Black finger layout beta tester needed

[Zero the hero]

People, I've drawn a pcb layout for this pedal, but I have no time to test it.
1 month ago I asked what PCB I should have drawn, and these are the results.
I need someone who built it for me and tells me if it works!
I'll build it in a couple of weeks, but I'm very busy at the moment, so I hope someone will help me in trying this circuit.

Pm me your e-mail, I'll send you the complete package with PCb, layout, component list and instruction for building it.
Thanks!!!

[jimbob]

Is this the tube version?

[Zero the hero]

No, it's the first version with ca3080 and 741.

[Nasse]

I have the original one with 741 and 3080, so this is interesting project for me. If you need some info about the old one, I might be able to help somehow.

Is your project a new layout design or a reproduction of the old?

[cd]

What does this pedal sound like, is it a compressor with a character (like a Dyna/Ross) or is it more transparent?

[Nasse]

I would say it has a character. You cand dial in a subtle and not much coloured setting for rhythm guitar, but both tone control and sustain settings have wide adjustment range. You can have dark and warm tone with lots of bass and go for clear and trebley tone. And compression goes from subtle to so much you certainly notice it is artificial. What makes these extreme settings not so very useful is high noise and nasty distortion, which goes quite bad when batteries are not fresh anymore. And maybe the 741 opamp magig tired-sounding transistor tone is there, too

[Zero the hero]

I have the original one with 741 and 3080, so this is interesting project for me. If you need some info about the old one, I might be able to help somehow.

Is your project a new layout design or a reproduction of the old?

THANKS EVERYONE! It's a new layout, improved with true bypass.
I'll keep you informed if someone will have problems in building it!
I'm going to etch a boar dan dpopulate it as soon as I can. I have plenty of job to do right now.
I've never heard the original unit, so thanks nasse for your detailed description of how this pedal sounds like!!! Nasse, do you want the PCB too?

[Nasse]

Nasse, do you want the PCB too?

 :shock:   Yes, why not.

[Zero the hero]

From Rick:

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I found a couple of things that you might want to deal with.

You've marked two resistors as R4. The one on the top (that goes to pin 2 of
IC1) is marked 1k on the schematic and 220k on the layout.

R8 is marked 47k on your schematic, 1k on the layout. The original schematic
has this resistor as 1k. Which is correct?

R11/R12 are 470k/470k on your schematic, 270k/120k on the original
schematic. Which are correct?

Not necessarily an error, but the transistor outlines are backwards for the
2N3904 and 2N3906 transistors that I'll be using. They may be correct for
the original transistors but you may wish to mark the pins for people who
want to use subs.

Again, not actually an error, but you might want to mark the polarity of the
electrolytic caps on the layout.


[RickL]

I went ahead and built it using the values from the original schematic and it works.

I tested it using batteries that measured about 8 volts under load and it sounds about the way others have described it - not particularly clean. It's also not overly loud, not much over unity with the volume control full up. When the tone control is all the way down it sounds a bit dull and it's even lower in volume.

I can try the other values for R11/R12 if someone thinks it will do any good or any other suggestions you think might be worthwile.

[RickL]

I tried TL072 and TL082 for the opamp hoping to cut down on some of the distortion but neither worked properly. It looks like this one needs the specific opamp to work.

[cd]

Which schematic are you guys referring to/using?  The really neat and clean japanese one I posted a while back?

[RickL]

Sorry, no. It's a cleaned up version of the factory schematic that was posted to me (and others?) as part of a package to try out a layout. I forgot that it wasn't available to everyone. I already had a copy of the factory schematic which I must have got through here at some point.

Zero it might help if you posted your redraw of the schematic so the rest of the community could help me determine the best values for some of the components.

For anyone who has access to the factory schematic I can confirm that if you build it using those values it will at least work, though, as my above posts indicate, not neccesarily as well as it could.

[Zero the hero]

Ok, I'll post it on this page... as soon as I'll have a picture editor installed on this stupid machine!!! I'm not at home now and I cannot update the exact values for those resistors in my schem / layout.

[Zero the hero]

I still haven't found what I was looking for (a photo editor...) so I post it anyway...

Schematic (I should change R11 to 270k and R12 to 120k):

Code Select Expand

http://img.photobucket.com/albums/v368/zero_thehero/electronics/Schem.gif

Layout (R8 value still wrong, should be 47k):

Code Select Expand

http://img.photobucket.com/albums/v368/zero_thehero/electronics/layout.gif

PCB:

Code Select Expand

http://img.photobucket.com/albums/v368/zero_thehero/electronics/PCB.gif

VERSION 1.1

[cd]

Interesting.... shall I confuse the waters even more by showing you another schem?

http://img99.exs.cx/img99/1179/Blackfinger.gif

Some of the component values are different, and some are added.  I wonder what difference there is in the sound?  I'm going to breadboard both and find out.

[cd]

I corrected the R11 and R12 values:

http://img82.exs.cx/img82/1206/BFSchem.gif

[Nasse]

In my unit C10 and C11 are soldered at solder side, and are not electrolytics but foil caps. I posted a pic maybe now not up but our friend a fine gentleman Gez Paton noticed very big yellow caps on the pic. Maybe I should open my pedal, or the pic is on my hard drive...

I am not sure but I have been thought that it looked like the original pcb was planned for different size smaller physical size caps, and those bigger but better were added later. Of course you can find small 0,47 uf or 1 uf quality caps today.

I bet they might be better and more stable in the long run in such place. Not so long ago I bought a big bag of caps at harakiri cheap price, and when I got home I opened the bag and looked what I got and some of these were same size and look that in my vintage pedal that I bought when I was not so old.

[cd]

Tried breadboarding the schematic I posted - circuit works and it's not too noisy.  I did not find much distortion from the stock 741, I tried a LF356 which did not work, but a LF411 does.  Slightly less noise but the compression characteristic is different.... hm, I'll have to do some more futzing around with the circuit.  I don't know how much volume I can get out of this circuit, offhand I cracked it open around 1/3 of a linear pot rotation and it was plenty loud.

[Zero the hero]

Thanks everyone for testing both schematic.
It seems I've chosen the wrong one. I'll try to re-adapt this pcb for the second schematic posted.
It's not very funny, I have to draw another layout for this circuit.
I've read all the impressions about the black finger on another thread, and it seems that's not very good as a compressor (well, worse than a dynacomp).
I'll get all of you informed.
Stay tuned!