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

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Grumskiz
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Post by Grumskiz » Fri Jan 29, 2016 6:16 pm

I suggest you measure the current draw yourself, because this way you can rule out any faults in your LVCOs. At least one may have developed a fault or short somewhere.

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medbot
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Post by medbot » Fri Jan 29, 2016 6:21 pm

Well each LVCO is like four modules in one, so if you think about it like that maybe it's not such a stretch.

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Post by Jop » Sat Jan 30, 2016 2:55 am

I did measure the current and got below results, quite a load per panel (3x vco & driver):

Image

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qfactor
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Post by qfactor » Sun Jun 26, 2016 11:39 am

Jop wrote:I did measure the current and got below results, quite a load per panel (3x vco & driver):

Image
Thanks for the measurement, Jop! :guinness:

Another question:
When I mix 3 of the Saw waves for a 3 Osc sound, I seem to get cancellation of the waves that makes me think they are out of phase with one another?
Do any of your LVCOs have this issue?
This is not the Random Source version, btw.

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Post by sduck » Sun Jun 26, 2016 3:26 pm

I don't get that with my r*s version, either with an external mixer or the on board one. What version are you using? (edit: doh :drunkhomer: didn't see which thread this was, never mind)
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qfactor
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Post by qfactor » Sun Jun 26, 2016 7:29 pm

sduck wrote:I don't get that with my r*s version, either with an external mixer or the on board one. What version are you using? (edit: doh :drunkhomer: didn't see which thread this was, never mind)
As mentioned, mine is not the r*s version but LogicGate's pcb.
I'm trying to identify if this is the case for those who built this version, or I messed up in my (possibly) inverting/non-inverting op amp part of the schems :doh:

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Post by cleaninglady » Mon Jun 27, 2016 12:50 am

I still haven't finished my build, i've had the finished PCB's sitting in my backlog for two years. If i can get onto it soon i'll let you know what i can see.

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Post by qfactor » Mon Jun 27, 2016 1:09 am

cleaninglady wrote:I still haven't finished my build, i've had the finished PCB's sitting in my backlog for two years. If i can get onto it soon i'll let you know what i can see.
Haha! And I thought my completing two of these over a 1.5year period is long as it is! :hihi:
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Post by nigel » Mon Jun 27, 2016 1:55 am

qfactor wrote: When I mix 3 of the Saw waves for a 3 Osc sound, I seem to get cancellation of the waves that makes me think they are out of phase with one another?
I built an older version, and the Saw was from 0V to 10V instead of -5V to +5V. When you mix them together they will very quickly clip against the positive power rail, which can sound like phase cancellation. Not sure if that is the problem here, but it seems possible.

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Post by qfactor » Mon Jun 27, 2016 4:02 am

nigel wrote:
qfactor wrote: When I mix 3 of the Saw waves for a 3 Osc sound, I seem to get cancellation of the waves that makes me think they are out of phase with one another?
I built an older version, and the Saw was from 0V to 10V instead of -5V to +5V. When you mix them together they will very quickly clip against the positive power rail, which can sound like phase cancellation. Not sure if that is the problem here, but it seems possible.
Hmm... That might be possible!
Looks like I've got to take it out of the case (been trying to avoid that!) and hook it up to an Oscilloscope to check this. :tu:
Thanks!

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Post by glennfin » Tue Sep 27, 2016 6:20 am

Is there a build thread for the Random source Eurorack version?

.... If there is, I can't seem to find it...

I'm trying to locate a part number and a U.S. source for the tempco resistors required for the R*S pcb...
Last edited by glennfin on Tue Sep 27, 2016 8:44 am, edited 4 times in total.

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Post by Dogma » Tue Sep 27, 2016 8:38 am

leterell wrote:https://www.mouser.de/ProjectManager/Pr ... c63ef68f45

EDIT: so please omit the resistors here, since they are too big.

i will order the ones kindly suggested earlier by gbiz, LR0204F from TE connectivity. from farnell, mouser has a kind minimum quantity of 4000.

for me this will not include the ones over 1Mohm, and the 0.1% ones, these i will just cram on there somehow :guinness:
Is this for the Rs living vco?
look up!

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Post by Synthbuilder » Tue Sep 27, 2016 8:53 am

glennfin wrote:Is there a build thread for the Random source Eurorack version?
This one:

viewtopic.php?p=2071084
I'm trying to locate a part number and a U.S. source for the tempco resistors required for the R*S pcb...
Find them at Mouser, their part number is:

279-LT300014T261K0J

This is the small 3000ppm/K one. You get slightly better compensation by using the KRL 1K 3500ppm/K but these are much bigger and their leads don't go through the holes in the PCB.

Tony

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Post by glennfin » Tue Sep 27, 2016 9:32 am

Thank you Tony.

Quite the amount of components to source on this project. :mrgreen:
Synthbuilder wrote:
glennfin wrote:Is there a build thread for the Random source Eurorack version?
This one:

viewtopic.php?p=2071084
I'm trying to locate a part number and a U.S. source for the tempco resistors required for the R*S pcb...
Find them at Mouser, their part number is:

279-LT300014T261K0J

This is the small 3000ppm/K one. You get slightly better compensation by using the KRL 1K 3500ppm/K but these are much bigger and their leads don't go through the holes in the PCB.

Tony

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Post by Starspawn » Tue Sep 27, 2016 10:33 am

Do you still need the tempcos if you opted for the supermatched smd transistor pair? They wont be in thermal contact anymore for one ...

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Post by sduck » Tue Sep 27, 2016 10:38 am

Yes, you need them still. And they still can be in contact. The smaller variety of tempcos are easier to use in this application.

Edit: I didn't notice which LVCO thread this was - so my answer may not be correct. In general though, if a tempco is needed, you at least need some kind of resistor in that spot for it to work.
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Silver
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Post by Silver » Fri Dec 23, 2016 9:03 am

Does anyone still have any panels available for the Barcode edition? I got the pcbs, but I'm hesitant to build until I know I can get a panel (without making it myself. Preference would be for lower hp, but at this point, any would be good. Please pm me if you have one to sell. Thanks

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just finished mine

Post by nd595 » Mon Jan 02, 2017 12:12 pm

Just finished mine - it took some time as I had a very busy period.
I made all possible mistakes - applied a wrong polarity to driver board AND to one of VCO's - nothing serious, just had to replace all chips and electrolytic caps; strangely, all transistors are fine.
Tracking is as perfect as it can be - excellent over 7 octaves. Mutable Module Tester is a great tool, as it saved me lots of time.
The only thing left is that spike on triangle and sine converters; even Robert Moog himself had that problem with his triangle converter and he sorted it with an extra capacitor. Will have to deal with that, otherwise - this is a great module, not easy to assemble, but it was enormous pleasure.
Million Thanks to logicgate - hooray!!!

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pix
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Post by pix » Sat Feb 18, 2017 7:44 pm

I have a problem with my vibrato circuit. When increasing the amount nothing happens until a point where pitch goes super low.

Vibrato rate has no effect.

any hints on where I should start looking for problems?

thanks!!

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pix
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Post by pix » Wed Feb 22, 2017 1:12 pm

:help:

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elmegil
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Post by elmegil » Wed Feb 22, 2017 1:19 pm

I don't have the Euro schematics handy, so I don't have proper reference values.

In the original JH schematics, page 4 of the schematics for the driver board shows that the vibrato is coming off of an LFO circuit made up of U14A and U14B. The rate is part of that circuit.

Then there is an LM13600 (or LM13700) OTA that's used for the depth to operate as a VCA on the output of the LFO.

So

1) verify the LFO is oscillating, measure the output of whatever the equivalent is of U14B.

2) if it is oscillating, verify that your OTA is functional (maybe just swap the chip if you have spares).

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Post by shiftr » Thu Mar 22, 2018 6:34 pm

After almost 3 years I'm nearly finishing my barcode edition living vco s
I also have a problem with the vibrato on the driver. It does seem to do something but it's very weird and subtle. I'm not sure if I'm expecting something different or if it doesn't work correctly.

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sduck
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Post by sduck » Thu Mar 22, 2018 10:30 pm

There's a different thread for that version - try either this one

viewtopic.php?t=93892

or this one

viewtopic.php?p=1704049
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Post by shiftr » Fri Mar 23, 2018 3:07 am

Thanks.. But I've searched those threads and they point back to this thread ;)

There also seem to be a lot of pictures of similar PCB's of mine in this thread.
I guess I'm already lucky having a pretty good working vco. I'll have a look if I can fix the vibrato or maybe leave it like this. This is a project I'd really like to finish. Maybe I'll just use the module "as is" .

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sduck
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Post by sduck » Fri Mar 23, 2018 11:31 am

Oh nuts I misread the thread title. Yes, this is the place for your version. Woops, and sorry.

I've only built the random*source version, but it should be similar circuitry. And I seem to recall there was a resistor that needed to be tweaked to get a decent amount of depth from the vibrato - but I'm not sure which one it was, sorry. Maybe that'll point you in the right direction at least...
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