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    Physics of n-p Junction in a diode

    The barrier voltage is the sum of the "built-in voltage" and the applied voltage. The built-in voltage is determined at the time of manufacture, and depends on the intrinsic concentration of the semiconductor and the concentration of the P and N sides of the diode...
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    Physics of n-p Junction in a diode

    Your question is not very clear. Please rephrase it. Yes, and what difference does it make? I am saying that the diffusion current across the diode junction is not dependent on the depletion region width like the link says it is. It does not matter if the depletion region width expands or...
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    Physics of n-p Junction in a diode

    I have a problem with the explanation of the above tutorial. It states that the forward and reverse current is controlled by the width of the depletion region. I aver that the depletion width does vary with the voltage, but the width does not cause the current change. The real cause of...
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    Understanding the nature of the electric field

    Yes, charges do cause static electric fields. A propagating electromagnetic wave through space contains both magnetic and electric fields with no particles. https://www.google.com/search?q=electromagnetic...
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    Basic Transistor Amplifier Circuit help

    NanyBany, The current in the emitter and collector are almost equal. If R3 is greater than R4, than it will have more voltage across it for the same current and the signal will be larger. The input voltage is measured at the top of R4, and the output at the bottom of R3. Therefore their...
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    Basic Transistor Amplifier Circuit help

    NanyBany, You are asking how excess charge on one plate flows to the other plate containing a defciency of charges? One way is leakage through the dielectric. A dielectric is supposed to be an insulator, but nothing is perfect. The other way is through the circuit itself. I hope you...
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    Basic Transistor Amplifier Circuit help

    Would you believe that a capacitor with a high voltage across it has the same number of charges (electrons) as an identical capacitor with no voltage across it? If a zillion charges are added to one plate, an equal zillion charges are removed from the opposite plate so as to give a net charge...
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    Basic Transistor Amplifier Circuit help

    NanyBany, I discern that you don't know what a capacitor does or how it operates. So let's start at the beginning. What do you mean when you say a capacitor is "charged"? Charged with what? Ratch
  9. R

    RLC circuit question

    Why did you put 60° into the excitation voltage? The excitation phase is not going to change the impedance or the current values with respect to the voltage. You want to figure the current with the max voltage of 120 volts, not at some lessor value like 60°. Why do you change those figures...
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    RLC circuit question

    You should be able to get help on RLC circuits on the web, such as http://hyperphysics.phy-astr.gsu.edu/hbase/electric/rlcser.html . That should be your first attempt at help. Your next step is to calculate the impedance and divide that into the voltage (120 volts) to get the current. Since...
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    How does diode dissipate energy?

    Voltage is the energy density of the charge (joules/coulomb). Charge is going to go from a higher energy density (voltage) to a lower density if a conduction path exists. In a conductive resistor, charges are going to move from the higher voltage (energy density) to the lower one. During...
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    How does diode dissipate energy?

    I have explained how a junction diode works before, but it appears that a lot of folks don't still don't understand it. First and foremost, a junction diode is a diffusion device. It works on the same principle that a drop of ink diffuses throughout a glass of water. When the diode is first...
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    How can I set a frequency in a Wien bridge oscillator

    And here is another circuit that uses two op amps and one tuning resistor. A better AGC could be substituted for the two back-to-back diodes. Ratch
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    How can I set a frequency in a Wien bridge oscillator

    That's a lot of heavy math and feedback control. Only a lamp was analyzed. What about other forms of AGC, such as back-to-back diodes, FET's, bridges, etc? Looks like making a Wien with very low distortion is not easy. Ratch
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    How can I set a frequency in a Wien bridge oscillator

    So the inferior op amp had the right kind of nonlinearities that contributed to better stability in the circuit, and the circuit needed more or different nonlinearity than the lamp was able to provide when the superior op amp was used. Just speculating. Anyway, the article sounds interesting...
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    How can I set a frequency in a Wien bridge oscillator

    Jeri says you are welcome. Ratch
  17. R

    How can I set a frequency in a Wien bridge oscillator

    No, you appear to be OK. I thought you said something was not working right. You do need to set up an automatic gain control (AGC) like a light bulb so you don't have to constantly fiddle with the feedback resistors. Ratch
  18. R

    How can I set a frequency in a Wien bridge oscillator

    Match the resistors and caps in the phase shift network as best you can. Then adjust the feedback R1 and R2 to get it oscillating. Then adjust R3 and R4 together keeping the same value to get the right freqency. Ratch
  19. R

    How can I set a frequency in a Wien bridge oscillator

    Those resistors DO affect the phase, otherwise they would not be in the frequency equation. The gain requirements are different if you don't use the same values of resistors in the phase shift network. Did you Google and did you read post #9? Ratch
  20. R

    How can I set a frequency in a Wien bridge oscillator

    I can see why you don't want to listen to old tired burn-outs like us. So why don't you let a sweet young thing like Jeri tell you how to do it without using any lame parts you might have. Ratch
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