Something New from Doc Sketchy

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Dr. Sketch-n-Etch
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Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Wed Jun 03, 2020 9:02 pm

Shit, hit quote instead of edit. I hate this new forum software.
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Re: Something New from Doc Sketchy

Post by Revok » Wed Jun 03, 2020 9:52 pm

I would also be interested in a 4u version. How deep is the 5u version? The slimmer boards would be nice but the depth is probably a no go.

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Re: Something New from Doc Sketchy

Post by Cat-A-Tonic » Thu Jun 04, 2020 12:51 am

Sounds great Doc!

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Re: Something New from Doc Sketchy

Post by Prunesquallor » Thu Jun 04, 2020 3:30 am

Dr. Sketch-n-Etch wrote:
Wed Jun 03, 2020 5:50 pm
Prunesquallor wrote:
Wed Jun 03, 2020 2:26 pm
You'll probably scoff, but 4-5 octaves ain't bad for experimental shits and giggles. (Bear in mind I have Buchla 258s in my set-up.) The quadrature LFO sounds fun as well.

But the all-important question we're all asking, of course, is could it be Serge-ified? :hihi: :sstorm:
Of course, but our friend Loudest Warning will have to design the panel.
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Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Thu Jun 04, 2020 3:06 pm

Revok wrote:
Wed Jun 03, 2020 9:52 pm
I would also be interested in a 4u version. How deep is the 5u version? The slimmer boards would be nice but the depth is probably a no go.
For the 4U version, I'd have to layout the boards anew. In addition to the panel board, there would be two circuit boards. All trimmers would be on the top board, so the spacing would be determined by the height of the decoupling caps on the lower board. However, the whole stack would only be about an inch thick. This is shallow enough for a Serge case. The boards would be a minimum of 4" wide, so it would require a 4" wide panel. This is a bit generous, given that the 5U version fits comfortably on a 2U panel, but them's the breaks. Also, I'd have to get clever about wiring the circuit together. There is quite a bit of spare real estate on the lower board, so maybe I can use that as a sort of Translator area. As I said, laying this out for a 4"-wide 4U application will be a significant challenge.
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Re: Something New from Doc Sketchy

Post by Dr Gris » Thu Jun 04, 2020 3:07 pm

Fantastic!!!
Congrats on a successful build.
I've been waiting for this since we started a PM conversation about you building one of these for me back in December 2017.
Since then I've acquired 2 Frequency Shifters but I still want this.
I guess I'm a FS junky....

//M

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Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Thu Jun 04, 2020 3:39 pm

Dr Gris wrote:
Thu Jun 04, 2020 3:07 pm
Fantastic!!!
Congrats on a successful build.
I've been waiting for this since we started a PM conversation about you building one of these for me back in December 2017.
Since then I've acquired 2 Frequency Shifters but I still want this.
I guess I'm a FS junky....

//M
Hey Dr Gris, can you use a 5U build? I could build one of those for you right away, or I'd sell you the version in the video at a discount price (because it doesn't have the oscillator outs built into the panel, although they're easy enough to access).
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Re: Something New from Doc Sketchy

Post by Dr Gris » Thu Jun 04, 2020 4:13 pm

I'm mostly in 5U territory so no problems. I'll PM you.

//M

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Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Fri Jun 05, 2020 3:47 pm

Update:

1) I've sold the first prototype (in the video) to a local buddy here in Vancouver, so it is now unavailable.

2) I can build anyone who wants one a fresh unit (with the VCO outs on the panel, and with an improved panel-PCB connection strategy that I've just put the finishing touches on) for the low, low price of:

$450

Please let me know if you want one with a PM. Thanks!
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Re: Something New from Doc Sketchy

Post by indigoid » Sat Jun 06, 2020 8:24 pm

Ace! That sounds super cool.
Zap him again! ZAP THE SONOFABITCH AGAIN!

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Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Sun Jun 07, 2020 3:23 pm

Well, I'm ready to build the next 5U Frequency Shifter prototype. This one will have no panel wiring, except for 11 wires which connect from two headers (a 5-pin and a 6-pin) on side Connector PCBs to similar headers on a Jack PCB, or to the jacks themselves (10 signals and 1 GND). All Circuit and Panel PCB interconnections are on two side Connector PCBs, which have five rows of sockets into which the 5 PCBs in the stack (4 Circuit and 1 Panel) will plug on both sides.

I've tried to account for everything: Most of the Circuit PCBs will be 0.5" apart (12mm spacers), but the Multiplier PCB requires 0.8" of clearance because of the electrolytic capacitors, which are 0.5" tall and require a small amount of extra clearance top and bottom. I've made a mock stack with two resistors and a cap, and made up the spacers (15mm plus a nut), and found the spacing to be exactly 0.8". Also, since the Panel PCB will be upside-down relative to all the others, it's pins will be on the opposite side of the board relative to the others. When a 12mm spacer is used to separate it from the 90-PDN PCB, the pins are exactly 1" apart.

So, for the five rows of sockets on the Connectors, the spacings are: 0.5", 0.8", 0.5", 1.0" With 0.1" on either side for edge clearance, this makes the Connector PCBs 3.0" high (and 5.5" long, as are all the other PCBs), so the total depth of the module will be a little less than 4", given the height of the Panel PCB off of the panel, and the components and power plug on the outer PCB. This will fit into most 5U cabinets with ease.
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Re: Something New from Doc Sketchy

Post by KSS » Sun Jun 07, 2020 11:12 pm

Is the panel PCB 'passive' or does it contain components besides those appearing on the front panel?

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Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Mon Jun 08, 2020 5:50 pm

KSS wrote:
Sun Jun 07, 2020 11:12 pm
Is the panel PCB 'passive' or does it contain components besides those appearing on the front panel?
The Panel PCB is powered, and it has a single IC on it: a DG409 dual 4-channel multiplexer. This chip works with the two VCO WAVE switches to route the four different waveforms (sine, tri, zigzag, square) in two different phase angles (0 and 90 degrees) to the multipliers (and the waveform output jacks). The two switches are just SPDT On-On switches connected to +5V and GND, which define whether the two bits controlling the DG409 are 0 or 1.

Also, some of the pots have +5V and -5V routed to their tabs (Coarse and Fine frequency control, and Symmetry).

The "final" build of the 5U Frequency Shifter is a seven-PCB build: Four Circuit PCBs, one Panel PCB, and two Connector PCBs. These Connector PCBs plug into the sides of the Circuit PCB stack, and take the place of pin-to-pin wiring. The only wires in this module will be those to connect the jacks to the Connector PCBs, and that will take about 15 minutes to do.

Lastnight, I etched, drilled and tinned all of the PCBs, installed jumper wires on all of them, and stuffed the Panel and Connector PCBs and plugged them together. Tonight I'll (mostly) finish stuffing the Circuit PCBs and make the new panel. I said "mostly" because I'm missing a few parts, but I won't be able to go to Lee's again until tomorrow. But I should be able to take some pictures tonight of the "finished" module.

I'm very excited to get this module finished. I hope someone else actually wants one of these things.
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Re: Something New from Doc Sketchy

Post by KSS » Mon Jun 08, 2020 6:56 pm

Thanks Doc! Looking forward to seeing the 'final' layout-build.

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Re: Something New from Doc Sketchy

Post by Moog$FooL$ » Tue Jun 09, 2020 7:59 am

nice!! sounds like some fancy switching. :)
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Re: Something New from Doc Sketchy

Post by Dr Gris » Tue Jun 09, 2020 1:22 pm

Care to elaborate about the symmetry pot and the aux/feedback input.

//M

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Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Tue Jun 09, 2020 3:30 pm

Dr Gris wrote:
Tue Jun 09, 2020 1:22 pm
Care to elaborate about the symmetry pot and the aux/feedback input.
The Symmetry pot is a part of the TZFM circuit for the dual-core Rubicon. It biases the Linear FM circuit with a voltage between -5V and +5V. It is functionally identical to the Symmetry pot on the Intellijel Rubicon and Rubicon 2 (although there is no "Lock" switch). If Symmetry is in the dead centre (0V) then the TZFM is four-quadrant balanced (you probably didn't know that TZFM is just having a four-quadrant multiplier in the current loop of a tri-square oscillator, rather than just a plain linear VCA -- plus you need a bit of reset logic circuitry so the triangle doesn't hit the rail when the TZFM direction reverses -- oops, there's the secret of the Rubicon, just given away -- I get my kicks from figuring this sort of shit out).

The Aux/Feedback input is just a second attenuated audio input for the frequency shifter. It gets summed with the Input. However, the Mix Out output is normalled to the Aux/Feedback input jack, so that if nothing is plugged into it, it feeds the Mix Out output back to the input. Hence, the "Feedback" part. This is very important when using the device as a phaser.
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Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Tue Jun 09, 2020 3:32 pm

BTW, I'm about 75% done with the new 5U Frequency Shifter -- I've got two of the four circuit boards done (except for some electrolytic caps, which I need to buy) and the Panel and Connector boards done. Everything done so far plugs together beautifully. I'll try to finish stuffing all the boards tonight and make the new panel (although I won't be able to go shopping until tomorrow). In any case, there will be pictures tonight!
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Re: Something New from Doc Sketchy

Post by notmiserlouagain » Tue Jun 09, 2020 5:08 pm

Ok, so after seeing the videos I´m positive I need one of these in my life.
The one module I always wanted, but couldn´t figure out myself.

450$ is sensationally low price imo, yet I can´t even afford that at the moment, so if you´d make pcbs available
I´d take a set, 4U preferred. But 5U will suffice too.

Two questions:
-isn´t the square wave (great idea to have it!) actually pinging the PDN+feedback?
-what would happen if the quadrature osc. is replaced by another signal through another PDN?
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Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Wed Jun 10, 2020 3:03 am

Tonight I finished the build (except that I didn't get the panel made -- I'll have to do that tomorrow. Also, I'm missing a few parts -- some long trimmers and some 47uF electrolytic caps -- I'll have to hit Lee's tomorrow as well). In any case, given that, here are some pictures of the build. I'm super-duper happy about how this turned out. It's exactly what I was hoping for.
FSBoxFront.jpeg
FSBoxBack.jpeg
FXBoxSide1.jpeg
FSBoxSide2.jpeg
The two large PCBs with the traces on the outside are the Connector boards. They just plug into the stack of Circuit boards in the middle. The Circuit boards are firmly held together with hex spacers, and the Connector boards are held firmly in place by about 10 sockets each -- one to three for each of the Circuit and Panel boards. Those beige connectors on the end of the Connector boards are for wiring to the jacks, and that will be the only wiring in the entire build.

The Connector boards are 3" wide, so the module will be about 3.5" deep behind the panel.
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Re: Something New from Doc Sketchy

Post by synkrotron » Wed Jun 10, 2020 3:10 am

Amazing build :)

So, once those side panels are soldered in place is everything else also fixed and not removable?

Looking at that thing is like trying to understand Spock's 3D chess game :mrgreen:

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Re: Something New from Doc Sketchy

Post by Dr. Sketch-n-Etch » Wed Jun 10, 2020 12:33 pm

synkrotron wrote:
Wed Jun 10, 2020 3:10 am
Amazing build :)

So, once those side panels are soldered in place is everything else also fixed and not removable?

Looking at that thing is like trying to understand Spock's 3D chess game :mrgreen:
NO !!!!!

The side panels are not soldered in place. The board stack plugs into them. Anything can be changed at any time. Here's a picture of the thing taken apart:
FSBoxApart.jpeg
This wasn't like "Spock's 3D chess" to lay out. It was actually pretty easy, because I lay out my circuits in MS Excel for Office 2003. I simply copied the pin placements from all the boards, lined them up, spaced them out by the proper amounts (1.0", 0.5", 0.8", 0.5"), labelled them with little text boxes, and then connected the similarly labelled pins together with traces. Laying out the Connector boards took about an hour, for both boards. Also, making them was really easy, since they each involve nothing but a few jumper wires and some pin sockets. Here's the layout for one of the boards:
ConnectorLayout.png
See how I use color coding of the traces to make things even easier to follow? Yellow/Green/Orange for +5V/GND/-5V, Brown for jack connections, Cyan for the LFO switch connections, Blue for waveforms, and Pink for other stuff. Excel is great for laying out circuits -- don't let anybody tell you different.

There is one tiny problem with this build, though: I forgot to place holes in the Connector boards for accessing the sine shaper trimpots. I think it'll be OK because there seems to be some blank space in more or less the right place, but for future builds I'll shift the traces around and etch circles where the holes should go to access those trimpots.
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Re: Something New from Doc Sketchy

Post by synkrotron » Wed Jun 10, 2020 12:53 pm

Dr. Sketch-n-Etch wrote:
Wed Jun 10, 2020 12:33 pm
NO !!!!!
LOL :mrgreen:

Thanks for confirming that! Had me worried, temporarily :)
I lay out my circuits in MS Excel for Office 2003.
Really? I would never have thought of using a spreadsheet for stuff like this.

I'm a CAD designer by trade so I instantly think of CAD software for this sort of thing.

Thanks :)

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Re: Something New from Doc Sketchy

Post by devinw1 » Wed Jun 10, 2020 1:13 pm

MS Excel for CAD? You sir, must be a glutton for punishment!

Great job though, really. That's a different way to bus a stack of boards together!

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Re: Something New from Doc Sketchy

Post by KSS » 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?

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