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A fundamental electronic component that stores energy in an electric field, commonly used in filtering applications.

0 votes
3 answers
592 views

Question about AC and DC on a RC circuit

The capacitor is discharged. The power supply is AC, sinusoid with amplitude 10 V and a frequency of 50Hz. So, the power supply is 10 Sin(100πt) The resistor is 100Ω and the capacitor is 1F. …
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  • 847
3 votes
1 answer
791 views

Isn't C1 and C2 nulling the input signal?

I am a relative newbie to electronics. Looking at the following schematics I see something strange: C1 and C2 at the input. I always knew that capacitors block DC signals and let AC pass. By having …
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  • 847
0 votes
3 answers
223 views

A question about impedance

The reactance of the capacitor will decrease with frequency. …
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  • 847
3 votes
1 answer
3k views

How do I calculate the DC blocking capacitor at the output of a transistor amplifier?

Suppose this circuit of an audio amplifier: How is C calculated? I suppose C is there to block DC, so it is a high pass filter. If this is the case the formula for C would be something like C = …
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  • 847
0 votes
1 answer
269 views

How was this formula of voltage on capacitor achieved?

We know that voltage across a capacitor is given by But there is this other formula How this second formula was deducted mathematically from the first one? or from another one? …
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  • 847
0 votes
2 answers
199 views

Trying to understand why the constant of integration was ignored on this RC circuit

I am watching this video where the guy deducts the voltage across the capacitor during the transient phase. There is an integral, in the middle of the equations. … This is not just this guy, I am not aware of any of the capacitor/inductor formulas where the tutor considers them. Why is that? …
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  • 847
1 vote
2 answers
239 views

Trying to understand why the signal was inverted on this RC step response equation

I am watching this video where the guy is deriving the equations for the step function of a series RC circuit. At some point he has the following equation: \$ \frac{dt}{RC} = \frac{dv}{v_s - v} …
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  • 847
5 votes
6 answers
3k views

How can current phase shift be 90 degrees behind voltage just "inside the capacitor" on an R...

In this video, the instructor claims current will be 90 degrees behind voltage inside the capacitor but not inside the resistor or the whole circuit. If that's true, I don't understand. …
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  • 847
0 votes
2 answers
2k views

What is the voltage across the capacitor 3ms after the switch is closed

So, the circuit is stabilized and the voltage across the capacitor is 40V. At t=0, the switch is closed. What is the voltage across the capacitor 3ms after the switch is closed. … Now I want to know the voltage across the capacitor 3ms after it starts discharging. …
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0 votes
1 answer
519 views

How do I find the current equations for the RLC Series Circuit?

To find the equation for the voltage across the capacitor, I apply KVL to the circuit and get this: \$ V_1(t) = Ri + L\frac{di}{dt} + V_C(t) \$ this later turns in to this: \$ \frac{V_1}{LC} = \frac … The only thing I can see is that the current on a capacitor is equal to \$ i_c = C \frac{dv}{dt} \$ If R, L and C are in series, the current is the same for the three. …
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0 votes
2 answers
216 views

What are the initial conditions used to find the coefficients in the current equations?

omega_d t) + K_2 \thinspace Sin(\omega_d t) ] \$ To find the coefficients of those equations I apply the two initial conditions: I solve the equations for t=0 and for the initial voltage across the capacitor … In the voltage equations I used the initial voltage across the capacitor and the derivative of voltage (current). Now I have the current equations. …
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  • 847
0 votes
2 answers
895 views

Simulating all transient solutions for RLC series circuits

Solid curves are voltage across capacitor. Dashed curve = current. V1 is a pulse, 10 VDC amplitude, 1ms. What am I missing? …
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  • 847
0 votes
4 answers
7k views

How to calculate the input and output capacitors of a common emitter amplifier using BJT?

The documentation about this is vague and conflicting but as far as I have researched you calculate these capacitors like this: C1 Several authors say to calculate this capacitor equal to the input impedance …
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