn. However, don’t make it too low or you will burn the led, maybe not imimdiately but in the future.
    Well, hope this could help.

  5. captaincro Says:

    hey man,

    great job, My projectis the same than you ?
    What is please the tall of the circuit ?

  6. JW Says:

    so, is this a good one? i have heard two different sounding clones before. i have heard one that was spot on, but then i have also heard ones that are darker and dont sound like they should.

  7. captaincro Says:

    Hey man,
    Where did you find you 50k potentiometer ! I can’t find it anywhere !
    Help me please, that is the only component I miss !!

    Thanks !

  8. Douglas Says:

    I built one of these for a friend a while ago, and used the stock pot of his old crybaby, and it worked like a charm!

  9. fello Says:

    the schematic says Q1 and Q2 are a 2SC6445, that Q4 is a 2SC828R and diodes are OA90 (Ge)
    there is a difference between what you say and what the schematic say?
    which option is the best?

  10. Alberto Says:

    Hello! I built the pedal but i have very low volume compared with my other pedals. THere’s any option for that? Thanks a lot

  11. Chrix Rubix Says:

    What’s the difference of these two schematics?
    * the position of the .0022uf/2n2 cap near 47K

    1) http://analogguru.an.ohost.de/001/schematics/Kay_F-1_FuzzTone.gif

    the original “schematic”
    2a) http://www.somewhereoutwest.com/graphics/fuzztone01.jpg

    computer drawn
    2b) http://diystompboxes.com/pedals/kayf1.JPG

    is there a difference in the tone?

    there’s a difference in this 2 i think..

    this one has… 4 transistor and 2 diodes…

    this one lacks… 4 transistor and 2 diodes…

    the tone?


  12. Chrix Rubix Says:

    gOOd Day!!!
    Success!!! i have build the Kay Fuzz tone using the original
    schematic… point to point .. no PCB.


    i had problems after building this..
    1. no output.
    2. low volume with minimal effect.

    1. wrong pin ECB for Transistor (always check transistor you bought,
    the internet has a complete data sheet for transistors,Google)
    2. all Ground to Input jack ground

    1. I’ve used 2SC945 for Q1 and Q2 & 2SC828 for Q3 and Q4
    thing to consider here is the PIN Orientation of the transistor
    your using. where is E,C & B? yes, this was my mistake.

    2. For the diodes i’ve used 1N4148.

    3. i didn’t include the 200k coupled to the 50K pots to ground, i’ve just used
    a 100K pots (sound fine regarding the sweep, bonus here is at zero
    no volume at all, like a volume/filter together)

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