electro-music.com   Dedicated to experimental electro-acoustic
and electronic music
 
    Front Page  |  Articles  |  Radio
 |  Media  |  Forum  |  Wiki  |  Links  |  Store
Forum with support of Syndicator RSS
 FAQFAQ   CalendarCalendar   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   LinksLinks
 RegisterRegister   ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in  Chat RoomChat Room 
Live streaming at radio.electro-music.com

  host / artist show at your time
  Antimon Antimon's Half Year Report
Please visit the chat
 Forum index » DIY Hardware and Software » Ken Stone designs - CGS
The CGS VCO
Post new topic   Reply to topic Moderators: Scott Stites
Page 2 of 4 [81 Posts]
View unread posts
View new posts in the last week
Mark the topic unread :: View previous topic :: View next topic
Goto page: Previous 1, 2, 3, 4 Next
Author Message
andrewF



Joined: Dec 29, 2006
Posts: 1171
Location: australia
Audio files: 4

PostPosted: Sun Aug 17, 2008 8:24 am    Post subject: Reply with quote  Mark this post and the followings unread

How's your Japanese?
http://houshu.at.webry.info/200710/article_1.html
You can enjoy a babelfish translation by pasting the url on here -
http://au.babelfish.yahoo.com/
I dunno why but babelfish always translates 'analog synth' as 'the oak' or 'wood'

no thru 0, the controls attenuate or invert the CV only. I built a few of these, straight off Houshu's schematic, they work but don't track well. For a $1, one chip VCO you can't really complain.
Back to top
View user's profile Send private message Visit poster's website
CJ Miller



Joined: Jan 07, 2007
Posts: 371
Location: 127.0.0.1

PostPosted: Sun Aug 17, 2008 6:56 pm    Post subject: Reply with quote  Mark this post and the followings unread

For whatever reason, CV processors are seldom included in people's systems. It's funny, because they are cheap and easy to design/build. This is something that Buchla, Serge, and Ken have always understood to be very useful - people are slowly coming around. Basics to have?:

mixing, attenuation, inversion, offset, scaling, ranging, comparator, envelope follwer

Between combinations of these, one can get really creative with voltages. And they each only need an op amp or two, which makes them easy enough for me to do on perfboard. I started by copying the schematics from Barry Klein's book, (which are mostly from Electronotes) and slowly trying to understand what was happening there.

Klein's book also opened my eyes to nonlinear waveshaping, which ultimately offers more timbral possibilities than subtractive filters while using cheaper parts and being easier to build. Since I had this stuff on the brain, I was psyched to check out Ken's VCO!

Oh, and this morning, before I went to bed - I just finished my two VCOs finally! They've got their styrene caps, trimpots, and tempcos. Now I just need to get my bench clean enough to test them, so the wire clippings and parts don't blow them up.
Back to top
View user's profile Send private message
ericcoleridge



Joined: Jan 16, 2007
Posts: 885
Location: NYC

PostPosted: Tue Nov 25, 2008 10:51 am    Post subject: Reply with quote  Mark this post and the followings unread

Luka wrote:

anyway, so i didnt bother trying it for 3 octaves yet, i wanted to check what it was like, so i reconnected my tune pots and found that the range of the course pot was completely fuxed. The whole audio range was located in a degree or 2 of the pot. So this is obviously wrong.


This is the response that I'm getting also after wiring up the tune pot on this CGS VCO. Were you able to solve this problem?
Back to top
View user's profile Send private message
Luka



Joined: Jun 29, 2007
Posts: 1002
Location: Melb.

PostPosted: Tue Nov 25, 2008 3:26 pm    Post subject: Reply with quote  Mark this post and the followings unread

my wiring was wrong and some wrong pot values

i got a bit excited and had made lots of panels and just fitted them with any pots i could find to see if everything fit, i forgot about this and assumed that the components were all correct. on top of that i got a bit lost with my panel wiring. i started fresh, puled everything out, examined the page again and re-wired it up. tuning went without a hitch

it is great now

_________________
problemchild
melbourne australia
http://cycleofproblems.blogspot.com/
http://www.last.fm/user/prblmchild
Back to top
View user's profile Send private message
zthee



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

PostPosted: Fri Dec 12, 2008 7:20 am    Post subject: Reply with quote  Mark this post and the followings unread

Quote:
For +/- 15V operation, you may prefer to replace the 330k/240k sawtooth bias resistors with 600k/200k as per the ASM-1


Anyone done this? I'm in the middle of building my 2 CGS48s and I'm going for this option..

Or is it better to do the 220K/240K with AC couple output?
But then I need an DC output aswell.. which might be good. Since I'm gonna build a CGS38 saw pitch shifter that needs a saw that goes from 0 to +5V. (Or is the DC output 0 to 10V?)

I can't make up my mind! Very Happy
Back to top
View user's profile Send private message
zthee



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

PostPosted: Thu Jan 29, 2009 10:49 am    Post subject: Reply with quote  Mark this post and the followings unread

The saw DC output - should be between 0-5V approx?

Mine seems to be between 0.5V - 5.5V? (I haven't got the best oscilloscope in the world, but it seems like the DC offset is kinda high..).

Any ways to trim it down? Should I change the 220K resistor in the 330K/220K configuration to something else?

And my "sine" like shape looks really more like then "sine". Anyone got a photo of theirs? Smile

Edit -

So I've been playing around with different resistor values.

300K instead of 240K gave quite a good result. The DC saw seems to be just a tad over 0V. Hard for me to actually measure. But it's not much. It looks and "feels" good! I haven't listened to it, so I don't know. I'm doing all this, because I wanted to use it as a modulation source for other stuff..

And as the sine part of the circuit. I was to stupid to undestand that I was supposed to wait for a few second while turning the trim pot, to let it all settle! So now the sine looks good aswell Smile

My new moto should be: Try first. Post later Very Happy

(Edit like a week later - my spelling is cwap! Sad)
Back to top
View user's profile Send private message
inform3r



Joined: Sep 03, 2006
Posts: 59
Location: nyc

PostPosted: Thu Jul 09, 2009 8:33 pm    Post subject: VCO Wiring Diagram Reply with quote  Mark this post and the followings unread

Can anyone post a wiring diagram (similar to the one's that Ken posts on some of his other module's pages) for the VCO with every option implemented? It would be a great asset to all of us that are getting ready to build this great VCO!
Back to top
View user's profile Send private message Send e-mail
synthmonger



Joined: Nov 16, 2006
Posts: 578
Location: flada
Audio files: 3

PostPosted: Tue Jul 14, 2009 10:03 am    Post subject: Reply with quote  Mark this post and the followings unread

sound sample and or video demo would be great too!
_________________
Youtube!
modular demos!
Whacky tunes!
Back to top
View user's profile Send private message Visit poster's website
zthee



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

PostPosted: Tue Jul 14, 2009 11:41 am    Post subject: Reply with quote  Mark this post and the followings unread

I'll post audio and video as soon as I'm done with mine. Just need to add a TL074 + parts to the sine and TSO output, so they're 5Vpp. Cause right now they're to low to be usefull.

Though I have to say, modulate the TSO in audio rate and you get very nice timbres...

Posted Image, might have been reduced in size. Click Image to view fullscreen.

The wiring isn't that hard to do. I think it's all in the schematics. Except for the PWM. But wire a pot with +15V on one leg and -15V on the other, then put a 330K resistor between the pot and the PW pad and you can change between 10% to 90% pulsewidth.

_________________
http://www.thehumancomparator.net/
Back to top
View user's profile Send private message
synthmonger



Joined: Nov 16, 2006
Posts: 578
Location: flada
Audio files: 3

PostPosted: Tue Jul 14, 2009 1:09 pm    Post subject: Reply with quote  Mark this post and the followings unread

does the pulsewidth remain at 10-90% range at any frequency? I've noticed in some PW designs the width can change with the frequency or cut out completely.
_________________
Youtube!
modular demos!
Whacky tunes!
Back to top
View user's profile Send private message Visit poster's website
zthee



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

PostPosted: Tue Jul 14, 2009 10:35 pm    Post subject: Reply with quote  Mark this post and the followings unread

The PW output is the saw out through a comparator. I can't see that as frequency dependant.
_________________
http://www.thehumancomparator.net/
Back to top
View user's profile Send private message
synthmonger



Joined: Nov 16, 2006
Posts: 578
Location: flada
Audio files: 3

PostPosted: Tue Jul 14, 2009 10:49 pm    Post subject: Reply with quote  Mark this post and the followings unread

I've breadboarded that comparator section and a few others using a +/-5V saw with that kind of result. My vco was different but I don't think it would have mattered unless the cgs vco levels differ.
_________________
Youtube!
modular demos!
Whacky tunes!
Back to top
View user's profile Send private message Visit poster's website
zthee



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

PostPosted: Tue Jul 14, 2009 11:12 pm    Post subject: Reply with quote  Mark this post and the followings unread

Next time I have my scope out I'll take a look at it!
_________________
http://www.thehumancomparator.net/
Back to top
View user's profile Send private message
monokinetic



Joined: Aug 01, 2006
Posts: 100
Location: prague

PostPosted: Thu Jul 23, 2009 4:42 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi zthee,
You mentioned this recently:
zthee wrote:
Just need to add a TL074 + parts to the sine and TSO output, so they're 5Vpp. Cause right now they're to low to be usefull.


I had not realised that kens VCO is 2.5vpp. Any chance you could post a schematic of the mods you are going to do to get up to 5vpp?

David
Back to top
View user's profile Send private message
zthee



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

PostPosted: Thu Jul 23, 2009 4:52 am    Post subject: Reply with quote  Mark this post and the followings unread

Posted Image, might have been reduced in size. Click Image to view fullscreen.

I haven't tested it yet though. But it's just 2 inverting amplifiers after each other, and the second op amp has a feedback resistor that is twice the size of the input resistor - which should cause a gain of 2?

_________________
http://www.thehumancomparator.net/
Back to top
View user's profile Send private message
zthee



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

PostPosted: Thu Jul 23, 2009 4:56 am    Post subject: Reply with quote  Mark this post and the followings unread

synthmonger wrote:
...unless the cgs vco levels differ.


I checked yesterday, and the higher the tune pot, the lower the output. I'll hook up my frequency counter to it and see aprox where it starts to go down.

_________________
http://www.thehumancomparator.net/
Back to top
View user's profile Send private message
monokinetic



Joined: Aug 01, 2006
Posts: 100
Location: prague

PostPosted: Thu Jul 23, 2009 5:06 am    Post subject: Reply with quote  Mark this post and the followings unread

Wow that was quick, thanks Smile
zthee wrote:

But it's just 2 inverting amplifiers after each other, and the second op amp has a feedback resistor that is twice the size of the input resistor - which should cause a gain of 2?


Let's see if anyone objects to your theory.... Wink

Cheers

David
Back to top
View user's profile Send private message
zthee



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

PostPosted: Thu Jul 23, 2009 5:08 am    Post subject: Reply with quote  Mark this post and the followings unread

Well, it isn't my theory, just something I got as a reply when I searched for "op amp calculator" on google. Cool

I'll probably build it this weekend and try it. If it doesn't work I'll let you know.

_________________
http://www.thehumancomparator.net/
Back to top
View user's profile Send private message
hobgob_inc



Joined: Jun 09, 2009
Posts: 46
Location: Australia

PostPosted: Thu Jul 23, 2009 6:41 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hey Zthee,

Assuming that your theory is correct, should it be possible to increase gain closer to 10V with just the two op amp stages?

Going off your design i would just increase the 200k to 400k.....?

I have been thinking about doing this since I noticed they were a fairly weak signal, so I'm glad someone brought it up.


Luke
Back to top
View user's profile Send private message
TekniK



Joined: Aug 10, 2008
Posts: 1062

PostPosted: Thu Jul 23, 2009 9:12 pm    Post subject: Reply with quote  Mark this post and the followings unread

andrewF wrote:

Correct me if this is wrong, I think these are based on the functionality of the CV inputs on the circa '73 Serge VCO. (Ken's design is different though.


I can tell you ,these vco's are everything except close to the serge one.
Back to top
View user's profile Send private message
CJ Miller



Joined: Jan 07, 2007
Posts: 371
Location: 127.0.0.1

PostPosted: Thu Jul 23, 2009 9:33 pm    Post subject: Reply with quote  Mark this post and the followings unread

TekniK wrote:
andrewF wrote:

Correct me if this is wrong, I think these are based on the functionality of the CV inputs on the circa '73 Serge VCO. (Ken's design is different though.


I can tell you ,these vco's are everything except close to the serge one.


Ken replaced his '73 VCOs with these, the only similarity is some of the panels controls. It does not work, feel, or sound anything like the original Serge "Oscillator". The original '73 circuit is extremely clever, and fun, but Ken wanted something which could actually track for more than a single octave or so.

Look up Osamu Hoshuyama's schematic of the 1973 Oscillator, and compare with the diagram for Ken's CGS48 VCO. They are very different.
Back to top
View user's profile Send private message
zthee



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

PostPosted: Thu Jul 23, 2009 11:07 pm    Post subject: Reply with quote  Mark this post and the followings unread

hobgob_inc wrote:
Hey Zthee,

Assuming that your theory is correct, should it be possible to increase gain closer to 10V with just the two op amp stages?

Going off your design i would just increase the 200k to 400k.....?


I can't see why it should be a problem. But the more you gain the more noise you'll get..

_________________
http://www.thehumancomparator.net/
Back to top
View user's profile Send private message
hobgob_inc



Joined: Jun 09, 2009
Posts: 46
Location: Australia

PostPosted: Fri Jul 24, 2009 12:10 am    Post subject: Reply with quote  Mark this post and the followings unread

Cool thanks i may try 300k as well then.

Thanks for posting the strip board layout too.


Luke
Back to top
View user's profile Send private message
TekniK



Joined: Aug 10, 2008
Posts: 1062

PostPosted: Fri Jul 24, 2009 12:26 am    Post subject: Reply with quote  Mark this post and the followings unread

CJ Miller wrote:
TekniK wrote:
andrewF wrote:

Correct me if this is wrong, I think these are based on the functionality of the CV inputs on the circa '73 Serge VCO. (Ken's design is different though.


I can tell you ,these vco's are everything except close to the serge one.


Ken replaced his '73 VCOs with these, the only similarity is some of the panels controls. It does not work, feel, or sound anything like the original Serge "Oscillator". The original '73 circuit is extremely clever, and fun, but Ken wanted something which could actually track for more than a single octave or so.

Look up Osamu Hoshuyama's schematic of the 1973 Oscillator, and compare with the diagram for Ken's CGS48 VCO. They are very different.


i have a serge and cgs vco at home,but i like the cgs pcb because of its dencity and amounth of components,I did buy plenty of them 18 but i still not build 6 of them finished pcb's onto panels,i wander if its worth it as i have redrawn the PCO and have pcb layout ready and read recently the troubles ppl have with it (not v/oct on 5 oct despite the expensive matched transistor pair,low outputs,and what i can expect more?..)
Back to top
View user's profile Send private message
zthee



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

PostPosted: Fri Jul 24, 2009 1:01 am    Post subject: Reply with quote  Mark this post and the followings unread

I think the problem with the low output is a limitation from the LM3900? Since it's only single sided...?

I think the CGS VCO is great. I haven't calibrated mine, but I generally see no use in trying to get as much tracking as possible out of my VCOs..
Modulating the waveshaper in audio rate is great fun!

_________________
http://www.thehumancomparator.net/
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic Moderators: Scott Stites
Page 2 of 4 [81 Posts]
View unread posts
View new posts in the last week
Goto page: Previous 1, 2, 3, 4 Next
Mark the topic unread :: View previous topic :: View next topic
 Forum index » DIY Hardware and Software » Ken Stone designs - CGS
Jump to:  

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
e-m mkii

Please support our site. If you click through and buy from
our affiliate partners, we earn a small commission.


Forum with support of Syndicator RSS
Powered by phpBB © 2001, 2005 phpBB Group
Copyright © 2003 through 2009 by electro-music.com - Conditions Of Use