DIY Guitar Pedal

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Introduction: DIY Guitar Pedal

About: My name is Randy and I am a Community Manager in these here parts. In a previous life I had founded and run the Instructables Design Studio (RIP) @ Autodesk's Pier 9 Technology Center. I'm also the author of …

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

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.

*** Carbon film resistor kit. Only kit necessary for all labeled parts.


Please note that some of the links on this page contain affiliate links. This does not change the price of any of the items for sale. However, I earn a small commission if you click on any of those links and buy anything. I reinvest this money into materials and tools for future projects. If you would like an alternate suggestion for a supplier of any of the parts, please let me know.

Step 2: 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

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

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

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

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

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

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

Trace and cut out its outline.

Step 9: 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

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

Repeat the process for the second dial.

Step 12: 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

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

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

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:

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

Mount the switch to the enclosure using its mounting hardware.

Step 18: 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

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

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

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

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

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

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

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12 People Made This Project!

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77 Comments

0
swainscheps
swainscheps

6 months ago

I started this with a plastic project box (obviously will have to limit the stomping) - I'm assuming I can just wire the pot to ground rail on the board directly - is that correct or am I dead in the water until I find a metal enclosure?

I think what would really help is one big component level connection diagram...I am just really struggling to follow the instruction copy in steps 18,19, and 20...

0
randofo
randofo

Reply 6 months ago

The pots should be wired as shown / described. There are no potentiometer ground connections being made through the enclosure.

There is one mono jack grounded through the body of the enclosure. The barrel of that jack should be wired to ground.

0
benyboy3
benyboy3

Question 6 months ago

Hey, thanks for sharing this, sounds great and was fun to build! Mine has a couple of quirks - when the gain pot is turned all the way up, its makes this weird sort of screaming sound and it seems like the volume ramps up significantly. Is this normal, or have I wired something wrong? I've checked the pot with a multimeter and it seems fine. The volume is also waaay louder when the pedal is engaged, with 2/10 on the volume pot matching the loudness of the bypass (at 10/10 it's so loud I'm worried I might blow a tube or pop my speaker!). Not that that's really an issue, just curious if its a feature of the pedal or my poor handiwork! Thanks once again for the great project!

0
randofo
randofo

Answer 6 months ago

From your description, something like something may be off, but I can't really say what off the top of my head. If you have any extra components, you should try experimenting with the circuit on a breadboard and see if you get the same results.

0
Charlie Gibson
Charlie Gibson

Question 11 months ago

Does anyone have a demo video so I can hear what this pedal sounds like before I built it?

0
DavidP820
DavidP820

Question 3 years ago

I can't get it right and don't know why...
I think I did everything as you wrote, but no matter what I do there is no fuzz. I get sound, but no effect...
could be related to the type of audio jacks that I have?

20190322_214044.jpg20190322_214132.jpg
0
randofo
randofo

Answer 3 years ago

1) Did you build the circuit first on a breadboard to confirm all of the components are working...?

2) Yeah... that is probably the problem... that is not a stereo jack. It is a mono jack with a switch. That unfortunately won't work as a power switch. That type of jack is meant to connect / disconnect the guitar signal from the circuit.

3) See if you can bypass that jack and power the circuit directly from the battery. It should work.

0
DavidP820
DavidP820

Reply 3 years ago

I didn't build it on a breadboard because I don't have one. It happend twice with two sets of components so I don't think that one of them doesn't work (but who knows). I connected the lines in my board like they would be connected in a breadboard (where there were connections to be made...), I added a picture.

I also tried connecting the battery directly to the board, but I got the same results.

I attached pictures to explain what I did with hope you can find where I messed up...

P.S
I tested it without connecting it to the metal case, but I connected both of the audio jacks' barrels together with a wire during the testing. When I tried connecting the battery directly to the board I test it with the two barrels connected and without this connection. Still got the same result

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0
DavidP820
DavidP820

Reply 3 years ago

One more thing,
I reviewed the schematics again and found out that I forgot to connect the circuit to ground at one point, but after connecting it I tested again and no change

0
DavidP820
DavidP820

Reply 3 years ago

WOW!!!
OK I'm very sorry for all the nagging. I figured it out!
It sounds amazing, THANK YOU!

Now I have another problem, It's the Stomp Switch...
The effect is only on when the switch is pressed (so I have to press it the entire time I'm using it).
I checked the order page on the site where I bouht it, it says that it's a "momentary" switch...

And I added an LED that works forever because I couldn't think of a way to only make it work when the line goes through the circuit, but it's still cool :)

0
sierra218
sierra218

Reply 1 year ago

Hi, how did you figure it out???? I have the same problem!!!

0
randofo
randofo

Reply 3 years ago

Sorry, just seeing this. You likely want a latching switch, not a momentary. This is easy to swap out.

0
geoffreany
geoffreany

1 year ago

My new “peach fuzz” sounds good but I have to keep the volume a hair over minimum and the fuzz a hair under maximum to get the sound I want. Do I need to swap out my pots? Or are there other components I should change?

0
randofo
randofo

Reply 1 year ago

You can try replacing the 5.1K resistor with a 10K trim pot. That might help dial it in. You can also replace the capacitors at the input / output with different values. That should have some (small) effect on the sound.

0
geomy1
geomy1

1 year ago

I finally got it sounding right (I had a bad pot), but now I seem to be picking up a radio signal. I hear voices! Any suggestions?

0
randofo
randofo

Reply 1 year ago

Are you using a metal enclosure? It sounds like maybe you are having some issues with grounding. Do you have a lot of extra wire connecting the jack to the PCB or switch?

0
geomy1
geomy1

Reply 1 year ago

I was testing it on the bread board. Now that it is in the enclosure it sounds better.

image.jpg
0
benzwahlen
benzwahlen

2 years ago

I'm trying this circuit out on a breadboard but I'm getting a loud persistent crackling through the amp. I've checked te wiring multiple times but not luck :( Does the circuit need to be shielded or something?

0
geomy1
geomy1

Reply 1 year ago

I had the same problem. I found one of the pots was bad. Swapped it out, now it's fine.

0
Mcbernhart
Mcbernhart

1 year ago

I was able to build it but I get very low volume when the circuit is engaged. I have to turn the fuzz pot up all the way to get any sound out (which is really fuzzy and has great sustain) but the volume is significantly lower than the bypass. The volume pot adjusts the volume (within the limited range oncoming out) so I don’t think the issue is there. Any idea what could be causing it?