ltspice, simulate negative resistance, avalanche effect
This circuit will not work because the commonly used BJT's models in simulation tools do not support (model) the &quot;avalanche breakdown&quot;.
You need to download the Bordodynov's lib available here:
http://bordodynov.ltwiki.org/
And used the avalanche BJT's.


Additionally in real life, these circuits will not work with all small-signal NPN transistors. And will never work with PNP transistors. And it will not work with a low supply voltage. Therefore, you should treat these circuits as an interesting way of using the &quot;parasitic properties&quot; of BJT not intended by the designer. And this is for sure not a reliable solution.