Questions tagged [analysis]

Questions attempting to analyze the mathematical properties of a formula, the inner workings of a protocol, or the design of a given circuit.

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2answers
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Thevenin equivalent resistance of circuit with diagonal resistors

I'm trying to find the Thevenin equivalent for part A of this circuit: I begin by opening the circuit at the dotted line of part A. Then I try to find \$V_{oc}\$ across the two terminals that are ...
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1answer
3k views

alternative fix to: How can I calculate a Joule Thief

This is based on the original question: "How can I calculate a Joule Thief. How Can I calculate a Joule Thief. Since the gain of common emitter voltage amplifier and it will depend widely on the ...
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5answers
4k views

Puzzled by Nyquist frequency

Say I have a 1kHz sine, so no higher harmonics, then I need to sample it at least at 2kHz to be able to reconstruct it. But if I sample at 2kHz, but all my samples are on the zero-crossing, then my ...
4
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2answers
5k views

Why we use conjugate of current than the original phasor in the calculation of Complex Power i-e S=VI*

i have studied different books and sites for the above question but did not get the right concept that why the complex power encounter current conjugate not the original Phasor.if someone explain it ...
8
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2answers
4k views

How to analyze this diode circuit?

I am trying to analyze this simple diode circuit by hand, but I can't seem to get too far. simulate this circuit – Schematic created using CircuitLab Using circuit lab, it is evident that ...
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5answers
4k views

Predicting thermal equilibrium: what's wrong with my time constant?

I understand that this is arguably a peripheral electronics problem, but it seemed to fit here better than in physics. I've been doing some power electronics design work with large IGBTs mounted on ...
6
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6answers
562 views

Reading a circuit

Disclaimer: I am a beginner. I am reading a knol book on electronics, and I am faced with this schematics: How do I read a circuit to understand what it does ? Do I have to imagine the electrons ...
4
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1answer
5k views

Circuit analysis - software?

Surely there is some software that lets you draw a simple circuit diagram (DC voltage source and resistors) and then tell you the voltage, current, resistance, and power on R1, R2, R3, etc as well as ...
9
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1answer
1k views

Why does this circuit oscillate?

The circuit below is an oscillator. When I simulate it with ltspice, it does indeed generate a waveform (although it doesn't seem to be a very pure sine wave). What I fail to understand is why it ...
6
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1answer
2k views

Type 2 compensation network

I'm working through the excellent text on SMPS design "Switching Power Supplies A to Z", by Sanjaya Maniktala. Right now I'm reading the section on the feedback loop and stabilization. As a first-...
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2answers
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Calculating an R-RC circuit

This is not homework. I have this circuit, and I want to calculate V2. I know it is equal to V1 at t=0, and equal to \$V1 \cdot \frac{R2}{R1+R2}\$ at t=\$\infty\$, but I don't know how to calculate ...
3
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1answer
1k views

How do I find out which current/voltage to use for an unlabelled LED panel?

I have a 600mm x 600mm LED panel with 576pcs 3014-type SMD LEDs in some unknown configuration/topology (edge-lit, similar to this one here: http://i01.i.aliimg.com/wsphoto/v0/1990066259_5/Wholesale-...
3
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1answer
1k views

How to calculate equivalent resistance?

This is not homework. Imagine an infinite resistor grid which the picture shows a part of. The question is what's the resistance measured across any of the 1k\$\Omega\$ resistors. I don't want you ...
2
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2answers
8k views

Z(in) for small signal analysis with BJT for unbypassed emitter and r0 in place

I have been studying the small signal analysis of BJT with re model with the emitter terminal not bypassed. I am able to derive those Zi, Zo,Av, Ai long as ro is assumed to be infinite. But I am ...
5
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3answers
451 views

Proper assignations of current directions

What is the best way to know the proper direction of current? Lets say we have this circuit below: The correct directions are given below: What are your techniques to know which is the proper way? ...
3
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2answers
230 views

Under what circumstances can impedances be simplified to simple resistances?

Consider the following circuit: This is a simple first-order low-pass RC filter. The cutoff frequency is: \$ f_c = \dfrac{1}{2 \pi (1k\Omega) (1\mu F)} \approx 159 Hz \$ The reactance of C1 at \$...
3
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1answer
2k views

How do I treat a PMOS compared to an NMOS in small-signal analysis?

What exhaustive list can I use to determine the differences between NMOS and PMOS devices when doing small-signal analysis? Equivalently, what are the fundamental differences between NMOS and PMOS ...
2
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2answers
639 views

Nodal Analysis of an electrical circuit

I have several doubts about solving circuits. Can any circuit be solved using Nodal Analysis? If some circuit can be solved using Nodal Analysis, can it be solved using Mesh Analysis too? Why do we ...
2
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1answer
3k views

How to get started using ngspice?

I've recently finished some work with hspice, and now I don't have access to the server. I've installed ngspice on my Fedora 15 machine, but I'm unfamiliar with how it works. In hspice, I was able to ...
2
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1answer
639 views

Derive transfer function from block diagram

I have this block diagram which I already reduced pretty much: Now I want to derive the transfer function from phi_o1 to q. ...
2
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1answer
74 views

When to process beam forming algorithms?

I am building a system that uses beam forming to locate noises at different spots. All of the spots will be in front of the microphones (180 degree range of spots). My first question is if the beam ...
0
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1answer
191 views

AD620 - pot assembly alternative - filter

I have been posting questions regarding the AD620, reference voltge and output. I followed all the instructions from Stack Exchange and voila! The circuit works like charm, thank you! It gives the ...
0
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1answer
108 views

Power amplifier input source current path

Can anyone draw (or write in text) the small-signal path from signal source XFG1 at input of Q1 base to amplifier load for positive and negative input signal swing?
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2answers
576 views

BJT with Zener diode

I got the picture from my prof's notes, and I don't quite understand why there can be two different currents at the given node. If there are only two currents shouldn't the currents' values be the ...