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.

Friday, December 22, 2017

EarthQuaker Devices Erupter

Merry Fuzz Friday, everyone! Here's EQD's latest fuzz offering, the Erupter. Essentially it's a JFET buffer into a pickup sim (the transformer) into a Fuzz Face-esque circuit. The Bias control controls the amount of voltage going to Q3 and is a center detent pot (though a regular B10k pot will work just fine). This one might benefit by adding a volume control to the output. Should fit in a 1590B just fine. The 2N497 transistor might be hard to source, but other low gain transistors should work. Schematic can be found here.


24 comments:

  1. Transformer arrives today from Mouser. I'll try to verify over the weekend.

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  2. if i want a volume what pot should i use ? is there any good remplacement for 2n497 ?

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    1. Probably an A100k or maybe an A500k since it's so similar to a Fuzz Face.

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  3. There is one original version of the Erupter that uses a 100k trimpot as an output volume control.

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  4. Does it have to be that transformer or can a similar one be used?

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    1. A similar one could probably be used, just compare datasheets.

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  5. What kind of part is represented by the blue box with the 5K on it?

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  6. I just finished the circuit and tested it without success. Any tips on debugging or common mistakes with this board?

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  7. Any suggestions for the 2n497? they're $22 at mouser, yikes!

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    1. That section of the circuit is essentially a fuzz face, so anything with lower-mid hfe gain will probably be fine.

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  8. good morning, any suggestion to replace 2n497, I live in Brazil and here is so difficult some transistor...Please help me

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    1. Low-medium gain NPN silicons will work just fine. 2N2222A, 2N2369, 2N5550, etc.

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    2. For Q1 can i use an 2n7000? I cant find the j201 and 2n5457 in my town :( any other replace??

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    3. The 2N7000 is a MOSFET and isn't a direct replacement for the J201 or 2N5457. You'll need some sort of N-channel JFET. Comparing datasheets of what you can get to the J201 is probably your best bet.

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  9. Ok thanks... one last question, what kind of think do the trimmer? I need to regulate or something like that,?

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    1. The trimmer is there to set the minimum amount of voltage supplied to Q3 by the Bias pot. It's something you'll need to adjust by ear. I'd start by setting it half way and making sure the the circuit works at all rotations of the Bias pot. Then adjust as necessary

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