Picture of DIY Rat Clone Distortion Guitar Effect Pedal - The Dead RAT
This ain't no Mickey Mouse distortion pedal!
This pedal is a clone of one on my favorite effects pedals from the 80's... ProCo's RAT Distortion. It's a basic OpAmp distortion pedal using the classic LM308N IC chip that is a fairly simple build for those handy with a soldering gun, have a free weekend, and love rock-n-roll.

The layout we are using was designed by Francisco Pena who has done an excellent job with this and other pedal designs on Tonepad.com. (please refrain from editing the circuit board artwork unless you have permission from the author. (sorry Francisco!!))

The schematic and PCB are available in PDF form at TonePad.com following this link , which also has a great library of other effects pedal and guitar related projects to build from beginner to advanced. You will also need the PDF for Off-Board Wiring for wiring the input/output jacks and power for the pedal.

TonePad.com also carries ready-made Printed Circuit Boards to purchase if you don't have the time or effort to make your own. The PCBs on tonepad.com come with a screen printed component side, tinned solder pads and also a solder mask - all for a pretty decent price considering the cost of supplies you have to buy to make your own! I recommend going this direction if you want as close to error free build as possible.

You can buy the majority( if not all) of the parts from Small Bear Electronics which offers pretty reasonable prices and are supporters of TonePad and several other DIY music project sites. (Also recommended!)

I created the graphics in Adobe Illustrator and have made it available below to all that wish to use it. It is a PDF file saved out of Illustrator so it is easily edited with any vector graphic software that can open pdf's..... have fun with it and go wild.

(I'll post some sound clips and maybe some video soon to give you an idea what it can do.)

Now lets get ready to Rat-n-Roll.....
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marrymay7 months ago

It`s very hard for me to find knowledgeable people in this particular topic, thank you for the pdf sharing, I like this post. and i recommand to do the DIY with this post's duide and in the meantime with another blog about distortion pedals, check here: Germanium Distortion Tone, it will help to understand this post.

chicalidude9 months ago

Can I use this one instead? http://www.mouser.com/ProductDetail/STMicroelectronics/UA741CN/?qs=wnz1wyZ0ZnWrt9WAQ171Aw%3D%3D

KacperK10 months ago

How to connect stomp switch?

For thoses looking for a LM308. They`re super easy to find on ebay.

Check out these sellers:



How does the print shop handle your pcb layouts? Do you bring in a digital copy on a thumb drive , for example , or paper prints for them to copy from?
silverHalo (author)  circusbrains1 year ago
I believe they can only work from a digital file, such as an .EPS or other vector format.
Mtk871 year ago
Hi to all, sorry for the noob question, i just finished to build a pedal really similar to this (due to the difficulty and cost of the LM308, i searched for a similar one and opted for a NE5534).

I tried to see if it works (i'm on battery) but all I hear is a continous buzz (like if i were touching the cable with my hand) that is reduced whenever i play a note (but the note itself is not heard): can it be all due to the fact i haven't put it in a metal case: i know that basically that stuff can work as an antenna, but if feel strange that i get so much noise)
deadlyraven2 years ago
can you put some video of the fx?? i need to listen this fx before i make it :D
koroshjj2 years ago
How about 500k pots vs. 100k pots?
Also the circuit only has one transistor in it, which is a 2N series. what would an AC128 sound like in there? or some other transistors, like a germ one?
Maybe I'm not searching right, but I can't find a 30pF cap anywhere. I tried Jameco, Smallbear, eBay and some local resources. I tried searching with the units converted to micro and nano, but even with that nothing comes up? Any hints at where else I could look?
silverHalo (author)  junkyardking2 years ago
pF = Picofarads.... 30pF = .03nF = .00003uF
smallest measurement to largest = Pico < Nano < Micro
Hope that helps....
..and the final budget to create this?
silverHalo (author)  Goldswordfish2 years ago
I rarely keep track of costs since a lot of my parts are scrounged from broken electronics and dumpster finds. Plus, if I kept a paper trail of the true cost of my hobbies, my wife would never let me have them!
MUNSTER382 years ago
Hey where did you find the .001uF & .0033uF Capacitors. I cant find those on any of the suppliers that you mentioned. Do you have part numbers?
silverHalo (author)  MUNSTER382 years ago
These are available at the "Small Bear Electronics" link posted in the build notes. You are looking for "Polystyrene Capacitors" you can find them via this link as well ... http://www.smallbearelec.com/servlet/Detail?no=1232
hii. i cant download pdf file from your site can you help me and send it to my mail? babakkamiyab@google.com
bzalavári3 years ago
Hi I would like to ask for the schematic if possible. Thank you in advance
silverHalo (author)  bzalavári3 years ago
Look in the first step, third paragraph... click on the link to Tonepad.com for the schematic.
macboy983 years ago
hey dude , where is the pdf file for the circuit board , pls reply ASAP
Lexoo934 years ago
how do I have to change scheme #5 if I just want a DC input and no battery?
Yeah, if anyone out there knows the answer to this one, I'd really like to know too.
silverHalo (author)  EPIC Kelly3 years ago
Just took a sec to look at the wiring diagram for "Offboard Wiring 5", which is what I assume you guys are referring to. I kind of confused to what you guys are asking about... if you don't need the battery, just leave out the 9v battery snap. The wiring doesn't change at all...it would be the same if you wired it up with the battery snap and never connected a battery to it. Let me know if this answered your question.
Thanks, that did answer the question. I figured that was the case, and tested it out and lo and behold it worked! Couldn't believe my mess of wires and solder and sweat actually worked. So, thank you for a very satisfactory project!
toxin204 years ago
hi silverhalo,

i just finished my rat build, very cool instructions, thank you!

i have a question about the sound though: when you strum some powerchord palm muted, does it have "punch"? because my build sounds a bit weird i think... palm muted it doesnt' have that certain punch its a bit more noisy than i think it should be.

the other question is about the potis: when i set any one of the potis to zero (doesn't matter which) i hear nothing. is that normal or is it an error in my build?
Could you plaase tell me how you got the top of the PCB printed (with the shapes of the components to be fitted)?
silverHalo (author)  streetcrab_helmut4 years ago
The component screen was just printed on some clear sticker material and placed on the board before adding all the parts.
Good luck.
deco974 years ago
I was just wondering how you tell which side of the jacks is which?
icanmunch4 years ago
how should I be connecting the wires to the stomp switch? my switch has 1,2,3 down the left side of it if this helps. its only got 6 lugs on it
slapointe4 years ago
I am not building your box but changing one I own. I have a EXH Big Muff Pi with no ac jack. I cut the battery connect off and soldered a power jack to the existing wires then connected a 9v 300mA power adapter. Seemed logical to me until I turn it on to play. Sounds great playing but if it is on and I am not playing I get a lot of humming feedback from the pedal. Any ideas about causes or solutions?
silverHalo (author)  slapointe4 years ago
Hmmm, there are a few things that can go wrong. First, the AC power supply (9v 300mA) isn't actually 9v's....it's probably more like 12v or something close. "Wall wort" power supply's (as they are commonly refered to), vary in their voltage despite what they say on their label, this is because they rely on the internal circuitry of the device to regulate the voltage flow. Mainly, there is a voltage converter in almost all devices that can accept 10-15V and then steps it down to a clean and steady 9V for the device to use. To see this, test the power supply with a multimeter and note the true output voltage. So running it as you have it now is probably over-volting the circuit, which may or may not cause damage or weird happenings...hard to tell.
Secondly, AC voltage is noisy by nature. In order to clean up the noise of AC voltage, engineers design the circuit with filter capacitors and other goodies to clean out the AC ripple. Without these components, you will pick up the oscillations of the AC current and hear the feed back and hum.
Without a schematic of the circuit board it is hard to tell what you would need to do to clean up the hum....
aritoner5 years ago
 so i blew the last one and decided to try again but i noticed that in your picture your true bypass switch looks to almost have a square shape but mine has a rectangular shape the question is how do i know which way is the right  way to start soldering
silverHalo (author)  aritoner4 years ago
On a 3pdt (triple pole, double throw) switch there are 9 contact leads (3 rows of 3).
When the switch is on, the first lead on the top row and the first lead on the second row are connected. So if you tested it with a multi-meter on continuity setting you would get a "beep", stating that current is able to flow from one lead to the other. So the 1st lead of the top row and the 1st lead of the middle row, as well as the 2nd lead of the top row and the 2nd lead of the middle row and same for the 3rd lead. BUT, when the switch is off, then the 1st lead of the middle row connects to the 1st lead of the third row, and the top row is disconnected. Confused yet?
So if your switch is rectangle than the rows should go the long way across.... but you can test with a multi-meter just in case.
nellie184 years ago
nice project!

anyway, if you mind, may i ask if how many watts you used on your resistors?
and how many volts for the capacitors.
silverHalo (author)  nellie184 years ago
I probably used a mix of both 1/8 and 1/4 watt resistors. There isn't a whole lot of current flowing through the board so wattage isn't that important. 1/8 and 1/4 watt fit better than say a 1/2 watt resistor would.
The electrolytic capacitors need to be rated at least double the power supply voltage for safety. So for a 12 volt power supply you would use 24v caps or higher. You might get by with 12v caps but its always better to error on the side of caution.
Better safe that sorry.
Teburon4 years ago
love the graphics! but how did you get them onto the enclosure? did you use special transparent sticker paper or something?
silverHalo (author)  Teburon4 years ago
The stickers are printed onto transparent vinyl through a process called foil printing.
Pretty much any decent sign shop has the correct equipment to do that. Try your local Fast Signs, Signs-in-a-day, or FedexOffice(one that has a sign shop in it).
You can also also use "waterslide decals".. they make both lazer & inkjet waterslide paper that you can print your own graphics on. It's the same kind of material that they use to put the word "Fender" on the headstock of a Stratocaster. Google it, its a pretty simple process and has great results.
eduardrenz4 years ago
How can I buy an LM308 IC and IN IN914 Diodes? I live at Phillipines.. can u help me for my Project?? Eduard
silverHalo (author)  eduardrenz4 years ago
Ebay maybe? I would just do a Google search and find a company that will ship internationally.
lfebrero4 years ago
Hi man! I was wondering in wich direction I should put the 3PDT switch to make the connections according to the diagram #5 in tonepad.I mean, with the tips horizontaly o verticaly?? thanks
eduardrenz4 years ago
How can I buy an LM308 IC and IN IN914 Diodes? I live at Phillipines.. can u help me for my Project?? Eduard
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