| Author |
Message |
frijitz
Joined: May 04, 2007
Posts: 1734
Location: NM USA
Audio files: 54
|
 Posted: Sun May 06, 2007 10:33 am Post subject:
|
  |
|
| bearblock wrote: |
i have a lorenz attractor in my modular, the circuit by Paul Horowitz that was mentioned. it would be nice for it to have a time-base control for musical applications though - maybe could be done with vactrols? i.e. each opamp would be replaced with one opamp to sum, then the vactrol, then another to integrate... but i'm rambling.
Ian, I will have to get a couple of PCBs in a week or so when i have some more free time. Is 3080 a good OTA for the Jerkster? |
You could use vactrols, but with an OTA-based approach you have the summer built in and you get a bigger range -- even 1V/oct, if you want.
I use LM13700's in the Jerkster. The trouble with the 3080 is they usually have a fairly large offset and a large offset variation with bias current. It turns out that the chaos pattern depends on the offset, so it's best to use a better device. In my big systems I actually selected devices for low offset variation and included offset trimmers. But that was a lot of work! |
|
|
Back to top
|
|
 |
fonik
Joined: Jun 07, 2006
Posts: 3950
Location: Germany
Audio files: 23
|
| Posted: Sun May 06, 2007 12:16 pm Post subject:
Re: Thanks for the welcome! |
|
|
| frijitz wrote: | | Fonik -- Always glad to see someone working on waveshapers. This is one of my favorite areas. Are you using the double pulser from my site, or the old Electronotes one? |
i built it following the schematic from your site. it's not working properly for now, i will have to do some troubleshooting next days, i guess.
_________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source |
|
|
Back to top
|
|
|
jksuperstar
Joined: Aug 20, 2004
Posts: 2503
Location: Denver
Audio files: 1
G2 patch files: 18
|
| Posted: Sun May 06, 2007 12:30 pm Post subject:
|
|
|
| EdisonRex wrote: | | jksuperstar wrote: | | EdisonRex -- WPI? as in, Worcester Polytech? (I was there from 91-95) |
Yes, I was there from 1979 to 1984. The CS department was still in Atwater Kent when I was there and all the big computers were at WACCC in the basement of the library. I was, predictably, active in Lens and Lights, until it got in the way of my studies, and oh did it ever. I did a PQP writing a digital filter (FFTs was the main thing to learn) on a PDP-11. Those were the days, we didn't have enough CPU to do anything real time.
Glad to see another survivor from the Institute.  |
Nice, woopie pie's all around! Maybe this world really *is* shrinking... |
|
|
Back to top
|
|
|
EdisonRex
Site Admin
Joined: Mar 07, 2007
Posts: 4579
Location: London, UK
Audio files: 172
|
| Posted: Sun May 06, 2007 1:50 pm Post subject:
|
|
|
| frijitz wrote: | | Quote: | | This is the part that fascinates me. Do tell, please. |
Well, first you understand that an opamp integrator is just an opamp with a cap between the output and (-) input. A constant voltage at the input gives you a ramp at the output. But looking at it the other way around, the input is the derivative (slope) of the output.
|
yeah I understand the use of the capacitor to make the integrator, but your converse look, I suppose should be intuitive but I had never thought about it that way. 
| Quote: |
So if you have a first order differential equation, then its left hand side is the derivative of a variable, say x', and there is a bunch of stuff on the right hand side which depends on all the variables in the system, say x,y,z.
|
yes, this makes sense.
| Quote: |
So you take an integrator and call its output x. Then its input is x', so you simply sum up all the signals that represent the terms on the right hand side of the equation and feed the result into the integrator. Presto, you have a circuit representation of the starting equation.
|
That's bloody brilliant. Nobody ever explained it to me like that before.
| Quote: |
Then you repeat the above for all the differential equations in the system and you end up with a circuit that couples all the variables together as described by the system of equations, and therefore solves them.
|
You've just set my mind wandering far more than it needed to, but this is probably a good thing.
| Quote: |
Pretty simple, once you see it!
|
Well, none of this stuff was ever simple to me, but your explanation actually ties a lot of pieces together I never "integrated", if you'll forgive the term.
| Quote: |
JC Sprott has looked at using simple circuit nonlinearities to obtain chaos. These nonlinearities I call "kink", the response of a diode and "step", the response of a comparator. Combining these with straight lines gives a variety of useful nonlinear responses. Sprott did exhaustive computer searches for chaos in different systems of equations with these nonlinearities. You can find most of this work on his website:
http://sprott.physics.wisc.edu/technote.htm
|
Good link, thanks. Talk about simplifying a problem statement...
| Quote: |
So I started out by poaching his ideas and putting them under voltage control, using OTAs to make variable-rate integrators as well as voltage controlled damping and gain. Then I added switches and pots to get different nonlinearities. Oh, and I also hacked an additional signal path with its own nonlinearities. So it's a big complicated system. I used it to get the scarey quadruple scroll attractor on my site and the sound clip that goes with it.
|
And very impressive it is, sir.
| Quote: |
Regarding the double-well system, I was trying to find a simple system that would give lots of interesting outputs, with the idea of giving people something easy to build to get started in this area. So no fancy voltage control and a halfway clever way of combining the nonlinearity, damping and external drive to get the system down to three opamps.
|
Which is why I am so interested here. This is the sort of module I could use. I've been trying to approximate it, but this really seems to make it work. I remember those patterns now, quite clearly, and I remember completely not understanding any of the calculus involved, but I think I was maybe 17 when Bernie published the first article, so I might be excused. I can't be excused for my horrible calculus grades at Uni but it's catching up now.
| Quote: |
I still have a lot of work to do getting the rest of my experiments up on my site, but I'm hacking away at it bit by bit.
Ian |
Oh, keep it coming, please. This is most interesting. Thank you for the explanation! I really appreciate it.
-Paul
_________________
Garret: It's so retro.
EGM: What does retro mean to you?
Parker: Like, old and outdated.
Home,My Studio,and another view |
|
|
Back to top
|
|
|
frijitz
Joined: May 04, 2007
Posts: 1734
Location: NM USA
Audio files: 54
|
| Posted: Sun May 06, 2007 6:10 pm Post subject:
dpwg |
|
|
| fonik wrote: |
i built it following the schematic from your site. it's not working properly for now, i will have to do some troubleshooting next days, i guess. |
I just checked the schematic and it seem OK. Did you change anything? |
|
|
Back to top
|
|
|
fonik
Joined: Jun 07, 2006
Posts: 3950
Location: Germany
Audio files: 23
|
| Posted: Sun May 06, 2007 11:06 pm Post subject:
|
|
|
thank you very much for taking care.
i built it right off your schematic - or better said: i tried to. it doesn't work, so i did a mistake somewhere. i will have to check this out first.
_________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source |
|
|
Back to top
|
|
|
fonik
Joined: Jun 07, 2006
Posts: 3950
Location: Germany
Audio files: 23
|
| Posted: Mon May 07, 2007 3:30 am Post subject:
Re: Fritz chaos circuit |
|
|
concerning the double well chaos again:
would a mixed inverted output make sense? i wonder what to do with the unused 4th opa of the quad i want to use?
_________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source |
|
|
Back to top
|
|
|
frijitz
Joined: May 04, 2007
Posts: 1734
Location: NM USA
Audio files: 54
|
| Posted: Mon May 07, 2007 12:34 pm Post subject:
Re: Fritz chaos circuit |
|
|
.....
Last edited by frijitz on Tue Mar 04, 2008 2:27 am; edited 2 times in total |
|
|
Back to top
|
|
|
elektro80
Site Admin
Joined: Mar 25, 2003
Posts: 21959
Location: Norway
Audio files: 14
|
| Posted: Mon May 07, 2007 12:38 pm Post subject:
|
|
|
Hey! 
_________________
A Charity Pantomime in aid of Paranoid Schizophrenics descended into chaos yesterday when someone shouted, "He's behind you!"
MySpace
SoundCloud
Flickr |
|
|
Back to top
|
|
|
EdisonRex
Site Admin
Joined: Mar 07, 2007
Posts: 4579
Location: London, UK
Audio files: 172
|
| Posted: Mon May 07, 2007 12:45 pm Post subject:
|
|
|
| frijitz wrote: | | Quote: | | I was an original subscriber to electronotes. I had a copy of every issue. Then I lent them to someone and I've never seen them again. |
Woah! There must have been only a dozen or so original members. I subscribed to EN as a way to catch up on modern electronics. You know, opamps and all that. I had done ham radio stuff earlier, but got away from electronics while in school. It was a real kick for me to eventually get the the level where I could make some contributions.
I don't know if it has been mentioned here, but Bernie is still selling all his material. You can get a package with everything for something like $300. Or you can get a core package, or the Handbook or the circuit collection separately. I still use the Handbook fairly often, since my head doesn't hold all that much.
Ian |
I subscribed from 1974 to about 1981 or so. I had binders full.
I've been thinking of getting some of the back issues back, there were some really good ideas in them. Amazing Bernie still has them.
_________________
Garret: It's so retro.
EGM: What does retro mean to you?
Parker: Like, old and outdated.
Home,My Studio,and another view |
|
|
Back to top
|
|
|
Photon
Joined: Mar 22, 2005
Posts: 363
Location: Boston
Audio files: 1
|
| Posted: Mon May 07, 2007 1:27 pm Post subject:
Re: Fritz chaos circuit |
|
|
| frijitz wrote: | If you don't mind also adding a couple of pots, it really would be a great addition for anyone building the circuit from scratch.
Ian |
Are the two pots in series a coarse and fine adjustment? |
|
|
Back to top
|
|
|
frijitz
Joined: May 04, 2007
Posts: 1734
Location: NM USA
Audio files: 54
|
| Posted: Mon May 07, 2007 1:47 pm Post subject:
Re: Fritz chaos circuit |
|
|
| Photon wrote: | | frijitz wrote: | If you don't mind also adding a couple of pots, it really would be a great addition for anyone building the circuit from scratch.
Ian |
Are the two pots in series a coarse and fine adjustment? |
Well, not really. The upper one mixes the x and y signals. The lower one sets the amplitude of the signal going into the nonlinear stage. |
|
|
Back to top
|
|
|
fonik
Joined: Jun 07, 2006
Posts: 3950
Location: Germany
Audio files: 23
|
| Posted: Mon May 07, 2007 2:07 pm Post subject:
|
|
|
thank you very much, ian.
i appreciate it very much how you share your knowledge and efforts here.
_________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source |
|
|
Back to top
|
|
|
fonik
Joined: Jun 07, 2006
Posts: 3950
Location: Germany
Audio files: 23
|
| Posted: Tue May 08, 2007 3:04 am Post subject:
Re: Fritz chaos circuit |
|
|
| frijitz wrote: | | The upper one mixes the x and y signals. The lower one sets the amplitude of the signal going into the nonlinear stage. |
thinking ahead i started to wonder how to designate the lower potentiometer on the frontpanel. X/Y feedback?
_________________
cheers,
matthias
____________
Big Boss at fonitronik
Tech Buddy at Random*Source |
|
|
Back to top
|
|
|
frijitz
Joined: May 04, 2007
Posts: 1734
Location: NM USA
Audio files: 54
|
| Posted: Tue May 08, 2007 9:36 am Post subject:
Re: Fritz chaos circuit |
|
|
| fonik wrote: | | thinking ahead i started to wonder how to designate the lower potentiometer on the frontpanel. X/Y feedback? |
Wow, moving on this already!
I would suggest labels like "x/y blend" or "blend" or "shape" for the upper pot, and "loop gain" or "gain" for the lower one. |
|
|
Back to top
|
|
|
frijitz
Joined: May 04, 2007
Posts: 1734
Location: NM USA
Audio files: 54
|
| Posted: Tue May 08, 2007 9:44 am Post subject:
hacked EZ Chaos |
|
|
I made a short demo file using the hacked EZ Chaos circuit with a special sample/hold circuit I like to use. Also, a scope shot of the attractor is included, if you want to get some idea about the different kind of shape you can get with the hack.
http://home.comcast.net/~ijfritz/ch_cir3.htm
(Down at the bottom of the page.) |
|
|
Back to top
|
|
|
frijitz
Joined: May 04, 2007
Posts: 1734
Location: NM USA
Audio files: 54
|
| Posted: Thu May 10, 2007 10:58 am Post subject:
Re: hacked EZ Chaos |
|
|
| There is still a decent supply of boards for both the EZ Chaos and the Jerkster projects. Let me know if interested! |
|
|
Back to top
|
|
|
Scott Stites
Janitor
Joined: Dec 23, 2005
Posts: 4127
Location: Mount Hope, KS USA
Audio files: 96
|
| Posted: Fri May 11, 2007 1:45 pm Post subject:
|
|
|
| Got my boards yesterday - nice boards! Looks like they can be assembled in no time, then one can have all kinds of frenetic, fractal fun. Too bad I'm gone from home this weekend.... |
|
|
Back to top
|
|
|
bearblock
Joined: Sep 27, 2006
Posts: 90
Location: uk
Audio files: 1
|
| Posted: Fri May 18, 2007 7:39 am Post subject:
Re: hacked EZ Chaos |
|
|
| frijitz wrote: | | There is still a decent supply of boards for both the EZ Chaos and the Jerkster projects. Let me know if interested! |
PM sent.
One concern; anyone know where to get 1M dual-gang pots? This is what is specified for the EZ Chaos rate control, and none of my usual suppliers stock them. |
|
|
Back to top
|
|
|
Uncle Krunkus
Moderator
Joined: Jul 11, 2005
Posts: 4761
Location: Sydney, Australia
Audio files: 52
G2 patch files: 1
|
| Posted: Fri May 18, 2007 7:51 am Post subject:
|
|
|
My standard supplier doesn't have them either. If I ever get around to building one of these, I'll probably make my own. How? Well, the two standards I use, the 24mm and 16mm types are held together by bent tabs on the pot body. Purchase 2 * 1Meg single gang and a double gang of any value, all from the same type. Dissassemble the dual gang one and replace the two "boards" with the 1Meg boards from the single gang ones. 
_________________
What makes a space ours, is what we put there, and what we do there. |
|
|
Back to top
|
|
|
fluxmonkey
Joined: Jun 24, 2005
Posts: 708
Location: cleve
|
| Posted: Fri May 18, 2007 8:33 am Post subject:
|
|
|
1meg dual gang: mouser part #31VW601-F
b |
|
|
Back to top
|
|
|
andrewF
Joined: Dec 29, 2006
Posts: 1176
Location: australia
Audio files: 4
|
| Posted: Fri May 18, 2007 6:23 pm Post subject:
|
|
|
| i just used a dual 100k pot figuring they are both just wired as voltage dividers. works, maybe not as Ian intended. |
|
|
Back to top
|
|
|
para
Joined: Oct 16, 2006
Posts: 276
|
| Posted: Sat Jun 30, 2007 11:08 pm Post subject:
|
|
|
alright so i've been searching so very patiently for 4.3v zener’s every time i place an order somewhere and i can't find any. i stripboarded this up a long time ago and only had 4.7v's and the result was actually very cool, it was a sort of low freq res filtery effect with an odd slow bell curve cutoff that turned a simple squarewave into a nice huge thick bass drum tone and i’m probably going to have to try and reproduce that on purpose when i get time, but back to the chaos… so i assumed that i needed some 4.3's to get the chaos correct but i could have something else wrong. i pored over it for a long time and that was the only difference i could find. so am i wrong and 4.7’s should have worked or can someone please direct me to a place that sells 4.3v zener's?
i'm not even sure what the effect of having the two facing each other like that does?
steven |
|
|
Back to top
|
|
|
frijitz
Joined: May 04, 2007
Posts: 1734
Location: NM USA
Audio files: 54
|
| Posted: Sun Jul 01, 2007 6:45 am Post subject:
|
|
|
| para wrote: | | alright so i've been searching so very patiently for 4.3v zener’s every time i place an order somewhere and i can't find any. |
Steven ... Just about any major electronics part supplier should have them. Here's a page from Mouser:
http://www.mouser.com/catalog/630/352.pdf
You want either 1N5229B or 1N749A in the DO-35 package.
The 4.7V Zener will work OK, but the shape of the nonlinearity will be somewhat different.
Ian |
|
|
Back to top
|
|
|
para
Joined: Oct 16, 2006
Posts: 276
|
| Posted: Sun Jul 01, 2007 11:50 am Post subject:
|
|
|
thanks Ian,
i almost never order from mouser if i can get away with it. i buy from smaller houses and they usually don't have full stocks. but even someplace like jameco didn't have any - http://www.jameco.com/webapp/wcs/stores/servlet/CategoryDisplay?storeId=10001&catalogId=10001&langId=-1&categoryId=107560
i think i must have had something else wrong if the 4.7 should have worked. i'll need to go over it some more. doing stripboards in a rush is a bad idea but i was excited to get it running and short on time. i used a 074 though, there isn't anything wrong with that is there?
steven |
|
|
Back to top
|
|
|
|
Forum index » DIY Hardware and Software
FAQ
Calendar
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
Chat Room
