Introduction: DIY Guitar Pedal

Picture of DIY Guitar Pedal

Making a DIY guitar fuzz pedal is a fun and easy electronics weekend project for hobbyists and guitarists alike. Making a classic fuzz pedal is much easier than you think. It just uses two transistors and a handful of other components. Aside from sharing the schematic, throughout this project I will also be going over basic tips and tricks for guitar pedal construction.

If you would like to learn more about electronics and reading schematics, check out the free Electronics Class!

Step 1: Materials

Picture of Materials

For this project you will need:

(x1) Hammond BB metal enclosure
(x2) 2N3904 transistors (or equivalent) **
(x1) 22uF capacitor
(x1) 0.1uF capacitor ***
(x1) 0.01uF capacitor ***
(x2) 100k resistors
(x1) 10K resistor
(x1) 5.1K resistor
(x1) 5K potentiometer
(x1) 100K potentiometer
(x1) DPDT heavy duty push switch
(x1) PCB
(x1) 9V battery plug
(x1) 9V battery
(x2) 1/4" stereo jacks
(x2) Dial plates
(x2) Knobs
(x2) Velcro squares
(x1) 3M 30-NF Contact Cement
(x1) Drilling guides (download and print)

** Different NPN transistors create slightly different sounds. Feel free to experiment on a breadboard with the circuit before you build it.

*** The 0.1uF and 0.01uF capacitor can also be swapped out for slightly different values to create different sounds. Again, experiment on a breadboard before you solder anything in place.

Step 2: Attach the Drilling Guides

Picture of Attach the Drilling Guides

Cut out the drilling guides and attach them with masking tape centered upon the top and side faces of the enclosure (as appropriate).

Step 3: Mark the Centers

Picture of Mark the Centers

Mark the centers of each hole using a punch (or a nail if you don't have one).

Drill pilot holes for each marking using a 1/8" drill bit.

Step 4: Drill 9/32" Holes

Picture of Drill 9/32" Holes

Widen all of the holes in the enclosure with a 9/32" drill bit (or appropriate for you potentiometers).

Step 5: Drill 3/8" Holes

Picture of Drill 3/8" Holes

Widen the holes in the side of the enclosure using a 3/8" drill bit.

Also, widen the center hole in front of the enclosure with the same drill bit.

Step 6: Drill a 1/2" Hole

Picture of Drill a 1/2" Hole

Finally, widen the center DPDT switch hole in the front of the enclosure with a 1/2" drill bit. You will likely want to clamp the enclosure down to your work table (or in a vise), before you drill this hole. A 1/2" drill bit can be aggressive.

Step 7: Mark the Mounting Tabs

Picture of Mark the Mounting Tabs

Insert the potentiometers into their front mounting holes backwards and upside down.

Wiggle, them back and forth, and notice you have scratched a line on the surface that corresponds to its mounting tab.

Drill a 1/8" hole along this line just to the left of the larger potentiometer mounting hole.

Step 8: Create a Stencil

Picture of Create a Stencil

Lay one of the front dial plates on a piece of painters tape.

Trace and cut out its outline.

Step 9: Place the Template

Picture of Place the Template

Center the front plate atop one of the potentiometer holes.

Place the tape template down around it, and stick it to the front surface of the enclosure.

Step 10: Glue Down

Picture of Glue Down

Apply contact cement to the center of the stencil and also the back of the front dial plate.

Wait for it to dry long enough to become tacky to the touch.

Once dry, press the dial firmly to the enclosure to glue it in place.

Step 11: Repeat

Picture of Repeat

Repeat the process for the second dial.

Step 12: Build the Circuit

Picture of Build the Circuit

Build the circuit as specified in the schematic. For now, do now worry about wiring jacks, potentiometers, or anything else that might not attach directly to the circuit board.

This circuit is basically a 2-transistor gain circuit and a variation on the classic Fuzz Face guitar pedal. To learn more than you ever wanted to know about this circuit, check out R.G. Keen's Technology of the Fuzz Face article.

Step 13: Wire the Potentiometers

Picture of Wire the Potentiometers

Solder 5" green wires to the center and right-hand pin (if the potentiometer knob is facing you) on both potentiometers.

Also solder a 5" black wire to the remaining outer pin on the 100K potentiometer.

Step 14: Mount the Potentiometers

Picture of Mount the Potentiometers

Mount the potentiometers to the enclosure by inserting it's shaft up through the hole in the enclosure, and fastening it in placing with its mounting screw.

Step 15: Wire the Power and Jack

Picture of Wire the Power and Jack

Connect a 5" black wire to the terminal connected to the center barrel jack.

Connect the black wire from the 9V battery clip to the terminal connected to the smaller signal tab.

Finally, connect a 5" green wire to the terminal connected to the longer signal tab.

Step 16:

Picture of

Mount the jacks and potentiometers to the inside of the enclosure using their mounting nuts.

In my pedal, the input and gain pot will be on the left of the pedal, and the 100K volume pot and output jack will be on the right.

Step 17: Mount the Switch

Picture of Mount the Switch

Mount the switch to the enclosure using its mounting hardware.

Step 18: Wire the Switch

Picture of Wire the Switch

Connect one of the switch's center pin to the green wire connected to the audio / power jack.

Wire the other center pin to the identical pin on the other audio jack.

Wire together one set of outer pins.

Solder a wire between the remaining pin in-line with the output jack to the center pin on the volume potentiometer.

Finally, solder a green wire to the remaining free pin. This will later be attached to the circuit board.

Step 19: Ground Connection

Picture of Ground Connection

Connect the black ground wire from the volume potentiometer to the terminal on the audio jack connected to the barrel.

It is important to understand what is happening here, and that it will only work with a metal enclosure. Basically, since the other jack is using the barrel connection as a switch for the ground, the entire case is electrically connected to the ground plane. Thus, the barrel jack on the other jack is also connected to ground. So, by connecting the potentiometer to it, you are effectively connecting it to ground on the circuit board (without actually attaching it to the circuit board).

Step 20: Wire the Circuit Board

Picture of Wire the Circuit Board

Now is time to attach the components mounted to the enclosure to the circuit board.

The red wire from the 9V power clip should go to the power rail, and the black wire from the stereo jack should be attached to the ground rail.

The gain potentiometer should be attached as specified in the schematic.

Lastly, the remaining unconnected switch wire in-line with the input should be connected to the input on the circuit, and remaining wire from the volume potentiometer should be connected to the output on the circuit board.

Step 21: Velcro

Picture of Velcro

Attach the circuit board to the bottom of the enclosure using self-adhesive Velcro tabs. This both holds it in place,
and prevents it from touching the lid and shorting the circuit.

Step 22: Shut the Enclosure

Picture of Shut the Enclosure

Plug in the battery if you have not done so already and fasten the lid onto the enclosure using its mounting screws.

Step 23: Attach the Knobs

Picture of Attach the Knobs

Turn the potentiometer knobs counter clockwise until they stop turning.

Place the knobs in place with their pointers pointing at the starting position on the dial.

Fasten the knobs in place with their set screws.

Step 24: Plug In

Picture of Plug In

You are now ready to plug everything in and rock out.


Reconsider59 (author)2017-03-14

Thanks for posting this! I love the aesthetic of the pedal, and a fuzz face clone will definitely be a welcome addition to my board!

Have you considered adding an LED, to indicate when the pedal is activated? I'm doing a little research to figure out how to add one on my own, and will post info if I figure it out, but I'm new to circuit-building and worry I'm going to screw it up. If anyone has any ideas on this, please add them!

Donald Bell (author)2017-02-13

Beautifully done! Can you drop in a link on where to pick up those awesome dial plates? A link for those knobs would be great too. Thanks!

randofo (author)Donald Bell2017-02-13

Ah yes. Forgot to put in links! Will get on that in the next day or two. In the meantime, the dials are from Amazon, and the knobs are from Small Bear Electronics. Nevertheless, I will get some links in there soon.

randofo (author)randofo2017-02-13

On second thought, changed my mind. Just buckled down and put all the links in right now.

Yogi70 (author)randofo2017-02-21

Very new to this would it be possible to get more pictures of how everything is placed in the breadboard. I am just not seeing the layout would like to try this with my son.

ThothLoki (author)2017-02-18

Can you give some more detail on the stomp switch? Is it latching or momentary? Your ible talke about the outside terminals and inside terminals. According to the pictures, are you wiring them up to the N/O or N/C? I am sure it doesn't matter, but I am curious.

I know electronics decently, I am just not a music guy. I am hoping to build this for my father who loves to jam out on the guitar.

randofo (author)ThothLoki2017-02-20

It is latching. There is a link in the materials list.

The jacks get wired to the two center pins. Beyond that, it doesn't matter which set of outer pins you use. One set is always closed to the center pins when the other set is open.

16jwilliams (author)2017-02-16

thanks for the instr

JeromeS29 (author)2017-02-16

how does it sound?

slimtender. (author)2017-02-16

Nice project, especially the orange enclosure!

RonC100 (author)2017-02-14

Interesting that you put the input on the left and output on the right. All three pedals I'm currently using (TC Electronics Polytune, MXR Variphase, Exotic XW-1 Wah) all have their inputs on the right and outputs on the left. Your design would screw up the pattern, at least in my case. Any reason you went that way?

anglinnr (author)RonC1002017-02-14

Don't think electricity cares if it travels left to right or right to left. When you build it just swap the jacks to whichever side of the box makes you feel all worm and "fuzzy".

LegobetoT (author)anglinnr2017-02-15

It does matter which side you plug in your guitar and which side you plug the amp. Its not going to work if the signal goes in the wrong way. it is supposed to enter through the Base of the transistor. However If you really want the input jack on a certain side, just put it there. Some pedals have the jacks on the back of the box.

RonC100 (author)anglinnr2017-02-14

It's not about "warm (not worm) and fuzzy". It's about uniformity with other pedals... obviously you can swap the jack positions but I was wondering if he had a reason for his decision.

DamonC3 (author)RonC1002017-02-14

I agree. Why are the jacks backwards?

CharlesA9 (author)DamonC32017-02-14

Maybe he's left handed

RonC100 (author)CharlesA92017-02-14

That doesn't matter. If you put this on a pedal board, you'd want the input and output jacks to be uniform.

DaveErving (author)RonC1002017-02-14

Maybe, the guy means, since he is left handed, he does stuff backwards(though I can't speak for him). I know I'm left handed and have to double check, so I don't do stuff backwards. I think it was just a little mistake, we all make them. It's part of learning

randofo (author)RonC1002017-02-14

Nope. Just how I decided to do it when building it. Would be easy enough to reverse. Just flip the wiring connection from the jacks to the switch.

RonC100 (author)randofo2017-02-14

Okay. Just wondering if you had a specific reason. Anyone who follows this might not figure that out until after they have built it, so I wanted to ask and bring that up in case anyone else might be building this to work with other pedals in an effects chain.

chrisp15 (author)2017-02-15

Do the 1/4" jacks have to be stereo? wouldn't they be mono since its a guitar cable? Just curious because I'm ordering parts to give this a shot.

randofo (author)chrisp152017-02-15

Only one needs to be stereo, because we are using the stereo jack as a switch. When the mono plug is inserted, it connects the unused stereo terminal which gets connected to battery ground with the barrel jack that is connected to the circuit's ground. Thus, the mono plug completes the ground connection between the battery and the circuit within the jack and turns on the guitar pedal when the plug is inserted.

SkodaWabo (author)2017-02-15

Yea', good post, thanks.

TooSlowTube. (author)2017-02-14

I recently breadboarded a PNP silicon Fuzz Face (I'm waiting for some Germanium PNP to do it properly). It's basically the same circuit, but with opposite power rails, but I still used negative ground for the two jack sockets.

You need to be able to bias it properly, to get a good sound. Replace the 10k fixed resistor from the collector of Q2 (the output transistor) to +9V, with a 470R to 1kR resistor, in series with a 5k to 22k pot (depending on the gain of your transistors).

I deliberately looked through all my transistors for the lowest gain ones I had, measuring hfe (DC current gain), on a multimeter. You can make a simple test circuit to do it with any meter that can measure voltage or current. The original Fuzz Face used very low gain Germanium transistors. I found two PNP silicon with a hfe of 130, which is low by modern standards.

The 0.1uF input capacitor should be bigger, if you have low gain transistors - because the input impedance will be lower, which means the roll off frequency of the input decoupling will be higher. Think of the base of the transistor as a resistor to ground. For a low gain transistor, that's a small resistance. Lets call it R, and the input capacitor C. The roll off frequency is then

1 / (2 x pi x R x C)

below that frequency, the sound will be reduced (by 3dB per octave, I guess). So, you can see that if R is small, C needs to be big. On the original fuzz face, it was something like 2.2uF - a pretty big capacitor.

Using higher gain transistors, as most of them are these days, you won't get the same sound as the original Fuzz Face, but you still will get fuzz. How much fuzz will depend on how you bias it. In my circuit, I used the normal 470R resistor in series with a 5k pot. I can adjust it from an almost clean amp sound (pot at zero Ohms), through various types of fuzz, to breaking up on everything but really loud notes, to no sound at all.

Personally, I feel a bias pot that makes a useful extra control. At the very least, you should try a preset, and set it how you want it. Some people measure where they like it best then choose a fixed resistor.

SkodaWabo (author)TooSlowTube.2017-02-15

Thanks for your extra info, gives us even more ideas to play with.

doctor_g (author)2017-02-14

It's really, really important to label each control and each jack, especially if they're in a non-standard place like your input and output! I expect the input jack on the right, to match all my other pedals, and would plug the pedal in backwards without labeled jacks.

jimdkc (author)2017-02-14

I like those dial plates! It's worth noting, if you want to build other projects to match this, that they are less expensive the more you buy

You get 2 for $4.34 ($2.17 each, the link you provided)

Or... you can get 5 for $6.44 ($1.29 each)

Or... you can get 10 for $8.41 (84¢ each)

TheAquabats (author)2017-02-13

Great guide! Are you going to post a demonstration?

diesel_travis (author)2017-02-13

This is great! I'm going to have to translate this picture to a fritzing before I build it though so I can make sure that I'm plugging things in the right places.

About This Instructable




Bio: My name is Randy and I founded the Instructables Design Studio. I'm also the author of the books 'Simple Bots,' and '62 Projects to ... More »
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