Way Huge - Fat Sandwich [traced]

[Nocentelli]

Green Rhino
Fat Sammich
Swollen Pickle
Angry Troll
Pork Loin
Supa Puss
Ringworm

!!!

The new Swollen pickle has been traced here at FSB, but I'd love to see guts of the rest.

[LaceSensor]

pretty sure the pork loin is already traced.
ill try to take some pics of the green rhino over the weekend

[Intripped]

pretty sure the pork loin is already traced.

thanks, i totally missed that!

[lukatosh]

Green Rhino Guts please Sir!

Best Regards from chile!!

[MoonWatcher]

just got one of these for $65 and it is AWESOME. I will take pictures when I have more time, but I think its safe to say that it is an opamp clipper driving a series of 4049/4069 Inverters. The Presence and Resonance appear to be a Baxandall-type EQ. The Tone control is a simple roll off.

I can make out two pairs of clippers - a pair of silicons, and a pair of LED's.

There's a trio of transistors. In order to have a tone circuit function in a "standard sense" with inverters, I'd think these would be a necessity. The 3rd transistor could be just a low Z out. Or - maybe there's some active tone shaping beyond the presumed Baxandall? Maybe a gyrator tied to something?

So there's the op amp, there's the transistors, there's the 4049 - what's the other long chip in there? None of that stuff should be for switching, because that's all on the separate board w/all the SMT stuff.

I see a lot of small ceramic caps that I'm assuming are primarily for attenuating treble. It looks like this circuit is more complexly crafted than one might realize from just using the pedal. I sort of can imagine parallels (in a design sense) with the Pork Loin. Doesn't the PL use a mosfet on its input? Maybe that is what is going on here, and maybe the pair of canister-type transistors are some sort of pre-emphasis circuit?

It's kind of amazing that this one hasn't been traced sooner. Really slick work. Tripps is an amazing dude.

[coldcraft]

Surprise!

[zedsnotdead]

Ty!

[jubal81]

Way Cool. Planning on doing a layout, Coldcraft?

[coldcraft]

no, sorry, feel free to do that if you want.

[Nocentelli]

Surprise!

Thanks! Is the 4049 actually powered? There's no indication on the schematic, but I kind of assume +9v to pin 1 and grounded pin 8. Just breadboarding this beast now, and I've got to the end and really have no idea.

[coldcraft]

yes it is. sorry i left off the standard power filtering.

[Nocentelli]

Got massive squeal and self oscillatiion with the drive pot on just about anything above zero. Everything else seems to work ok, though. I have a 1k from +9v to the 4049 pin 1, like the red llama. It's very late, so I'm using headphones but i'll have another play around tomorrow.

[coldcraft]

try bypassing the Pin 1 (9v) with a large electro to ground

[MoonWatcher]

Surprise!

Thanks! Is the 4049 actually powered? There's no indication on the schematic, but I kind of assume +9v to pin 1 and grounded pin 8. Just breadboarding this beast now, and I've got to the end and really have no idea.

Take a look at what the makeup is of the 4049 - it's mostly a Red Llama, but it uses triplets of inverters for each stage. But the cap values with the Llama are the same as is used with the Fat Sandwich. It must make a ton of treble frequencies to have both a 270pF and 220pF cap in the negative feedback loops at the tail end of the circuit.

[stevo83]

Thanks for the schematic guys.

Interesting circuit with a lot going on; 3 stages of clipping/distortion etc.

Is there a reason for the CD4049 inverter stages stacked in parallel, more gain?

[MoonWatcher]

Is there a reason for the CD4049 inverter stages stacked in parallel, more gain?

I think it's for less noise.

[coldcraft]

if I had to guess, that would be what tripps did in the Red Llama MkII as well.

[zedsnotdead]

Didn't know there was a llama MKII... whats the main diffenreces for MKI? Is there a schematic/layout?

[coldcraft]

no, not yet. there is no difference from the outside, but I bet tripps just paralleled the inverter stages like he did here.

[MoonWatcher]

if I had to guess, that would be what tripps did in the Red Llama MkII as well.

I think the MkI's had the old Fairchild CD404NUBCN which was pretty good. The one by Texas Instruments - the "UBE" has a lot more hiss.

Fairchild has ceased production of a non-SMT CD4049UBCN, at least for export to what I'd assume are most countries.

The Rotagilla pointed out that the MkII had a MC14049UB by ON Semiconductor, and that the noise with it was lower, too. But no one traced that out, and no one thought to look for 6 100R's.

I think Texas Instruments is the remaining large company that distributes the 4049U worldwide with the through hole style. If the parallel configuration is to lower noise, it might be because WHE (or I guess Dunlop) is expecting to exhaust their inventory of chips by ON Semiconductor?

I think Rohm may make a 4049U, but it may not be manufactured in the numbers that a company like Dunlop might require. I just don't know.

Maybe it's just good design principle as opposed to how it's typically been done - connecting the unused inverters to either ground or V+. I also wonder if it's a way to reduce the need to limit current to the 4049.