@Circuitfantasist Ah, (1) Tony's Q&A site is down (today) for indefinite time. (2) The Q&A site is only for short Q (guide line: 70 word with a picture/datasheet) and short A (Tony's A is only 50 words!). (3) I always prefer the Agile style, muddling through, chatting over, problem based learning/solving or case study approaches. I think a college level lecture and tutorial suits me better.

Also I am a picture guy. So your explanation of negative resistance jump over and load line is too abstract for me. So I prefer the following picture rather than abstract description:

USC's Prof Khan actually shows a series of slides/steps explaining the ideas of simple load line before finally arrive at the tunnel diode load line. His explanation of the TD I-V curve using a series of pictures (it would be nice to create an animated GIF, as I suggested) is also very good. I will show you the JPG/GIFs later

Now the animated GIFs we can borrow.

@tlfong01 Hi! The picture representing the unstable point 2 is nice... There is only a "small" problem - there is no such point:) During the "jump", the operating point does not pass through this place (point 2 does not belong the the trajectory). So, the picture is simply wrong. Please read carefully my expalnations about the bistable mode of the negative differential resistance - en.wikibooks.org/wiki/Circuit_Idea/….

So I have set up PCF9851 ADC/DAC to do the tunnel diode I-V curve tracing. Earlier I wrongly though that I needed a high frequency sweep of 200kHz, 0~1V, to catch the fast jumping over the negative resistance region. Of course the electrons quantumly tunneling through the P-N barrier do it in no time, but we can plot the curve point by point as slowly as we like.

In other words, I can use Rpi Thonny python to ask the PCF9851 analog output at a voltage level, and take our time to use two channels of the ADC to get the differential voltage across the tunnel diode.

Regarding the blog... I think it is good to keep it in parallel with other forms of publishing (SE and Codidact) because there are a lot of visitors and there are discussions...

I consider this phenomenon (and others circuit phenomena) at a "functional level" only... like in my WB story about NDR.

Let's return to the "magic" point 2 located at the negative resistance region... You can ask Tony to show this point in his simulation... if it exists... Try it, maybe this time it will answer you...

@Circuitfantasist Ha, thanks for pointing out my silly mistake of the non existent Point 2. Actually I am losing confidence of my thinking what is going on. Tell you one joke, I once mixed up the curve as a picture of the P-N junction, ie, left part of the graph is the real world P region, and right part is the real world N region. :)

I suggest to you to ask such a question in SE EE (and add it to your question in CoDidact) with this picture attached... I will answer with pleasure to you... and, in return I will probably get a lot of -1s ... :)

It will be a big "show"...

Are you talking about the USC Prof Khan's beautiful picture about the Point 2? Perhaps I would spend more time studying his lecture, especially on the load line stuff, and ask newbie questions later. In the mean time I will start basic testing of the AD/DA module PCF9851.

This is not your fault. I've seen this drawing since time immemorial, in the 80's maybe. That's how they explained it in the textbooks and that's how my teachers taught it to me.

Exactly, I am talking about this beatiful picture...

Ha, so the fake Point 2 is a third generation mistake!

I remember, it was somewhere 20 years ago, I really wanted to know exactly this - where the operating point moves when it "jumps" ... its trajectory ...

And I started asking my former teacher ... it was even during a department council ... And he answered me in this way and started looking at me badly because of my insights ...

My mind is still in a confusing state. I also forgot what you said about your Lancaster Elegant Simplicity transformer + 1k resistor + tunnel diode + Tektronic scope curve tracer. I have not kept a record of the deleted comments. It would be nice if you can give again the links of the your movies, Lancester stuff, I was sleeply when chatting those unthinkable stuff.

en.wikibooks.org/wiki/Circuit_Idea/… Read this explanation for the first "jump" and see how the point moves along the load line. But here it is horizontal, because I am examining the tunnel diode through a current source. In your case with a resistor, the load line will not be horizontal but inclined to the left as shown in the figure.

:)

By the way, do you also have any document on testing the ordinary diodes, like 1N4048, 1N4001 etc? I think I am over ambitious and running too fast. I am thinking of using my PCF9851 AD/DA to plot 1N4148, getting a smooth non broken curve, then go back to do tunnel diode.

Ha, I need to first read carefully the load line stuff, understand it inside out, before reading you unreadable hard stuff, I mean your tunnel diode WikiBook.

I have pictures and movies from the laboratory... Here are my students in the lab yesterday - photos.google.com/photo/…. But this was the last. From next week we only go online.

There you are, the "No sweep, but point by point, python programmable, tunnel diode I-V curve tracing hardware setup, ...

Completely in the spirit of the new time .... Okay, I'm leaving you now and I'm going to do some tasks. It's almost noon here now. Surely it's evening there?

Thanks for the movies, I will watch them later. It is almost supper time. I will jog a bit to settling down my overheated little brain, and eat, .. See you later.

Ah I forgot one thing, that is about the remote online physics lab in an US college, where their students can remotely turn the "knob" of real instrument in the lab and get the results. I should search the link and put it in the tunnel blog. No my Secret Plan - The reason that I divert from the first version of using manual digital button to adust PSU for Vt, and also the triangular sig gen is that they cannot control remotely.

Now my last version is Rpi python controllable, so I can set up a web server, with a web cam etc, and my bad lock down maker friends can use their smart phones, log to my "lab-from-home" show of electrons jail breaking through the tunnel of a diode, quantumly, in no time, ｓｏ　ｍｙ　ｂａｄ　ｆｒｉｅｎｄｓ　ｗｏｕｌｄ　ｎｏｗ　ｒｅｓｐｅｃｔ　ｍｅ　ｍｏｒｅ　ｔｈａｎ　Ｉ　ｄｅｓｅｒｖｅ，　．ｓｏｒｒｙ　ｆｕｎｎyｙ　ｃｈａｒ　ａｇａｉｎ，　ｂｙｅ．

@Circuitfantasist Your photo library link seems broken. Please send another one.

photos.app.goo.gl/TP1Jpza7UWZfvsx17

Now I have drawn the schematic, before doing python programming. tunneldiode.blogspot.com/2020/11/blog-post_1.html

@Circuitfantasist Ah, I think this chat room is open to all users．

Ｈｏｗ　ｃｏｍｅ　ｊｕｓｔ　ｏｎｅ　ｐｈｏｔｏ？

Ａｈ，　Ｉ 　ｔｈｉｎｋ　ｎｅｅｄ　ｔｏ　ｒｅｇｉｓｔｅｒ　ｔｏ　ＥＥ　ＳＥ　ｆｉｒｓｔ．Ｓｔｉｌｌ　ｆｕｎｎｙ　ｃｈａｒａｃｔｅｒｓ．　Ｉ　ｈａｖｅ　ｎｏｔ　ｆｏｕｎｄ　ｏｕｔ　ｈｏｗ　ｔｏ　ｇｅｔ　ｒｉｄ　ｏｆ　ｔｈｅ　ｆｕｎｎｙ　ｃｈａｒａｃｔｅｒｓ．　Ｐｅｏｂａｂｌｙ　ａ　Ｃｈｉｎｅｓｅ　Ｗｉｎｄｏｗｓ　Ｌａｎｇｕａｇｅ　ｂｕｇ．

Now I am using FireFox and so far so good. I found my Chrome write funny characters in EＥ．．．　Ａｈ　ｂａｄ　ａｇａｉｎ，　ｅｖｅｎ　ＦｉｒｅＦｏｘ　ｈａｓ　ｐｒｏｂｌｅｍｓ，　ｂｙｅ．

Ｙｏｕ　ｍｉｇｈｔ　ｌｉｋｅ　ｔｏ　ｉｎｖｉｔｅ　ｙｏｕｒ　ＥＥ　ｓｔｕｄｅｎｔｓ　ｔｏ　ｊｏｉｎ　ＥＥSE and, OMG, normal char again.

You might also like to invite your students to visit my newly opened tunnel diode blog. They are most welcome to browse and leave messages and ask questions. The funny chars seems gone. I will go back to Chrome and try my luck again.

Ｓｔｉｌｌ　ｃａｎｎｏｔ　ｇｅｔ　ｒｉｄ　ｏｆ　ｆｕｎｎｙ　ｃｈａｒ　ｉｎ　ＥＥ　ＳＥ．　Ｐｅｒｈａｐｓ　Ｉ　ｓｈｏｕｌｄ　ｔｅｌｌ　ｅｖｅｒｙｂｏｄｙ　ｍｙ　ｔｕｎｎｅｌ　ｄｉｏｄｅ　ｔｅｓｔｉｎｇ　ｐｌａｎ　ｉｎ　ｔｕｎｎｅｌ　ｄｉｏｄｅ　ｂｌｏｇ．