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.
Mate ! this is AWESOME !
ReplyDeleteTransformer arrives today from Mouser. I'll try to verify over the weekend.
ReplyDeleteVerified!! Works perfectly!
ReplyDeleteGreat! Thanks for verifying
DeleteWhat transistors and hfes did you use?
Deleteif i want a volume what pot should i use ? is there any good remplacement for 2n497 ?
ReplyDeleteProbably an A100k or maybe an A500k since it's so similar to a Fuzz Face.
DeleteAhhh, Less HFE much better
DeleteThere is one original version of the Erupter that uses a 100k trimpot as an output volume control.
ReplyDeleteAny substitute for the pf5102?
ReplyDeleteJ201, 2N5457, etc.
DeleteDoes it have to be that transformer or can a similar one be used?
ReplyDeleteA similar one could probably be used, just compare datasheets.
DeleteWhat kind of part is represented by the blue box with the 5K on it?
ReplyDeleteA trimmer
DeleteI just finished the circuit and tested it without success. Any tips on debugging or common mistakes with this board?
ReplyDeleteAny suggestions for the 2n497? they're $22 at mouser, yikes!
ReplyDeleteThat section of the circuit is essentially a fuzz face, so anything with lower-mid hfe gain will probably be fine.
Deletegood morning, any suggestion to replace 2n497, I live in Brazil and here is so difficult some transistor...Please help me
ReplyDeleteLow-medium gain NPN silicons will work just fine. 2N2222A, 2N2369, 2N5550, etc.
DeleteFor Q1 can i use an 2n7000? I cant find the j201 and 2n5457 in my town :( any other replace??
DeleteThe 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.
DeleteOk thanks... one last question, what kind of think do the trimmer? I need to regulate or something like that,?
ReplyDeleteThe 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
DeleteHello,
ReplyDeleteIs there any gerber file and pcb specifications for this pedal?
Built it but getting really bad oscillation at any bias below 6v - any ideas? Cheers!
ReplyDeleteIM also getting oscilation unless my bias pot is over 85% clockwise. Woud this be due to the transistors? i used pn2222 and have checked the pinout. I also used a pf5102 for the jfet
ReplyDeleteThe transistor is 2n4970, not the 497...in case you're having trouble finding them/cheap
ReplyDelete