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  1. R

    Ic=C x dv/dt

    Plot the wave this one time showing its amplitude vs time. What is its shape? What is its max value. Let's see what you come up with. Ratch
  2. R

    Ic=C x dv/dt

    First, write the equation for V. Then, differentiate with respect to "t" it to get dV/dt . Then multiply dV/dt by 0.47 uf to get the current that exists when the voltage changes. If you do not understand what dV/dt means, then the answer to the problem will be for nothing. Ratch
  3. R

    Ic=C x dv/dt

    If he could just learn to differentiate the voltage equation, then he would not have to get involved with reactance. By the way, Ohm's law is not R=V/I and all its variations, like most folks believe. That formula is the definition of resistance or impedance. Ohm's law is a property of a...
  4. R

    Ic=C x dv/dt

    You just have to look further. See https://en.wikipedia.org/wiki/Derivative. Once you know the concept of a derivative, we can go from there. Ratch
  5. R

    Ic=C x dv/dt

    It's not. OK, let's start at the beginning. Do you know what dv/dt means? Can you write out the voltage source equation? Ratch
  6. R

    Ic=C x dv/dt

    Although you don't say so, I assume you are talking about a sinusoidal voltage source. Do you know calculus? If so, then you can easily find the derivative (dv/dt) of the sinusoidal wave. If not, you are in the wrong class. Don't forget to turn the cycle frequency (100 Hz) into radian...
  7. R

    Resonance

    How could we explain it better that the hundreds of definitions and examples given in textbooks and on the net? What specifically don't you understand about resonance? What non-simple words don't you understand? Ratch
  8. R

    transistors, and capacitors

    Although a transistor is a transconductance device, it it is not a linear parameter because of its diffusion operation. Driving the transistor with a current source shows a linear relationship with the collector current. This is because the high resistance of the current source swamps out the...
  9. R

    transistors, and capacitors

    Correct, caps store energy, transistors don't. Ratch
  10. R

    Pure Capacitor Circuit Help

    Correct. The derivative of a sinusoidal is another sinusoidal. No infinite derivatives will be involved, so the voltage source should able to supply the required current. The voltage across the cap will simply be the applied voltage. Ratch
  11. R

    transistors, and capacitors

    A transistor is transconductance device (voltage controls current). It cannot be compared to a capacitor because a transistor is an active device, whereas a capacitor is not. The base current of a transistor is an indicator of the collector current (CC), but it does not control the CC. Vbe is...
  12. R

    Pure Capacitor Circuit Help

    Certainly. The derivative of the step voltage across the capacitor is plus infinity until it reaches the applied voltage, followed by a derivative of zero when the capacitor reaches the constant applied voltage. Ratch
  13. R

    Pure Capacitor Circuit Help

    If you are trying to energize a capacitor to any voltage and no resistance, it will reach the applied voltage in an infinitesimal amount of time and draw an infinite amount of current during that time. Of course, your voltage source must be able to supply that infinite amount of current for...
  14. R

    Can anybody explain about how bjt works??

    The larger the emitter resistance is, the more linear will be the Ic curve. Sedra and Smith recommends 10 mV max for the signal voltage. Ratch
  15. R

    Can anybody explain about how bjt works??

    By making the emitter resistor high enough, most of the base volt will drop across the emitter resistor and determine the collector current. The more most of the voltage is dropped across the emitter resistor, the more linearly the transistor will amplifier the current. Ratch
  16. R

    Can anybody explain about how bjt works??

    Didn't I say in post #9 that one cannot design using the base-emitter voltage because it is too nonlinear? That is why you have to add lots of resistance to overcome the nonlinearity. Nevertheless, the Vbe, not the Ib controls the Ic in the active region. Ratch
  17. R

    Can anybody explain about how bjt works??

    I am not clear on what you mean by "one or the other" and what the approaches are. Ratch
  18. R

    Can anybody explain about how bjt works??

    What you see on a data sheet is a test circuit using the device. The test circuit contains current sources. I never said that a BJT should be designed as a voltage driven device. It is too nonlinear for that. However, it is not a current amplifier by itself like a lot of books and magazines...
  19. R

    Can anybody explain about how bjt works??

    You cannot show current gain without driving the base with a current source, or adding a lot of resistance to the base and/or emitter. From then on, you are demonstrating a current amplifying circuit using a transconductance device, not a BJT alone. A BJT by itself is not an inherent current...
  20. R

    Can anybody explain about how bjt works??

    A BJT is a transconductance (voltage controls current) device. In the active region, the base current is an indicator of the collector current, but does not control it. The base current is an unavoidable waste that does not contribute to transistor operation. Ratch
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