I use 2.5 cm all the time for simple/utility panels.
You can get 2.5cm aluminium strips at the hardware store for just a few euro per meter.
I’ve also found them on the side of the road or pulled them out of waste containers 
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There are numerous alleged Rat clone circuits out there. (There also are numerous actual Rat versions.) Here’s another:
(Hmm, looks to me like this has pins 2 and 3 on the op amp reversed.)
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Those are both guitar pedals, I wonder if they made any mods for the euroversion.
Hadn’t considered 7.5… if I repanelled two of my 10cm DIYs as 7.5, I’d have space for another 5’er… hmm! What have you done…
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This looks very similar to the circuit I have in my pedal that sounds great. I run my synth through a pot to bring the levels down so the drive works okay - then I either go back into a VCA or straight into my mixing desk with a pre-amp, so levels seem to work out fine.
Cheers
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Yes, that’s the one I used.
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I think the only change I did was use an OP7 op amp in stead of the LM308.
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Thank you, surely test it like you with the “stomp box adapter” circuit.
some do not make any changes, other yes, I think I add a circuit to reduce the input level and increase it again at the output as @ChristianBloch has done
or dirrectely a module version … someone here had tested the Synthrotek (houu!) circuit ?
I don’t know this one
Could we use a common TL in this circuit ?
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Not sure how it would sound, but the OP7 is the direct replacement. I think the op amp is a big part of the sound of the Rat, but I don’t know for sure. I say try it!
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From the schematics posted here, it looks like rhe synth version is not very different at all.
With the 100k gain pot and the 560r/1k resistor, it’s voltage gain is very high and it will probably clip any signal going in.
I’m not sure if attenuating the input signal will make much of a difference at all.
If you’re looking for that ‘edge of breakup’ sound, you’ll be better of using an overdrive pedal, but that’s not what the rat is about.
The output will be limited to the voltage drop of the clipping diodes, which can be a bit low for synth levels.
The turbo rat (i believe) uses red LEDs as clipping diodes, which will give you about double the output amplitude.
I’ve been thinking for a while of making one with blue leds and a switchable mosfet booster/buffer at the output
Also, an important part of the sound is probably the op amp slew rate. The originals were pretty useless above like 5khz, but this is pretty nice for guitar pedals as it will make the distortion less fizzy. If using faster opamps you can try increasing the compensation capacitor in de opamp feesback loop
Edit: just saying, i would LOVE a guitar pedal discussion thread not sure how many people here are into that
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That’s probably a matter for breadboarding, but quick simulation suggests that while you have to go very low in amplitude to avoid clipping (I’m just looking at the LM308 output, and it’s actually a TL074 since I don’t have LM308 in LTspice), at low pot settings there is a fairly distinct difference in the slope between the clipped levels for 5 V and 0.25 V sine inputs.
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Yes, you are right. Of course at the very beginning of the rotation there will be a small range where it won’t distort as heavily
Though, in my opinion, there are better circuits for that. Be it better sounding, easier to control or lower parts count
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Hm, you’d think then that the distortion pot would also have little effect except at the low end, and that’s in fact what I’m seeing here.
(And pretty much no effect at all for a ±5 V input.)
I note they do specify a log pot, though.
Can you help me a little bit? I’ve never done simulations before so i’m not sure what to look at.
Trying to learn though
Is the blue waveform at low distortion settings and the grey one highest?
Because, except for the blue one, they look kind of similar to me. Maybe it is indeed because of the lin vs. log potentiometer.
(As a side note, i repair and modify guitar tube amplifiers and sometimes pedals too, and i know range of potentiometers is a very common issue on equipment like this. A lot of designs, to this day, are based on old knowledge, tradition and ‘mojo’, whatever that may be. Circuits are often not very well optimized at all and are sometimes just ripped out of textbooks, because gain pedals are often based on basoc building blocks and filtering?
It just seems to me that an amplifier with a max voltage gain of over 2000 will slam into the power rails very early in the waveform.
I’m not sure how one could hear at how many degrees in the wave this point is?
They didn’t teach us about non-ideal op amps in school. And basicly the circuits i learned about are quite opposite, as distortion is rarely a desirable factor.
maybe it has to do with harmonic content? Are there non-ideal artifact added by trying to push the output 2000x higher as opposed to 1000x?
I’m leaving out assymetrical clipping here for simplicity
(EDIT:Pushed post by accident)
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Yes, see the legend: The blue trace is at “100 m” (that is 0.1 of the pot range), the others are at 0.3, 0.5, … 0.9. Here all but the blue are more or less on top of each other, so there’s no real change in the output much above 0.1 of the pot range.
This is with a 0.25 V sawtooth input at 250 Hz. With a sine there’s even less difference between the blue trace and the others, and with a 5 V input the blue is essentially the same as all the others.
But as I said before… this is probably better studied on a breadboard.
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Oh wow thank you that was very quick. I hit post by accident and you replied before i even finished mine
Then, if there is an actual difference, it must be due to non-ideal behaviour i guess. Except that guitar signals are often even lower, which will then shift the non-saturated range of the distortion knob up a bit.
Time to whip out the breadboard i guess
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Yes, the log pots are essential here…
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