Troubleshooting a Chaotic Circuit for Lab Testing

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Discussion Overview

The discussion revolves around troubleshooting a chaotic circuit, specifically Chua's chaotic circuit, in preparation for lab testing. Participants explore issues related to voltage readings, oscillation behavior, and the use of oscilloscopes for accurate measurement.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant reports no voltage on one side of the circuit and questions whether this is due to frequency or a potential error in setup.
  • Another participant requests a circuit diagram and suggests verifying the wiring and power supply voltages on the ICs as a starting point.
  • A schematic of the circuit is provided, along with a description of Chua's diode and its function.
  • Concerns are raised about the ability to detect oscillation using a multimeter, with a suggestion to wait for oscilloscope measurements for confirmation.
  • Participants discuss the affordability and availability of oscilloscopes, including digital and handheld options, while emphasizing the importance of checking connections before lab testing.
  • A participant expresses intent to experiment with different resistor and capacitor values, explaining the choice of a breadboard over a PCB for flexibility.
  • There is a question regarding the capabilities of the chosen oscillator, specifically about its ability to graph in three dimensions.
  • Clarification is provided that oscilloscopes do not graph in three dimensions, although some may have a Z input for trace brightness modulation.

Areas of Agreement / Disagreement

Participants express differing views on the cause of the voltage issue and the oscillation behavior of the circuit. There is no consensus on whether the problem lies in the circuit setup or the measurement method, and the discussion remains unresolved regarding the effectiveness of the multimeter for detecting oscillation.

Contextual Notes

Limitations include potential missing assumptions about circuit behavior, dependence on specific component characteristics, and unresolved questions about the oscilloscope's capabilities.

Lasha
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So I built this circuit(Chua's chaotic circuit) and I have to take it to the lab for plugging it to oscilloscope.I need to make sure it works, cause I won't have any time there to fix it or rebuild it.So when I i tested it with the multimeter,there was no voltage on the left side and there was a voltage of a constant value on capacitors(I checked the connections and everything is okay).So is this because of the frequency? Or am I doing something wrong?(Note:left side has to behave like an inductor)
 
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Could you supply a circuit diagram?

Check all wiring. The power supply pins on the ICs should have the right voltages on them. These stay constant so they are a good starting point.
 
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This is the schematic:
chuas_circuit_realized_labeled2_with_batteries.jpg
.

This is the function of a chua's diode, g(x)is resistance vs current:

chuas_diode_nonlinear_resistor_graph_nondimensional.jpg

This is the double scroll

analog_double_scroll_attractor.jpg
:

Yes, but shouldn't it oscillate?I highly doubt its a connection problem.
 
Last edited:
You can't tell if something is oscillating when you use a multimeter. You might get a reading on AC volts but these ranges are often pretty insensitive.

So, you may have to wait until you get an Oscilloscope connected to it.

Incidentally, you may be surprised how cheap oscilloscopes can get.

Digital oscilloscopes from China have entered the market and that leaves a lot of unused, perfectly OK analog oscilloscopes available.

There are also plenty of handheld oscilloscopes like this one:
http://www.ebay.com.au/itm/Mini-ARM-NANO-DSO201-Digital-Storage-Oscilloscope-Handheld-Digital-Pocket-Sized-/221192769564?pt=AU_B_I_Electrical_Test_Equipment&hash=item33801dd01c

I don't know if you would find $70 expensive or if the 1 MHz bandwidth would be a little too low in performance for you.

In the meantime, I would really check those voltages and connections. I don't trust breadboards, so the time to find any problems is before you leave home.

I saw a report that said those circuits were difficult to get going, so it will be interesting to see how you get on.
 
Last edited:
vk6kro said:
You can't tell if something is oscillating when you use a multimeter. You might get a reading on AC volts but these ranges are often pretty insensitive.

So, you may have to wait until you get an Oscilloscope connected to it.

Incidentally, you may be surprised how cheap oscilloscopes can get.

Digital oscilloscopes from China have entered the market and that leaves a lot of unused, perfectly OK analog oscilloscopes available.

There are also plenty of handheld oscilloscopes like this one:
http://www.ebay.com.au/itm/Mini-ARM-NANO-DSO201-Digital-Storage-Oscilloscope-Handheld-Digital-Pocket-Sized-/221192769564?pt=AU_B_I_Electrical_Test_Equipment&hash=item33801dd01c

I don't know if you would find $70 expensive or if the 1 MHz bandwidth would be a little too low in performance for you.

In the meantime, I would really check those voltages and connections. I don't trust breadboards, so the time to find any problems is before you leave home.

I saw a report that said those circuits were difficult to get going, so it will be interesting to see how you get on.

Thanks for the advice, I'll post an update on how it worked out.The reason I chose the breadboard
over a PCB, was that I'm planning on experimenting(different combinations and values of resistance and capacity)
As for the oscillator,I'm planning on buying the Sinometer ST16B 10MHz oscillator,cause price difference is only 100$,but quality looks a lot better.Only problem is that it says "X Y mode" does that mean that it can't graph in 3 dimensions?
 
You can't "graph in 3 dimensions" on any oscilloscope. Some scopes have a "Z" input channel that modulates the brightness of the trace as it is being drawn, but that's not the same as creating 3-D graphics.
 

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