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 Forum index » DIY Hardware and Software
Chaotica
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frijitz



Joined: May 04, 2007
Posts: 1712
Location: NM USA
Audio files: 54

PostPosted: Wed Nov 09, 2011 1:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

The Chaotica project continues to progress. Elby has agreed to make a Euro-format version, and its panel layout has been agreed on.

Updated schematics have been posted above. The originally posted ones had two errors: R3 should be 100k (not 47k), and R69 should be removed. This should help anyone who was having trouble getting the original to work properly.

The new circuit uses analog switches from a DG211 chip for the reset/inhibit function. This was done because the MPF102 FET originally used is being discontinued.

A DIY PCB is being tested. This is mainly for my own use, but I may distribute some if there is enough interest. (My regular distributers are not interested in doing this.)

Very Happy

Ian
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asterisk



Joined: Sep 17, 2011
Posts: 17
Location: burlington, VT

PostPosted: Wed Nov 09, 2011 10:59 pm    Post subject: Reply with quote  Mark this post and the followings unread

this is great news ian. im looking forward to the elby eurorack version of this module.
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fluxmonkey



Joined: Jun 24, 2005
Posts: 696
Location: cleve

PostPosted: Thu Nov 10, 2011 9:27 pm    Post subject: Reply with quote  Mark this post and the followings unread

great to hear! if you do some DIY boards count me in, i'm a completest...

bbob[/right]

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Argitoth



Joined: Jun 24, 2008
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Location: Gilbert, Arizona
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PostPosted: Fri Nov 18, 2011 6:44 pm    Post subject: Reply with quote  Mark this post and the followings unread

frijitz wrote:
A DIY PCB is being tested. This is mainly for my own use, but I may distribute some if there is enough interest. (My regular distributers are not interested in doing this.)


OH GOD YES! I need a PCB. I hate not being able to create my own panel for a circuit board and make my own decisions about controls. Shocked

Twisted Evil
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micheline



Joined: Mar 11, 2009
Posts: 9
Location: inside a CMOS

PostPosted: Fri Nov 18, 2011 7:29 pm    Post subject: Reply with quote  Mark this post and the followings unread

This machine is quite impressive ! Bravo !
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Captain Biscuits



Joined: Jun 11, 2010
Posts: 112
Location: Northampton, UK

PostPosted: Sat Nov 19, 2011 9:43 am    Post subject: Reply with quote  Mark this post and the followings unread

I'd love to take a pcb if you do a batch, sounds like lots of fun.

Cheers

Ian
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Uncle Krunkus
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Joined: Jul 11, 2005
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PostPosted: Sat Nov 19, 2011 2:32 pm    Post subject: Reply with quote  Mark this post and the followings unread

I only just saw this thread, as I've been absent for a while.
Very nice work Ian.

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frijitz



Joined: May 04, 2007
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Location: NM USA
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PostPosted: Sat Nov 19, 2011 6:00 pm    Post subject: Reply with quote  Mark this post and the followings unread

Uncle Krunkus wrote:
I only just saw this thread, as I've been absent for a while.


Hi Uncle, good to see you back. Most of contributers that were around a couple of years ago seem to have drifted away. Not much going on here, anymore. I'm thinking about following Scott and just doing stuff for myself.

Very Happy

Ian
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Uncle Krunkus
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Joined: Jul 11, 2005
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PostPosted: Sun Nov 20, 2011 3:45 am    Post subject: Reply with quote  Mark this post and the followings unread

I might actually be about to move into a house that my partner and I have bought.
Things are chaotic.
I'll elaborate on a new thread.

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mark_olson



Joined: Oct 26, 2006
Posts: 177
Location: Lawrence, Kansas

PostPosted: Sun Nov 20, 2011 11:52 am    Post subject: Reply with quote  Mark this post and the followings unread

frijitz wrote:
Not much going on here, anymore. I'm thinking about following Scott and just doing stuff for myself.

Very Happy

Ian


I hope that you don't. But obviously it's your business if you do. I've learned a lot from you and others, too many of whom are mostly silent here nowadays. I stumbled in here a few years ago, about the time the development of the Klee was at its most feverish. Good times indeed. And so stimulating to somebody just getting into diy electronics. I miss those days on the forum but at least I "met" a lot of talented and generous people that I mostly can still contact even though they aren't too active here anymore.

Sorry to take your thread further OT Smile just wanted to express my appreciation, thanks.

Mark
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Abby Normal



Joined: Feb 20, 2010
Posts: 66
Location: USA
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PostPosted: Sun Nov 20, 2011 7:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

frijitz wrote:
Uncle Krunkus wrote:
I only just saw this thread, as I've been absent for a while.


Hi Uncle, good to see you back. Most of contributers that were around a couple of years ago seem to have drifted away. Not much going on here, anymore. I'm thinking about following Scott and just doing stuff for myself.

Very Happy

Ian


Speaking for myself and I'm sure many others here - Even if you don't see replies in your threads, please know that your posts are being read and are VERY much appreciated. In fact, I usually seek out any threads where you have posted because I always find your input very interesting. I may not understand the more technical aspects of your various circuits (mainly the math), but what I do understand, I find enormously interesting.

Though money is tight these years, I do plan to build more than a few of your circuits. I already have a half-built Double Deka, so I've already started!

Last edited by Abby Normal on Sun Nov 20, 2011 9:52 pm; edited 1 time in total
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inlifeindeath



Joined: Apr 02, 2010
Posts: 315
Location: Albuquerque, NM

PostPosted: Sun Nov 20, 2011 9:12 pm    Post subject: Reply with quote  Mark this post and the followings unread

i just want to back up the past few posts. Your projects are probably the most interesting parts of this forum and I'd hate to not see them in the future. I also plan on building a few of your modules as soon as i wrap up some other things. I'm into modular synths specifically because of circuit designers like yourself that go outside the typical synth standards and create magic. there are a lot of us on here that really appreciate your postings, whatever you decide to do, just know that.
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jordroid



Joined: Jan 17, 2010
Posts: 193
Location: ithaca, new york

PostPosted: Wed Nov 30, 2011 8:54 am    Post subject: Reply with quote  Mark this post and the followings unread

Jumping in a little late... whatever you do, thanks for all the circuits you have shared Ian. I don't always post about it, but i have built a number of your modules in the last year, to my great enjoyment. Your updated EN saw VCO is pretty much the only one i use anymore, except for the occasional Teezer.

anyways, thanks

jordan
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ach_gott



Joined: Sep 09, 2008
Posts: 79
Location: Chicago

PostPosted: Thu Dec 01, 2011 3:07 pm    Post subject: Reply with quote  Mark this post and the followings unread

I want PCBs too! I take it Scott D is among those who have turned down the opportunity. Confused
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Dingotush



Joined: Oct 04, 2010
Posts: 3
Location: Milton Keynes, UK

PostPosted: Fri Jan 06, 2012 2:30 pm    Post subject: Reply with quote  Mark this post and the followings unread

Like others, I do appreciate the circuits you and others have posted here. And I must say I'm particularly excited to build this one. I first started looking around these forums when I got interested in laser abstracts; perhaps not surprisingly there's a lot of commonality between the voltages in modular synth circuits and those needed to control laser galvos.
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egasimus



Joined: Feb 11, 2011
Posts: 112
Location: Bulgaria

PostPosted: Sat Jan 07, 2012 7:11 am    Post subject: Reply with quote  Mark this post and the followings unread

My wife approves of these sounds. Expect me to build this thing Laughing
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decaying.sine



Joined: Aug 31, 2009
Posts: 92
Location: New Haven, CT, USA

PostPosted: Sun Jan 08, 2012 12:06 pm    Post subject: Reply with quote  Mark this post and the followings unread

I received an email update from Laurie saying he is waiting for the Chaotica prototype board to test and expects to get the final boards for Elby sales in February 2012. Looking forward to these!
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Dingotush



Joined: Oct 04, 2010
Posts: 3
Location: Milton Keynes, UK

PostPosted: Tue Jan 10, 2012 7:58 am    Post subject: A few queries Reply with quote  Mark this post and the followings unread

Sorry to be a pain, but I've a few questions:

Is C4 470nF?

And because I'm curious:

Is there a good reason for using the other half of the U3 in the reset input rather than the spare half of A3? It's just working as a comparator isn't it?

I noticed that the drive for the Rate bias current has an emitter-follower Q50 rather than the diodes in the other bias current circuits. Why is that?
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Mongo1



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

PostPosted: Tue Jan 10, 2012 9:05 am    Post subject: Reply with quote  Mark this post and the followings unread

I THINK I received the last of the parts I was missing last night, so I'm going to try to get my prototype working. Apologies for the delays on doing this - can't wait to get it working....
Gary
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frijitz



Joined: May 04, 2007
Posts: 1712
Location: NM USA
Audio files: 54

PostPosted: Tue Jan 10, 2012 10:31 am    Post subject: Re: A few queries Reply with quote  Mark this post and the followings unread

Dingotush wrote:
Is C4 470nF?

Yes it is: .47uF = 470nF

Quote:
And because I'm curious:

Is there a good reason for using the other half of the U3 in the reset input rather than the spare half of A3? It's just working as a comparator isn't it?

I noticed that the drive for the Rate bias current has an emitter-follower Q50 rather than the diodes in the other bias current circuits. Why is that?

Curiosity is good.

The reset circuit could have been differently. I had half of the OTA "left over" so I used it as a current switch to make a short pulse. The A51b circuit squares the pulse up and biases the switches properly. I used a single for A3.

The rate control is exponential, the others are linear.

Ian
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Dingotush



Joined: Oct 04, 2010
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Location: Milton Keynes, UK

PostPosted: Wed Jan 11, 2012 5:42 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for that. I thought is was the "uF" that is commonly missed off in schematics from the USA, but wasn't 100% sure. 470n made sense for a visible blink.

I missed that A3 was a single; that's what comes of re-drawing schematics. I find it a good way to get to understand how things work, but also a good way to introduce errors!

Just one more: is this set up for +/- 15 or +/- 12 rails? If I had to guess I'd go for 12v based on the resistors in the rate current bias and trying to keep the max around 1mA.
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Mongo1



Joined: Aug 11, 2011
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PostPosted: Wed Jan 11, 2012 7:53 am    Post subject: Reply with quote  Mark this post and the followings unread

It's for 12V rails, but there are 5 resistors that change to make it 15V

R55 = 1.8k
R67 = 330k
R62 = 82k
R74 = 82k
R65 = 680k

Gary
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frijitz



Joined: May 04, 2007
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Location: NM USA
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PostPosted: Fri Mar 16, 2012 6:07 pm    Post subject: Reply with quote  Mark this post and the followings unread

andrewF wrote:
haven't got it quite working perfectly, removed the reset FETs when trouble-shooting

I have found an error in one of the early drawings, which would certainly keep the FETs from working properly. There is a 1 M resistor from the gates that should go to -12V rather than ground.

Sorry 'bout that.

Ian

Last edited by frijitz on Fri Mar 16, 2012 9:37 pm; edited 1 time in total
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decaying.sine



Joined: Aug 31, 2009
Posts: 92
Location: New Haven, CT, USA

PostPosted: Fri Mar 16, 2012 9:24 pm    Post subject: Reply with quote  Mark this post and the followings unread

frijitz wrote:
andrewF wrote:
haven't got it quite working perfectly, removed the reset FETs when trouble-shooting

I have found an error in one of the early drawings, which would certainly keep tha FETs from working properly. There is a 1 M resistor from the gates that should go to -12V rather than ground.

Sorry 'bout that.

Ian


Ian,
It looks like this is corrected on the most recent documentation and PCBs. Is that right?
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frijitz



Joined: May 04, 2007
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PostPosted: Fri Mar 16, 2012 9:36 pm    Post subject: Reply with quote  Mark this post and the followings unread

decaying.sine wrote:
It looks like this is corrected on the most recent documentation and PCBs. Is that right?

Yes. This applies only to the earlier version with discrete FET switches for the reset.

Ian
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