Project Audit: Analog Lorenz Attractor (The Chaos Case)

[mikutch468]

Hey everyone!

I'm making this post in the Beginners section of the forum for a couple of reasons:
1) I am a recent graduate of an engineering technology program that focuses on automation and electromechanics. I have taken a handful of courses on electricity and circuits, however its been a few years since those courses and am definitely in need of a refresher.
2) I'm making an effort to present the project materials in as accessible a way as possible, such that maybe it helps other beginners to dive deeper into electronics and circuit theory.

I am working on an analog Lorenz Attractor (modeled after the classic Horowitz/Art of Electronics approach - see attached .jpg for reference).
For more context about the Lorenz Attractor, here's a quick rundown: http://seti.harvard.edu/unusual_stuff/misc/lorenz.htm

I would love a general design audit on my current schematic to help me refine the circuit and BOM before I order parts to start breadboarding and eventually laying out a PCB and designing a custom wooden enclosure with a metal front plate.

The Chaos Case is designed to consist of a few main sections:
- Power Intake, Protection and Regulation (Main toggle switch -> main fusing -> crowbar clamping circuit for reverse polarity overvoltage protection -> reverse polarity protection diodes -> crowbar clamping circuit for proper polarity overvoltage protection -> power okay LED indication -> toggle switch -> voltage regulators)

- PWM Case Fan Control (Master Cooler fan and astable 555 circuit for variable PWM control)

- Lorenz Attractor Analog Computer (Two multipliers and three integrators. Features three speed options and toggle-ability between preset parameter values [regular ol' resistors] or variable values [potentiometers]. 1% tolerance MKP film capacitors are specified for this section)

- Output Buffering and Interface (high impedance non-inverting buffer [per-output] -> oscilloscope probe points [nuts + bolts in wood] and the mixing / audio out circuit)

I am least confident about the overvoltage protection, separating analog / digital ground, what types of capacitors to use for the rest of The Chaos Case, and the master volume / audio out portions of The Chaos Case.

RE: fusing, I'm planning on using a 35mm DIN rail for fuse holders. If all goes well, I may one day upgrade the power supply situation to a DIN rail mounted one with a single 120VAC cable to plug into the wall.

I have attached PDF copies of my current (incomplete) BOM (ALA_BOM.pdf) and my current schematic (ALA_MasterCopy.pdf), on which there is a bit more information / project context.

If I've misjudged where to post this, please let me know!

[tautech]

Welcome to the forum.

A forum search for Lorenz Attractor provides a few hits that can guide you on this.

[RoGeorge]

Nice project! 

Analog multipliers are rather rare (and pretty expensive).  In case you want to experiment cheaper, there are other types of chaotic oscillators, a few examples here:  https://www.eevblog.com/forum/projects/t20347/

[nonius_]

Nice project! Will follow your progress with interest. I've built a few simple chaotic generators but none that produced the classis Lorenz butterfly attractor. Every time I fancied building one and started looking for components, the price was far too much above the 'just for fun'-range that a circuit like that is (or should be). Every few years I revisited the project in the hope that cost would have become more reasonable, but no luck so far.

There were other circuits that were much easier (and most importantly, cheaper!) to build, such as the one from Elektor, which worked very nicely and illustrated the principle just as well, it's just that.... it isn't the classic butterfly....

In case you didn't know yet, they look much, much better on analog scopes than on digital ones. Practically all XY-mode electronics (curvetracer; scopeclock; chaos-generator) look better on analog scopes, for that matter.

If you're not yet familiar with the book 'Chaos' by James Gleick then I highly recommend reading it. (on my book shelves it sits next to 'Cosmos' by Carl Sagan  )

[mikutch468]

Nice project! 

Analog multipliers are rather rare (and pretty expensive).  In case you want to experiment cheaper, there are other types of chaotic oscillators, a few examples here:  https://www.eevblog.com/forum/projects/t20347/

Thank you for the kind words and for the link! That is an awesome thread, I can already tell I’m going to get completely lost in it for hours 

Nice project! Will follow your progress with interest. I've built a few simple chaotic generators but none that produced the classis Lorenz butterfly attractor. Every time I fancied building one and started looking for components, the price was far too much above the 'just for fun'-range that a circuit like that is (or should be). Every few years I revisited the project in the hope that cost would have become more reasonable, but no luck so far.

There were other circuits that were much easier (and most importantly, cheaper!) to build, such as the one from Elektor, which worked very nicely and illustrated the principle just as well, it's just that.... it isn't the classic butterfly....

In case you didn't know yet, they look much, much better on analog scopes than on digital ones. Practically all XY-mode electronics (curvetracer; scopeclock; chaos-generator) look better on analog scopes, for that matter.

If you're not yet familiar with the book 'Chaos' by James Gleick then I highly recommend reading it. (on my book shelves it sits next to 'Cosmos' by Carl Sagan  )

Thank you for the interest!

I just recently ordered a refurbed HM203-7 analog oscilloscope which I'm super excited for, it should arrive in a couple of weeks 

Funnily enough, 'Chaos' by James Gleick is actually exactly what inspired this project for me! I've always been fascinated by math and electronics and as soon as I started reading 'Chaos' I was absolutely hooked. I haven't heard of 'Cosmos' before and after giving it a quick search, I'll definitely have to pick up a copy!

[mawyatt]

Thank you for the interest!

I just recently ordered a refurbed HM203-7 analog oscilloscope which I'm super excited for, it should arrive in a couple of weeks 

Funnily enough, 'Chaos' by James Gleick is actually exactly what inspired this project for me! I've always been fascinated by math and electronics and as soon as I started reading 'Chaos' I was absolutely hooked. I haven't heard of 'Cosmos' before and after giving it a quick search, I'll definitely have to pick up a copy!

Check the IEEE papers from Michael Kennedy, these are quite good.

Best