J.Haible's Living VCO for Eurorack [Build Thread]

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shiftr
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Post by shiftr » Fri Mar 23, 2018 3:38 pm

:hihi: :party:
thanks! :sb:

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Post by shiftr » Mon Mar 26, 2018 2:48 pm

I found an error.
I put a 620k resistor in the vibrato circuit where there was supposed to be 510k. I found a whole collection of 620k resistors wrongly marked as 510k in my drawers.
I took out the 620k and the circuit works fine without it. I tried putting in a 510k resistor but i liked it better without. The vibrato runs slower without.
Now i've got a problem with one of the sine shapers. One om the generates a clipped sine.
This project seems more work then building a TTSH :)

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Post by cleaninglady » Mon Sep 24, 2018 10:12 pm

Because I am quite busy and lazy too, could any kind Wiggler point me to a wiring diagram for the the Living VCO's.
I have completed Barcode edition V1.3 pcbs sitting here that I finished about 5 years ago. I'm planning to just ratshack it all into one box so I won't need a panel. Actually as the pots are all PCB mounted and the outputs are obvious, all I really want to know is :

1. How do the Driver pads on each OSC pcbs connect to the Driver PCB ?

2. The switch wiring. (I'm going to look at the Option 3 Diagram on Jurgen Haible's legacy site).

EDIT : Problems above solved. Option 3 diagram was great ! :sb: :sb: :sb:

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Post by cleaninglady » Wed Sep 26, 2018 2:53 am

More questions...

So, (first question), I was just checking over the BOM on page 1 of this thread, i'm sure that i never matched R1,R2 and R3.

Is there a high res image of the unstuffed PCB around ? (I have the
Logicgate 2014 Barcode Edition v1.3 PCB)

I can find R1 and R2 from making the first image above bigger but i can't find R3 anywhere. :deadbanana:

Also, (second question) i have a very badly misshapen TRI wave on one of the OSC PCB's. It actually wen't from being just a Triangle with a spike to a bad TRI / SAW combination with a spike after i changed C7 and C8 to BP electrolytic.

Is a clean TRI wave heavily dependent on R1,R2 and R3 being matched ?

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oscarthesquirrel
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Post by oscarthesquirrel » Sun May 12, 2019 7:48 am

Not sure if anyone can help with this but here goes...


Finished building my Living VCO today, but I've got a problem. No output from any VCO...

OK - so I already have a LVCO (built by someone else) and I've used that as a reference during my build.. so I started by measuring a few voltages


The power header for the VCO section is reading -10.66V and 11.17V

I've also checked all 3 IC1's and IC7's (I'm using OPA2134s here for better tracking) and all 3 IC1s show 10.7V at pin 3 , with IC7's showing 12.48V at pin 3. The values from the working LVCO ICs are 11.9V and 12.2V respectively.

Voltage at the driver pin header seem fine at -11.95V and 12V

So I've checked for solder bridges, cold joints, IC orientation, transistor orientation, diode orientation and also cross referenced against the working LVCO.

I'm stumped as to where to start looking...I'm no electronics engineer.

Any immediate suggestions as to a potential culprit ??? The fact that all 3 VCO circuits have the same issue leads me to think I've installed the same thing incorrectly in all 3 circuits....but I can't figure out what that would be.
"You can never have too many LFO's..."

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oscarthesquirrel
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Post by oscarthesquirrel » Sat May 18, 2019 9:44 pm

After a week of checking I'm no further forward.

Have literally checked every single component for value and placement, I've reflowed all the joints, i've checked IC sockets to make sure they're all seated OK..but still I have a non-functioning module.

Any kind-hearted soul out there able to help ?

:ripbanana: :bang:
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Muff McMuff
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Post by Muff McMuff » Sat May 18, 2019 11:09 pm

I have noticed many times on muffs people posting photos and somebody points out potential issues straight away. I would post some good images.

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Post by elmegil » Sun May 19, 2019 12:08 am

After you post photos, start with a single VCO.

Sounds like you've verified the voltages and components. Have you verified your panel wiring?

Are you sure the driver voltages are reasonable and not pushing you up into ridiculous inaudible rates or down into near-DC? If you can detach them you probably should.

When you adjust the frequency knob(s) do you get voltage changes at the output of the summing amp? I don't recall Barcode's designators and whether they match Juergen's original schematics, but talking about the output of U1A from the original.

Are you seeing any oscillation on the output of U1B? I hope you have a scope of some sort....

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oscarthesquirrel
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Post by oscarthesquirrel » Sun May 19, 2019 3:22 am

Attached is a pic of the board. Not the prettiest I know... if a higher res is needed, I can dig out my Nikkor 105 macro and send a monster file...

1. Yes, I have a scope
2. I have a working LVCO to compare voltages, components etc and that helped me spot 2 ceramics that were wrongly positioned in the driver section - that's now fixed..driver section works (I fed in quantised voltages from an A-155/156 combo and the signal through 1V/O seems fine)
3. Voltage at the pin header is weird +11.2V / -10.6V What might cause this voltage imbalance ?
4. Saw output steady +7.6V,across all 3 outputs (ie flat line)
5. Pulse output was 4.66V when I measured it, then I noticed it was slowly dropping..almost as if it was cycling very slowly..same across all 3 outputs+0.0008, +0.0041)
6. Sine outs -1.01, -0.4056, -0.2267 (flat line)
7.R33B is on the other side of the board - long story, but the solder simply wouldn't flow out when replacing R33B, so I ended up placing it on the other side. >,<
8. No panel wiring - am using the R*S bard set, so its a simple jacks, pots 'n' switches solder job and no complicated wiring.

Now the saw is the feed for the other waveforms via wave shaping, so I guess I need to start at IC1A/B/C. I've checked the transistors - correctly positioned, correct components

So where to go next ?

Image
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Last edited by oscarthesquirrel on Sun May 19, 2019 5:10 am, edited 1 time in total.
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oscarthesquirrel
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Post by oscarthesquirrel » Sun May 19, 2019 5:03 am

High res shot front of the board. Back to follow - for some reason can't upload - maybe file is too big.

Picture file
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oscarthesquirrel
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Post by oscarthesquirrel » Sun May 19, 2019 5:08 am

And the (ugly) back as an attachment
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oscarthesquirrel
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Post by oscarthesquirrel » Sun May 19, 2019 8:05 am

Latest update:

I pulled all of the ICs from the VCO section and measured the pin header voltage...perfect +12 V / -12V

So i started re-introducing the ICs one at a time and measuring...

All the OPAs - fine. Voltage is good at the header +/- 12V

The problem seems to be with the 311P chips I have - I suspect they're a fake batch from China. With each one I added in, the negative voltage dropped by 0.2-0.3V, and the positive voltage dropped too. I'd ordered them locally in Malaysia, so its a possibility they're duff...I've tried several from the batch in various locations and they all give the same (or worse) results.


The TL074CN ICs I've used also seem to be pulling down the voltage, although with them in place (and no 311Ps) the voltages are + 12v and -11.3V at the header.

So there are still issues, but hope this helps someone more knowledgeable than me to point in me a suitable direction

thanks !
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Post by elmegil » Sun May 19, 2019 11:27 am

4. Saw output steady +7.6V,across all 3 outputs (ie flat line)
This means you're right, the comparator section isn't working. The cap charges up, but never gets reset. I would suggest you find an alternate source of 311 chips.....

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sduck
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Post by sduck » Sun May 19, 2019 4:22 pm

By the way, this isn't the build thread for the R*S version, this one is for a different flavor of LVCOs. The actual R*S thread is at - viewtopic.php?t=150988 - but it seems this one is working for you.
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Post by oscarthesquirrel » Mon May 20, 2019 12:31 am

sduck wrote:By the way, this isn't the build thread for the R*S version, this one is for a different flavor of LVCOs. The actual R*S thread is at - viewtopic.php?t=150988 - but it seems this one is working for you.
Yeah - sorry... I went for the thread that has [BUILD] in the title !

If you need to move this bit of thread across that's cool with me. :tu:
Last edited by oscarthesquirrel on Mon May 20, 2019 12:34 am, edited 1 time in total.
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Post by oscarthesquirrel » Mon May 20, 2019 12:32 am

elmegil wrote:
4. Saw output steady +7.6V,across all 3 outputs (ie flat line)
This means you're right, the comparator section isn't working. The cap charges up, but never gets reset. I would suggest you find an alternate source of 311 chips.....
This makes sense...at least to a novice like me...thanks for the explanation.

New 311 chips already on order from Farnell.
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Post by elmegil » Mon May 20, 2019 7:29 am

Sounds good. We can pick it up in the other thread if if continues to be an issue... :)

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Post by sduck » Mon May 20, 2019 10:50 pm

oscarthesquirrel wrote:[

If you need to move this bit of thread across that's cool with me. :tu:
Doesn't matter to me. Seems like it's doing fine here. And with this ancient software you can't really move sections of threads around anyway. Carry on!
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Post by oscarthesquirrel » Sat Jun 01, 2019 9:21 am

Update..

All sorted...the new 311 ICs did the job. I must have picked up a bad batch (ie fakes)...let that be a lesson for anyone thinking of buying from eBay if they can't find the chips on Tayda, Mouser or Farnell.
"You can never have too many LFO's..."

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elmegil
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Post by elmegil » Sat Jun 01, 2019 1:38 pm

I buy nothing on ebay any more unless I can find absolutely no other source, and if it's something that ought to be expensive, not even then.

311's are not expensive, but like original SSM/CEM chips and such, would not touch ebay for the world. Not to mention a lot of those are getting re-manufactured again....

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Post by oscarthesquirrel » Sun Jun 02, 2019 9:58 pm

elmegil wrote:I buy nothing on ebay any more unless I can find absolutely no other source, and if it's something that ought to be expensive, not even then.

311's are not expensive, but like original SSM/CEM chips and such, would not touch ebay for the world. Not to mention a lot of those are getting re-manufactured again....
I agree 100%.... I'd only ventured to Ebay because Farnell didn't have any stock locally, nor did Tayda and Mouser wanted to charge me a gazillion dollars to chip 3 chips to Malaysia ....anyway lesson learned. :ripbanana:
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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by ashley27 » Mon Apr 27, 2020 11:19 am

Hi.

I'm wiring up my Living VCOs but am confused as to why I have two 1V/Oct inputs on the Driver PCB. Also what is the Driver Output for?

Has anybody come across a high pitched buzz from output of triangle and sine waves after connecting the sine wave out via the driver board?

Thanks

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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by ashley27 » Tue Apr 28, 2020 5:17 am

Has anybody noticed the above? My triangle wave is fine with the driver turned off but has a slight high pitched noise that you can see taking a nick out of the top of the waveform with the driver on. It’s also there on the sine wave. I’ve only wired up one Osc to the driver so far so will see if problem is consistent with the other two oscillators

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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by SyndieBot2000XL » Tue Apr 28, 2020 12:55 pm

I’ve never hooked mine up to a scope, seeing an intermittent spike down into the top of the wave. Only on the sine and tri. Turning the driver off makes no difference for me.

But it’s not audible noise - I *do* get crazy amounts of noise from this thing if I power it from my AI Synthesis PSU (based on the MFOS wall-wart power supply). Other PSUs are fine for me.
It began as a mistake.

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Re: J.Haible's Living VCO for Eurorack [Build Thread]

Post by sduck » Tue Apr 28, 2020 1:37 pm

Ashley27 - it might help if you tell us which version of Living VCOs you have. There are several flavors of these. This is the build thread for the barcode version, but that fact gets confused quite often.
Last edited by sduck on Thu Apr 30, 2020 10:18 am, edited 1 time in total.
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