This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Friday, September 18, 2015

Fulltone 70

For #fuzzfriday, here's the Fulltone 70 fuzz. Like the Fulltone 69, the 70 is a tweaked Fuzz Face circuit, following the silicon version. Like the original silicon Fuzz Face it uses BC108 transistors, though others can be used. Q2 should be higher gain than Q1. One of the nice things about the 70 is the added Mids control, which adjusts the some of the voltage reaching Q2 and the output capacitor. You can board mount the pots using right angle PCB mount types from the solder side.





22 comments:

  1. Works like a charm. My favorite fuzz so far. Thanks for the layout bud.

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  2. I'm still having issues.
    Getting throughput, fuzz activate when it's hit hard, but dies immediately. Can't quite figure it out

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    Replies
    1. Sounds like mis-biased transistors. Which ones are you using? Have you played with the trimmer much?

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    2. I'm using Bc108c's. The trimmer doesn't seem to to affecting anything.
      The 108's I have a reasonably high hfe, averaging around 540.
      I do have some others or I could also try some 7777's.
      Any ideas?

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    3. Mine took a bit of trial and error to get a good set of trannies. The BC108B's I settled on ( from TAYDA) ended up being around 170-200 hfe. Sound just a bit smoother than that outright in your face fuzz I got with some 2N2222A.

      Interesting you mentioned the trimmer. I cant get my C to get down around the 4.5V so maybe we need to play around with it...

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    4. Lol 7777 😜
      Just realised I'm note seeing anything on C of Q2

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    5. Alright, I removed the 5K trimpot and replaced it with a 50K. Adjusted the C of Q2 to 4.5V and the trimpot is reading 25K of resistance. Result, a fair bit more sustain... smiles all round.

      Maybe give that a try JaswWH.

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  3. Just curious, the trimmer can only go in one way right?

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    Replies
    1. Yeah can only really fit one way. Center pin (by itself) down on this layout.

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    2. Yeah cool! Just eliminating any foolish mistakes!

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    3. Hey if you want foolish mistakes I'm your man... :)

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    4. So, foolish mistake rectified! Hairline connection across the trace :/
      Sounds good! Left the 5k in who's doesn't seem to change voltage to C of Q2 at all?

      I also only had a c10k on hand.

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  4. hello, you could post the circuit Fulltone Full drive II. Thank you

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  5. Hi! I made it and it sounds very nice! thanks a lot! I would like to try with 2sc1815 (as written in the project) but how can I put 2sc1815 since they are ecb and not ebc?!

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    Replies
    1. Easiest way is to just bend the legs around so they're CBE. Just make sure the legs aren't touching each other.

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    2. ok, maybe I can put some insulating tape on them? thanks!

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  6. Does anyone know how I could get a a little more top end into this??

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    Replies
    1. Try reducing the value of the 2.2µ input cap to like 1µ.

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