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    Thevenin equivalent circuit

    The circuit is easy to solve by the nodal method. You have one unknown node and one equation. The answer is a simple integer. Can you set up the single node equation and solve it? Don't let the dependent current source throw you off. Ratch
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    torque question

    What speed is 5 km? That is a distance. Assuming no friction except for gripping, one can coast without using any power on a level surface. Calculate the power needed to climb the incline and solve for the torque. Can you take it from there? Half the torque needed if you have two wheels...
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    Vacation

    To the Ineffable All, I will be on vacation starting tomorrow. Be back toward the end of February. Ratch
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    Simple mesh or junction method

    Yes, you are completely wrong. All the values of impedance are given for each component, so you don't have to calculate them. You never did indicate what you are trying to calculate, by the way. I don't understand what you mean when you slay that the voltages and currents have to be phase to...
  5. R

    Simple mesh simple problem

    Where is Vs2? I don't see it anywhere. Anyway, Vs3 is drawn backwards. Switch the voltage polarity and the voltages will come out correctly,. Ratch
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    Help me calculate output impedance

    I believe that equation will have to be modified if an external base resistance (Rb) is present. Ratch
  7. R

    Help me calculate output impedance

    You have a point. I should have used capital letters to designate the external base resistors (Rb), the external emitter resistor (Re), and source resistance (Rs). My analysis disregards the internal resistances of the transistor diodes (rb and re) because they are usually small compared to...
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    Help me calculate output impedance

    First of all, you should read this thread and learn about the PIT or GIT https://www.electronicspoint.com/threads/output-resistance-of-equivalent-op-amp-circuit.278977/ . For your circuit, rs = source resistance, and rb = r1||r2 . Applying the PIT below, rout is calculated. Note that rout...
  9. R

    Hacking Nodal and Loop Analysis

    Easy. Count the number of loops and nodes. Then use whatever is the smallest number. Each loop or node takes an equation, so fewer equations is easier. Ratch
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    Math Question, How Do You Really Figure This Out

    If you want to calculate directly what the current will be at the supplied voltage and a particular external resistor, you have to know the logarithmic I-V equation of diode. Each diode has a slightly different equation due to manufacturing inconsistencies. There is a branch of mathematics...
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    Vacuum Tubes

    Yes, and the filament is an energy hog. Ratch
  12. R

    Vacuum Tubes

    Both FETs and BJTs are transconductance devices. Ratch
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    Second order filter - quadratic formula and standard normalized form

    Sorry, I meant for the reply to go to Jonathon56. I am saying that a quadratic equation has two solutions, not one as he stated. Ratch
  14. R

    Second order filter - quadratic formula and standard normalized form

    What makes you think that the "standard normalized form" has only one frequency? Ratch
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    Vacuum Tubes

    Both FETs and BJTs function as a transconductance amplifiers. The charge carriers in vacuum tubes are electrons only (unipolar). The charge carriers in BJTs are both electrons and holes (bipolar). The charge carriers in FETs are either electrons or holes, but not both (unipolar)...
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    Understanding Positive and Negative charges

    An atom is the smallest unit of matter. Its constituents are electrons, protons, and neutrons. These three atomic particles are thought to consist of still other subatomic particles. The movement of electrons, protons, and neutrons cannot be thought of as abstract concepts, because they have...
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    Good Resource For Learning Bjt Transistors And Amplifier

    It is because most folks parrot what others have said before instead of checking and confirming something for themselves. Another good example of that phenomena is thinking that Ohm's law means E = I R. Ohm's law is really a property of a material, specifically the linear resistance. E = I R...
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    Good Resource For Learning Bjt Transistors And Amplifier

    I am afraid those books don't get ir right either. The first book by Pike never mentions diffusion as the cause of charge carrier moving from the emitter to the base. The second book by Brite hardly gives any explanation at all about how a BJT works, other than saying that a small current...
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    Good Resource For Learning Bjt Transistors And Amplifier

    I don't think it would scramble a beginner's brains to state at the beginning that F=ma is very good approximation at less than hyper speeds. That would be simple and correct. Teaching a beginner that Ib is an indicator, not a control of Ic, is also correct and simple. Later the student can...
  20. R

    Good Resource For Learning Bjt Transistors And Amplifier

    This video also goes against the laws of semiconductor physics, which I and most others believe in. The professor makes a direct false statement that base current controls collector current, whereas base current is just an indicator of collector current. He never says that the current carriers...
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