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  1. R

    np=ni^2 in doped semiconductors

    What is EHP? You should define acronyms at least once before you use them. What is a C band electron? You wanted to know why the hole concentration goes down when the electron concentration goes up and vice versa. Did you understand my explanation? Now you want to know about zero K? What...
  2. R

    np=ni^2 in doped semiconductors

    When an atom of intrinsic (pure crystalline) silicon ionizes, an electron-hole pair is released. When arsenic is substituted for silicon within the structure, the ionization only releases an electron, because the remaining 4 valance electrons of arsenic fit nicely into the neighboring silicon...
  3. R

    How does an op-Amp make the inputs the same?

    I will try to help you. Op amps have a extremely high voltage amplification factor, especially at low frequencies. If the + and - inputs are different by just a few microvolts, it will sent the output of the op amp to either the plus or minus supply rails. Suppose, the voltage on the - input...
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    Resonance Frequency

    Wait a minute. You first asked for the resonant frequency, and now you are treating it like a high pass filter, which means computing a transfer function. Which is it? You should make your questions clearer so we know what you want. Ratch
  5. R

    Resonance Frequency

    There is no conflict between your answer and mine. If you plug in the numbers for my solution of omega=sqrt(-1+C Rc^2)/(C sqrt(L) Rc), you will find our answers are identical. Your equation for Zin is identical to mine if you expand it and substitute j w for s. C*Rc²>1 is a condition for...
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    Resonance Frequency

    This is a series resonant circuit. There are no reactive elements in parallel. Therefore, there is only one resonant frequency. Ask if you have any questions. Ratch
  7. R

    Linear Combination OP Amp Design

    I think an operational amplifier summer is in your future. See if this link gets you started. http://electronicdesign.com/ideas-design/efficiently-design-op-amp-summer-circuit Ratch
  8. R

    LC Oscillator

    An oscillator needs an energy source to supply any load you attach to it and make up for circuit losses. If you are rejecting all the active elements you named above, what are you planning to use in their place? Ratch
  9. R

    Zener diode

    I just wanted to point something out. R1 has 90 volts across it, right? That means around 0.18 amps will be present in the 10 volt diode. So the 1 watt diode will be dissipating 1.8 watts. Not good. Ratch
  10. R

    need help with RLC circuit

    Is It = 11.57 supposed to the total current? There is a capacitor and an inductor in the circuit. Are not the currents in the capacitor and inductor branches supposed to have a orthogonal component, or what you might call an imaginary component? The same applies to the total current. What...
  11. R

    LPF and HPF

    Much of the descriptive language used to describe technical activities are really slang terms. In the electrical field, we find phrases like "current flow", which literally means the redundant and ridiculous phrase, "charge flow flow", instead of saying current exists or is present. Or...
  12. R

    LPF and HPF

    Good answer. Ratch
  13. R

    LPF and HPF

    Why is the time constant "tau" being discussed with respect to a filter and its frequency response? A simple RC filter can have an infinite number of values with the same time constant. Time constants are fine for transient responses, but in the steady state, the resistance, reactance, and the...
  14. R

    HELP ME PLEASE......

    Help you with what? We cannot give you a complete course in electrical technology. Time and space only allow answers to specific related questions. Do you have any questions about understanding a particular concept? Ratch
  15. R

    D flip flop

    What's the question? If x and y are both 1, the output of the leftmost XOR gate will be 0. Combined with 0 from the A output, and the next state will be 0. All perfectly correct. Ratch
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    LPF and HPF

    Interesting narrative. I don't see how we can stop it. Passing laws only slows the snoops down. Sooner or later they pop up again. The information gleaned is too vital for government needs and wants. And sometimes, they really need it. One has to assume that anytime one steps out in...
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    LPF and HPF

    Actually this is more of a situation than a problem. Unlike determining a yes or not answer of whether a model accurately reflects reality, this problem is a matter of personal preference that has no definitive solution. It is like determining how much sugar to put in your coffee. The...
  18. R

    Finding rate of change of capacitor discharge?

    To further your understanding, note that there are an infinite number of R and C combinations that give the same time constant RC. As long as the time constant is the same, the capacitor will energize and de-energize to the same percentage at the same time. Can you explain what the difference...
  19. R

    LPF and HPF

    I understand what you are saying. Both methods work for circuit analysis. What I am further stating is that the model cannot justify the differential term unless there is a discontinuity in the charge flow. Specifically, no charge flows through the capacitor. Ratch
  20. R

    LPF and HPF

    I have shown that the mathematical differential equation describing the current existing in a capacitor branch cannot be written without assuming current does not exist through the dielectric. By showing what happens when current does and does not exist through the capacitor, I believe I...
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