Circuit Stories

This is my answer to the  SE EE question  about the famous "long-tailed pair". -------------------- Basic idea It can be revealed at а functional level by equivalent electrical circuits. In this brilliant circuit solution initially called with the figurative name "long-tailed pair", a total of three sources - two voltage and one current - interact like living beings. In some cases they help each other and in others they oppose each other like people in the game tug of war . Implementation The two voltage sources are implemented by the source followers Q1 and Q2. The current source (or, more precisely speaking, current sink ) is implemented by another transistor (not shown in the OP's circuit). So these sources are not actually true sources (producing power) but dynamic resistors that only regulate voltage and current (see more about this approach in another related question and answer  of mine). Conceptual circuit To simulate the circuit, actually we have to

This is my  answer  to this  SE EE question .  Here I have tried to show the similarities and differences between the two types of negative resistance - differential and absolute. -------------------- Why does voltage decrease when current increases? The OP said: "By negative differential resistance, I mean a circuit where the current decreases when the voltage increases." Well, true... But what is the physical meaning of this statement? How does this magic work? Is it something useful and therefore desirable? If so, what can we use it for? Let's understand it thinking as humans and explain it without using meaningless verbal clichés. Basic idea The purpose of a negative resistor is to do the opposite of what a "positive" resistor does, i.e. to add rather than dissipate power. True negative resistors do this by adding voltage in series or current in parallel from their own built-in sources. But how is the humble resistor to do so when it does not have that? The

This is my answer to this  SE EE question . I have been working intensively only on StackExchange for several months now; the current question is not over yet, and the next one arises. The scenario for the next answer ripens in my head, I sit down with the greatest pleasure to experiment with my beloved CircuitLab, and begin to arrange one schematic after another. I have the feeling that I am completely obsessed with it and have no time for anything else. Now I use the moment of a little lull to bring here one of my best stories. The interesting thing is that the idea for it was born three years ago in the midst of the pandemic. But then it all ended for me through a long chat. Early last year I started using CircuitLab, and this fall I decided to do an extensive answer with multiple simulations. Here is my story about the mystic true negative resistance phenomenon . -------------------- Some history Looking at the writing here, I nostalgically remember that anxious time of the pand