Got a request for Zakk Wylde's signature overdrive from MXR. It's essentially Boss SD-1 Super Overdrive without the buffers. Original units have MC33178P, but socket and experiment with dual op-amps. You can use right angle PCB pots to mount them on the board from the solder-side.
Hey guys! One doubt:
ReplyDelete- The piece labeled "C B E" is a jumper?
That's a transistor. MPSA14 darlington type.
DeleteNPSA18 is listed. It's an NPN high output.
Deletethanks. I'll finish this week and will post the result.
ReplyDeleteI have the same error as crunch box. I'm ashames cause not accomplishing to do that. I'm beggining in this process. I'm thankful for the patience.
ReplyDeleteOne question, There's a way to invert the position of 3pdt key? there's the possibility to be using upside down?
i'm sorry for my english.
DeleteNo worries. You can't really invert the switch unless you turned it sideways, but then you wouldn't be getting bypass signal. Double check your wiring and make sure you don't have any shorts on the circuit board. Did you etch a pcb or are you using perf?
DeleteI made the pcb at home. I drowned with a dvd pen and used Iron Perc. I'm thinking that i Had some problem with static energy. Cause there was a hole I needed to open a bit more, and I drill it again, with some components at their places. Maybe this.
DeleteI'm verifying three pedals: Berzerker overdrive, Crunch box and mxr microamp.
Verfiied! =D
ReplyDeleteWorks so well!!
I tryed before, and fixed my error, I inverted the position of diodes.
Thanks @dtgehring!! You're the Man bro!
Great! Glad you got it working.
DeleteThanks Bro! as we say in my country: "tamo junto" it's like "we're together"
Deletecheers!
Do you know what we can do to increase volume to a Project?
ReplyDeleteYou can always through a booster after it. Several good ones on this site. Though I believe this thing should be plenty loud. Are you not getting max volume above unity?
DeleteThe volume is so low than dod 250, maybe the half capacity. but I made a microamp to fix this in my pedalboard. Thx!
DeleteThis Project is amazing: A warm tone without the noise, I'll record a demo.
Deletecan I use styroflex caps for 120pf?
ReplyDeletePlease where I can find the schematic. Thanks
ReplyDeleteGoogle it.
DeleteI build this one and the gain pot doesn't make much gain/drive. How to increase the drive? thanks
ReplyDeleteHello
ReplyDeletePlease tell me what software did you use to design the pcb?
DIYLC
DeleteMPSA14 (E B C) or (C B E)???
ReplyDeleteEBC and CBE pinouts are the same. Just rotated 180º...
DeleteУже разобрался спасибо поставил аналог BC550
ReplyDeleteHi ! Is the Q1 a MPSA18 or MPSA14 ? based on the diagram states that is the first one, but does not seams to be a dartlington transistor.
ReplyDeleteMPSA14. The 18 is a typo
Deletegreat !! thanks for the quick response.
DeleteHi, I finished to build this pedal and I like the tone. But I have a question, the output is very low than other overdrives that I have. Anybody had this problem too?, Can I do anything to solve this problem?... Thanks, It's a great overdrive.
ReplyDeleteI have the same troubles with low output/ For more volume i changed resistor 10k between 1&2
ReplyDeletelegs of chip to 300k, & changed output potenciometr 10k to 100 k. I will change from 6 leg resistor 4,7k to 1 k & cap 47n to 0,22n for more gain & low.
Adding:For more volume i changed resistor 10k between 1&2
ReplyDeletelegs of chip to 300k, & removes cap 10n, & changed output potenciometr from 10k to 100 k. I will change from 6 leg resistor 4,7k to 1 k & cap 47n to 0,22n for more gain & low & changed gain resistor 33k to 2-10k. I have got nice sound,volume & gain!
You're awessome.... thanks a lot, I will gona change the pieces that you mean.
DeleteI made this modification and I have more treble and I feel that Output gives gain. The pot of gain almost does not respond ... the resistance that you put 2-10K, I put it on 10K ... will I have to lower the value?
Delete2 k will be norm, try to change 10k between 1&2
Deletelegs of chip to 100k, I have more treble too...
ReplyDeleteHello, I want to make this pedal, it’s my first build, and I want to make it “heavier”. I want to build itto put out more overdrive than the original, but with the same (or almost the same) tone. How can I do this? Thanks in advance :)
Easiest way would be to increase the value of the 33k resistor to the left of the clipping diodes (D1-3). That's the resistor that sets the minimum/maximum gain of the circuit. Increasing it will increase the max gain but also increase the min gain.
DeleteHi friend, so to have more gain would be the only modification to make? I made all the modifications mentioned by "Vit Zzoyd" but the tone and volume have changed a lot. Also when moving the gain pot, practically does not change ... thank you very much
DeleteGood morning everyone. I wonder if BC517 is a good replacement for MPSA14. Thank you.
ReplyDeleteAny other equivalent i can use instead mpsa14?
ReplyDeleteAny high hFE transistor should be fine as it's just being used as an input buffer.
DeleteHi guys. Just built this pedal. It works from first start but it has very low gain. Nothing close to original. I don't have 120p and 18n caps so used 100p and 220p instead. Could that be a reason? Thank you.
ReplyDelete