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 Forum index » DIY Hardware and Software » Ken Stone designs - CGS
The CGS114 DUSG
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Mon Nov 21, 2011 6:32 pm    Post subject: The CGS114 DUSG
Subject description: Report on my first build
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Well, I finally got my first DUSG module built, and wanted to share a little bit of what I learned in the process.

First off, I have to say this is an amazing module. It's hard to even list all of the different things I've done with it. It seems that the only limit is your imagination.

Here's an example I did tonight - I ran my keyboard's CV into the 'IN' connection on both halves of the module. I turned up the RISE pot on one, and the FALL pot on the other. Then I ran the OUTPUT of the first to one VCO, and the OUTPUT of the other half to a second VCO. The VCO's were tuned a fifth apart. What this did is caused one VCO to glide in the upward direction, the other to glide in the downward direction. The overall effect of this was really complex and pleasant.

Then I removed the slew stuff, and took the output of one of my VCOs and ran it into one of DUSG TRIGGER inputs. I took the OUTPUT of that module into the mixer. If I minimized the RISE and FALL pots, it made the module track the VCO. Then I started increasing the RISE or FALL time - the result was a suboctave. If you keep going you can generate lower suboctaves, but you can get alias frequencies at some point. The more you increase the RISE or FALL, the worse that problem becomes.

I set both of my DUSG halves into oscillate mode (I have a switch that shorts the TRIG input to the END output). I took the OUTPUT of the first unit into the VC of the second. The OUTPUT of the second unit was fed into the VCA. That allowed me do all sorts of the FM and drone stuff.

Of course I could also do easy things like use the module as two transient envelope generators and so on. You name it, you can probably do it.

Now with all of that goodness, there are a few downsides.

1) The documentation is a little weird. Most of this comes from the fact that the original Serge version used transistors which aren't readily available. You can substitute more common parts - I used 2n3906 and 2n3904. Basically if you do this, the key is that you just have to look at the silk screen, and insert each transistor backwards. Similarly you can use different op-amps than the ones specified. Ken says to use TL072s, and I intended to do that, but when I looked through my parts cache I only had TL082s. I said 'what the heck' and stuck em in. They work just fine.

2) It's a single sided board, so there are a number of wire jumpers that have go in place. I missed one of those that was stuck in between some resistors, and it cost me a couple of hours trying to find the problem that caused. The lesson here is simple. Stick in the wire jumpers before you put in any other components.

3) The power connections are not up to Ken's usual standards. There's no connector, so you just have to solder the wires to the board. Oddly, the +V and -V inputs are not located near each other, so the power wires are kind of spread out. It's no big deal, it's just a little different than normal.

4) This is fairly complex build. A lot of components, and a lot of connections to the panel. That's not a problem, but it's just something to be aware of. Allow yourself some time to get this one done.

Almost everything is working properly but there are a few things still up in the air.

A) Although I can get the units to act as VCOs, I could not get them to do 1V/Oct. It's close to right, but I haven't been able to get enough 'span' if that's what you want to call it. It's not clear what the problem is there, but I'll keep poking around until I figure it out.

B) I don't understand is precisely what the single trimmer pot is supposed to exactly, and how you set it. I haven't paid too much attention to it yet, so the answer may be forthcoming.

C) Finally I had some issues when trying to make the module do Log Response. I have a switch that feeds the OUTPUT back into the INPUT, which is supposed to create a log response, but I've observed that doing this will sometimes cause the unit to lock up. I haven't tried to troubleshoot that yet.

D) The VC pot is hard to zero out. There are some ways to get around that, but I'll have to figure out the best approach.

All in all I'm really impressed with this unit. Serge is a freakin' genius, and Ken has done a fine job creating this board. Due to some weird things that happened with the airmail service, I ended up with 4 of these on hand. I'll probably build a second one, and keep the other two around just in case.

Hope that helps someone out there
Gary
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iopop3



Joined: May 28, 2010
Posts: 95
Location: Malmö, Sweden

PostPosted: Wed Nov 23, 2011 12:23 am    Post subject: Reply with quote  Mark this post and the followings unread

Great write up, always nice to see someone summarize their experiences. I assembled mine some week ago, really strange module, think Ive just scratched the surface on whats possible to do with it.

Regarding the 1v/oct, I think Ken mentioned somewhere that he called it EXP on the VCS instead - since it wasnt really 1v/oct.
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zthee



Joined: Feb 20, 2008
Posts: 413
Location: Stockholm

PostPosted: Wed Nov 23, 2011 6:31 am    Post subject: Re: The CGS114 DUSG
Subject description: Report on my first build
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Mongo1 wrote:
A) Although I can get the units to act as VCOs, I could not get them to do 1V/Oct. It's close to right, but I haven't been able to get enough 'span' if that's what you want to call it. It's not clear what the problem is there, but I'll keep poking around until I figure it out.


Make sure you haven't messed up the pads. "Please note that prior to September 25, 2011, this documentation had connections "C" and "E" swapped on the wiring diagrams. If you used the former diagram as a wiring guide, I would suggest you check your wiring again. These connections are in reverse to those used on boards produced by Serge. "

As it says on the CGS site.

Mongo1 wrote:
B) I don't understand is precisely what the single trimmer pot is supposed to exactly, and how you set it. I haven't paid too much attention to it yet, so the answer may be forthcoming.


Set the module to cycle at approx 100Hz. Turn the trim pot until the output is 0-5V.

Mongo1 wrote:
C) Finally I had some issues when trying to make the module do Log Response. I have a switch that feeds the OUTPUT back into the INPUT, which is supposed to create a log response, but I've observed that doing this will sometimes cause the unit to lock up. I haven't tried to troubleshoot that yet.


I think you're supposed to feed the OUTPUT to the CV input to get a exponential response. But I could be wrong.

It will lock up from time to time, so that is normal. Feed it too much and it chokes.

Mongo1 wrote:
I ended up with 4 of these on hand. I'll probably build a second one, and keep the other two around just in case.


I think I've built 10-15 of these. And I keep building more of them. For me it is the best module ever!

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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Wed Nov 23, 2011 7:40 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the replies - I was beginning to think I was the only guy to build one of these. Razz

Regarding the 1V/Oct thing, the way it is right now it's pretty close - maybe 1 semitone off over the space of an octave. My thinking right now is that the little voltage divider on the 'E' pin may be the problem. I may try to put a trimmer in and see if I can alter the tuning a little bit.

Quote:
I think you're supposed to feed the OUTPUT to the CV input to get a exponential response. But I could be wrong.

AH! That's right - looks like I have a little rewiring to do tonight....



Last night I spent a little time using this module as what one might call a 'Frequency follower' - I took my VCO and piped it into the TRIGGER pin, and then ran the 2nd unit's OUTPUT into the VC pin. I set the RISE and FALL pots to near minimum so the frequency tracked the main oscillator. I set the 2nd unit up as a fairly low rate envelope generator, and triggered it from the keyboard trigger. I mixed the OUTPUT of the first module in with my VCO's output. The result was quite interesting. You can hear the main tone, and then the frequency follower does this sweep effect from a very low octave up through to the main tone, stepping at the octaves along the way. By changing the amount of VC modification, I was able to do some sounds very reminiscent of a brass section this way. I think I drove my wife crazy with it.

Quote:
I think I've built 10-15 of these. And I keep building more of them. For me it is the best module ever!


Wow! What the heck do you do with them all? Seriously, I'd love to hear some of your patch ideas. There are so many options with this thing.

I think the thing that I find most interesting about this module is that it seems to be the very embodiment of the West Coast philosophy. This isn't a module that stands there and says "I'm a VCO. I do VCO stuff". Instead it looks up at you and say "Uh....what would you like me to be Dude? - cuz I'll try to be that". It's a little like that great quote from Bruce Lee

Don't get set into one form, adapt it and build your own, and let it grow, be like water. Empty your mind, be formless, shapeless — like water. Now you put water in a cup, it becomes the cup; You put water into a bottle it becomes the bottle; You put it in a teapot it becomes the teapot. Now water can flow or it can crash. Be water, my friend.

I think this may be the Bruce Lee module.

Gary
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Wed Nov 23, 2011 1:50 pm    Post subject: Reply with quote  Mark this post and the followings unread

Regarding the 1V/Oct tuning, Stephen Richards pointed me to a thread on the muffwiggler forum that addresses the problem:

http://www.muffwiggler.com/forum/post-495151.html&highlight=#495151

The short answer is replace the 1k8 with a 1K fixed resistor and a 2k trimmer.

I'll give that try ASAP.
Thanks

Gary
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macumbista



Joined: Sep 12, 2007
Posts: 363
Location: berlin
Audio files: 3

PostPosted: Tue Feb 28, 2012 7:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hey folks,

I'm having a horrid time trying to get this to work. Can't get either section to trigger, only the signal input seems to have any affect. The CV inputs also behave erratically. Grounding the EXP CV in stops the circuit from working, for example.

I'm using a slightly modified wiring setup documented here, but I have triple-checked it and it seems solid.

I have also double-checked the transistors with the multimeter for proper pin-out. I am using 2N3904/3906 transistors and they have been reversed in relation to the package drawn on the PCB. I have also checked polarity of all diodes on the board and replaced transistors a couple times.

The problem seems to be around either the End Out of the Trig In sections. I do not have an oscilloscope around, but I would be happy to give folks any other info they need to help me get this working.

Thanks!

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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Wed Feb 29, 2012 11:05 am    Post subject: Reply with quote  Mark this post and the followings unread

I'm not sure how to help you on this one.
Let me see I can figure out any intelligent questions, and I'll get back to you...
Gary
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Mongo1



Joined: Aug 11, 2011
Posts: 411
Location: Raleigh NC

PostPosted: Sun May 20, 2012 3:09 pm    Post subject: Reply with quote  Mark this post and the followings unread

Well. I've built my second card, and it's been a complete disaster. Another one of these boards where I spend all day looking for broken traces. I'm really getting weary of this.

While I was in the middle of this, my friend Vince asked me to troubleshoot a VCS board he's having problems with. It's the same sort of symptoms.

I really like this designs, but the single-sided boards are terrible. I'm so tired of not being able to trust whether a trace actually gets to where it's supposed to go. On Vince's card, I found a place where a transistor had been push down a little somehow. That was enough to break the trace on the collector.

Sheesh.How much does it cost to add plated-through holes to a design?


Gary
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macumbista



Joined: Sep 12, 2007
Posts: 363
Location: berlin
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PostPosted: Sun May 20, 2012 3:26 pm    Post subject: Reply with quote  Mark this post and the followings unread

I wrote Ken about this issue on some other boards. He told me that the easy-to-break traces have something to do with being ROHS compliant. No foolin' Wink I'm not sure if they need to be double-sided, but plated holes or something to stabilize the traces would be hugely beneficial, as I've also had to re-do traces with jumper wire almost every time I remove or replace a part...
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Dhamaryder



Joined: Jan 21, 2011
Posts: 14
Location: Cincinnati

PostPosted: Wed Jun 25, 2014 6:18 pm    Post subject: DUSG Reply with quote  Mark this post and the followings unread

I just built my second one of these and I also had broken traces on both
boards. I was super careful in building this last one. The top half worked but I just couldn't figure out what was wrong with the bottom half. I was super careful putting this one together and double and triple checked every connection and every part but I still had to have someone look at it for me and he found the broken traces. That is pretty frustrating. But I do really like this module. I appreciate the previous poster giving details about how they use it. That was great. I can't wait to try some of them.

steve
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G2Psy



Joined: Feb 06, 2009
Posts: 58
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PostPosted: Wed Oct 01, 2014 4:18 pm    Post subject: Reply with quote  Mark this post and the followings unread

The problems with the PCBs worry me. They aren't cheap at $30 US. They are sold from Australia but are bought in US dollars, as an Australian that's like an extra tax in currency. And now people report that the holes are not plated through and have trace problems.

Are these boards good quality? Or are there alternative DIY boards for a DUSG design?

I have always loved the possibilities of the slope generator design but I'm still hesitating on building some.

B
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