Pavel,
You aren't included in the peanut gallery. It is for those folks who throw the shells.
But let us start with the first two questions.
In analyzing a circuit the first question is what is the power source and where does it all go? We normally do this by looking at where the current goes. This includes every place it goes.
As all the current is accounted for the loop equation must equal zero! (Question # 2)
So for this simple circuit the equation would be:
i - i(R1) - i(C1 + R2) = 0
Now when the current source is first started it goes from 0 amps to 1 amp instantly. As CV=Q (Definition of capacitance!) and the is no charge on the capacitor it will have a 0 voltage drop so the 1 amp current is shared equally by both 10 ohm resistors.
So i -i(R1) - i(R2) = 0 could be expressed as i - V/R1 -V/R2 = 0 by Ohms law.
as R1 = R2 at the instant of turn on we could change this to i R / 2 = V
Thus 1 amp into 2 each of 10 ohm resistors will produce 5 volts. By using the formula for power we get 5 V x 1 A = 5 Watts. As there are two resistors each would see 2.5 watts.
Now why do we do such a complicated method when there are easier to use shortcuts? BECAUSE THIS METHOD IS COMPLETE AND ACCURATE! Shortcuts may reduce accuracy. For example calculating a coupling capacitor into a circuit may ignore that the input impedance may rise with signal.
Now does anyone want to offer what happens to the voltage across R2 after the initial turn on?
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No. 5 is easy. 8 for that matter too.
This is very poorly posed if the above is an answer.
Scott the answer for 8 is easy, can you show the equation for it?
And I have just started the answer, do you care to expand on how to continue the analysis?
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I thought his question was related to previous claim about Fourier and finite time window. Similarly, here here waveform will start asymmetrically, going to symmetrical form during infinite time.
This will only lead folks astray, transform techniques will give the correct answer with a Heaviside step times a square wave stimulus. If you want instantaneous power (@ T = 0+) ask for it, this question does not.
At infinitely big time from start?
Otherwise please define "Steady".
Steady state refers to when all transients have settled. So infinite time would work. However as engineering requires finite solutions any time that would give 3 digit accurate answers would do.
1) Don't have to, Vstar times I is always zero since they are 90 degrees apart regardless. You do want the easy route?
2) I already told you, twice. First thing we learned was Laplace transforms and initial conditions.
At either 0 or infinity the answer is trivial. Now he wants at "steady", so going back to an elementary differential equation to get the result at some given time that needs to be defined. Also, power measurement interval needs to be defined as well, otherwise the problem has no solution.
Yes but can you simply explain why V and I are 90 degrees apart in a capacitor?
If you want to go to a Laplace transform why don't you show the steps. This is intended as a tutorial.
HUGE thread! 27,000+ posts and this is Part2!
So, can I be bold enough to ask what exactly is this thread about? I assume it was to work out what was in John Curl's pre-amp?
Has this been figured out yet?
No doubt some smart-ar$e will suggest reading of the entire thread...
Andy
I thought from reading the audio reviews Boulder has superceeded the CTC BT anyway with discrete op-amp modules (Dick Burwen did it first but that's another story) and more than doubled the price point. So I think we should do a group discrete op-amp and give it free to the community.
Pavel had no trouble understanding the questions and the answers. Neither did the students who answered these questions.
But go ahead keep redefining things on a tangent, it expands the issues,allows more room for opinions instead of simple numeric answers.
HUGE thread! 27,000+ posts and this is Part2!
So, can I be bold enough to ask what exactly is this thread about? I assume it was to work out what was in John Curl's pre-amp?
Has this been figured out yet?
No doubt some smart-ar$e will suggest reading of the entire thread...
Andy
This thread is about John Curl's Blowtorch preamplifier and various other topics, some of them are related to that preamplifier, others aren't related.
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