Wednesday, 4 May 2016

DOD FX22 Vibro Thang

Here is a layout for the DOD FX22 Vibro Thang (Vibrato / Phasor)


04/05 Layout Updated: LM358 pin 4 and the 18K resistor from the bottom LM13600 pin 9 were connected to V+ instead of ground.

34 comments:

  1. Replies
    1. And there is a slight chance that'll fit in 1590B! Now let's see when i can build myself one...
      +m

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    2. Yeah....that's lethal!!!

      The LED acts as a Rate indicator so consider taking that offboard. An easy task with this excellent layout!

      Cheers Alex!

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  2. Thanks guys!
    And thanks for the help!
    Hope the layout works.

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  3. This doesn't really do like, intense pitch modulation though right? Sounds more like a tremolo to me? Or like a harmonic tremolo or whatever.

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  4. For pitch modulation you gotta build the Boss VB-2!

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    1. I had an original. From memory it was quite tame. Great sound quality but simply was not what i was looking for at the time, so it got sold on quickly. I'd be interested in seeing if anyone could mod it to make it more versatile.

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    2. I'm fairly certain your memory fails you. Tame is not the word i would use to describe FX22, not my original, nor my build.
      +m

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    3. @mirosol. Thats interesting! I did some digging.. http://www.americaspedal.net/fx22/

      "Circuit revisions: The lone example of the 'original' graphics FX22 we have seen did not permit a fast vibrato effect, while both examples of subsequent versions we have examined did. If the difference was intentional, it was not noted on its circuit board ID number ("P/N# 80-1022-A0" for all versions we have examined). However, one of the resistors located between the RPMs/Speed pot and the JRC 2904D chip was changed from 22 kOhms (1995) to 10 kOhms (1997). We haven't traced the circuit or attempted to modify the only original FX22 available to us at this time, but carefully clipping another 22 kOhm resistor in parallel to the existing 22 kOhm resistor (for a net resistance of close to 10 kOhm) might be an easy way to determine whether or not the change in resistance is responsible for the change in vibrato speed."

      I am fairly sure my VibroThang was the original 1995 graphic one.

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    4. That could explain things. Mine is later version and thus, per the revision of the factory schematic, and this layout. Although that should affect the LFO speed and not the modulation itself.
      +m

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    5. Hey Miro!
      On a different subject, I've uploaded a DOD FX33 layout in the Forum-Contribution section.

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    6. Cool. I'll try to find some time to build it soon (ish).
      +m

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  5. Alex! There's something horribly wrong with the power strips. Check the connections to 358 pin 4. Which should be ground. Once you find a cure, let me know how to fix my board - which is otherwise finished...
    +m

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    1. Oh. You fixed it already. So mine won't be enough to call it verified... Even though it works now. You still have one error in there. The 18K from lower LM13600s pin 9. Should be to ground, not V+.

      Like i said, mine's working but with a few fixes that are quite crude. And these fixes are for the first version layout.
      +m

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    2. That's the problem with LM13600! I assumed pin 11 was ground like in a TL074 in both mistakes!
      Thanks Miro.
      It has been fixed!

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    3. I'm fairly certain that the layout will work. So it'll be a safe build even without the verified tag. And it sounds like it should. Maybe a C100K for width could be better than linear.
      +m

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    4. Cool! Thanks Miro! Wasn't sure what to use instead of W100K.

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    5. not tayda cheap but still not bad...

      http://www.ebay.com/itm/5-pcs-100KW-W100K-pot-potentiometer-17mm-Audio-Balance-center-detent-/140892112347?hash=item20cdd305db:g:sQEAAOSwdpxUV5M4

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    6. Usually, a linear is the way to go.

      Either way, the layout is awesome and sounds great. Thank you Alex! Any plans what you might take on next? :)
      +m

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    7. Thanks Miro!
      Just uploaded a layout for the Ampeg VH140C in the forum Contributions-Unverified section.
      Didn't upload it on the main page cause I wasn't sure the schematic was verified.
      It came out as large as usual! :)
      Wanted to do a layout for the ISP Decimator but I'm not sure the clones made with the only schematic available work that well.
      Any suggestion on possible projects?

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    8. A few that i've got my eye on for some time are more DODs :)
      FX33 Buzz Box (http://www.diystompboxes.com/smfforum/index.php?topic=60730.20)
      and
      FX76 Punkifier (http://www.nodevice.com/manual/fx76-punkifier/get130298.html)
      Even started the job on those both but couldn't quite handle them. Both are circuits that i would build asap..

      I admit defeat to you in perceiving larger circuits :)
      +m

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    9. I can give it a try.
      Once again, I've added a possible schematic without switching system for the FX76 in the forum section.
      Do you think it would work that way?

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    10. There's no shame in being defeated by Alex. He is a monster!

      Alex I know this isn't the request section, but I know several of us would love to build an LM13700 Small Stone!

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    11. I've never drawn a layout that doesn't fit in 1590B in terms of board size. I'm still bound by that restriction i've set for myself. It takes truly a keen eye to perceive things as compact as Alex does.

      I'll check the stripped schem..
      +m

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    12. Thanks guys but I think I've just had more practice on larger layouts. That's all. Like putting together a large puzzle. Unfortunately I'm not technically as knowledgeable as most of you. We all compensate each other to make this blog what it is. If I had my own blog it would be filled with large layouts and plenty of ???? :)
      Do you have a schematic for the Small Stone?
      Can't seem to find a properly verified one.

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    13. Found these:
      http://img.photobucket.com/albums/v517/uncle_boko/EHsmallst2.jpg

      http://s853.photobucket.com/user/bernardduur/media/Schematics/SmallTone.jpg.html

      http://lectric-fx.com/wp-content/uploads/2014/06/SpaceHarp.pdf

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    14. I know the one at GGG has been around for a long time. I think it's verified but can't say 100% for sure.

      http://www.montagar.com/%7Epatj/smlstone.gif

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    15. I've seen that one but those are CA3094, not LM13700.

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    16. Skimming the FSB gave me Bernardduur's Turkish Small Tone:
      http://www.freestompboxes.org/viewtopic.php?f=1&t=3567&hilit=small+stone&start=20#p80686

      http://s853.photobucket.com/user/bernardduur/media/Schematics/SmallTone.jpg.html

      Seems to match the Uncle Boko one and thus, should be ok to build.


      As a side note, i seem to learn more every day and i've been quite actively at this since mid 2010.
      +m

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    17. Ah. Just noticed you've already linked to Bernardduur's schem.. Since it's Bernandduur, it should be safe to draw and build.
      +m

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