J.Haible's Living VCO for Eurorack

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raisinbag
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Post by raisinbag » Tue Oct 01, 2013 6:49 pm

Crap that's what I thought (was just doing some reading back through the thread). I hadn't noticed that it switched from 3046 to 8pinerz. I have like a billion 3046 but none of the other stuff and they are hard to find and big $. What was someone talking about matching 3904's? Can we do that instead of ls318?

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logicgate
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Post by logicgate » Tue Oct 01, 2013 7:44 pm

Your best choice is a hand matched 2N3904 pair, that's what I'm gonna use ;)


There's a very simple transistor matching circuit you can lay in a little piece of veroboard:

http://www.dragonflyalley.com/construct ... tching.htm

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raisinbag
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Post by raisinbag » Tue Oct 01, 2013 8:37 pm

How (and by how I mean where do you place matched pair) do you use the matches pain instead? Are the two tranny pads for a matched pair instead? If so do somehow get the tempco to be in contact with them?

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Post by wavehead » Tue Oct 01, 2013 8:51 pm

any vague idea on a time frame when you will be doing a run of these? assuming you are close to a final layout and will order tests soon thereafter?

having both PWM attenuator and PW offset isn't just kinda imo what every VCO needs, but the "over-modulation" of the PMW is something JH made a pretty big part of the LVCO sound.
Like the Yamaha CS-80, the Living VCOs have a limited pulse width. Even with strong pulse width modulation, you never "loose" the VCO signal, because you never get down to 0% or up to 100% pulse width. What may sound like a limitation at first, actually opens the possiblitity of "overmodulation": You can modulate the pulse width with a triangle LFO of rather slow rate, and with a depth that would normally be bigger that 100% modulation index. As a result, the modulation is clipped, becomes trapeuoid-shaped. Musically, this is like a periodic "push" of the modulated oscillator's pitch - something that sounds less detuned than ordinary PWM and allows a sonically very rich modulation.
i do think it would be ideal if not only the VCO driver PCB was included, but a panel-mount PCB for everything (3 VCO + driver) with something like this wiring scheme could happen.
http://www.jhaible.com/living_vcos/livi ... g_opt3.pdf

it seems like a fairly crucial part of what makes JH's design so awesome is the vibrato, portamento, octave switch (so nice to have on any VCO like this) and most of all settings for PMW on both the driver and the individual oscillators.

this could feasibly all happen while still making making cheap smaller boards (with the exception of a pretty big panel mount PCB) for anyone who doesn't care about all of that, but i'm happy just having this available in any form. i'm not complaining!

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Post by seanpark » Tue Oct 01, 2013 10:34 pm

raisinbag wrote:How (and by how I mean where do you place matched pair) do you use the matches pain instead? Are the two tranny pads for a matched pair instead? If so do somehow get the tempco to be in contact with them?
Generally check the pinout on LS318 datasheet and assign your matched pair's pins accordingly to the board.

Check out ray's pictorial here:
http://www.musicfromouterspace.com/anal ... Tempco.php

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Post by mxmxmx » Wed Oct 02, 2013 1:10 am

logicgate wrote:


The total height now is 100.5mm (I believe I can still get rid of the .5mm so we can reach the US$2.50 per board mark), and total width is 56mm.
nice progress here! so one of these should fit behind 14HP or so, assuming the idea is to have the jacks lined up in a single row? not sure whether one could squeeze in two rows, ie, if 12HP or less was the objective (hmmm, since smd intolerance seems to be on the wane around here ... ).

but 14HP/single row should be perfectly doable, probably not with erthenvar but kobicon or lumberg ones. (in that case, any chance to arrange the headers in a more systematic fashion? something like : v/oct; fm; pwm; pulse; saw; tri (but i guess there's a reason to that)).


@wavehead - as to that driver board, i'm sure someone could/will whip up a board in no time. but if i'm not mistaken, except the op amp stage, which logicgate included, that's just a little CV processor that's got nothing to to with the sound of things really. keeping it out of the equation i think is a good thing, financially, logistically and psychologically speaking (i, at least, would loath building up such a huge thing and it would probably just rot away in some drawer ... anti-living memory)

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logicgate
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Post by logicgate » Wed Oct 02, 2013 5:03 am

@mxmxmx

Given 1HP is 5.08mm, 14HP = 71.12mm :woah:


The PCB has 56mm of width = 11HP, I guess the panel must have 12HP


I guess one can have single or double row of jacks.


I would go with double.

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logicgate
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Post by logicgate » Wed Oct 02, 2013 7:58 am

@wavehead

I believe this weekend I'll be able to etch the proto and test if everything is working as it should.

If yes, then it's just a matter of arranging the manufacturing.


I think that it would be a lot easier if all the people interested could order their own boards. It will be cheaper this way.

There's no reason why I would order a ton of PCB's to Brazil, only to re-send them around the world, not to mention that the customs here is a mess, and things get stuck there for a month, at least.


It's very easy to place an order at Iteadstudio, you just have to choose the board size you want and send them the files.


I'm glad to answer any questions.

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wavehead
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Post by wavehead » Wed Oct 02, 2013 8:15 am

re: driver board - this isn't really essential at all compared to just having a simple PW offset along with the PWM attenuator IMO.

i'm sure there could easily be a group-buy/order setup out of the US or euro, but maybe this should just be something people can order for themselves.

regardless - i just want some living oscillators. a lot of them.

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raisinbag
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Post by raisinbag » Wed Oct 02, 2013 8:35 am

Haha that's an interesting idea. I have never ordered pcbs myself so if you hold my hand, id go for it.

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Post by sduck » Wed Oct 02, 2013 9:04 am

Way back in the beginning of the random looping sequencer thread there's an example of crowd-sourcing the group buys - the guy just released the files, and gave relatively easy instructions on how to order from itead. Then various people (including myself) had their own nation specific group buys - it was quite successful, and low burden for the original designer.
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Post by Kunfuz » Wed Oct 02, 2013 9:09 am

OSHpark is also a good alternative if you just wanna order a few boards :ghost:
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Post by mxmxmx » Wed Oct 02, 2013 9:23 am

logicgate wrote:@mxmxmx

Given 1HP is 5.08mm, 14HP = 71.12mm :woah:


The PCB has 56mm of width = 11HP, I guess the panel must have 12HP


I guess one can have single or double row of jacks.


I would go with double.
true, preferably 12HP. i have a few of those 100mm boards from itead, and fitting one row of erthenvar jack below or above the board is no problem obviously, not sure about 2 though. but something will work out. i'd prefer double, too. worst case scenario i guess would be to use something like a lumberg KLB 4, which are just 8mm and do zig zag, like so











Image

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Post by thetwlo » Wed Oct 02, 2013 11:02 am

If we're ordering our own boards would it be too much to also offer a version using the CA3046? Sorry, no idea if that's a simple change or a bit of work.
thanks!

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Post by raisinbag » Wed Oct 02, 2013 11:11 am

Well I have been thinkin of using a 3046 as well but didn't think it makes any sense to logicgate to redo the whole thing. So I was thinking if I put a 3046 on pref board, ran appropriate pins to some header pins and put those into a socket on the main board it would work fine as long as I got the pins right.

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logicgate
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Post by logicgate » Wed Oct 02, 2013 11:37 am

@thetwlo and raisinbag

Check CA3046 to determine wich pins correspond to CBE (better check the schematics of the LVCO so you will know wich pins to connect more precisely)

Best way is to use perfboard, as you mentioned.

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Post by Isaiah » Wed Oct 02, 2013 11:48 am

Hmmm... I wonder if there's sufficient interest for a 6" x 2, 3 or 4" PCB for CGS/Serge-style builds...
I'm sure a 6" x 4" PCB would accommodate a bank of three Living VCOs and the driver circuitry.
Mounting holes 0.15" from each edge, same as CGS PCBs.

Just thinking out loud :hihi:

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Post by logicgate » Fri Oct 04, 2013 10:56 pm

Heya!

I tried to etch the PCB in it's actual state, but I think that for home fabrication I will have to make the PCB bigger, I found that the holes for the components ended up too small even for my smallest drill (0.8).


Tomorrow I'm gonna widen all holes and pads, space them out a bit more and etch again. Was a fun practice, though! Pity it's going to the trash can.

Image

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Post by Tombola » Sat Oct 05, 2013 1:30 am

@sduck That's always been my idea - And new services like OSH Park make it even easier - you can order just 3 boards.

They now have a 'shared projects' area just order like it's a shop - https://oshpark.com/shared_projects - and the quality of the boards is incredible

To do that you'd have to open source the design (as I've done with mine) - I'm not sure anyone here would have permission to do that with this particular circuit - unless we're being super legalistic about the theory that 'you can't copyright a circuit, only a particular layout'

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Post by msprigings » Sat Oct 05, 2013 6:27 am

Interested! The driver board to me is pretty awesome! And the Serge format I vastly prefer for my own selfish reasons.
Isaiah wrote:Hmmm... I wonder if there's sufficient interest for a 6" x 2, 3 or 4" PCB for CGS/Serge-style builds...
I'm sure a 6" x 4" PCB would accommodate a bank of three Living VCOs and the driver circuitry.
Mounting holes 0.15" from each edge, same as CGS PCBs.

Just thinking out loud :hihi:

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Post by raisinbag » Sat Oct 05, 2013 7:57 am

logicgate wrote:Heya!

I tried to etch the PCB in it's actual state, but I think that for home fabrication I will have to make the PCB bigger, I found that the holes for the components ended up too small even for my smallest drill (0.8).


Tomorrow I'm gonna widen all holes and pads, space them out a bit more and etch again. Was a fun practice, though! Pity it's going to the trash can.

Image
That looks great! Glad to see its comin along. DON'T THROW IT OUT, ahhhhh! If you are really gona throw it out, send it to me with my midi bud, ill hang it I my wall and frame it!!!!! So when you are a famous synth desiger, it will be like a "gold record". :hail:

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Post by yan6 » Sat Oct 05, 2013 9:27 am

Great work, looking forward to the next version.

+1 for driver board :hihi:

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logicgate
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Post by logicgate » Sat Oct 05, 2013 9:24 pm

raisinbag wrote:
That looks great! Glad to see its comin along. DON'T THROW IT OUT, ahhhhh! If you are really gona throw it out, send it to me with my midi bud, ill hang it I my wall and frame it!!!!! So when you are a famous synth desiger, it will be like a "gold record". :hail:[/quote]


Haha if you are really want it I can send it to you :lol:


Now, famous synth designer, that is a couple of light years ahead, perhaps :hihi:



Alright, new board etched, I've changed the layout so it was easier to etch and drill, we're almost there!


Image


Hand is sore of so many holes!! :waah:

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raisinbag
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Post by raisinbag » Sat Oct 05, 2013 9:45 pm

WOO HOO! THanks! Ya between you and Hex, you are like synth Crack dealers! Man, anytime you come to Canada, my drill press is open to you for free use! :sb: :sb: :sb: :sb: :sb: :sb: :sb: Looks like you got the two sides lined up really nice, good job

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logicgate
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Post by logicgate » Tue Oct 08, 2013 8:44 pm

Thx mate! A drill press would be perfect! :party:

We are halfway thru now:


Image

Image

Image


It's looking like trash!!! :lol:

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