Swiss Army Fuzz: Universal Tone Bender MKII/Fuzz Face Board

Big Monk

Well-known member
I've just finished putting together the design for a Universal Classic Fuzz board:

Schematic.PNG
VSEDC-UFUZZ-01.PNG
VSEDC-UFUZZ-01-DIP.PNG

It's designed around the Pedal PCB 3 Knob predrilled enclosures from Tayda.

Some of the design parameters:

1.) Power Supply filtering on board, including electrolytic and ceramic caps and protection diode;
2.) Alpha 9mm PCB mount pots;
3.) 1/4W MF resistors, 5.08 mm box caps, 6.3 mm Electrolytics
4.) Can be used to make the Tonebender MK II, Supafuzz, Tonebender MK 1.5 and Fuzz Face
5.) Has optional Rb2 for doing Silicon Tonebenders;
6.) Optional trim pots for collector voltages on Q1, Q2 and Q3;
7.) Optional output trim pot (Rc3a and Rc3b network)
8.) On board ground pads for audio jacks, DC jack, shielded wire shields, and switch ground;
9.) Pads for optional base to collector caps on all three transistors;
10.) Pads are provided for using 3 Pole CUI Term blocks, transistor sockets or hardwired transistor connections.

Any thoughts?
 

Feral Feline

Well-known member
Wow!

Nice work! This must've taken a while to sort out all the wee details. Many thanks for sharing

Looks like it will fit 1590B if I do my own drilling.

Self etch or will boards be available for sale?


I think the only way to make the layout stop staring at me is to build it, poke out its eyes with the centre pot.
 

Big Monk

Well-known member
Wow!

Nice work! This must've taken a while to sort out all the wee details. Many thanks for sharing

Looks like it will fit 1590B if I do my own drilling.

Self etch or will boards be available for sale?


I think the only way to make the layout stop staring at me is to build it, poke out its eyes with the centre pot.

I sent away for 5 boards from JLCPCB today. I need 3 and could definitely part with the other 2.
 

finebyfine

Well-known member
Absolutely mindblowing. Looks awesome, and I want one.

Which pads are the grounds for jacks/dc/switches? I’m guessing its the larger ones the 4 on top and two in the middle. I personally would do all offboard connections as a row or two of 2.54mm pitch pads so people could have tidier offboard wiring with ribbon wire (or even use my trademark favorite: 2.54mm screw terminals 😉)

edit: oh those are for the 9mm pots arent they

you could also go even more overkill on the transistor options and add SOT-23 pads
 
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Big Monk

Well-known member
Which pads are the grounds for jacks/dc/switches? I’m guessing its the larger ones the 4 on top and two in the middle. I personally would do all offboard connections as a row or two of 2.54mm pitch pads so people could have tidier offboard wiring with ribbon wire (or even use my trademark favorite: 2.54mm screw terminals 😉)
FUZZ I-O.PNG

My thought process behind laying out the I/O was that I personally like to be able to send the various grounds and I/O to the board as close to the components they are coming from as possible. To me that's neater.

If you can visualize what this would look like in a PedalPCB, pre-drilled 125B with top jacks, the following would happen:

1.) Shielded wire from the input jack will go to the switch, hugging the side of the enclosure, and then another shielded run comes back from the switch, again hugging the side (these can be secured together with a zip tie mount low in the enclosure) and landing on the 2 pads provided in the top left corner;

2.) Jack and DC grounds land with a very short run at the top of the board;

3.) Your switch ground lands with a short run at the bottom of the board;

4.) Output shielded wire has the same journey as the input on the opposite side of the board.

This is a pretty good grounding setup ala R.G. Keen when you use an isolated output jack and avoid power switching on the input. In this case, since the Pedal PCB enclosure does not support a battery anyway, for PNP or Battery power, you can simply sub the DC Jack for an ON/OFF battery switch and always use a mono Input Jack and make sure it makes good contact with the enclosure for shielding.
 

Big Monk

Well-known member
Did some dry fitting this morning:

FA42D695-318B-4081-8087-9A418C9F114C.jpeg C4A5FC16-9341-4663-AE0C-EF3D5F3F4B88.jpeg CFB9720A-1181-411B-AECF-223CC251BF89.jpeg

The only things I’ll change on the next revision are the following:

1.) Provide another pad for the collector to base caps. My measurements were for the small monolithic lead spacing and not the wider yellow ceramics from Tayda. Not a deal breaker as I was able to bend them to sit flush down on the board.

2.) Provide more pads for the trim pots to accommodate the non-cermet types. You can see in the second picture I had to bend those legs in a little.

3.) Move the ground pads for the input/output jack sleeves. The PCB pot has a support leg on the back that is deirectly over the pad. It has no connection to the pot itself so there is no shorting issue here, but a better location is just to the right and left of each.
 
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