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

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

Post by logicgate » Tue Jul 08, 2014 2:45 pm

Yesterday, after 3 months after ordering, I've finally received the PCBs. As I promised, here is the build thread. Very simple, nothing fancy.


Start with the SMD capacitors cause it would be almost impossible later so, don't forget! A good technique is to put some solder in one of the pads first, only a tiny bit so you can fix the capacitor using tweezers. Then, solder the other side and add a bit more to the other (side).

Image


Then you can move to the diodes, resistors, beads and IC sockets (if using them). You can see that I forgot to solder one diode :lol: . IT's VERY IMPORTANT to leave the TEMPCO resistor for last, after you finished everything!!!

Image



After that, you can pretty much solder all the rest, besides the pots. I would start with the small capacitors, then the trimmers/pin headers for power and panel wiring/ big caps. You can see I used two film caps for C7 and C8, but you can also use Non-Polar Elecs. Actually, the original BOM of the Saw/Tri converter calls for them. I tested with both and I couldn't perceive any difference.

Image



Now it's time for a good wash, I always clean the solder side with isoprop alcohol or acetone, and afterwards scrub with warm water and detergent, then we get a nice, clean and shiny solder side like in the pic below. It's a very good time now to pick up a magnifying glass and check for cold solder joints or shorts.

Image



For the panel wiring, I like to use pin headers and those 24AWG dupont cables you can find on ebay for cheap, it's easier to disassemble if needed:

Image



The wiring and calibration are pretty much self-explanatory, just wire all grounds together and the signals outs and ins from the PCB to jack signal tips. If you want you can wire the FM/PWM input as a passive attenuators.


The calibration can be found here:

http://www.jhaible.com/living_vcos/jh_living_vcos.html


The v/oct trimming is done by ear, everything actually is down to taste, besides the pulse width:

"Pulse width adjust. With the front panel Pulse Width knob in 12 o'clock position, adjust the trimmer for 50% pulse width."


Also, attached to this post is the BOM made by Barcode which is very good. And of course, feel free to post here your build pics too!!! Would be awesome. I still have to wire mine and build a couple more so I can post some videos or soundcloud tracks.


I hope you all enjoy it! :nana:
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Last edited by logicgate on Tue Jul 08, 2014 2:47 pm, edited 1 time in total.

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Post by Randy » Tue Jul 08, 2014 2:47 pm

Fantastic, thanks logicgate! I'm looking forward to starting this one.

Randy

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Post by logicgate » Tue Jul 08, 2014 3:13 pm

Randy wrote:Fantastic, thanks logicgate! I'm looking forward to starting this one.

Randy

You're welcome!


I would recommend going slowly with the build. It's very dense/crowded so it's easier to make a solder bridge by mistake.

Diptrace component's footprints are misleading if you never used it before! Only after receiving the PCBs I can see how close the transistor pads are! Very close, be extra careful and soldering the transistors.

The resistors are very close together too, but it was necessary to make the PCB fit the cheaper size option. Anyways, as you can see, that wasn't a problem.

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Post by Maco » Tue Jul 08, 2014 7:41 pm

:yay:

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Post by logicgate » Sat Aug 23, 2014 10:33 am

Finally got some time this morning to drill my panels, I hope that tonight I'll have them wired and running!

Just wanted to show you guys how I'm making my standalone LVCOs:

Image

Image


I only soldered the detune pot and used it to fix the PCB to panel.

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Post by Skaput » Sat Aug 23, 2014 10:54 am

Awesome stuff Logicgate, love the Pittsburgh look :sb:

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Post by mush » Sat Aug 23, 2014 11:05 am

About the transistors when the pads are tight. Always start with the middle leg, then you can put the solder iron on the outside of the other legs to minimize the risk of solder-bridges.

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Post by diablojoy » Sat Aug 23, 2014 10:00 pm

IT's VERY IMPORTANT to leave the TEMPCO resistor for last, after you finished everything!!!
Hmm my preferred method on tempco's is to mount them under the chip
just cut 2 lengths of SIL pins and instal a standard DIL socket in them to get the spacing right then solder the SIL pins in and remove the socket. Tempco runs between the SIL pins as drawn on silk screen and is soldered in so that the top of it sits in line with the top of the SIL pins
this way it sits below the chip itself once the chip is installed hard up against the bottom of the chip.

couple of benefits to this
the tempco is kept closer to the temperature of the chip as it's less affected by droughts and replacing the chip itself if necessary is easier as there is nothing to desolder .
if you look at logicgate's 'picture it should look similar to how he has done all of his 8 pin DIL packages , must have been out of 8 pin DIL sockets I guess
It probably wont happen today but if it does it definitely wont go smoothly.

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Post by logicgate » Sun Aug 24, 2014 7:56 am

diablojoy wrote:
IT's VERY IMPORTANT to leave the TEMPCO resistor for last, after you finished everything!!!
Hmm my preferred method on tempco's is to mount them under the chip
just cut 2 lengths of SIL pins and instal a standard DIL socket in them to get the spacing right then solder the SIL pins in and remove the socket. Tempco runs between the SIL pins as drawn on silk screen and is soldered in so that the top of it sits in line with the top of the SIL pins
this way it sits below the chip itself once the chip is installed hard up against the bottom of the chip.

couple of benefits to this
the tempco is kept closer to the temperature of the chip as it's less affected by droughts and replacing the chip itself if necessary is easier as there is nothing to desolder .
if you look at logicgate's 'picture it should look similar to how he has done all of his 8 pin DIL packages , must have been out of 8 pin DIL sockets I guess

Interesting method, never thought of that. Haha and yes, I'm out of 8 pin sockets, but I got loads of socket strips.

Actually there's no need to desolder anything, you just need to slide the tempco resistor to one side and replace the IC and slide back on top of it again, I had done it before. You just need to solder it "not tight" against the IC, leave some room so you can press it down. Do you apply thermal paste under the IC?

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Post by logicgate » Sun Aug 24, 2014 9:00 am

@skaput

Haha thanks!! Ghetto pittsburgh look :lol:


@mush

Good technique! It's also good to spread the outer legs.

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Post by diablojoy » Mon Aug 25, 2014 3:58 am

Do you apply thermal paste under the IC?
No I stopped using it a while ago ,most are conductive and they tend to creep over time which can cause really difficult to trace faults. I just try to make sure there is some physical contact .
Having the SIL pins surrounding the tempco pretty much keeps the chip and tempco at the same ambient temperature better which is really all you want.
It probably wont happen today but if it does it definitely wont go smoothly.

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Post by raisinbag » Tue Aug 26, 2014 12:52 am

looks great! BOM is totally painless. Will the Anekom tempcos work in this bad boy?

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Post by logicgate » Tue Aug 26, 2014 6:30 am

@raisingbag

Yep they will work just fine :party:

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Post by logicgate » Fri Aug 29, 2014 12:33 pm

Finally all wired up and calibrated!

Gonna try to record something and post here!


Image

Image

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Post by raisinbag » Fri Aug 29, 2014 12:48 pm

Looks great me big knob! I'm so excited to build mine.

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Post by sduck » Fri Aug 29, 2014 3:47 pm

It looks like we have 2 threads that are build threads for these - why don't we consolidate? repost anything that's recently been posted here into the other thread, and I'll lock up this one (or vice versa - you tell me).
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Post by logicgate » Fri Aug 29, 2014 4:12 pm

sduck wrote:It looks like we have 2 threads that are build threads for these - why don't we consolidate? repost anything that's recently been posted here into the other thread, and I'll lock up this one (or vice versa - you tell me).

Good Idea.

I just think that the other thread has so many pages and people can get lost and don't find what they are looking for.

Anyways, I don't think it's up to me to decide, maybe more people could chime in.

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Post by sammy123 » Fri Aug 29, 2014 4:15 pm

As long as the other is still available I am fine with closing it to new posts.

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Post by sammy123 » Fri Aug 29, 2014 6:06 pm

So I have a bit of a problem. I have no 22uf electros for c9 and c10 of the vco boards. Can I use a 47uf or 33uf? Thanks.

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Post by sduck » Fri Aug 29, 2014 7:25 pm

Ok, a little later I'll lock up the old one and provide a pointer to this one - unless anyone has objections. One of them should be shut, having two threads going with build information is bad form. Personally I'd choose closing this one, as there's very little in it, but whatever.

Or I could just leave them both open, and you guys could try to direct build queries here, and board sourcing and such questions to the other thread. After all, there are numerous TTSH threads, which works fine as long as they have different content. Whatever...
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Post by logicgate » Fri Aug 29, 2014 7:55 pm

sammy123 wrote:So I have a bit of a problem. I have no 22uf electros for c9 and c10 of the vco boards. Can I use a 47uf or 33uf? Thanks.

You can use anything between 22uf and 100uf, it's just power filtering.



@sduck

That sounds like a good plan :hihi:

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Post by sammy123 » Fri Aug 29, 2014 9:09 pm

thanks logicgate

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Post by sammy123 » Sat Aug 30, 2014 9:46 am

So I have this up and running and have a couple questions.

-My detune pot seems backwards as well on all 3 VCOs. It is indeed very subtle.

-The triangle seems to be affected by the PWM cv. Does anyone else have this issue?

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Post by logicgate » Sat Aug 30, 2014 10:51 am

sammy123 wrote:So I have this up and running and have a couple questions.

-My detune pot seems backwards as well on all 3 VCOs. It is indeed very subtle.

-The triangle seems to be affected by the PWM cv. Does anyone else have this issue?

Hi sammy,

If your boards are the barcode edition then you have to apply the fix for the detune pots. From what I gather it's indeed subtle, it's not intended to work as a "fine tune" feature, but only to, well, detune them a little bit for some pleasant frequency beating (some lush "phasiness" by the way).



I have just tested here and the triangle and saw are not affected by PWM cv nor PW pot, you must have a solder bridge somewhere. I checked the schematics and there's no interation between the two circuits, the only thing that goes to the SAW to TRI circuit is a copy of the SAW signal.

Look around these components, they are the SAW to TRI circuit:

R52, R53, C7, TL074, R54, R55, R56, D5, D6, R57, R58, C8, R59, R60


Good luck, and if you have any questions just ask! :guinness:

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Post by sammy123 » Sat Aug 30, 2014 11:04 am

I knew there was a coarse tune fix for the driver, but I dont recall seeing any detune fix for the cores. I'll do some more research.

The PWM just bends the tops of my triangles. It affects all 3 VCOs so I would thinks its more than a solder bridge. ..but of course I'll check to be safe.

Thanks logicgate.

In other news. I only had 2k tempcos so I just socketed some standard resistors and it has been pretty stable. Also for those doing a setup similar to the Barcode panel, buy side adjust trimmers for scale and offset...it will make life a bit easier...especially if you try and tune it while panelled. Thedriver is pretty much impossible to tune while panelled. I really wish tayda sold the side adjust. Otherwise tuning was easy...but I've done it a bunch before.

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