@Circuitfantasist "IV curve does not depend on time. So, ... I use the simplest AC signal generator - the mains voltage reduced by a step down transformer, ." - Yes, that is the second silly conceptual mistake I made about plotting the tunnel curve. Your hardware setup using a transformer and one manual turn potentiometer looks backward, and I wrongly thought that if I used a high frequency triangular DC sweep, and used my US$300, 50MHz, 1GSs/s to watch the tunnel is slow motion, ...

I should see the electrons swimming inside the tunnel. It is only when I use the digital sig gen to create the 200 kHz triangle 0~0.8V sweep, then I suddenly realized that time is an independent variable. This why in the (deleted) CD comment/chat when I read about the Lancaster guy explaining the idea of "Appropriate Technology" then I understood your stupid looking mains 50Hz sine signal with one hand turn pot is most appropriate in our Galaxy, ...

Now I am studying the ADC part of the PCF8591 ADC/DAC module. I am glad to see the reference voltage range and analog ground can be hardware programmed, to setup ***a differential Vt voltage range (0V ~ 0.8V) *** for powering the tunnel diode.

Loading can be 100kΩ and 10k conversion rate. Everything looks OK. So I can start programming. The first function is to setAnalogOutputVoltage().

Interesting... I wonder if there is such a high speed scope to see the trajectory of the operating point during the jump...

I guess we should ask the physics blokes: physics.stackexchange.com/search?q=tunnel+diode

There is an interesting question there - Differential resistance vs. R = V/I. I would prepare an answer for it...