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**Note: This Instructable is based on parts from RadioShack, which is no longer in business. We encourage fellow makers to provide alternatives. This is the RAW Bill of Materials. We have written this academic paper on making the Chua's circuit out of parts from Fry's Electronics.**

This Instructable shows you how to build a chaotic circuit using parts from RadioShack, a widespread hobby electronics store in the USA. The only part RadioShack does not provide is an oscilloscope, but those are expensive anyway. Hence, we'll also show how you can use a USB Audio Adapter or a Desktop soundcard as an oscilloscope (or as we call it, the Poorman's scope).

It allows you to build a Chua's circuit with parts locally accessible in a short period of time without dealing with online shipping.

Chua's circuits are some of the simplest kinds of chaotic circuits. They are considered to be a classic example of true chaos due to their design and output. Using an oscilloscope you can witness a Chua's circuit create the strange attractor known as the double scroll. These beautiful patterns are truly chaotic and can be modeled by relatively simple nonlinear equations.
On top of being a great example of chaos, they are easy to build. These circuits, invented by Leon Chua, also have many real-world uses ranging from research, to music and encryption. In fact, customized circuits can be implemented almost anywhere where real chaos or nonlinear output is necessary.

You'll be able to have a chaotic attractor in the palm of your hands in just one day, be it for a hackathon, class demonstration, research, or personal curiosity.

Step 1: Go Shopping

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RadioShack stores differ from location to location. Some are entirely focused on consumer electronics and have very few items for hobbyists. Know which RadioShacks in your neighborhood actually have component drawers in the back. (Here in Downtown Brooklyn, 457 Fulton Street – Bad, Court St – Good, Atlantic Ave – Better).

Even if your RadioShack does have drawers in the back be prepared to improvise or visit a couple of places. Below are tables, parts, and other equipment-all available at RadioShack-that will allow you to put together and view the output of your Chua’s circuit without fancy equipment.

Basics Components*

#DescriptionStoreSKUQty.
1Duracell 9-Volt Battery Two Pack*N/A1
29V Snap Connectors (5 PCK)270-324, 270-3251
3Linear-Taper Potentiometer (10k or 5k)271-1715, 271-17142
4Resistors (500-Piece Value Pack)271-0031
5TL082 (8-PIN DIP)TL082/TL082CP4 (2 + 2 extra)
60.01uF 10% Film Capacitor272-1065, 272-10511
70.1uF 10% Film Capacitor272-1069, 272-10531
8DPDT Toggle Switch275-666 or any other DPDT switch1
920 Assorted LEDs276-1622**1

Note*: If you want the raw BOM (Bill-of-Materials) instead of a RadioShack shopping list click here.

Note**: It is my personal recommendation to use brand name 9V batteries such as Duracell. RadioShack has it’s own brand of batteries that gave me trouble in the past.

Note***: We only need two LEDs for this project. They come in two per package under the following SKUs: 276-021, 276-209, 276-022. I recommend the 20 pack because it's a bargain in comparison and the LEDs will fry if you hook them up wrong, hence having extras is always good.

Tools and Materials

#DescriptionStoreSKUQty.
iHookup Wire (22AWG Solid)278-12211
iiSolderless Breadboard Jumper Wire Kit276­-1731
iiiBreadboard276WBU202 or any other breadboard1
ivWire Stripper/Cutter6400223, 6400224*, 64002251
vMini Long-nose Pliers64000621
vi­5-Piece Basic Soldering Set**
(not in figure)
64­-28021
vii­Rosin Core Solder (2.5 Oz.)
(not in figure)
64­-0051

Note*: Best option.

Note**: This project does not require any precision soldering. The simplest/cheapest iron will suffice. I’ll be using my Weller WESD51 Digital Soldering Station.

Oscilloscope/Poorman's Scope

To see the chaotic attractor you need an oscilloscope, and we can make a cheap one with these parts...

#DescriptionStoreSKUQty.
A3 Ft. Stereo Patch Cable, Dual-RCA Plugs to Dual-RCA PlugsRCA*1
B14" (35.3CM) Insulated Test/Jumper Leads278-11561
CBEHRINGER U-CONTROL UCA222**UCA2221
C1 Mega-ohm Resistor271-1356
***
1

Note*: You can get the same RCA cables at your local dollar store as well.

Note**: You can get a UCA222 online, however any USB Audio Adapters that has a stereo input will work. Some are sold in music instrument stores such as Sam Ash.

Note***:This resistor is actually in the bag of 500 resistors listed in the first table

<p>I saved the schematic. I will have to build one of these someday. I have all of the parts kicking around already so that saves me a trip to the Shack.</p>
<p>Great! Excited to see the results when your done.</p>
<p>Very nice project, next few weeks I&rsquo;m going to try synchronization and interaction with other units! </p>
<p>nice. did you use exact resistances? a few of my resistors are close but not exactly the resistances specified, and I'm just getting normal sine waves on both channels</p>
<p>Hey! Yes I used the exact resistances, if you get the periodic behavior try tuning the potentiometers! That is the fun bit!</p>
<p>How close? Post what resistors you are substituting and we can help you. Also what's the tolerances on them?</p>
<p>I ended up just getting the exact parts and it works! thanks anyway</p>
<p>Thank you carlosI55!! Keep us posted.<a href="https://www.instructables.com/member/carlosl55"><br></a></p>
<p>Cool!</p>
<p>Thanks mom. :)</p>

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Bio: I'm a researcher who wants to make experimenting with chaos accessible to everyone. You don't need to be a rocket scientist to dabble ... More »
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