Friday, 28 August 2015

Mosrite Fuzzrite germanium

Hello folks! Travis here and I'm very excited to join the tagboardeffects squad. Thanks to Mark and Miro for the opportunity, and thanks to Zach, Javi, and Alex for joining along as well. I'm sure we're gonna have a great time, so without further adieu, here's my first contribution to the main site!

As some of you may know, I was lucky enough to pick up an original germanium transistor equipped Mosrite Fuzzrite earlier this year. It has without a doubt been my favorite pedal I've ever owned, and I traced the circuit to share with you fine folks.

EDIT: There were some mistakes in my initial trace due to a couple hidden links and an oddity with one cap connection. I have updated the layout, and this is pretty much your standard Ge Fuzzrite with component values matching mine, and an added voltage inverter for easy daisy chaining


Here's a photo of my dearly beloved which I based this layout on



And the layout!

27 comments:

  1. Welcome Travis.
    Glad to see the action's back!

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  2. Is there a suitable sub for the 350k reverse pot?

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    1. As Miro stated in Mark's Ge Fuzzrite post, you can use a C500K pot with a 1M2 resistor between lugs 1 and 3

      By the way, I just noticed a mistake I must have made when shifting things around on the layout. The cut to the right of Q1 base needs to be moved so that it's between the 2n cap and Q2 collector. I will edit this when I get back from work. Sorry!

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  3. Congrats Travis!
    Looking forward to the new direction of this fantastic blog.

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  4. Congrats Travis!
    Looking forward to the new direction of this fantastic blog.

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  5. Holy shite! I made a couple serious errors in my trace as a result of being too careful when I took the pedal apart to trace.

    I built it up and it wasn't working right, so I tore open my Fuzzrite, and this time I bent everything out of the way and disconnected wires to get a better look.

    Well, I missed two links on the board, and totally biffed it up in general. Sorry guys, I feel like a total fool for messing up my first post like this! But I'll post an updated layout so you can at least have a nice Fuzzrite with inverter layout. It is still my favorite fuzz after all.

    The most confusing part on my Fuzzrite is the 25uf cap. That really mislead me into thinking it was an emitter bypass cap on Q2, but after finding one more link, I now see this cap seems to be doing nothing at all in my pedal. Both legs are actually connected to ground.

    I have no idea why they would do this, unless maybe if the pedal didn't have enough gain maybe they would snip the link that would turn this into an emitter bypass cap on Q2

    It's a little strange, and I'm sorry for my confusion! Please hold off on building this until I post an update

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  6. Welcome Travis and thanks for your contribution!

    Just one but very important thing:
    Your layouts (uploaded picture files) are not supposed to be called "MGFESbcxjasol25663" and stuff like that.
    They are supposed to have a logical name, so that we can find it again after downloading it to our harddrive.
    Remember:
    Nothing is more annoying than searching trough over 1000 files, just because someone did not name the file properly/logically. Don´t be one of those guys...!!!!

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  7. Besides the funky naming of the image file, I find that I can't open the file once I save it. I get a message saying it's corrupted or too large. I've tried this on Windows and Linux with no luck. I didn't have this problem with the original images you posted. I noticed those were .jpg and the new one is .png.

    And regarding the 25uF cap, I think you'll find that it's connected between power and ground. It might measure as 0 ohms with a meter, but that's because it's discharged. Hold the probes there long enough and the cap will start to charge and the resistance will increase.

    Please don't take this as a negative comment. I'm really happy to see some activity here again, and I'm sure you'll get the swing of it soon.

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  8. One side of the 25uf cap is connected to the emitter of Q2, which is also connected to ground. The other side is connected to the positive (ground) battery lead which is tied back to another ground connection on the switch. So both legs of the cap appear to be grounded.

    I'm not sure why you can't save the image though. I'm uploading the images through the site with a photobucket URL. It's .PNG which works on the site

    I would upload the images directly from my computer but I'm having issues logging on the site with my computer.

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    1. I tried saving the image again, for the fourth time, and now I'm able to open it. Go figure. Maybe Photobucket went haywire for a while.

      I take it your Fuzzrite is hand built. I bet somebody at the factory screwed up, the negative side of the cap really ought to connect to the negative battery lead, not the positive lead. This cap just filters the power and batteries don't really need filtering, so you probably wouldn't hear any difference even if you connected it correctly. A lot of early stompbox circuits didn't include a filter cap, but they can be noisy when powered by an external supply.

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  9. Yes I know. What threw me off is that I missed the link connecting the Q2 emitter to ground, which would have made sense as the cap would then be an emitter bypass cap boosting the gain of Q2. I also made a couple other mistakes which should all be corrected in this update, though it is currently unverified. Sorry for the inconvenience!

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  10. Hi! A Fazz face transistor set it would be usable in this circuit. Which range of Hfe for Q1 and Q2?
    Thanks
    Daniele

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  11. Typically people will use a higher hfe for Q1 and lower for Q2

    I thing generally something like 100-150 for Q1 and 40-60 for Q2

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  12. Hey Travis! Welcome and thank you!
    Is the layout updated? I was just thinking of resurrecting my Ge FuzzRITE project last night and you have come through in the clutch!

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  13. Thanks bud. This has been updated but not verified

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  14. Bottom right cut (near 22K resistor) is useless i think...

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  15. 1 and 8 IC's legs are shorted - is it ok?

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  16. Oops yeah that cut was left there by accident. It won't matter if it's there or not.

    Pins 1 and 8 of the IC need to linked

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  17. I builded this and it works. Thanks for the scheme! I changed some elements (because a didn't have the right parts): 2 nF caps to 2.2 nF and 40 nF to 47 nF. Also I dont have 2N2613 & 2N408 and I try to use some different - soviet МП42Б with different hFE (~100 & 50), 2N5087 (much more gain) and 2N3906 (much much more gain) - all sound good, but pedal have a very low output level compared to bypassed signal. What can be the reason of this?

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    1. I forgot something else to say: both pots are 500K.

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  18. The cap subs are fine

    Solder a 1M2 resistor across lugs 1 and 3 of the depth pot to turn 500K into ~350K. For the volume pot 500K is fine

    The higher resistance of the depth pot may be cutting the output, but this thing should be pretty loud. My Fuzzrite in the picture is wayyyy louder than unity, so there seems to be some problem either with my layout or your build.

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    Replies
    1. Thank you for your help, Travis! It's my mistake. I soldered 5000 Ohm volume pot instead 500K. Now its work very loud and good!

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  19. I there !
    Thanks for this layout !
    I wonder if I can replace the Ge transistors, since 2n2616 & 2n408 are really expensive ( something like 20$ on the bay just for 1 )

    thanks

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    1. as long as they are PNP Ge transistors with in the right gains you'll be fine. travis made the layout based on the Ge fuzzrite he actually owns, which i can tell you from playing through it myself, it sounds particularly amazing. that's not to say other Ge transistors won't sound as good.

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    2. Hello Zach
      Thanks for your reply !
      I saw in earlier response on this thread Travis used PNp Ge with hfe "like 100-150 for Q1 and 40-60 for Q2"
      I will try to find them :)

      Many thanks !

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  20. Believe it or not I haven't even built this thing yet! That was just a suggestion based on the common info online.

    I thought my pedal had some difference from the main schem that is floating around, but it is totally standard except for the 25uf cap being soldered literally from one ground pad to another making it completely useless

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