Introduction: Guitar Fuzz Pedal

So, hands up who loves fuzz? Everyone? Good. I know I do. There's nothing like the sound of dirty fuzz to brighten my day. Guitar, bass or even electric ukulele, everything benefits from heavy diode driven distortion.

I love making things almost as much as I love fuzz, so what should I do with a few spare hours?

This is not my first trip to fuzz town; I've been here twice before. All three are based on the beautiful bazz fuss circuit with some embellishments:

Mk1 was, I think a bazz fuss deluxe. It has long since been canibalised so I can't check. It was good, but instead of a proper enclosure I used an old tin. It looked all nice and homebrew, but the joints were too vulnerable as the lid wasn't properly secured.

Mk2 is my current everyday pedal. It is two bazz fuss circuits in series, one with germanium diodes that outputs to the second circuit which uses red LEDs. It has a tone control on the input and a master volume. Each circuit has its own gain control and the idea is that balancing the gains will blend the two fuzzes. I like it and it works well. The tone control merely changes the level of insanity rather than the tone. It suffers from poor sustain and can sound a little bit farty at times. It was built specifically for bass and the capacitors were selected for the lower frequency range. It sounds epic with a guitar through a bass amp, too.

So, mk3. It still uses the bazz fuss circuit, but this time I've opted for a single circuit. I like the choice of fuzz intensity so it will have two sets of diodes only this time there's one master gain. The diodes will be selected by a second stomp switch so you can have either set 1 or set 1 and 2. What each set is I'll choose on the breadboard.

To improve on the Mk2 sustain I'll stack two transistors into a Darlington. I won't have a tone and again, one master volume.

So, setting up the basic circuit...

Step 1: Breadboarding the Circuit

Unless you know exactly what to build, then I would seriously recommend breadboarding your design. I knocked up my pedal rig for the mk2 build and it's great. It has a panel housing two jacks and a footswitch which are permanently connected to the breadboard. It really makes life so much easier.

Being familiar with the basic circuit I started by setting up a working fuss, then started tweaking the diode configuration and getting the switch to work. You can choose whatever you like, but I went for three diodes in each group. I found before that only one diode makes for a less stable sound, so I went for one in each orientation then added more until I got what I liked. The final set up is:

Set 1. 2 X LN4148, 1 I cannot remember the details for (let's call it mystery diode).

Set 2. 2 X yellow LED, 1 X green.

As my LEDs are all of the coloured lens type I'm certain the colour doesn't matter to the sound. Like set 1, 2 were wired in flow, 1 wired the other way round. I tried with 4 and 5 in each set but found very little change in sound as a result so I stuck with 3.

The finished breadboard circuit is in the photo. It's a bit of a rat nest I'm afraid.

Once complete, I transposed the circuit to a wiring schematic that I could understand, then drew it out on a grid to translate to strip board or vero board, which is shown for info, or amusement.

Step 2: Don't Be Afraid to Experiment

The beauty of a breadboard is the freedom to quickly chop and change components until you get the right sound. This build is based around the parts I had in stock, so not really having a plan meant I had to play with the circuit to get the right combination.

A bit of googling will give up loads of advice on diodes and various bits and bobs, but you can't know until you hear it for yourself. Components are ever so cheap, so you can probably buy a load of different parts and really experiment. Do it!

Don't forget that as you experiment, you'll be using your guitar through your amp, so the sound won't necessarily be the same on another set up.

Step 3: The Final Circuit Design

As mentioned before, this is built around the classic bazz fuss. The diode and switch combinations were decided through availability and experiment and the final breadboard sounded truly awesome.

What I found was that on the LN4148 diodes, the effect was pure shred. I mean really gorgeous, nasal fuzz. Scoot up to the top of the neck and you have the guitar sound from 'el rodeo' by Kyuss. Bang over to the LEDS and you're met by a more overdrive distortion which is way way way louder, so the volume control is even more important. It could even work as a solo boost, I guess.

With bass, the circuit is tuned too high, so the dynamic is totally different. Again, the LED element is way louder and both sets lose a lot of bottom end. But, the bass fuzz is just as beautiful as the guitar fuzz, albeit for different reasons.

The gain control has little noticeable effect on the LN4148s, but on the LEDs it makes a genuine difference, particularly when using bass. It takes it right back to an almost clean sound and, to my ear gives that distinctive sound that Stingrays have, almost an active sort of sound. Get up to the top of the neck and the fuzz returns. Using the LN4148s - from here I'll call it setting A, up the top of the range the fuzz takes on an almost lo-Fi digital sound.

In terms of the rest of the guts, I used three 100k resistors in series before the transistors as through experimenting I found this to be the optimum resistance and I don't have any resistors between 100k and 1m, so three it is. The capacitors were a 0.22uf at the input and 0.1uf at the output. As I wasn't going for a tone control I lazily opted for standard guitar range caps.

The secondary stomp was salvaged from the mk1 and was already wired. Resorting to trial and error I got the thing to work. Evidently I'm no sparks, so although I wanted to have a choice of diodes I have no idea whether setting B uses just the LEDs or mixes the two, perhaps, dear reader you could enlighten me on this matter!

One thing you must have is the 1m resistor at the input cap which goes straight to earth. This helps to prevent the popping noise when the pedal is switched on.

So, the final component list is as follows, but remember, don't forget to muck about with it, you never know what you'll find.


1 x 3PDT switch

1 x 2PDT switch - you could go 3PDT and have a second LED indicator

2 x 3904 transistors wired as Darlington

3 x 100k resistor

1 x 1m resistor

1 x 0.22uf capacitor

1 x 0.1uf capacitor

3 coloured LEDs

2 x LN4148 diodes

1 x mystery diode

1 x 10k pot for gain

1 x 500k pot for volume

2 x jack plugs

1 x battery clip

LED indicator

LED bezel housing


Soldering gear

9v battery

Sticky pads

Vero board

Step 4: The Enclosure

What you put your pedal in is up to you. I used an old tin for the mk1 but went for a cast aluminium box for mk2. I'll do the same for mk3 and ordered a new 120 X 60 X 30mm box off my favourite component seller, which arrived 36 hours later.

When siting the insides it definitely pays to mock up the pedal before you commit. I learned the hard way with mk2 that checking for clashes is important, hence the massive box I ended up with for mk2. Mk3, or its working name of AE-35 has a smaller box but is better planned.

I like to sketch up where the controls will go so it looks balanced, then see how that will look on the inside. Measure up where the holes will go, then drill. I don't have any bit bigger than 10mm so I use a round file to widen the holes for the stomp switches.

Step 5: Finishing and Paint

Finishing the box is, for me, the hardest part as I'm not good at painting. The mark 1 had a diy rat rod feel to it and the mark 2 was left as an unfinished box.

For the AE-35, or Weirding Unit, or Overload Module as it is variously known I went for a lime green spray enamel. I foolishly thought this would make it invincible. Of course it doesn't and when in use the enamel quickly chips off.

Now, I love spotting continuity errors and anachronisms in films, so at this point in the instructable I am happy.

As you can see, the pedal has leapt from unfinished to being complete, used and properly chipped. This is because I forgot to finish this instructable off. So, here it is.

It's still green, and in homage to my love of art nouveau I set about it with a darker green marker for the Mucha inspired decorations and text. It's also got a green LED to tell you when it's switched on. In case you couldn't possibly hear the difference.

Step 6: Epilogue

So the Green Fairy has been around for about 6 months and is now my only effect pedal. The mark 2 went the way of the mark 1 and got cannibalised.

The fairy sounds great now I've spent time figuring it out and I use it all the time. It's good with guitar, but really kicks with bass. Currently I use a Mexican Fender jazz through a 1970s HH bass amp and home built cab and it sounds super. I've also just upgraded an old ibanez with Seymour Duncan quarter pounds and the output is very different. It will take a while to find my sound with the other guitar but it's worth it.

The one thing I would change and I strongly recommend using a 3PDT switch with an LED indicator for the second switch as when you're playing live it can be hard to know for sure which setting you're on.

One day I'll change it, and I might even repaint it while it's in bits.

Or maybe not.

When I get the chance I'll film it in action with the guitars I use and try to add the videos.

I'm the meantime, get fuzzy y'all!