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I would like to build a low power, low budget Van der Pol oscillator and need some guidance doing so.

The wikipedia article shows a possible circuit design using a triode which is fairly expensive.

In another schematic from a physics book, the authors use a tunnel diode but my friendly eletronic components salesman told me that they are not mass produced anymore and therefore it wouldn't be easy to get one.

I guess I could use a microcontroller to simulate the tunnel diode but this feels like cheating (and is probably the most expensive solution.)

Then, there is the possibility to "simulate the underlying differential equation" using opamps as in the old days but this again feels like cheating.

Do you know of other/better/easier ways to build one?

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    \$\begingroup\$ You can still get tunnel diodes. I ordered a few from Amazon. They are usually "new old stock" rather than new parts. The ones I got were made in the Soviet Union. I paid about 10 Euros for four tunnel diodes. \$\endgroup\$
    – JRE
    Aug 2, 2021 at 14:05

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Simulator Microcap12 free

The structure of this circuit is a very old "analog computer" used in the past day ... which could "simulate" equations in real time, but also with "anticipating" results in a real feedback loop "industrial chain" !

Based on the Van der Pol equation, here is a circuit that can be used for simulation. Realization through hardware components (the most "difficult" is multiplier).

With this circuit, you can fix parameter mu used in equation and see what is happening. Time is "compressed" through the use of integrators with components R and C which must be the same for the two.

Another version may be build with a processor (micro as arduino) ...

Write only equations in delta (t), delta (x) form, and make "delta" as low you want for precision. Integrator is then only a "summer".

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