This is a Rat with 6 different distortion diode configurations and an op-amp selection switch that will definitively answer the age-old question: can you hear the difference between an LM308 and an OP07, though the OP07 is internally compensated and doesn't require the 30pf cap. Allegedly.
You just have to twist legs source and drain on Q1 and swap them. Source UP position and Drain on MID position. S and D can be swapped in some cases, but not in this particular one.
Q1 looks okay - it's the output buffer of the circuit - drain is on 9 volts and source is leading to 1uf cap connected to volume 3. Q2 and Q3 are MOSFETS wired as clipping diodes, so they're serving an entirely different function.
Just take a look to the schematics. In this board drain and source are swapped referred to scchem. As itold before, drain and source can be swapped in many applications / circuits. In this very one, the way Q1 is wired, you'll get no sound. Swap pins and the effect will fire. Just happened in my buid 😊. Q2 and Q3 are used as diodes and will not mind if the effect works or not, just one rotary position more will sound like the "Booster' option (no clipping diodes).
By the way, soft germanium and diodes are two really delicious sounding positions.
The Proco RAT output is a common-drain buffer; nevermind the typo on the schematic, drain absolutely belongs on V+ and output comes from the source. It's correct here.
Holy shit, you're right! I've used a 2N5457 from a batch about 20 years old. Will check with the Atlas 55 the pinout, but I don't think it has change in these years. Anyway, is the only reason I can find to get it working swaping drain and source.
I've come across weird pin-out issues with different manufacturers, so it's not out of question. I bought a 2N5306 off Tayda for a Supersonic Fuzz Gun and couldn't get it to work for the life of me, only to check the datasheet attached to the product link to see it was an ECB pin-out, unlike literally every other production version. Glad you got it working!
Well, by the way, pinout of mi 2n5457s is correct, so some of the internals must be no correct. I tried with a 2N5458 and a J201, and both work fine. So I think We can consider this layout as verified.
This is a Rat with 6 different distortion diode configurations and an op-amp selection switch that will definitively answer the age-old question: can you hear the difference between an LM308 and an OP07, though the OP07 is internally compensated and doesn't require the 30pf cap. Allegedly.
ReplyDeleteHave you built this? Can you verify this layout?
DeleteYou just have to twist legs source and drain on Q1 and swap them. Source UP position and Drain on MID position. S and D can be swapped in some cases, but not in this particular one.
DeleteQ1 looks okay - it's the output buffer of the circuit - drain is on 9 volts and source is leading to 1uf cap connected to volume 3. Q2 and Q3 are MOSFETS wired as clipping diodes, so they're serving an entirely different function.
DeleteJust take a look to the schematics. In this board drain and source are swapped referred to scchem. As itold before, drain and source can be swapped in many applications / circuits. In this very one, the way Q1 is wired, you'll get no sound. Swap pins and the effect will fire. Just happened in my buid 😊. Q2 and Q3 are used as diodes and will not mind if the effect works or not, just one rotary position more will sound like the "Booster' option (no clipping diodes).
DeleteBy the way, soft germanium and diodes are two really delicious sounding positions.
Enjoy!
The Proco RAT output is a common-drain buffer; nevermind the typo on the schematic, drain absolutely belongs on V+ and output comes from the source. It's correct here.
Deletehttps://www.electrosmash.com/images/tech/pro-co-rat/pro-co-rat-output-stage.png
Holy shit, you're right! I've used a 2N5457 from a batch about 20 years old. Will check with the Atlas 55 the pinout, but I don't think it has change in these years. Anyway, is the only reason I can find to get it working swaping drain and source.
DeleteI've come across weird pin-out issues with different manufacturers, so it's not out of question. I bought a 2N5306 off Tayda for a Supersonic Fuzz Gun and couldn't get it to work for the life of me, only to check the datasheet attached to the product link to see it was an ECB pin-out, unlike literally every other production version. Glad you got it working!
DeleteThat’s why I always test my semiconductors.
ReplyDeleteThanks! By the way, I forgot to mention that there are 32 cuts, not 31. Great RAT on steroids. Maybe the most complete clone thar you can get.
ReplyDeleteWell, by the way, pinout of mi 2n5457s is correct, so some of the internals must be no correct. I tried with a 2N5458 and a J201, and both work fine. So I think We can consider this layout as verified.
ReplyDelete