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, June 17, 2016

MojoHand FX Iron Bell/Skreddy P19

For Fuzz Friday, here's another Big Muff based circuit to add to the collection. The Iron Bell is a variation of the Skreddy P19, the schematic of which was graciously posted by Marc from Skreddy a few years back. It's not based on any one classic Muff, but is Marc's unique blend of custom values, and features a boosted mids tone stack, with a switch to increase the mids. Shortly thereafter, the Iron Bell came out with a few mods, the biggest of which is the replacement of the Mids switch with a potentiometer and a few value changes. The layout below reflects the MojoHand iteration of the circuit, but the P19 can be built on the same board (see below for component changes). It's laid out for board mounted pots and should fit in a 1590B.



To make the Skreddy P19, made the following changes:
  • Replace the Colour pot with an SPST on/off switch
  • Change Q2-4 to BC550
  • Change the following components indicated on the layout:
    * 200Ω
    ** 10k
    • 47nF
    •• 2.7k
    ‡ 6.8nF

16 comments:

  1. Works , but in the schematic the capacitor is 100uf and not 47uF . thank you.

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    Replies
    1. That's just the power filtering cap. Either value will work. Thanks for verifying!

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    2. Transistor on left top is q1 right?

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  2. Do you have a layout what shows how to connect the pots and on/off switch? I'm dying to make this

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    Replies
    1. Check out the General Layout Notes tab at the top of the page.

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  3. Replies
    1. I've updated the layout. PCB side shows transistor names now. Sorry about that.

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  4. Guess there is a flaw somewhere, maybe in my build or in this layout. The gain is very low compared to tagboardeffects layout

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  5. What's the use of the 1M resistor at the input? Does it affect the gain? Cz mine has a very low gain (volume) somehow..

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    Replies
    1. The 1M at input is the pulldown resistor to minimize/eliminate the pop that can happen with 3PDT footswitches. It doesn't effect the gain of the circuit. Double check your build for shorts or bad components. If that doesn't solve your problem, use an audio probe.

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  6. Finally, i've managed to make this one work.
    Special thanks to my stupidity and unwiped rosin.

    Guts pic: http://i.imgur.com/n3H34F3.jpg
    Mxr size w top mount jacks FTW!

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  7. Salve....a cosa si riferisce l'ultimo simbolo: 6,8 Nf?

    ReplyDelete