Something New from Doc Sketchy

From circuitbending to homebrew stompboxes & synths, keep the DIY spirit alive!

Moderators: lisa, luketeaford, Kent, Joe.

Post Reply
User avatar
Dr. Sketch-n-Etch
Super Deluxe Wiggler
Posts: 7769
Joined: Thu Jan 21, 2010 1:46 pm
Location: Vancouver, BC, Canada

Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Wed Jun 10, 2020 4:01 pm

KSS wrote:
Wed Jun 10, 2020 3:46 pm
Dr. Sketch-n-Etch wrote:
Wed Jun 10, 2020 3:03 am
Tonight I finished the build
------------
The two large PCBs with the traces on the outside are the Connector boards.
What's the new minimum panel width to 'cover' solder sides of the connector boards?
Those Connector boards are 3" x 5.5". Do those exposed traces worry you? You could just cover them with strips of electrical tape (make it a sexy Black Tape Project).

BTW, I just drilled the holes for adjusting the trimmers -- I put a couple of "dummy" trimmers I had laying around on the board so I could place the holes correctly. I had to cut a couple of traces and kludge in two jumper wires on each board. It was very clean. I've changed the layout so the next set will be correct.
We've moved fast, we need love; a part we offer is our only freedom

KSS
Super Deluxe Wiggler
Posts: 2442
Joined: Mon Jan 25, 2016 7:28 am

Re: Something New from Doc Sketchy

Post by KSS » Wed Jun 10, 2020 4:08 pm

No, the overall width from leftmost exposed fillet to rightmost exposed solder fillet. What's that dimension now?

User avatar
Dr. Sketch-n-Etch
Super Deluxe Wiggler
Posts: 7769
Joined: Thu Jan 21, 2010 1:46 pm
Location: Vancouver, BC, Canada

Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Wed Jun 10, 2020 4:42 pm

KSS wrote:
Wed Jun 10, 2020 4:08 pm
No, the overall width from leftmost exposed fillet to rightmost exposed solder fillet. What's that dimension now?
5.1" on both boards (could be called 5.0" in a pinch).

But then again, who doesn't like a little bit of strategically placed black tape?
blacktape.jpg
You do not have the required permissions to view the files attached to this post.
Last edited by Dr. Sketch-n-Etch on Thu Jun 11, 2020 5:11 pm, edited 1 time in total.
We've moved fast, we need love; a part we offer is our only freedom

KSS
Super Deluxe Wiggler
Posts: 2442
Joined: Mon Jan 25, 2016 7:28 am

Re: Something New from Doc Sketchy

Post by KSS » Wed Jun 10, 2020 5:17 pm

Dr. Sketch-n-Etch wrote:
Wed Jun 10, 2020 4:42 pm
5.1" on both boards (could be called 5.0" in a pinch).

But then again, who doesn't like a little bit of strategically place black tape?
Thanks Doc. 3.1"? Seems a typo crept in? Wonder how that happened. :agonizer:

User avatar
Dr. Sketch-n-Etch
Super Deluxe Wiggler
Posts: 7769
Joined: Thu Jan 21, 2010 1:46 pm
Location: Vancouver, BC, Canada

Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Thu Jun 11, 2020 1:04 pm

I finished the build lastnight. The panel slipped onto the pots and switches very easily, and the jack wiring took about half an hour. When I get those PCB-mountable jacks, I'll take off these wires, make a Jack PCB, and rewire. Then I'll take some fresh pictures.

Also, I plugged it in and the oscillator didn't work, so I've got some troubleshooting to do. I guess my lucky streak was very short lived.
We've moved fast, we need love; a part we offer is our only freedom

User avatar
Dr. Sketch-n-Etch
Super Deluxe Wiggler
Posts: 7769
Joined: Thu Jan 21, 2010 1:46 pm
Location: Vancouver, BC, Canada

Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Thu Jun 11, 2020 1:09 pm

Finally, after giving this topic much thought, and even discussing it with a close friend, I have decided not to sell PCB sets for the Frequency Shifter. i only want to make complete modules. I will still make 4U boards for the two people whom I told that I would, but that's it, and I won't be building a 4U module myself to test layouts, so if there are problems with those boards, then caveat emptor.

Making the boards represents at least half of the labour of making the module, but brings in very little revenue. Also, this is not a terribly easy build, and I really don't want to be spending half of my time helping others troubleshoot their builds. It's hard enough to troubleshoot my own, and this build in particular is hard to troubleshoot because the boards are stacked, so all but one of them are inaccessible to probing. I'm going to have to get pretty clever as to how I actually go about troubleshooting.

Sorry.
We've moved fast, we need love; a part we offer is our only freedom

User avatar
notmiserlouagain
Veteran Wiggler
Posts: 715
Joined: Thu Feb 23, 2012 11:04 am
Location: Hamburg
Contact:

Re: Something New from Doc Sketchy

Post by notmiserlouagain » Thu Jun 11, 2020 2:20 pm

:guinness:

I´ll save up then, great module, I will still want it a couple of weeks from now!

The constructionstyle is unique, at least in synth world I think :yay:

On a sidenote, any idea on this? Too many harmonics (it´s a sine for a reason)?
what would happen if the quadrature osc. is replaced by another signal through another PDN?
He who eats with most pleasure is he who least requires sauce.
Xenophon

User avatar
Dr. Sketch-n-Etch
Super Deluxe Wiggler
Posts: 7769
Joined: Thu Jan 21, 2010 1:46 pm
Location: Vancouver, BC, Canada

Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Thu Jun 11, 2020 5:11 pm

notmiserlouagain wrote:
Thu Jun 11, 2020 2:20 pm
:guinness:

I´ll save up then, great module, I will still want it a couple of weeks from now!

The constructionstyle is unique, at least in synth world I think :yay:

On a sidenote, any idea on this? Too many harmonics (it´s a sine for a reason)?
what would happen if the quadrature osc. is replaced by another signal through another PDN?
Glad to hear it. That means I only need to make one 4U board set.

As far as using a second PDNed audio as the carrier waves to the multipliers (which is what you are saying), I fear that the result would be a complete mess, as all the frequencies in the first audio signal would be shifted by all of the frequencies of the second audio signal. The result would probably be very close to ring modulation with an audio signal as carrier.

I've been thinking about a couple of (potentially) clever patch possibilities. One is to put a simple constant-frequency sine wave into the INPUT input (as the audio) and then feed keyboard CV to the 1V/OCTAVE input and play the shifting in key. I'm not sure how that would sound, but I can see once I troubleshoot my current unit. Using a more complex waveform in, such as Saw, may give more interesting results.

Another idea was to set it up like I had it before (with the guitar or a microphone) but feed a Noise-->S&H to the 1V/OCTAVE input. With spoken audio, that would really give a "computer talk" effect. With an Analog Shift Register, one could feed shifted S&H to various FM inputs around the synth for other cool effects (i.e., to a filter cutoff control, or a VCO pitch control).
We've moved fast, we need love; a part we offer is our only freedom

User avatar
Dr. Sketch-n-Etch
Super Deluxe Wiggler
Posts: 7769
Joined: Thu Jan 21, 2010 1:46 pm
Location: Vancouver, BC, Canada

Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Fri Jun 12, 2020 3:33 am

OK, here's the third and final video, showing my classy new build, and also showing a neat trick you can do with it to get some pretty fantastic Lissajous figures. Enjoy!



(Incidentally, after spending quite a lot of time troubleshooting, the problem was (drum roll please) another defective 2164 chip (or maybe two). I also found one very tiny solder bridge which was affecting the 1V/Octave input (good thing I decided to tune the VCO, as I wouldn't have caught it otherwise). I don't know if the 2164s came to me defective, or if I fried them somehow while testing the build (probably the latter). In any case, the thing works perfectly now. I spent a lot of quality time hand-selecting caps (for the PDN) and resistors (for the multipliers and amplifiers) and it really shows in this build.

Also, while I was playing with it, I realized that I had forgotten to normal the MIX output jack to the AUX input jack for phasing, so I just plugged the DIFF output into the AUX input, and I took the MIX out to the speakers. Then, when I was playing my guitar through it, I started turning the Output Mix knob to go from SUM to MIX to DIFF outputs, and I was getting some very subtle and different phasing responses. If I had just normalled MIX to AUX, then I would have fed back whatever the mix was from the pot, and it would have sounded the same as the last video. However, by connecting DIFF (or SUM) to AUX and then changing the mix, it is feeding back only DIFF (or SUM) but taking the MIX to the output, and it sounds different. The point is, there is a lot of very nice and subtle variation to be discovered by plugging different outputs into the AUX input when phasing.

And it can be yours for the low, low price of $450 (USD) plus shipping.
We've moved fast, we need love; a part we offer is our only freedom

User avatar
Paradigm X
Super Deluxe Wiggler
Posts: 2050
Joined: Tue Nov 02, 2010 5:43 am

Re: Something New from Doc Sketchy

Post by Paradigm X » Fri Jun 12, 2020 3:42 am

need to go thru this thread, as one of the now minority motm format users. great stuff, mad genius!

User avatar
synkrotron
Ultra Wiggler
Posts: 939
Joined: Wed Nov 09, 2016 12:48 pm
Location: Warrington UK
Contact:

Re: Something New from Doc Sketchy

Post by synkrotron » Fri Jun 12, 2020 3:45 am

Watched the video... Cool oscilloscope traces... Would look great projected onto a factory wall with a laser :mrgreen:

And over all a really cool build. I'm not familiar with your stuff as I haven't been frequenting these parts for long but everything I have seen up to now looks fantastic.

:hail:

User avatar
tobb
Super Deluxe Wiggler
Posts: 1041
Joined: Sat Nov 26, 2011 5:41 am

Re: Something New from Doc Sketchy

Post by tobb » Fri Jun 12, 2020 7:32 am

Clever pcb assembly :tu:

User avatar
devinw1
Super Deluxe Wiggler
Posts: 1446
Joined: Tue Aug 07, 2018 11:20 am
Location: Portland, OR
Contact:

Re: Something New from Doc Sketchy

Post by devinw1 » Fri Jun 12, 2020 11:06 am

Trippy!!

Great shirt btw!!

User avatar
Dr. Sketch-n-Etch
Super Deluxe Wiggler
Posts: 7769
Joined: Thu Jan 21, 2010 1:46 pm
Location: Vancouver, BC, Canada

Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Fri Jun 12, 2020 11:49 am

Well, synkrotron, if you have any Intellijel modules that are more than a few years old, then you have experienced my designs, as I designed more or less the entire Intellijel analog lineup up to about 2015. I'm in the process now of converting some of those designs (that I haven't done already) into my preferred 5U format. Preferred because I can use through-hole parts (I don't build with SMD because I'm too clumsy, and I etch my own PCBs in Excel on a 0.1" grid) and the panel controls are more suitable for big-boy hands.

The shirt was a gift from one of my younger daughter's friends. I thought it was appropriate for the video.
We've moved fast, we need love; a part we offer is our only freedom

Schlumpfhut
Common Wiggler
Posts: 94
Joined: Tue Oct 31, 2017 11:47 am
Location: Germany

Re: Something New from Doc Sketchy

Post by Schlumpfhut » Fri Jun 12, 2020 1:07 pm

Dr. Sketch-n-Etch wrote:
Fri Jun 12, 2020 11:49 am
Well, synkrotron, I'm in the process now of converting some of those designs (that I haven't done already) into my preferred 5U format.
And you can be sure that there will be some guys out there (myself including) who are wanting to get their hands on your great builds :hail:

User avatar
Dr. Sketch-n-Etch
Super Deluxe Wiggler
Posts: 7769
Joined: Thu Jan 21, 2010 1:46 pm
Location: Vancouver, BC, Canada

Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Sat Jun 13, 2020 1:53 pm

I made a tiny design change this morning. Lastnight, while playing with the Frequency Shifter, I noticed a bit of oscillator bleedthrough when there is no audio signal. After a bit of thinking and simulation, I realized that this was most likely caused by a little bit of DC coming in from the signal inverter leading into the linearized 2164 VCA acting as a 4-Quadrant multiplier. If there is no audio, then nothing should be multiplied, because the product of zero and anything else is zero (right?) so there should be nothing coming out the other end. However, if there is a small amount of DC, then this multiplies by the carrier wave (from the quadrature VCO) and gives control bleedthrough.

I had put two 47uF electrolytic caps back-to-back on the audio input to the multiplier (and on the control input to the multiplier) to avoid DC into the multiplier, as this compromises the 4-Quadrant multiplication (and gives sidebands other than the two you actually want). However, because I put this onto the audio signal coming into the PCB, this audio signal goes both through an inverter into the 2164, and around the inverter and the 2164 into the final current-to-voltage converter (output amp). What I failed to realize is that a) DC on the signal going around the inverter and 2164 has no effect on multiplication, and b) the opamp will impose a small DC level of its own (especially since I'm using TL072CD here, which has up to 10mV of offset). So, the bottom line is that the caps need to be between the inverter and the 2164 to also block the opamp-derived DC from the multiplier.

The good news is that I was able to make this change on the PCB by just shifting a few traces around in one spot and adding one tiny jumper -- I didn't have to move any components or pin headers, which means that I don't have to alter the Connector PCBs, and I can easily kludge this change onto the existing Multiplier board to test its effectiveness.

I guess it's a good thing that I haven't sold any of these things yet.
We've moved fast, we need love; a part we offer is our only freedom

User avatar
synkrotron
Ultra Wiggler
Posts: 939
Joined: Wed Nov 09, 2016 12:48 pm
Location: Warrington UK
Contact:

Re: Something New from Doc Sketchy

Post by synkrotron » Sat Jun 13, 2020 2:07 pm

Dr. Sketch-n-Etch wrote:
Fri Jun 12, 2020 11:49 am
Well, synkrotron, if you have any Intellijel modules that are more than a few years old, then you have experienced my designs, as I designed more or less the entire Intellijel analog lineup up to about 2015.
I'm afraid I only started my Modular Journey late 2017. And the only Intellijel module I have is Metropolis, which is a great sequencer. Did you have a hand in that?

User avatar
Dr. Sketch-n-Etch
Super Deluxe Wiggler
Posts: 7769
Joined: Thu Jan 21, 2010 1:46 pm
Location: Vancouver, BC, Canada

Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Sat Jun 13, 2020 6:47 pm

synkrotron wrote:
Sat Jun 13, 2020 2:07 pm
Dr. Sketch-n-Etch wrote:
Fri Jun 12, 2020 11:49 am
Well, synkrotron, if you have any Intellijel modules that are more than a few years old, then you have experienced my designs, as I designed more or less the entire Intellijel analog lineup up to about 2015.
I'm afraid I only started my Modular Journey late 2017. And the only Intellijel module I have is Metropolis, which is a great sequencer. Did you have a hand in that?
No, that's a digital creation of Danjel van Tijn. I may have been consulted on one or two tiny analog aspects. I designed the circuits for Dixie, Rubicon, Doc Oc, uVCF, Polaris, Korgasmatron, uFold, uFade, uMod, uVCA, Quadra, Planar, co-designed Atlantis, Springray, and Azimuth, and did a small amount of work on Dubmix. I think that covers it. Most of those modules have now been discontinued, and some have been reborn as digital modules, as Intellijel has gone in a more digital direction.
We've moved fast, we need love; a part we offer is our only freedom

User avatar
Dr. Sketch-n-Etch
Super Deluxe Wiggler
Posts: 7769
Joined: Thu Jan 21, 2010 1:46 pm
Location: Vancouver, BC, Canada

Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Sat Jun 13, 2020 6:53 pm

Incidentally, I moved the caps to post-inverter on my multiplier board, and it didn't really help the bleed-through situation, although I still believe that its the superior approach. The problem is pretty minor anyway (you have to crank up the modular pretty high to hear it -- it's hard to see it on the scope because it is down around the noise floor), and it could just be control bleed-through from the 2164, which is always there a little bit. I use 562k resistors at the Mode pin to minimize it (because that's what the relevant figure in the datasheet seems to suggest), but it's never zero. Nature of the beast, I guess.
We've moved fast, we need love; a part we offer is our only freedom

User avatar
notmiserlouagain
Veteran Wiggler
Posts: 715
Joined: Thu Feb 23, 2012 11:04 am
Location: Hamburg
Contact:

Re: Something New from Doc Sketchy

Post by notmiserlouagain » Sun Jun 14, 2020 4:16 am

Just an idea, you probably checked already:
Does the waveform of the bleedthrough change with the wf put into the multiplier?
If not, is the multiplier 0V reference free of currents from the oscillator?
He who eats with most pleasure is he who least requires sauce.
Xenophon

User avatar
Dr. Sketch-n-Etch
Super Deluxe Wiggler
Posts: 7769
Joined: Thu Jan 21, 2010 1:46 pm
Location: Vancouver, BC, Canada

Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Sun Jun 14, 2020 6:25 pm

Update: Moving those caps was a mistake, although I don't really understand why. The thing acts weird when the caps are between the inverter and the multiplier, but doesn't act nearly as weird the way I had it originally. Somehow, it is becoming some kind of weird filter or lag network with the decoupling caps when they are in the wrong place. Hence, I've put them back to their original positions, and will just use TL074BCN for the multiplier opamps, because they guarantee lower voltage offsets than TL074CN.

I'm using two 47uF caps back-to-back to decouple (which gives a bipolar cap of 23.5uF), and maybe these are a little too large. Perhaps I should be using 22uF (to get a bipolar cap of 11uF). I don't want to add phase error to the audio signal, and these caps are big enough that any delay is well below the lowest effective frequency of the PDN (15Hz). However, maybe I'm overdoing it a little. The thing is, I bought a small pile of those 47uF caps for this purpose.
We've moved fast, we need love; a part we offer is our only freedom

User avatar
Dr. Sketch-n-Etch
Super Deluxe Wiggler
Posts: 7769
Joined: Thu Jan 21, 2010 1:46 pm
Location: Vancouver, BC, Canada

Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Sun Jun 14, 2020 6:34 pm

notmiserlouagain wrote:
Sun Jun 14, 2020 4:16 am
Just an idea, you probably checked already:
Does the waveform of the bleedthrough change with the wf put into the multiplier?
If not, is the multiplier 0V reference free of currents from the oscillator?
If you're asking whether the GND rail has oscillator bleed on it, I don't know. However, I'm always feeding a 10Vpp oscillator waveform into the multiplier (as Y). The question is, will this inevitably bleed through to the output (XY) even when the audio signal (X) is silent? I think that it probably will. I've got it pretty small now, by replacing the relevant opamps with TL074BCN and decoupling the X and Y signals to remove DC bias. I don't think I can do any better. The bleedthrough is very very faint now -- you really have to crank the synth up to dangerous levels to hear it. I can't really distinguish the bleedthrough from the noise floor on the scope. If I feed a square wave, I can sort of tell that it's squarish amongst the noise hash.
We've moved fast, we need love; a part we offer is our only freedom

User avatar
Dr. Sketch-n-Etch
Super Deluxe Wiggler
Posts: 7769
Joined: Thu Jan 21, 2010 1:46 pm
Location: Vancouver, BC, Canada

Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Mon Jun 15, 2020 2:09 am

So, final update on the new build...

Tonight I strapped on my guitar and tested the FS with the new Multiplier board with the alternative placement of the decoupling caps, and... the phaser function didn't work at all. It would start to work, and then it would go whoop whoop WHOOP and then silence. This happened when the AUX/FEEDBACK knob was cranked up to where the phasing should have sounded good. Frequency shifting worked fine, but with no noticeable improvement over the first arrangement. Hence, that new board has been retired. I actually more or less destroyed the original board when I kludged it for the new cap placements, and I had harvested all the parts off it and thrown it away yesterday. Hence, I made a completely new Multiplier board (the third for this build) with the original layout this morning. I stuffed it this morning and was a bit impatient with selecting resistors. Hence, this evening, while I was watching TV with my wife ("I May Destroy You" on HBO -- freaky shit, but good) I sorted all of my 200k resistors and about 300 of my 100k resistors into bins to the nearest 0.1k. Tonight, after I tested the "bad" board, I decided to solder-suck all the 100k and 200k resistors off the "good" board and replace them with 99.7k and 199.4k resistors (because I ended up with a lot of those and the important thing is that they are all the same or exactly a factor of 2 different). I also replaced two of the TL074CNs with TL074BCNs. It now sounds pretty stunning (again). I'm happy with it, and I'm gonna quit fucking around with it.

Somebody please buy one!
We've moved fast, we need love; a part we offer is our only freedom

User avatar
Rex Coil 7
Super Deluxe Wiggler
Posts: 6560
Joined: Thu Nov 29, 2012 11:29 am
Location: Captain Of Outer Space

Re: Something New from Doc Sketchy

Post by Rex Coil 7 » Mon Jun 15, 2020 2:22 am

Dr. Sketch-n-Etch wrote:
Mon Jun 15, 2020 2:09 am
...Tonight I strapped on ...
... yea, see ... I always knew you were a horny old shit ....

8-)
Never Quit, Die Falling Forward
5U PROJECT - (skip pages 4 through 6, boring junk) ... https://www.muffwiggler.com/forum/viewt ... highlight=

User avatar
Rex Coil 7
Super Deluxe Wiggler
Posts: 6560
Joined: Thu Nov 29, 2012 11:29 am
Location: Captain Of Outer Space

Re: Something New from Doc Sketchy

Post by Rex Coil 7 » Mon Jun 15, 2020 2:28 am

Dr. Sketch-n-Etch wrote:
Wed Jun 10, 2020 3:03 am
... I'm super-duper happy about how this turned out. It's exactly what I was hoping for.
... and you damned well should be happy with it. Simply outstanding ... thinking beyond pre-conceived notions about PCB configuration and use of boards instead of ribbons to facilitate layer connection. Fookin noice, Ace!

:)
You do not have the required permissions to view the files attached to this post.
Never Quit, Die Falling Forward
5U PROJECT - (skip pages 4 through 6, boring junk) ... https://www.muffwiggler.com/forum/viewt ... highlight=

Post Reply

Return to “Music Tech DIY”