Very Simple and Cheap Guitar/Bass Distortion Pedal

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Introduction: Very Simple and Cheap Guitar/Bass Distortion Pedal

About: I'm a student from Cheshire, currently studying at University of Nottingham!

Here, I will teach you how to make a very simple 1 transistor low power guitar pedal. (I designed the circuit diagram and PCB). This circuit can be ran off old 9v batteries (In version 2, I was running it off a really cheap mobile phone power supply, 5v SMPS) that still have a charge above 1.5v meaning you won't have to throw them out!

Edit:If you increase the input capacito (the 100n capacitor) more bass frequencies can flow through the common emitter amplifier, causing more of the distorted effect.

Also, if you change the bias of the transistor (swap the 100k Resistor for a much higher value, e.g. 680k or more, the transistor will be forced to asymmetrically clip, increasing the distortion. Go to the last page for sound clips :)


In my new circuit, I use a 470k resistor for the bias resistor.

AGAIN! A problem arises at the cost of extra distortion. The attack of the
instrument may get chopped off(silenced in this case). With my bass, this only seems to happen when I am using the slap bass technique.

Step 1: Find the Parts!

Firstly, to make the pedal you obviously need the parts! Most of the parts can be found in the base of a CFL light bulb. I already had the parts to make this and have customised the parts to my liking. In the schematic, it says the input capacitor is 100n. It doesn't matter what value the input capacitor is really aslong as it is within the range of: 47n - 100uF. All the capacitors mainly do is affect the level of distortion at the output (as well as the diodes at the output!). For my transistor, I used a BC337 (On my old one) because I had it at the time but I'm sure that any NPN transistor will work fine. At the output stage, different kinds of diodes produce different levels of distortion. I used simple 1N4001 diodes (The most common diode around) But to get different kinds of output waves, many combinations of diodes exist such as schottky diodes (To produce a lower amplitude giving a nice germanium diode sound due to both germanium and schottky conducting at lower voltages) or rectifier and schottky diodes (Lopsided wave) etc. I tested the input down to 1.5v. at this voltage, it had some quite high distortion and a bit of an annoying hum but worked fine overall. Therefore, a 9v battery would last extremely long is the circuit works down to 1.5v.

The input and output capacitors depict the frequency response of the circuit e.g. The lower the input capacitor, the more bass is cut. This is good if your looking for a nice Trebly overdrive. Otherwise, this capacitor can be increased to any value. The values of these components doesn't particularly matter if your just looking for a simple distortion circuit.

The 100Ohm Resistor that is just above the Diodes can be removed to make the output wave much 'Harsher'.

The 100K resistor at the base of the Transistor mainly depicts the gain. Increasing this resistor increases the gain up to a certain point (It changed the bias of the transistor).

Edit: I have now included my new circuit diagram for the much more RAW! Distortion. Go to the last page for sound samples!Unfortunately, with this new circuit, the distortion isnt so epic at 1.5v :(

For this new circuit, i used a BC337-25, a much more gainier transistor.

Step 2: Build the Product

I build this on a breadboard as i have not had time to produce the PCB yet. The parts for this pedal are really cheap (around 50p if postage doesn't have to be paid) and can be made of almost any parts available.

Step 3: Final Product

Here's what my final product looked like! (Sorry for the blurry picture, I had to take it on my phone)

Step 4: What Both Versions Sound Like

Here is an sound file of how my overdrive pedal sounds. The first riff is clean and the second riff is the same as first just distorted. Thanks for reading!

Revised sounds:

The reason that the amplitude is lower on the second sound clip, that is because that was my bass clean through my amp. No volume changes or moving away the microphone. My setup was the same for each recording. The amplifier was on:
0 Bass
0 Treble
For both recordings.

My bass used was a Warwick Rockbass Streamer 2P'up Version.

Edit: On my new recordings, the moded circuit is used. I will include both a bass and guitar recording :) (excuse my TERRIBLE guitar playing :P)

My amplifier was recorded with a simple condensor module through using Audacity :)


Same bass, Guitar is a: Cheapo Spider Fender copy (I play bass not guitar!)

The files: "Guitar file" and "Bass File" Are the new versions :D




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125 Comments

Hi everyone,

I have made a video of this circuit so you can hear how it sound like .

I have just added a bit of reverb.

First, thanks you the instructable, It works for me but only as a preamp, it doesn't distort the sound in any way at all.

I have added a photo, If you would be so kind as to tell me what I need to change in order to get distortion.

Cheers,

Shand

IMAG0139.jpg
6 replies

Hey!

Nice free wire soldering dude. For the two diodes, if you short out the 10k resistor, the distortion effect should be increased. Also, if you increase the value of the 100k resistor, this should shift the bias closer to the middle increasing the gain some more, a 1M resistor would place the bias quite close to 4.5v giving the maximum gain.

Hope this helps!

Finished product, I'm chuffed with it for my first effects module/pedal.

I would take pictures of the insides (robot porn) but its too messy.

Cheers for the Instructable

FuzZtortion Pedal.jpgFuzZtortion Pedal pics.jpg

Heey.. I know this is really a long time ago, but I hope you can still answer. Just want to know if it's possible yo put a spst 6 pin switch there and if it is , can I know where? I actually tried making it but it's not working. I just really need this because our professor ask us to make a guitar effects. Hope you can help.

Thanks mate, I'll try that now and post back with results.

I removed the resistor above the diodes by putting a small piece of wire in its place and I changed the 100k res to a 390k (largest spare that I could find) but all I get is the hum through my speakers

Tomorrow, I will go to maplin for parts, I'll try a few different values and I'll let you know what happens.

Cheers

Shand

i happend to use the bc9014c at school sometimes, you had the two outer legs backwards... the rest is done good, i suggest using perfboard, as it makes the cirquit more compact and sturdy.

if you search for a fuzz-ish distortion, repalce the transistor with a Szikai Pair transistors (NPN configured) made with a BC547 and a BC557, also, eliminate the diodes, replace the 100k with a 2.7M both caps 100nF and run if of 2 AA's (3V) this gives e verry gnarly fuzzy distortion

Hello can u give me exactly that circuit diagram with details which you used in Base file mp3??I heard that mp3 nd that was really cool..so plz guys if any one knw that or any other easy circuit which can delivery that kind of distortion thn plz plz share with me or giv ur email I'll contact you there..i badly need a distortion pedal.. Thnk u frnds

Hi,im a bassist nd i need a distortion pedal bt its to costly to purchase thats why i cant afforde it ryt now so aftr i saw your diagram i decided to ,make my own pedal bt im lil bit confused about that circuit diagram... In ur pic i saw u used 3capacitor bt in diagram i can see only 2 see can u plz tell me exactly where i use those 3 capacitor...im waiting for a answer bcz i really need a distortion pedal ryt now..thnx

Can I ask why theres 2 schematics? And also would it be possible to connect a booster schematic in front of this signal and run it as 1 pedal?

It's good.Nice work. thank all of you!!

just like good songs are writed, simplicity makes it´s magic gj bruh

Nice work!

But perhaps try it also with LED-s. The LED-s have different voltage depending on their colour, and you can combine the sound with them - more exactly the LED-s' and other diodes' "breaking" voltage will set the clipping voltage, and so the shape of the sound envelope) at the output. Now if you build pc-fan sockets instead the soldered diodes, you can try all the combinations with your LED-s and Ge- and Si- diodes separatelly - these variations may converge to infinity:-). I've made a bass fuzz, similar like yours, it has a very wide distortion spectrum depending of the color of the diodes. Try it, it will be very funny.

Well, and try to use it with only 1 diode - the assymetrical output you get makes a total different, massive "lion-roaring" sound on bass - at least in my fuzz, which I love, being a real old rocker guy;-).

Cthulhu Fhtang!

1 reply

Exactly that buddy! Thanks for the comment :)
Harris

Hi...I wanted to say how brilliant this works! Worked first time, and sounds fantastic! I also bypassed the circuit with a switch, but I found the distorted output volume was much higher than the clean, bypassed output. I put a resistor in the circuit before the output...tried a couple of values until I got one that balanced the output volumes. I also added a led light indicating power, as I mounted this into a rack.
Thanks again!!

I'm really new to this kind of stuff so this is probably a dumb question, but what exactly is the part that you used to connect the guitar input to the circuit?

1 reply

No problem! We've all got to start somewhere. Its called a 6.3mm socket, if you're a user of ebay, you're looking for something like http://www.ebay.co.uk/itm/Connector-Jack-6-3mm-Chassis-Socket-Mono-Switched-PCB-01112-/370989457537?pt=UK_Sound_Vision_Audio_Cable_Terminations&hash=item5660b1e081 and you can plug your guitar in using a standard guitar cable