Since Chua's circuit appears to show the period doubling route to chaos, it is interesting to try to test the universality of this route.
Here are measurements of the capacitance (in pF) of a high precision capacitor making up part of C1 at the onset of the periodic orbits.
|
Period |
Capacitance C1 |
Difference |
Ratio |
|
2 |
1136.4 +/- 0.1 |
|
|
|
4 |
1104.6 +/- 0.1 |
31.8 +/- 0.15 |
|
|
8 |
1097.75 +/- 0.1 |
6.85 +/- 0.15 |
4.64 +/- 0.02 |
|
16 |
1096.0 +/- 0.1 |
1.75 +/- 0.15 |
3.9 +/- 0.1 |
The "Difference" column shows successive differences between the
capacitance values, and the "Ratio" column shows the ratios between
successive "Differences". i.e. (Cn-1 - Cn) /
(Cn - Cn+1 ) .This quantity should approach
the universal value 
= 4.6692016091.... Clearly the ratios
rapidly run out of precision as the period order increases and the
transitions get closer together - just where the constancy should get
better! The results do however appear to be remarkably consistent
(within two error bar widths) with the expected universal value.