Schumann PLL  [traced]

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digi2t
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Post by digi2t »

Hmm, I`ve been studying the new drawing uploaded above, and apart from some different resistor values, there seems to be a major departure as to where two of the wires between the two boards are going. Specifically, the wire from the TL074 pin12, and the wire from the TL074 pins 13/14. On the other drawing, their destination seems to be switched vis a vis the squarewave pot, and the 74HC14. This worries me, and I can`t check squat right now because I`m at work until 7pm. Did I screw the pooch and mix them up on my original drawing? I don`t know, and it`s pissing me off right now that I have to wait to find out.

I`ll verify this tonight, and report back promptly.

I also noticed that there might be a typo on the jonasx26 schematic for one of the lag timing caps. I`m pretty sure it`s a 33uF, and not a 3.3uF. I`ll double check that too.

I also noticed that some of the resistor values on the other drawing don`t make sense. 13M resistor to ground? 1.3M maybe? I dunno, but I ran all the resistors on the unit I have through the DMM, so I know I have what I have. Weird, but open to interpretation.
Will anyone be working on replacing the 12AC supply for standard 9vDC and charge pump setup?
Not from my end. I`m keeping the original config. I even worked into my vero. The other drawing also reports over +/-9vdc (10.3v), so I`m going with an AC supply, and voltage regulators.
No matter how many times I cut it, it`s STILL too short!

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KindaFuzzy
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Post by KindaFuzzy »

I might have goofed on the resistor values, I thought they were weird too. My buddy still has his so I can get him to confirm. I'm pretty sure I got the board to board connections right, but I haven't breadboarded anything but the fuzz section which works fine, so I'll dig up the trace pics and we'll see.

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KindaFuzzy
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Post by KindaFuzzy »

Here's a few more pics of the trace and the PCB trace sides. Of course I didn't take pics of the topsides, but no worries I'll get them. I did a one off of the fuzz section with a charge pump and it sounds almost identical to the original. One more note, I mislabeled the trigger and preamp knobs on my schematic too.

Image
Attachments
fuzz pcb.JPG
synth pcb.JPG
trace.JPG

tasteless
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Post by tasteless »

I've seen a bunch of the Youtube clips for this thing.
Certain settings sound a hell of a lot like a cheesy mini-synth thing that was in Electronics Australia magazine in the early 80's.
I killed mine But , I may still have the documentation somewhere.

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jonasx26
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Post by jonasx26 »

tasteless wrote:I've seen a bunch of the Youtube clips for this thing.
Certain settings sound a hell of a lot like a cheesy mini-synth thing that was in Electronics Australia magazine in the early 80's.
I killed mine But , I may still have the documentation somewhere.

This mini synth? http://www.generalguitargadgets.com/tec ... mini-synth


Thought I'd upload the revised schematic directly to the forum as well.
Attachments
Schumann PLL update
Schumann PLL update

digi2t
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Post by digi2t »

OK, I've done some checking, and testing, on the wire reversal, and here is what I've found;

1) The unit I have did indeed have the wire reversed from the KindaFuzzy unit. In other words, the jonasx26 schematic is what I have here. It may have left Schumann's shop like this, or maybe Water Places switched the wires around by accident. He had told me that he had resoldered some wires when the unit stopped working, to move the boards around. Maybe mixed up the wires? Could be one, or the other. Who knows. But...

2) Since this unit is wired the way it is, and the other is opposite, and both work, I decided to do a test. I switched the two wires around, and ran the unit through some tests.

The unit works both ways, but the octave section does pop more with the op amp feeding the 74HC14. Doesn't change the fuzz at all, if any. Overall, the unit does sound raunchier (read "better") now, wired as per KindaFuzzy's diagrams.

I would say that the KindaFuzzy scheme would be the right one. I've modded Jonas' schematic to reflect the KindaFuzzy unit;

Image
No matter how many times I cut it, it`s STILL too short!

https://www.deadendfx.com/

digi2t
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Post by digi2t »

Please disregard my last post, I was too late on the button to edit it.

OK, I've done some checking, and testing, on the wire reversal, and here is what I've found;

1) The unit I have did indeed have the wire reversed from the KindaFuzzy unit. In other words, the jonasx26 schematic is what I have here. It may have left Schumann's shop like this, or maybe Water Places switched the wires around by accident. He had told me that he had resoldered some wires when the unit stopped working, to move the boards around. Maybe mixed up the wires? Could be one, or the other. Who knows. But...

2) Since this unit is wired the way it is, and the other is opposite, and both work, I decided to do a test. I switched the two wires around, and ran the unit through some tests.

EDIT -

The unit works both ways, but the octave section does pop more, and is way glitchier with the op amp feeding the 74HC14 instead of the squarewave pot. Doesn't change the fuzz at all, if any. I prefer the original jonasx26 schematic. Wired the KindaFuzzy way, the upper octave really glitches high and freaks out with the trigger on the positive side.

Sorry to flip-flop the post like this, but it was an unexpected discovery. I would stick to what Jonas and I have published to date. One timing cap is not 3.3uF, but rather 33uF. That's a typo.
No matter how many times I cut it, it`s STILL too short!

https://www.deadendfx.com/

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Post by tasteless »

Hey jonasx26,

Yeah - That's the one.
I had no idea it was at GGG.
It's an interesting project from a theoretical perspective But , would need a lot of work to be musically useful.
I can't quite explain it But, there is a certain timbral characteristic that it shares with the Schumann ( the result of a raw CMOS waveform I guess ).

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Post by digi2t »

Here are the two versions. As I said before, both work, but the differences are;

- The unit Water Places sent me (the one I have here) is more stable. The octave effects are a bit less voluminous, but the Multiplier side doesn't get all glitchy and freaky on the decay when the trigger is leaning to the negative voltage side. The octave, or harmony effect is smoother. Fuzz is very good. Any reduction in volume of the octaves can be made up for with the Multiplier/Divider volume controls. There's enough dial to take care of that. Schematic and vero would be as follows;

Image

Image

- Other than differences in some resistor values reported, the KindaFuzzy unit (unit pictures and trace available here in this thread) is less stable with the 12 and 13/14 pins wired opposite. When leaning the trigger to the negative voltage side, the upper octave decay is glitchy and messy. The fuzz is the same as the Water Places unit. Multiplier and Divider volumes are louder as well. Again, volumes can handle this easily. I didn't bother changing the resistor values, since I don't think it would make a huge difference to the circuit overall. The wiring from the last op amp of the TL074 is the real crux here. Schematic and vero would be as follows;

Image

Image

All I can say at this point would be to try both, and go with what you like best. Or, use a DPDT switch, to switch between the two different wire connections. Kind of a Dr. Jekyll / Mr. Hyde switch. Just pull the two jumpers out, from pins 12 and 13/14 of the TL074, and wire a DPDT switch in their place, in a reversing configuration.

I don't know much about CMOS circuits, but as artifus warned me, the possibilities and tweaks could be endless. Just doing my best to report what I find. And maybe learn something along the way.
No matter how many times I cut it, it`s STILL too short!

https://www.deadendfx.com/

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destro
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Post by destro »

sweeeeet vero layout....looks like a parts order will have to be made this week :)

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Post by agoldoor »

Soo..... anyone build/verify this yet? I'm chompin' at the bit!

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Post by TubeOrgasmer »

I'm gonna order the parts within the week, but I'm working on making it run off 9V with a charge pump and bipolar supply first.

Sooo excited for this one! :horsey:

digi2t
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Post by digi2t »

This is where I'm at right now;

Image

I had a transistor array Superfuzz to get off the bench first. I'm going as per the original, with the +/-12power supply. I'm not sure that a MAX1044 will hold up to the power demand of this sucker.
No matter how many times I cut it, it`s STILL too short!

https://www.deadendfx.com/

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Post by AmpBastler »

Image
My 9V single supply redesign version :D DoubleSided PCB with all parts on it.

Waiting excitedly for the last missing components... :applause:

digi2t
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Post by digi2t »

AmpBastler wrote:[ Image ]
My 9V single supply redesign version :D DoubleSided PCB with all parts on it.

Waiting excitedly for the last missing components... :applause:
Mega nice and clean. I'm looking forward to hearing it running on 9v. There was a report from glops on the other forum that the on the breadboard, at 9v, the lag time pot may not work as well as with a higher voltage. You might have to play with this, yet it's also very important to remember that how the Lag time responds is also directly related to the Response, and Loop Track pots.

Will those boards be available for sale, or is it a one-off?
No matter how many times I cut it, it`s STILL too short!

https://www.deadendfx.com/

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Post by AmpBastler »

I have carefully read the cd4046 datasheet and think it makes no difference between 9V or 11V.

Possibly it would be better to add the lag time potentiometer a 1k resistor in series.

When the circuit goes well, I probably can produce a handful of industrial PCBs.

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Post by agoldoor »

Oh wow, nice work guys! I didn't realize y'all were that far along. Can't wait to hear the demos!!

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Post by KindaFuzzy »

The fuzz section alone works great on the 7660s chip with +/- 9v. Here's a pic of the second one I did:

Image

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Post by TubeOrgasmer »

So this is a long shot but if the +/-9V doesnt sound good, maybe upping the 9V with a charge pump and THEN making the upped voltage bipolar? :scratch:

digi2t
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Post by digi2t »

TubeOrgasmer wrote:So this is a long shot but if the +/-9V doesnt sound good, maybe upping the 9V with a charge pump and THEN making the upped voltage bipolar? :scratch:
That`s why I didn`t feel like taking a chance. If the original works that way, so should the clone. Sometimes a shortcut, is only a quick ride into oblivion.

Can`t wait for my remaining parts to get here, dammit! [smilie=a_furious.gif]
No matter how many times I cut it, it`s STILL too short!

https://www.deadendfx.com/

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