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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
at

20 comments:

  1. UnknownJune 22, 2016 at 9:32 AM

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

    ReplyDelete
    Replies
    1. Effects LayoutsJune 22, 2016 at 9:37 AM

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

      Delete
    2. UnknownJune 26, 2016 at 4:53 PM

      Transistor on left top is q1 right?

      Delete
  2. lonetone83June 22, 2016 at 10:38 AM

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

    ReplyDelete
  3. UnknownJune 24, 2016 at 9:50 PM

    Where Q1?

    ReplyDelete
    Replies
    1. Effects LayoutsJune 27, 2016 at 9:38 AM

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

      Delete
    2. UnknownJune 28, 2016 at 6:33 AM

      Thanks dude.

      Delete
  4. plushSeptember 3, 2016 at 2:40 PM

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

    ReplyDelete
  5. Ki Baradha LegiwaOctober 14, 2016 at 8:20 PM

    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..

    ReplyDelete
    Replies
    1. Effects LayoutsOctober 17, 2016 at 7:26 AM

      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.

      Delete
  6. plushOctober 31, 2016 at 8:17 AM

    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!

    ReplyDelete
  7. MassimilianoSeptember 22, 2017 at 7:57 AM

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

    ReplyDelete
  8. gennaroApril 23, 2018 at 11:11 AM

    I WOULD LIKE TO REALIZE THE P19 BY CHANGING THE COMPONENTS ABOVE USED IN THE FILE, BUT THE CONDENSER TO CHANGE OR THE 6.8NF WITH SYMBOL ++ WHERE IS IT REPLACED? WHAT SHOULD I REPLACE WITH THE CONDENSER?

    ReplyDelete
  9. gennaroApril 29, 2018 at 6:33 AM

    I WOULD LIKE TO REALIZE THE P19 BY CHANGING THE COMPONENTS ABOVE USED IN THE FILE, BUT THE CONDENSER TO CHANGE OR THE 6.8NF WITH SYMBOL ++ WHERE IS IT REPLACED? WHAT SHOULD I REPLACE WITH THE CONDENSER?

    ReplyDelete
  10. burn61February 19, 2022 at 12:43 PM

    for gennaro:
    following the skreddy p19 scheme, as the switch put two 6,8nf in parallel, the only condenser to replace is the 33nf condenser above in the layout, placed between contour pot and tone pot.
    enjoy your build

    ReplyDelete