Weird Parts needed - Stone Grey Dist

[motterpaul]

I was looking at this (actually built it)...

But I then realized I have CD4049s, not CD4069 (the latter are older and only have 14 pins).

It also calls for 2n3819 transistors which have a reallly weird pinout:



I read i can sub MPF102 for these, but I don;t have a sub for the CD4069.

Does anyone there have these parts and would be willing to trade or sell. I am in California.

[induction]

MC14069U is a sub for CD4069U, if you can find any of those.

[Travis]

Or build the 4049 version that Frank posted

[motterpaul]

Great input from both of you - thanks!

[Sphere80]

I used the layout with 2n7000's for clipping.  You can use them , but twist the legs, or refer to the 2n7000 layout  and redo the jumper links.

I also built one with a TL071 for IC2, and another with a NE5534 instead.  Side by side they sounded the same.

[Frank_NH]

I should note that the CD4049UBE version I posted uses LEDs for clipping.  You can experiment with other diodes or transistors, but the LEDs sound good to me in that circuit.

 

[motterpaul]

Frank_NH wrote

I should note that the CD4049UBE version I posted uses LEDs for clipping.  You can experiment with other diodes or transistors, but the LEDs sound good to me in that circuit.

I saw that in your notes. Sounds like a good idea to me.

[Frank_NH]

Speaking of clipping, someday I want to implement the ultimate clipper circuit shown here (right side of the tube circuit) in a tube screamer.  It uses a "diode ladder" to achieve a very smooth limiting/clipping:

[Travis]

That looks cool thanks for sharing Frank. Might also be cool to try that in a circuit like the Dist + where the diodes are going from the output to ground

[Silver Blues]

Before you try this, I'd have a look here. I posted something about this once that got no traction at all  seems like a neat circuit block though. Would probably sound pretty cool in this, maybe with some mods.

[Marbles]

Musikding in Germany sells them, if you manage to keep your order small enough for a letter, it's only 2.90€ shipping costs. Not the fastrest option probably though :)

[Frank_NH]

Silver Blues wrote

Before you try this, I'd have a look here. I posted something about this once that got no traction at all  seems like a neat circuit block though. Would probably sound pretty cool in this, maybe with some mods.

Thanks for the link, Silver Blues.  I would probably simulate this in LTSpice first before breadboarding, but I figured that it could be built on a daughterboard and compared with conventional diodes.  I would suspect  that the resulting overdriven sound would possess fewer "harsh" higher harmonics since the knee of the limited/clipped signal is a bit smoother than a diode pair.

[Frank_NH]

Travis wrote

That looks cool thanks for sharing Frank. Might also be cool to try that in a circuit like the Dist + where the diodes are going from the output to ground

I actually have a Distortion+ LTSpice model and could try this idea out in a simulation.  

[Travis]

Please do! I'm interested in seeing if a guitar signal is enough to drive it into clipping, since the article linked above seems to indicate that it would have quite a bit more "headroom" than a typical antiparallel diode pair

[Silver Blues]

Frank_NH wrote

I would suspect  that the resulting overdriven sound would possess fewer "harsh" higher harmonics since the knee of the limited/clipped signal is a bit smoother than a diode pair.

This is what I was thinking as well. If it could be adapted to work properly at a pedal's signal level then it would probably sound quite good.

[Frank_NH]

I did some additional research and the limiter circuit is little more involved than I thought.  Here's a link to a more workable approach which uses a non-inverting IC stage:

http://prairieboxes.blogspot.com/2015/05/an-op-amp-diode-ladder-clipper.html

[motterpaul]

FYI all..

I ended building both the 4069 and the 4049 versions of this pedal, and I ended up using the 2n7000 layout (I didn't see that one at first). Strangely, I got the correct transistors for the version (2n3819 I think, I can't see it as I post this). But the layout did not work. I noticed that on the 2n7000 version one tranny is turned around 180-degrees. Maybe it doesn't matter in theory, but I changed nothing else and the original version did not work, but the 2n7000 version did.

Both 4069 and 4049 work just fine, but MAN are they ever bright. I tried swapping out several caps but nothing I did really changed anything.

These are loud and really cut through - but not a very pleasing sound IMHO.

[rocket88]

The pinouts are not reverse. The 2n3819 is DGS with the flat side pointing left, while the 2n7000 is SDG with the flat side pointing left. You would have to twist the S leg to make the pinout the same, not rotate the FET 180. You could just look at the data sheet to see the pinouts before instrering transistors, rather then just throwing them in pinouts match.

[motterpaul]

Just to be clear, I was referring to how one of the FETs is turned around 180-degrees in the 2n7000 layout as below: (and obviously the links are different).

[rocket88]

I understand that.

Motterpaul - "Strangely, I got the correct transistors for the version (2n3819 I think, I can't see it as I post this). But the layout did not work. I noticed that on the 2n7000 version one tranny is turned around 180-degrees. Maybe it doesn't matter in theory, but I changed nothing else and the original version did not work, but the 2n7000 version did."

You said the 2n3819 didn't work but the 2n7000 did. I'm saying you can't replace one for the other directly without twisting the pins as its marked on the layout. Rotating them the FET or not. The reason it did not work with the 2n3819s is because the pinout does NOT match the pinout a on the layout.

It's not a matter of theory why it didn't work, it's builder error. On the layout the 2 FETs are clipping diodes, so they are antiparallel, they're are supposed to be flipped 180 degrees. This way you get clipping in both halves of the signal.