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Project Chaotic circuits
Status Completed
Contact User:Gori
Last Update 2012-11-26

see also IgorsProjectIdeas

Build a simple electronic chaos demo for my course. Chaos can be observed using an oscilloscope. A portable one can be built with an arduino

Background reading

Version 2.0

Create the circuit that works at a lower frequency. Smith also describes a circuit that operates at 75 KHz instead of 2 MHz. Main bottle neck is the required large inductance

Goal is to:

  • Be able to hear the chaos
  • Have the whole thing portable, without the need for an external oscilloscope and signal generator
  • Have it nice and presentable so it can be used as a demo


  • Calculate the inductance and capacitance required to achieve a resonant frequency in the audible range, preferably around 440 Hz. Conservative human hearing range is from 20 Hz to 15 kHz.
  • Identify the operational limits of the arduinoscope - max seems to be around 200 kHz, well above audible range
  • Make sure that an arduino based scope can observe the signal.
  • salvage/build/buy an appropriate spool
  • create a suitable analogue signal generator that can drive the whole thing. Arduino can no do this, as it has no analogue circuitry for the job. PWM will (propbably) not do.
  • Add speakers in order to hear the chaotic harmonics under/overtones
  • package it is something transparent so that it makes a nice demo

Version 1.0

  • Following:
  • Working oscilloscope and signal generator present, capable of 2Mhz
  • Components according to the manual:
    • 200 ohm resistor
    • inductor, 100 microHenry needed, available a PE-53653 , with 16.1�H
    • diode - either works: 1N4001, 1N4004, 1N4005, 1N4007
  • As built, the circuit does not display any chaotic behavior as we change the amplitude, The inductor is almost 5 times to weak.
  • I have several spools, adding an extra spool in series, bringing the inductance up to 32 �H does not help.
  • When adding random spools, it is good to measure its inductance. Here is a way to do it:


  • 1N4007 diode
  • 220 ohm resistor
  • (2 x 16) 32 �H + a random spool (code 471K 98139)
  • Signal:
    • 1.5 MHz
    • Amplitude op 0 dB
    • sinus signaal
  • Improvements needed:
    • Calculate / measure the currently installed inductance, and bring it up to spec, so that we get a nicer signal split than now
  • With smedings help, we determined that the inductance of the three coils is 1351 uH or approx 1.4 mH