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Mitch Richling: Simple Chaos Circuit

Author: Mitch Richling
Updated: 2021-09-15

Table of Contents

1. Introduction

The circuit explored on this page was the subject of the following paper:

Keuninckx, Lars, Guy Van der Sande, and Jan Danckaert. “Simple Two-Transistor Single-Supply Resistor–Capacitor Chaotic Oscillator.” IEEE Transactions on Circuits and Systems II: Express Briefs 62, no. 9 (September 2015): 891–95. https://doi.org/10.1109/TCSII.2015.2435211.

User @imo suggested I build this thing on the EEVBlog forum: https://www.eevblog.com/forum/projects/t20347/msg3619606/#msg3619606

2. Circuit

schematic.png

3. Simulation Results

v-t-plot.png

v-v-plot.png

4. Physical Implementation

s2tco_bboard_med.png

5. Behavior of Physical Circuit

This circuit is very sensitive. The movie below shows the behavior as the temperature of the second BJT changes from about 40 degrees Fahrenheit to about 75 degrees Fahrenheit. The data was captured with a Siglent Technologies SDS2504X Plus oscilloscope. The scope screenshots were captured directly from scope's VNC server.

ANNO_s2tco.gif

6. References

Check out the chaos in electronics section of my reading list. For more about chaos in general, take a look at the fractals section of my reading list.