This is a library of perfboard and single-sided PCB effect layouts for guitar and bass. I'm not an electrical engineer by any stretch of the imagination, just a DIY'er who likes drawing layouts. It is meant for the hobbyist (so commercial use of any of these layout is not allowed without permission) and as a way to give back to the online DIY community.

Monday, November 30, 2015

ProCo RAT Project

Here's the classic RAT distortion with on-board pots. All the ProCo RATs are essentially the same circuit, just with a few value changes over the years. For this project, the board can be used to make 4 different versions of this great distortion box: The original RAT, the RAT 2, the Turbo RAT, and the You Dirty RAT. Here's the basic schematic:


The component names from the above schematic follow those in the layout drawing below.



The project file with a full BOM, scaled transfer images, and drilling template can be found here.

Thanks to Cody for verifying this ahead of time for me. You sir, are a scholar and a gentleman.

85 comments:

  1. I was going to make your old layout tonight.... wow. Thanks man.
    Incidentally, which is your favorite version? Was going to start with the original.

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  2. On this layout I did the Original and a RAT2 and both were rockin! I lean more towards the Original myself.

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  3. Hello Cody.
    I'm going to build the RAT2. Here's a dumb question: what to do about R12?
    Congrats for this great work and thanks!

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  4. im kind a bit have issue thinking with the IC replacement,
    i recognize the small box is the pin 1 of the ic. but it is on the front

    in this tutorial, where do i put IC on slide ? on the face front or on the back ?
    and where should i put all the rest of the components ?

    is the IC is on the front and the rest on the back ?

    Thanks Sir, you are a great person to shared this.

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    Replies
    1. You might be over thinking things a little. All components are on the same side of the board (non-copper side). Components on one side, solder on the other. The only exception is the pots if you decide to go with board mounted ones–they need to be mounted from the solder-side of the board. Hope that helps.

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  5. thanks for the great job !
    there's a tiny mistake, the filter pot is supposed to work backward, so lug 2 should be tied to lug3 instead of lug1.
    keep doin' what you do mate (y)
    Rafik.

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  6. fantastic. I was able to get the perf working. great work you do here man with the layouts. top notch

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  7. 1n4148's? is that a typo by chance?

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    1. No typo. 4148s are essentially the same as 914s if that's what's throwing you. And you can put whatever you want there. Use sockets and try out some different diodes.

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  8. i went with 1n914's ..it was the 2N4148 that threw me off. I tried finding a data sheet on them and it kept pulling up 2n series transistors.

    I almost have this one done, no pots on yet and took readings but not sure how to interprete them

    fet is seeing source voltage

    .9 and .2 on the inverting/non pins 2 & 3

    .6 on pin 6

    and pin 7 is seeing Vs as well

    hope she fires up when I get the pots on.




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  9. hello. im trying to build the RAT2, but R1 keeps burning, any ideas of what am doing wrong, using a 7v psu

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    Replies
    1. Sounds like you're using a positive ground psu. You need a negative ground one.

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    2. Hello again. tried 2 more 9v psu's, with the same result, R1 keeps burning. the PDF says 47 or 100 ohm, i had 47 available so thats what i used, any chance i killed something else on the circuit??

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    3. You might have killed D1 as well. Try replacing it.

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  10. Got this built up at the moment on the bench, whats the deal with R12? Do i jump it?

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    1. Just don't populate it. I'm not entirely sure why I included it... *head scratch

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    2. Thanks man it just seemed strange as it wasnt in any of the typea! =)

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  11. i must be horribly missing something but where is the component values? i cant see them

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  12. Any suggestions on LM308 replacements?
    I've built the turbo with the OP07 and like it but would like to try something closer to the original.

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    Replies
    1. In my experience with the Rat, nothing beats the 308.

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  13. New to all this, and trying to figure out where the pots are mounted on the board? They're not reflected in the diagram. Also, I assume the switch will be in the General Layout notes?

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    1. The pot lugs/legs go the empty pads below the labels at the top of the board (lug 2 is implied).

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    2. I see. More towards the middle of the board?

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    3. I live in the States. What's a good source for quality bulk resistors and capacitors, etc.? Again, new to the DIY so trying to locate quality components I can order all together and not have to piece it all together through five different places.

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  14. http://www.coda-effects.com/2016/01/proco-rat-white-face-1985.html

    According to this site, r12 should be a 2m2 for the Turbo Rat.

    Thanks for the layout.

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  15. I'm having a bit of a weird issue with the volume. I did the v2, but the volume was extremely low. I measured the 100k pot to 8k max when connected to the cirquit. Tested the pot out of the cirquit and it worked just fine. I then tried a 1M pot, and it goes up to around 300k, but then back down to 0 again, acting almost like a balance pot. Can anyone shed some light on what might be causing this?

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    Replies
    1. I know this post is ancient. Anyways, did you use the perf layout (upper left). If you did, R11 and R13 are shown in the wrong order. That could definitely cause volume issues. Swap them and see if that helps.

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  16. There's differences in the 2 layouts above as far as component labeling:

    C6
    C7
    R7
    R8
    2x R9

    Which diagram do I use, the one on the top left or top right (the same as the one in the attached link with the component list)?

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  17. Hi! And once again about R12. Should it be a jumper or i should just skip it?
    Thanks!

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    Replies
    1. One of the things I've noticed with this build on perf board is the proximity of the tone knob to the gain knob can cause an issue with volume of the pedal. Or just clean signal coming through. Use a solder lug pot for the tone knob and set it back a few millimeters. Or put heat shrink wrap on the adjacent lugs of the tone and gain pots and then solder the connections topside.

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  18. I only got 10kA and 500kA potentiometer in hand. Which one would you recommend to use here? Are any resistor value in series to make it closer to a 100kA....thanks

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    Replies
    1. I don't think a static resistor will solve your problem here. The pots can go from 0Ω to 100kΩ. Try amazon or alibaba. You can find high quality pots for less than a pound.

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  19. Hi, it does'nt work for me. I maked 2 PCB and the 2 had a low volume. I check and recheck but there doesn't seem to be any mistake. Where should I look ? Thanks

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  20. C6, C7, R7 and R8 are indeed in different places in the two schematics but it's fine, both are correct. R11 and R13 though are not. The correct places are on the right schematic according to the diagram. I've tried this but didn't work unfortunately. Not sure if I burnt anything in the process since the PCB turned out correct.

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    Replies
    1. Update on this one: It's working after all. It looks like my LM308 was faulty or something. Replacing it with an OP07 did the trick. Nice one mate. Thanks for the schematics.

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    2. Great, it's finally working. The schematics are not the same. I switched R11 and R13 and the sound came back. Thank you very much

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  21. Hi. I get the clean signal through the Turbo RAT with the quiet distortion in the background. Voltages on the OP07 are: pin1- 0v, 2- 4.51v, 3- 3.68v, 4 and 5 - 0b, 6- 4.51b, 7- 8.96v, 8- 0v. 2n5458 voltages: D- 8,96v, S- 0,36v, G- 0v. Input voltage: 8,99v. I found on the internet that voltage on the pins 1 and 8 should be about 9v. I can't figure out where is the problem.

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    1. Source voltage must be 1.5v or more, this happend to me earlier, the jfet was a chinese copy so it didn´t work out. I had to make a small circuit in the protoboard to test the fet before soldering. The circuit was the same the rat uses for the last buffer, G:1M to groung/S:10k to ground / D:9V .(Test point: between source pin and 10k resistor.

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  22. What is the white face rat version ?

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  23. 2n5458 is a obsolote jfet, any modern replacement?

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  24. Did anybody assemble on this layout? Is there no mistake in potentiometer Filter? Is it right that 1 and 2 foot is connected on the layout? In other resources it is specified that 2 and 3 foot is connected.

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  25. This comment has been removed by the author.

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  26. Hi there im just starting this build but the bom lists r10 as 1.5k but I can't find r10 on the layout?

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    Replies
    1. It's in between C11 and C12, coming off lug 1 of the Filter pot.

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  27. Hi there! Can i replace the 1N4001 with something like a 1N4004 or 1N4007? Should be fine, but I'm not sure if it'd affect the tone

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    Replies
    1. Absolutely. That diode is just for polarity protection, so it won't change the tone whatsoever.

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    2. This comment has been removed by the author.

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  28. I finished the build, but The pedal has a huge drop in volume and pots seem to do nothing... pedal sounds like the distortion is all the way up and volume all the way down.
    Anyone has any idea what could be the problem? I might take the pots off and test them to see if that's the problem

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    Replies
    1. check R11 and R13, they are in different places on two schematics. right placement is on the right schematic

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    2. yeah, I did checked that, both R11 and R13 are on the correct placement (the image on the right)R11 (1M) is on top of r13 (10k)

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  29. I want to add the overdrive mod. Where do I wire up the two red link in this PCB
    http://beavisaudio.com/projects/FKR/images/MightierMouse.gif
    Thank You

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  30. I made few rats. Last week I'd finished one with buffer (two fets). Nice distortion. Too fuzzy and tuby but like
    overdrive it is the best. Problem for me was thin sounding pedal. I changed filter cap (3n3) to 4n7 and cap (22n) after tone to 220n. Now I have little different sound but with more bass. I shall implement tone control... I solved problem with Wampler euphoria
    so good that I can use rat sometimes with small amount of gain. I use A250k for gain at the end of my experiments with rat

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  31. Hi all,
    I've just built this one and it works fine. As mentioned above, the filter pot has been reversed and I find it more inuitive than the orginial rat.
    But, if I'm correct, if the filter pot has been reversed, its value should be C100K instead of A100K.
    I use C250K (don't have C100K right now) ans the course of the pot is more progressive than with a A250K (dont't have A100K either).

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  32. Note to everyone building this!

    On the layout R11 and R13 are mixed around. Take a look at the schematic and notice how resistor from Q1 gate to ground should be R11, not R13.

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  33. Just finished this build and all i get is low farty sounds. I really have to pound the strings to get anything to come through as it cuts out after a short ruing out. I have triple checked everything and nothing is shorting out, nothing is wired incorrectly.
    Any idea what could be up?

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    Replies
    1. Sounds like it's mis-biased. Check that you've got the right values, especially for R4, and R11-13.

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    2. Thank you for the input. I flipped R11 and R13 due to not reading this thread before making the pedal. So that was fixed. Now it plays but its incredibly noisy. Like I get a crazy whine on the distortion knob when turning it past 2 o clock. I thought it might be a bad pot so I replaced it with one I tested and still the same. Any ideas?
      Thanks again! You do amazing work here!

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    3. I did some troubleshooting and found that noise was just a poor ground solder on the volume pot. Now I have spent time playing the pedal and it sounds good until I get the distortion past noon. After noon, its acting almost like a glitched out Fuzz when there is a hard attack on the strings and it cuts out the first millisecond then it rings out. Also there is a weird phasing sound in the ring out. I am almost going to scrap this and just build it again but wanted to see if anyone might know whats up and I can salvage this pedal.

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  34. is there a difference in:

    4.7uf + 1k resistor to filter lug2 and lug3..

    1k resistor + 4.7uf to filter lug2 and lug3?

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  35. Hi and thank you for your great work. Can i use this pcb layout for a direct replacent of the board of my RAT 2? Can pots be put in line. I need to replace my original board. Does this board fit in an original enclosure?
    Thank you
    Peter

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    1. It will not be a direct replacement for the original board. It will fit in an original ProCo enclosure, you'll just need to wire at least 2 of the pots off-board. I'd leave one board mounted just so the board isn't floating.

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  36. Hi, I´ve build another rat with a NPN bjt for the output buffer if anyone interested. This thing sounds great. Just in case the jfet are not able or hard to find. This is just a little change in the schematic. Even I made the spice simulation. Verified.

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  37. Verified


    Anyway i can change log pot to linear circuit wise?

    How can i change circuit to have better sweep in linear than log pot

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  38. Hello , i ve invert polarity on my FATrat and i want to try to repair it ! i found the number of the resistor but i dont find the value ! could you help me ?

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  39. For volume ad filter I used b500k with 33k resistor from lug 1 to 3. (Simulatiomng b200k)
    And distortion a100k
    Used ua741 instead of lm308
    Didnt add compunsation cap 30pf.



    When i turn distortion i get lot of noise. I havent boxed it yet..will it go away if i box it?

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  40. Greeting!!!
    I have a problem with opening the BOM file .... it won't load at all .. Can it help?

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  41. Can I use Ua741 for sub the IC's?

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  42. I made this circuit the problem im facing is my guitar is being soo microphonic. Its like my electric guitar is attaches to piezo mic

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  43. Where are the component values? Not seeing them on the schematic or layout.

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