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Freq Band
Joined: Sep 05, 2006
Posts: 57
Location: Los Angeles
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blue hell
Site Admin
Joined: Apr 03, 2004
Posts: 24436
Location: The Netherlands, Enschede
Audio files: 297
G2 patch files: 320
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Photon
Joined: Mar 22, 2005
Posts: 363
Location: Boston
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 Posted: Sat Aug 11, 2007 8:29 am Post subject:
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Wow, that video is amazing. Please keep us posted with any developments that you find out about this.
I gotta go watch that video another 50 more times...
_________________
Freq Out
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frijitz
Joined: May 04, 2007
Posts: 1734
Location: NM USA
Audio files: 54
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Posted: Sat Aug 11, 2007 9:53 am Post subject:
Re: Chua's chaos oscillator
Subject description: check out the video |
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| Freq Band wrote: | I don't have much info yet, I'm still searching for a good circuit version...to build one.
There are lots of variations, mostly as lab/theory experiments, just a few dedicated to audio. |
You might want to have a look at my website. I've been working on analog chaos circuits for EM applications for a couple of years now.
http://home.comcast.net/~ijfritz/ch_over.htm
http://home.comcast.net/~ijfritz/ch_close.htm
http://home.comcast.net/~ijfritz/ch_circ.htm
Chua's circuit is a prototype for electronic implementation of chaos. The Kennedy article and implementation are classics in the field. As it stands this circuit is a bit awkward for appplications where you want to vary its frequency. In addition, the circuit nonlinearities I have been working with are much easier to implement than Chua's breakpoint circuit.
There are a number of electronic implementations of the Lorenz System around. The main drawback of this system is that it requires three multipliers. I found that my double-well system gives about the same variety of signals with a much simpler circuit. As suggested by JC Sprott, there is a lot that can be done with opamp+diode nonlinearities.
The modified Lorenz system is new to me. Thanks for posting it. They have a nice variety of attractors there. This might be worth a further look.
Ian |
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Freq Band
Joined: Sep 05, 2006
Posts: 57
Location: Los Angeles
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| Posted: Sat Aug 11, 2007 10:52 pm Post subject:
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Thanks everyone.
And thanks to you Ian (frijitz), some soldering .... I will do!
=FB= |
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Freq Band
Joined: Sep 05, 2006
Posts: 57
Location: Los Angeles
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mikeb
Joined: Nov 20, 2006
Posts: 59
Location: The Automotive Capital of Canada
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| Posted: Wed Aug 22, 2007 3:36 am Post subject:
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An instant 2001:Intermission machine, I like it!
Mike |
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frijitz
Joined: May 04, 2007
Posts: 1734
Location: NM USA
Audio files: 54
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| Posted: Wed Aug 22, 2007 7:51 am Post subject:
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Wow 
Fast work. And it looks like you have a period-doubling route to chaos.
How did you decide on what to use for all the parameters?
What did you end up using for the multipliers?
As far as usage, for me the most interesting applications have been to run the system at low frequencies and control different synth parameters with the different outputs. Sort of like a set of crazy LFOs. So one output could FM your VCO, another could FM your filter and the other could AM your VCA. Etc.
At audio frequencies you could process the outputs through your synth modules, or just attenuate the signals and rum them into your stereo.
Did you put in some method to vary the frequency of the system?
Great work!
Ian |
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Freq Band
Joined: Sep 05, 2006
Posts: 57
Location: Los Angeles
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| Posted: Wed Aug 22, 2007 11:11 am Post subject:
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| frijitz wrote: |
How did you decide on what to use for all the parameters?
What did you end up using for the multipliers?
Did you put in some method to vary the frequency of the system?
Ian |
I built the circuit exactly as in the PDF (with on-board +5volt regs for the MLT04). Point to point wired.
I used whatever trimpots I had, some were just single turn. And I just kept adjusting the pots until I saw action on the monitor. 1x probes would give an image too big for the monitor...10x probes were used in the above pictures.
I really need to sit down and review what the circuit is doing, and to understand how lowest frequencies are obtained, or could be obtained. Gimme a hint ?
BTW, AD713 or OP471 worked ok, but the OPA4228 seened to want to oscillate easier....maybe the higher bandwidth.
=FB= |
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frijitz
Joined: May 04, 2007
Posts: 1734
Location: NM USA
Audio files: 54
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| Posted: Wed Aug 22, 2007 11:58 am Post subject:
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| Freq Band wrote: |
I built the circuit exactly as in the PDF....
1x probes would give an image too big for the monitor...10x probes were used in the above pictures...
I really need to sit down and review what the circuit is doing, and to understand how lowest frequencies are obtained, or could be obtained. Gimme a hint ?
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Yes, building the circuit exactly as shown is the best way to start, in case there is a mistake in the drawing. 
I'm not sure what your voltage scale is, but you might want to check whether your signals are being clipped by the power supply rails. No big deal if they are, it just means you are using additional nonlinearities.
The run rate of the circuit is set by the RC time constants of the three caps and the resistors feeding the integrators. To vary the rate you could vary all of R5, R11, R12 and R17 simultaneously. So you could look for a 4-section pot of 100k or so.
Another method is to replace the resistors with voltage-divider pots and series resistors into the opamp, as in my EZ chaos circuit:
http://home.comcast.net/~ijfritz/ch_cir1.htm
This would still require a 4-section pot, but you can use just about any value, since it is the series resistors that defines the maximum rate.
A more general method is to use OTAs for the four resistors. This would also give you voltage-controlled rate. You do that using the subcircuit at the top of this page:
http://home.comcast.net/~ijfritz/ch_cir2.htm
You only need three of these, as the R5 and R11 signals can be combined at the input of just one OTA.
Hope this helps!
Ian |
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andrewF
Joined: Dec 29, 2006
Posts: 1176
Location: australia
Audio files: 4
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| Posted: Tue Jan 06, 2009 9:48 pm Post subject:
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I've drooled over this cct for a while now....
Would someone be able to suggest a substitute for the MLT04 four quadrant multiplier? |
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