BUILD THREAD: 266-style PCBs

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L-1
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Post by L-1 » Tue Nov 25, 2014 1:14 pm

I wanted to make QRV to play pure notes. I've matched all resistors at QRV circuit to 0.1%. QRV2 (n+1) out now tracks perfect but QRV1 (2n) out tracks not so good, will try to make something with it.

I fed QRV2 out into L-1 Basic VCO prototype which tracks perfect (+- 1 cent) within 5 octaves. Triangle out recorded.

Watch and listen how QRV2 out plays pure notes:

[video][/video]


QRV scope shots:

QRV1, pot at max:
Image

QRV2, pot at max:
Image


to be continued...
Last edited by L-1 on Wed Dec 10, 2014 3:08 pm, edited 1 time in total.

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L-1
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Post by L-1 » Wed Nov 26, 2014 6:02 pm

I've got good tracking at QRV1 out too!!! Now it plays pure notes.
It controls L-1 basic VCO prototype, square wave.
Watch and listen:

[video][/video]


The schematic has an error or inaccuracy. QRV2 plays pure notes when range is 5 octaves. QRV1 needs 5 octaves + 3 semitones to play pure notes.

To fix this I added a bit of gain to IC4B. I changed R19 to 5.3K.

Now the module can be used for creating music, not only noises.

to be continued...

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L-1
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Post by L-1 » Tue Dec 09, 2014 9:26 pm

SRV1

SRV has 256 possible output states. So to have 1/4 semitone per state, we need 5.33V output range.

I removed this 12K marked red, which was installed because I made modularsynthesis.com modifications.
Also I made R84-R91 exact 25K, 50K, 100K, 200K, 400K, 800K, 1600K, 3200K.

Image

I made simulation where added a resistor after D4. To have 5.33V range it must be 88K.

Image

I installed this 88K and got good tracking. Not cent-by-cent but pretty acceptable.
1/4 semitone or 25 cents per state. Watch and listen SRV1 out controls L-1 Basic VCO:

[video][/video]


Scope SRV1 out:

Image

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L-1
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Post by L-1 » Wed Dec 10, 2014 2:44 pm

SRV2

SRV has 256 possible output states. So to have 1/4 semitone per state, we need 5.33V output range.

I replaced R113 with 17.6K to have 5.33V range.

I got acceptable tracking. It's possible to understood from the video - interval between states is about 1/4 semitone or 25 cents. Watch and listen SRV2 out controls L-1 Basic VCO:

[video][/video]

Scope SRV2 out:

Image

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Post by L-1 » Wed Dec 10, 2014 2:47 pm

INTEGRATOR

I trimmed integrator to have a slope 10 s when pot is on max, and 10 ms when pot is on min.

Longest slope 10s:

Image


Shortest slope 10 ms:

Image

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Post by L-1 » Wed Dec 10, 2014 3:23 pm

SAMPLE AND HOLD

Sample and hold has PULSE IN, and two pulse outs which are near IN sighned ALT wth arrows. They produce positive odd and even pulses from IN.

PULSE OUT1 yellow and PULSE OUT 2 blue:

Image


PULSE OUT 2 blue with PULSE IN green:

Image


I fed triangle wave into CV IN.
Also it has 1+2 CV OUT and CV1 OUT and CV2 OUT which are sighned ALT with arrows.
CV1 yellow and CV2 blue outs:

Image


CV1+2 out produces only positive:

Image

But look - how thick and terry is the wave. It's selfoscillation from an opamp. To remove this I installed 100p capacitor between 1 and 3 pins of IC4.
And look how nice it's now:

Image

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davebr
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Post by davebr » Thu Dec 11, 2014 2:45 am

L-1 wrote:SRV1SRV has 256 possible output states. So to have 1/4 semitone per state, we need 5.33V output range.

I removed this 12K marked red, which was installed because I made modularsynthesis.com modifications.
Also I made R84-R91 exact 25K, 50K, 100K, 200K, 400K, 800K, 1600K, 3200K.

I made simulation where added a resistor after D4. To have 5.33V range it must be 88K.
Of course you could drop the 2 LSBs for semitones outputs (5.33/64 =83 mV).

Dave

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JJCarr
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Post by JJCarr » Thu Apr 02, 2015 10:18 pm

i've had one of these 266c modules for a while but i've never been able to get the s+h section to do anything?!
i'm guessing it got damaged in shipping somehow. any delicate parts or known issues i should be looking for?
cables and chips seem to be seated correctly.

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JJCarr
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Post by JJCarr » Thu Jan 21, 2016 9:08 pm

OK, I'm back after 2 years with the same Euro build to troubleshoot. yaaaay!

what is the DEFINITIVE/FINAL mod for the power converter section on PCB 1?
i've read through the thread and applied what seems to be the latest omissions/jumps/etc. but am still having problems.

this is what's currently implemented:

-All traces that were cut in schematic now reconnected
-omitted d12, d13, L3, L4, IC15, IC14, C14, C41, C40
-C37 currently installed but conflicting info in thread on whether this is needed
-i have L3 jumped to C14 so that +12v actually exits the circuit like the schematic reads even though I don't see anything about this anywhere.
-when I take readings at the THRU outputs right now out1 reads +12v, out2 ground, out3 +10v (should be -12v, right?).

is this module supposed to run on 15v? what is this mod doing and why is the module (when functioning) seemingly just fine running 12v now?

I did not build this module and was having issues with the S+H and possibly the SRV. again, this is for a Eurorack format module.

:deadbanana: PLEASE HELP :deadbanana:

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JJCarr
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Post by JJCarr » Fri Jan 22, 2016 8:57 pm

all issues with my module are solved.
for anybody else with this problem in the future, look for the photos of the power section of the euro pcb in the middle of the thread.
this thing has never worked so well, I'm so glad I finally figured out this issue. my S+H and SRV have never functioned properly since I purchased it and now it's BRILLIANT.
thanks to Janvolt for the info he provided in a pinch.
over and out (hopefully forever).

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Post by appliancide » Sun Sep 25, 2016 7:48 pm

Wow. It looks like there are a few additional modifications recommended since the last euro 266 I built.

None of the level shifters on PCB 3 are needed? So just jumper the input side of R11 to the output side of R13 on the IC1 shifters, and the input side of R19 to the output side of R21 on IC2?

I am curious to see which of the modularsynthesis and L-1 mods are useful on the 12v build. I'd much rather make adjustments to make it work on 12v, than to mess around with voltage boosters.

Madness!

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wohali
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Post by wohali » Thu Feb 22, 2018 1:28 am

I took delivery of a set of the v1 PCBs, vactrols, and faceplate about 6 months ago. I finally got around to completing the project this past weekend.

Picture: Image

Picture in my custom TTSH/Eurorack case: Image

Total power draw with LEDs on: 175mA +12V, 122mA -12V.

I did take a bunch of notes; the ModularSynthesis site covered most of it, with L-1's modifications in the last 2 pages of this thread being useful as well. I had to make a few additional adjustments on my unit to get it responding reasonably and working appropriately. I'll try and blog about this soon so others can follow along.

Thanks to L-1 and Dave Brown for their excellent work, it made dealing with this error-riddled set of PCBs much easier.

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squarewavesurfer
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Post by squarewavesurfer » Mon Oct 21, 2019 9:55 am

Anyone know if a GD4006B work in place of a CD4006B? It seems like it is intended to be equivalent but the datasheet makes me wonder if they are different.

GD4006b
https://orchidsound.com/pkg-of-10-gd400 ... r-pdip-14/

CD4006b
datasheet

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wohali
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Post by wohali » Tue Oct 22, 2019 2:51 am

You're in luck - Roman's 266c doesn't use the pin 2 output missing from the GD4006B, so it should be fine.

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