My thoughts extracted from a discussion with TL Fong

At the beginning of last month, I had the good fortune to meet TL Fong in SE EE. A very interesting discussion started between us which continues to this day and has no prospect of ever ending... Obviously we liked each other and encouraged each other to generate new circuit ideas. Our conversations somehow multiply my creative abilities... make me think, over and over again, about great circuit ideas... understanding them better... and finding better explanations...

Interesting thoughts are born during our discussions and I decided to extract and collect my most significant "pearls" in this post. They are numvered, subtitled and arranged in a chronological order from earliest to latest.

My thoughts

1. My philosophy. I am by vocation an inventor, a teacher and above all a "circuit thinker". I try to find basic ideas behind circuits... and it takes me years. Then I explain circuits by building (reinventing) them step by step and showing their evolution. I do it by using human-friendly explanations, analogies... and by visualizing the invisible electrical quantities. My circuit diagrams are conceptual but then I show various applications. But I cannot find followers. Why?
2. Learning through Arduino. Although for the "Arduino boys" your answer is great and very useful, for me it is quite specific. Here you can see some basic circuit ideas that are inherently electrical and were realized long before the "Arduino era" - even in the 19th century (well, not with transistors but with electromagnetic relays). Arduino is just one of many possible implementations of these basic ideas and all these details interfere with the understanding of the simple and clear (electrical) idea. It turns out that today people get acquainted with the basic ideas of elementary electrical and electronic circuits through Arduino.
3. The power of concepts. My purpose is first to reveal and explain the basic ideas behind circuits (concepts). I do it by using conceptual circuit diagrams with "ideal" and generic elements without specific values. Only then I show some specific implementations as examples. The power of this approach is that once understood the concept you can understand many other specific implementations. In contrast, if you explain only the specific implementation and not the principle behind it, then you will have to explain each next implementation. In the first case, you will know (understand) only one principle, while in the second you have to remember many different implementations.
4. My vocation. I have developed microprocessor devices but that was a long time ago. Gradually, I realized that my vocation is in finding powerful and simple intuitive explanations of basic electronic circuits. For years I have been looking for an answer to the question not only HOW they were made but also WHY they were made this way... and I was able to come up with reliable explanations. So if you feel the need to understand the idea behind op-amp inverting circuits, bootstrapping, dynamic load, negative "resistors" and other circuit phenomena, I can share it with you.
5. Negative reactions. This is what I am actually trying to do here in SE EE but I meet fierce resistance from my peers and I am forced to do it in a hostile environment. Reactions range from passive (silence), negative (-1) to aggressive (hiding, closing, deleting and ultimately burying my questions and answers). Regarding why OPS beginners find it difficult to understand my explanations, the explanation is very simple - they do not have the attitude to think that way.
6. SE EE example. Here is just one of the latest examples where I have explained the behavior of a diode (in this case LED) at the lowest possible and understandable (even by a non-professional) level. The existing explanations are on a higher and abstract level - something like "when the voltage approaches the LED threshold, the current starts to rise sharply" ... which is not actually an explanation but an observation. But why is the current rising? The next "explanation" is "because the IV curve rapidly changes its slope". In contrast, my explanation is based on a simple but powerful concept - "dynamic resistance". It is easy to understand (variable resistance), demonstrate (humble rheostat) and apply to any nonlinear element (diode, transistor, negative resistor...)
7. "Common collector" is reserved for AC (small-signal) applications when the base and emitter voltages vary but the collector is firmly fixed to VCC. Here we are talking about digital applications where the base voltage is fixed at zero or VCC.
8. Simulation. I know I have to use simulating software but I do not use it for a variety of reasons. First, I have to work hard to master it so that it is useful to me. Second, I know I am going to start thinking less about circuit phenomena. Third, it will reduce my enjoyment of mentally finding a solution. But sometimes I do some real experiments to test some of my assumptions.
9. Seeing the forest behind the trees. Saying "philosophical" I mean "conceptual", "generalized"... Most people think specifically and do not make a connection between the individual specific implementations of the same idea. As the saying goes, "they can't see the forest for the trees." Understanding a circuit requires seeing the general idea behind it.
10. Looking for co-thinkers. These op-amp resources are good but standard. I need more in-depth explanations from people who have a "philosophy" and want to share it. Unfortunately, I can't find any, so I've been trying to make it myself for years.
11. A little history. Look at the inverting amplifier. Do you understand what is the need of R1 and R2? I was trying to answer this question as a student in the middle 70s.
12. Flash movies. Regarding Flash... I created circuit-fantasia.com in 2002 in cooperation with Poptronics (the former Popular Electronics). It had to be impressive to attract readers. Macromedia Flash was the most powerful tool for creating interactive animated stories. And really, they became (too) impressive. Now I have no idea what to do. I wonder if there is some way to convert them to something workable. Inside the site, there are ordinary HTML pages, e.g. Circuit stories on the whiteboard or My students 2004.
13. My passion. These are great miracles but simple circuit phenomena are my passion. I am currently developing my next inventor's story only with the help of my experience, imagination, sheets of squared paper and colored fiber pens:)
14. Dave's movies. It's a big show with a lot of words and gestures, something like a Hollywood movie. He says many things but explains almost nothing ... or he does it on the usual formal level. In other words, "Much Ado About Nothing"... But I have watched it briefly... OK, I will watch it to see if there is something different in its content (not the form) than the usual web texts.
15. The art of explaining. My circuit diagrams look "a bit messy" because my goal is to provoke student's (reader's) creative thinking. If I had time and space enough to expose my idea (because I always have an idea to explain), you (readers) would understand all. This can't happen here in SE EE but I have done it on my site, in Wikibooks and ResearchGate. The true understanding of circuit ideas requires a very good contact with the person you are explaining to and goodwill on his/her part (what is missing here). My students always understand my explanations in the lecture hall and the laboratory because there is a very direct connection between them and me... and I don't stop explaining until I'm sure they understand me.
16. Where currents flow. I will share wisdom with you because you are benevolent and want to understand my way of thinking. It reads as follows: To truly understand the idea behind a circuit, you need to know where the currents flow inside it. Each current starts from the positive terminal of the power supply and returns there to its negative terminal. That is why I present the currents with their full loops (in green, from the association with running water).
17. What voltages are. Also, to truly understand the idea behind​a circuit, you need to know what the voltages across its elements are and the connection between them. That is why, I present voltages "geometrically" by voltage bars (in red). They can be easily summed according to KVL thus showing the relation between them. This geometric way of presentation is much more visual than the digital way used in simulation programs with very varying digits after the decimal point... which is meaningless for the purposes of understanding.
18. Meeting Bob Duhamel. I took an hour today to watch this RSD movie. This guy gave me pleasure because he made a live demonstration of the operation of the inverting amplifier that I have been using since the 80's. I think I have something to say to these guys (he and Dave) as long as I can make contact with them. I look for such people on the web who understand circuits but I still can't find them.
19. The simple idea behind the inverting amplifier. Then I began watching Dave's movie about op-amps -  but I didn't last until the end, I'll watch it some other time. What he tries so hard to explain (inverting amplifier) ​​is very easy with a simple demonstration. Two variable voltage sources (the one is the input voltage source, the other is the op-amp output) of opposite polarity are connected to each other through a network of two resistors (R1 and R2) in series.
20. Artificial differential resistance. Regarding the SE EE question, this is a typical example of how a simple idea can be presented in an insanely complex way to become a scientific article. It seems to me that this idea is familiar to me, perhaps from diode functional converters with a segment approximation... or from my LED voltage indicator. This is an example of artificially created differential resistance. Actually it is "over dynamic resistance" (I have explained it in Circuit Idea). Well ... I decided to sacrifice an hour of my precious time to write a in-depth answer although no one will appreciate it there...
21. Bob DuHamel vs me.  I became very interested in Bob DuHamel because I find that we look at circuits in the same way. The only difference between us is that his explanations are more specific and oriented to technicians, while mine are more general and "philosophical" and intended for creative thinking people (inventors, students and curious people like you). My explanations can also be useful for professionals but they have great self-confidence and are envious. Just look at how he presents diodes and transistors as dynamic resistors. Maybe he borrowed some of my ideas...
22. How the tunnel diode "jumps". OK, I will say to you another wisdom as a reward for your curiosity. As you can see, there is no explanation about how the tunnel diode "jumps" over the negative resistance region in Fig. 7.1. (not only here but everywhere). They only say that it "jumps" but not explain how it "jumps". Here is the geometric trick. The intersection point between two curves (the IV curve of the tunnel diode and the load line) is what is called an "operating point". If you look at my pictures, you will see that actually, it is an intersection point of two lines. Initially, the load line moves horizontally (translates) and the line representing the static diode resistance R stays immovable. When the intersection point reaches the peak, this line begins vigorously rotating while the load line stays immovable. So, the intersection point quickly moves (slides) along the load line... this is its trajectory.
23. The "jump" trajectory. 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 to the trajectory). So, the picture is simply wrong. Please read carefully my expalnations about the bistable mode of the negative differential resistance. 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. 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...
24. Horizontal "jump". 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.
25. The Lancaster's "elegant simplicity". Regarding the Schmitt oscillator, look at my explanation here where I have shown that there is no negative feedback in this op-amp circuit (although there is a physical connection between the op-amp output and inverting input).
26. How to measure the IV curve. I hope you already have realized that the IV curve does not depend on time. So, you can measure it by any kind of input signal (triangle, ramp, sine, etc.) Also the frequency of the signal does not matter ... and as I already wrote, you can even use a DS signal (for example, produced by a potentiometer) if the scope is digital with memory. Since scopes in my laboratory are analog type, I use the simplest AC signal generator - the mains voltage reduced by a step down transformer.
27. MICROLAB. Of course, the most professional solution is to generate the signal through a microcontroller and DAC as you have decided to do. I realized this idea in 1986 through a personal computer (MICROLAB system). This was an AD interface implemented by 4 12-bit DAC 1200 (National semiconductor) and an ADC with 4-input analog multiplexer - see the block diagram and the construction of the laboratory setup. Here is an example of measuring an IV curve of a Zener diode.
28. About the envy. Regarding the forum... The problem is not short questions... neither short answers... neither long discussions... These are just forms of knowledge transfer. It is not the form that matters, but the content. The main problem is the envy that arises in those who know but do not understand circuits. It makes them interrupt such valuable discussions under questions and answers with meaningless remarks such as, "This is a site for questions and answers, not for discussions," and more...
29. Differential amplifier vs differential resistance. They are different concepts. In a differential amplifier there is a difference between the voltages applied to two points (inverting and non-inverting input); in the differential resistance there is a difference between two values of the voltage applied across a dynamic resistance.
30. Op-amp name. In the past, op amps have been used to implement mathematical operations in analog computers; hence the name "operating". Today it is synonymous with "quality", "perfect", "almost perfect"...
31. The "elute". Hmm... very precise observations on the nature of the "elite". I also have rich observations and practice in this field... I can say that I have become almost a psychoanalyst... and a psychotherapist:)
32. The meaning of downvotes. I completely share your opinion on the negative votes. I even thought to warn readers to interpret them in the opposite sense - the more they are, the higher reputation I have ...
33. First interest in a blog. I would like to ask you about the blog as another tool for saying what you know... As far as I can see, it's like a diary that shows your thoughts chronologically and your development and progress. I like this because I like to illustrate circuit ideas through my thinking as a concrete example. I do it by "building" and "reinventing" scenarios.
34. Longing for a change. Interesting observations on the behavior of the "elite"... I also observe how certain groups consolidate against the "common enemy" and help each other... All this is unworthy and insulting because we are here led by goodwill. This started to make me nervous and I am already thinking about what I can change. I realize that you have to have something of your own so that you don't feel like a "guest" in a foreign place.
35. My web places. I have had a site since 2002 (circuit-fantasia com) but I no longer want to keep it at a low level (html). I am looking for a simple form to publish my ideas. Wikibooks is a rather cumbersome publishing system and has no feedback from readers. Discussions in ResearchGate are weak. Question&Answer sites like this one allow some awful people to make fun of you in all sorts of ways. The new site has restrictions... Your blog caught my attention as another possible form of publication. 
36. An interest in Google blogger. I think the free Google blogger is the best solution. I would like to ask you about the internal organization. I can make a few sections: Circuit stories, SE Q&A, RG questions, etc. How will they appear - as different blogs, pages, posts or something else? Will I be able to move them and insert them into each other? In other words, can I structure the content?
37. A need of a discussion forum.  Your links make me think about more and more things and realize them. I think we have a need for an open discussion forum. Indeed, these Q&A sites are very limited... But they give very interesting ideas to discuss...
38. My old drawing technology. You can say the same to Bob Duhamel... but as you can see, he uses an even more primitive tool - a whiteboard and a marker... About my old drawing technology... you can say the same to Bob Duhamel... but as you can see, he uses even more primitive tools - a whiteboard and marker... There must be some reason for that...
39. Starting the blog. I have created my profile page and five blogs. It does not allow me anymore (is that the limit?)
40. My circuit diagrams are conceptual; their role is to show the basic idea behind the circuit... not how to implement a specific solution. Voltage bars and current loops are my specific tools visualizing the invisible electrical quantities voltage and current.
41. My notation. I still can't understand what is my "strange notation". What are you talking about? Voltage bars (the "red lines" as Olin contemptuously said in his only comment below my articles) and current loops? If so, yes... it is strange since it is something original. Every new idea is strange for the conventionally thinking (or simply "non-thinking") people... I do not want to use "arrows"; I want to use exactly bars and loops...
42. Realizing the blog functions... I have finally realized that I need a blog... and that the chronological order of posts is not so bad... My idea is to use the blog as a common place for my materials (past, present and future). I will accompany them with additional info how they are created... and the circumstances around them. It is going to be an interesting activity...
43. ...blog structure. Maybe I will create a page with internal links pointing to posts and place a button on the homepage to it... as some navigation... Only, the "project" will never finish...
44. ...and post structure. I am not sure if you understood my great idea to regularly place next my (old, present or future) material and to tell in the intro how it was born, how it was accepted, what was its fate, etc.
45. A new topic - ECG amplifier. I have no experience in ECG circuits but I know they are very sophisticated. But I would be happy to figure out the tricks used in them. Here is how I have explained, with a lot of imagination and intuition, the so-called right leg driven circuit. As you can see, the idea was rated with 0 reputations while the elite received a dozen of them for a dry and formal explanation... This is a good illustration of Einstein's thought that I used as a motto at the top of my Wikipedia user page.
46. Right leg driven circuit. You made me think again about the exotic right leg circuit... I needed time to remember the idea behind this odd arrangement. I will reorganize my answer there and will create a post here about it. Now I'm moving to the blog to reply to your interesting comments there. Maybe I will redraw the conceptual circuit diagram...
47. Curve tracer. OK, this is a possible solution. In Lancaster's "elegant simplicity", a neon lamp serves as 7414. You can see the general idea in many everyday situations. Now, you need my 90's V-to-I module - a buffered inverting amplifier with a tunnel diode in the place of R1. I will publish a paper and post about it... also, about the "simplest IV curve tracer"...
48. About TL Fong. Again, I admire your gift for expressing yourself warmly and in such a human way. This is very rare on the web ... as if people there have lost their ability to communicate naturally ...
49. A theorist or a practitioner? Regarding the emphasis on "theories"... Maybe the reason is in me simply because I was created that way - to look for the idea and after revealing it, to explain it to others. At the same time, I am a practitioner. For example, yesterday I changed the timer of the stair lighting in the building where I live. For this purpose, I did some experiments with the buttons on the floors to find out if they are working. Also, I had to figure out the idea of the timer to make sure it was damaged. Of course, these are simple but still practical skills that require some intuition and experience... especially since it is not safe...
50. Virtual ground... It is a simple but difficult to understand concept. I myself continue to look for an even simpler explanation of this phenomenon... but in a more general form...
51. ... presented as a "voltage copy". Ok, let's try to explain it in a simple possible way: "Virtual ground" is simply a "voltage copy" of the real ground; this is the essence of the virtual ground phenomenon…So, to create such a "copy", you simply need a voltage follower. Connect its input to the real ground and take the virtual ground from its output. The simplest voltage follower is an op-amp whose output is connected to its inverting input. Thus, the output voltage is subtracted from the input voltage at the non-inverting input... the difference is amplified many times and appears at the output... and so on so forth…
52. Empathy. This can be explained in a human-friendly manner by personalizing the op-amp. Figuratively speaking, the op-amp "compares" the voltage at the inverting input with the voltage of the non-inverting input and changes it until the former becomes equal to the latter.
53. Follower inside the inverting amplifier. From this perspective, every op-amp circuit with negative feedback contains a follower (another wisdom which cannot be found in "reputable" sources). Even the inverting amplifier contains a non-inverting follower inside - the voltage of the inverting inputs, as above, copies the voltage of the non-inverting input... and, if the latter is zero (real ground), the former will be zero as well (virtual ground)...
54. Putting R2 as a disturbance. If we put a resistor (R2) in the connection (negative feedback loop) between the output and the inverting input, the op-amp will continue keeping a zero voltage of the virtual ground.
55. Where is the input voltage here? We include it to this following system as a "disturbance" (another wisdom). For this purpose, we connect the "disturbing" input voltage source through a resistor (R1) to the virtual ground. The op-amp reacts to this "intervention" by raising its output voltage... and we use its "reaction" as an amplified output voltage. But there is a virtual ground as before...
56. My lab. The equipment in my lab is quite old. There is a need for modern digital oscilloscopes and functional generators. But because I am an "old war horse", I can handle any situation. In terms of dressing, these students now have the freedom to dress as they wish. And at the time I dressed modestly. But in general, Bulgarians and especially women pay attention to their appearance... also to the home and the car . I think this is typical for small nations.
57. The simple idea behind the inverting amplifier. I will try to explain the inverting amplifier in another nonconventional way (you can find millions of conventional ways on the web). The general idea of this circuit solution is to set two voltages (input VIN and output VOUT) in some proportion, e.g., VOUT/VIN = 100. Then we say that VIN is amplified 100 times (with gain of 100). VIN is an external voltage; so we have to change VOUT so that it is always 100 times higher than VIN.
58. "Resistor scales". For this purpose, we compare the two voltages by a network of two resistors in series whose resistances R1 and R2 are in proportion R2/R1 = 100. This is a passive summing circuit with weighted inputs (1:100) that can be thought of as a kind of "electrical scales" or a "mechanical lever" (Bob Duhamel has such a movie)...
59. Wikibooks experiment. In 2008, my students and I created a Wikibooks story about this "elegant simplicity". At the end of the story, we showed how an inverting amplifier is made by this network...
60. Virtual ground. Let's continue this amazing story about the legendary circuit... To compare the two voltages, we have to subtract them. So, VOUT should be with opposite polarity. Then we change VOUT until the result of the comparison (subtraction) - the voltage of the middle point between the resistors, becomes zero... and we do it continuously. This point behaves as a ground although it is not a ground; that is why it is called "virtual ground"In the circuit of an inverting amplifier, the op-amp does this donkey work". It "observes" the virtual ground and changes its VOUT so that to keep zero voltage at this point. As a result, VOUT/VIN = -R2/R1 = - 100.
61. "Living" voltage diagram. Here is an attractive movie about the "living voltage diagram" - ... a very sophisticated experiment. And here is the explanatory text from the WB story above: "Software. Now let's start a program that can visualize the voltage diagram on the screen as a "living" animation. For this purpose, the program makes computer "interested" in the local voltages in three key points - the left resistor's end point, the slider intermediate point and the right end point. Let's then satisfy its curiosity:) by connecting, for a start, the DAC1's output to the ADC1's input and the DAC2's output to the ADC2's input; then, connect the ADC3's input to the slider. We can control the output voltages of the two DACs by the keyboard arrows; thus the two DACs act actually as programmable voltage sources. The computer continuously measures the three voltages (VIN1, VIN2 and VIN3) and draws three voltage bars whose length is proportional to the voltage magnitudes. Finally, it connects them with a line representing the envelope of the voltage diagram. Here is another but shorter movie on the screen. Do you see any connection between this geometrical interpretation and Bob Duhamel's "video using a ruler with a lady"?
62. "Living" load line. I meant my movie showing a "living voltage diagram" on the screen of Apple II... It gives a very good notion about the R1-R2 network that is widely used in op-amp circuits... BTW, in the early 90s, I was interested in TURBO PASCAL. Then I made a similar attractive experiment - "living load line". It was implemented on the base of a data acquisition system inside an IBM PC. I have printed screenshots.
63. The resistor notated by "Rf" is misleading since it is not only the resistor constituting the feedback network; both resistors make it (they form a voltage divider driven from the side of the output). Maybe "Rout" is more correct. I prefer to use "R1" for the input resistor (between the source and "-" input) and "R2" for the output resistor (between the op-amp output and "-" input). Of course, I always use drawings in my explanations but here it is not convenient.
64. Writing was interesting for me when I was younger... Now I am mainly interested in the content and less in the form of its expression. But yesterday I was thinking about something related to this - isn't it possible to somehow integrate text and graphics into one... let them be one thing? Because this reference from text to figure is very artificial... and the way of implementation is very different. I wonder if hieroglyphs are a more integrated way of conveying content. I don't know, maybe you will say ... This must sound very naive. In fact, I do something similar by describing a picture in words and by suggesting text in a picture...
65. The problem with Flash player. I found some solution to the problem with my Flash movies. I made them as executable files that contain a Flash player in themselves. They are full-fledged Flash movies.
66. This post. Today I started writing a big new and very interesting post (this text) about our chat here. Interesting thoughts are born in our conversations and I decided to extract and collect my most significant "pearls" in a post. I hope you will approve my idea.
67. The discussion. If you want, you can make a reciprocal post about your ideas. I just wonder how it is possible for a discussion with only one interlocutor to be so many times more fruitful than the many questions and answers on these sites?
68. Text vs picture. Your idea of mixing text and picture is very interesting. Flash provided great opportunities for such tricks and I was very fond of them.
69. "Living" IV curves. Your idea about IV curves is very interesting. As I probably mentioned, in the 90s I conducted an interesting experiment where two imposed IV curves lived on the screen. I intend to write a story about this experiment that will be illustrated with printed screenshots.
70. The magnitudes of quantities can be coded in various manners if only there is a good attitude towards this visualization technique. But when someone writes to you that these "lines" prevent you from seeing the diagram, what do you have to do?
71. Voltage bars are interdependent and the sum of the voltage drops across the elements in series is equal to the supply voltage (a "geometric KVL"). They do not always match the resistors, especially if the voltage drops are with a negative polarity. But this corresponds to the real situation. I had an idea to use them as an output of a simulating program... and even suggested it...

(to be continued...)