Impedance Definition and 488 Threads

how can i find input and output impedance of a ce amplifier- (voltage divider )..suggest practical methods?

A slotted line used on a 150ohm lossless transmission line connected to an unknown load impedance, ZL. The voltage standing wave ration is found to be equal to 3. The distance of the first voltage maximum from the load is found to be 9 cm, and the first voltage minimum is located at 3 cm from...

Will an audio amp burn up if the speaker connected to it has a lower impedance than the amp's output impedance?

I'm working on a high power multi-phase DC/DC converter where the load current has some fast transients. We can easily measure the output voltage in the time domain, and also measure the power distribution network impedance in the frequency domain. So, I think I would try converting the...

Homework Statement I'm trying to determine this insane circuit's |Z| so I can use an AC voltage to find the current as a function of time. This is my circuit (the switch is closed, and ignore the values): http://i.imgur.com/mA55I.png Homework Equations Impedances for each of the RLC...

Homework Statement A plane wave is passing through a metal. Show that the impedance Z can be given by Z = \sqrt{ \frac{2 \omega \epsilon _0} {\sigma} } \frac{Z_0}{1-i} where Zo is the impedance of free space and sigma is the conductivity. You may assume that E is polarised in the x...

Hi, :smile: Please have a see Example 1-5 on the given link: http://img854.imageshack.us/img854/8376/inputimpedance.jpg The example mentions input impedance. What is it in simple words? The book says: Because this input impedance is across the measured terminals , a small current flows...

Okay, so my short experience in radio has taught me that the input and output of every RF system is designed around some certain impedance. Typically 50 ohms or 75 or 300... So you take a transmitter and hook it to a tuned antenna with some sort of feedline like coax. The coax is the same...

Hi everyone, I seem to be having a little trouble with parallel impedance. I have the equations, but I don't understand why, I am not asking for a super proof, just an explanation. So basically we have a circuit of: ac source, then a capacitor and resistor in parallel. the formula...

Homework Statement Homework Equations V=IR ? The Attempt at a Solution My main problem with this question is that impedance seems to apply only when inductors and capacitors are involved, but this circuit includes only resistors, so it seems to me like I could just treat it as resistance...

Homework Statement Calculate the impedance Zab across ab. w=0.75 Hz wo=1 Hz. L=1 H R=1 Ohm C=1 F Inductor and Capacitor are in series, and together are in parallel with the resistor. circuit looks like a capital A, but square on top, and rotated 90 degrees clockwise.. if that...

Homework Statement here is the circuit I am trying to figure out Homework Equations I have to find the total impedance for the circuit. The Attempt at a Solution I know how to find the total impedance in a series circuit and in a parallel circuit when I have just the Resistor...

Homework Statement Find the input impedance Z. (i.e. Find Z equivalent.) Answer in the back of the book: Z=84.907-j20.12 ohms [PLAIN]http://img834.imageshack.us/img834/8508/circuit.png Homework Equations n/a ** j=sqrt(-1) The Attempt at a Solution I combined the 60-ohm, 50-ohm, and...

http://img146.imageshack.us/img146/9356/capturexh.jpg Attempt at Solution: Well I put R1 and C1 in my RCL circuit, and then used the GIC rules to calculate the "L" inductance for the remainder of the circuit using R2,R3,R4,R5, and C2. So I did X = (Z1*Z3*Z5)/(Z2*Z4) where Z1=R2, Z2...

Homework Statement Calculate the output impedance of the emitter-follower circuit called a pass transistor. Assume that beta=200 **See attached diagram** Homework Equations The Attempt at a Solution Not really sure how this works, I thought it would just be 1k cause that is the...

I'm just really curious about where I'd fit in this chart: http://en.wikipedia.org/wiki/Electric_shock#Pathophysiology

Hello all, This question might be at the same time both general and very specific. Admittedly, it has been over 10 years since I really thought about circuit analysis, but I hope I might get some help here! So, thanks in advance! I will ask a few questions here to make the presentation...

Homework Statement An emf Vosinwt is applied to a circuit which consists of a self inductance L of negligible resistance in series with a variable capacitor C. The capacitor is shunted by a variable resistance R. Find the value of C for which the amplitude of the current independent of R...

Hi guys, can anyone tell me the reason why we set Vi=0 (short circuit the input side) when we want to find the output impedance Zo but we don't do the same by setting Vo=0 when we find the input impedance Zi? and why do we let Io=0 (open circuit the output side) to find the gain Av? thank you

Homework Statement I have attached the problem and all my work. If someone can check my work for part a, that would be great. As far as part b, I need the most help here. Finally for part c, I think my work so far is correct, but I need help to graph it. Thank you in advance. Homework...

Homework Statement An impedance 1000(1 + i) Ω (and note it contains an imaginary part) is connected across an AC voltage source of amplitude 10 V and frequency 60 Hz. Whatʼs the power dissipated during one cycle within the impedance? Homework Equations P = Re(V*I), where V* is complex...

Homework Statement The circuit is a resistor (200 ohms) and a capacitor (200 nF) in series, and that is in parallel with an inductor. Homework Equations [tex]$Z=j \omega L$[\tex] [Gah, how do I make the latex render?] The Attempt at a Solution I'm not really sure where to start with this...

Urgent! About Impedance the total ohm of this impedance ( 30+j40 ) is 50ohm. but wat is the conjugate impedance ?? 30-j40? total ohm is wat? 30+j40 is 50ohm solution is square root of (302+402)

Homework Statement Question 2 on this paper: http://www.eng.cam.ac.uk/teaching/past_papers/examples_student/examples_IA/P3_LCD_Q/1ap3lcdq003 Homework Equations Z = V/I V=L di/dt The Attempt at a Solution for part a of the question: I began with V = Vo cos(wt) And I = Io cos (wt + k) I...

Homework Statement consider a circuit expressed by v(t)= 100cos \omega t and i(t)=2cos(\omega t+\pi / 3) . Find the reactance.Homework Equations Z=\frac{V}{I} = R+jXThe Attempt at a Solution Z=\frac{100}{2\angle \pi /3} = 50\angle -\pi /3 = 46 - j19 Does the negative imaginary part mean...

Homework Statement find total impedance of a circuit with R1 and L in parallel with R2. circuit looks like this (but with R2 instead of C): http://wpcontent.answcdn.com/wikipedia/en/thumb/7/75/RL_series_C_parallel.svg/160px-RL_series_C_parallel.svg.png Homework Equations formula for two...

In my book (Storey), there's an exercise with a parallel RC circuit, where R = 80 Ohm and C = 30 uF. The answer for the complex impedance is supposed to be 40-j40, however I can't seem to get there! I've showed my working under. Am I doing something wrong, or is the book's answer wrong? (freq...

Hello Am reading about amplifiers, and the articles i read suggests that for a successfull amplification the op amp should have an input impedance and zero output impedance. I want some explanation about this information, why the input and output impedance are important factors?

Hi, I'm trying to model the input impedance of a MESFET by using a series RLC circuit. For example I have the following reflection coefficients: .575 angle(-138) at 6 GHz .617 angle(170) at 8 GHz .610 angle(128) at 10 GHz As you can see, as the frequency changes so too does the angle. Does...

Hey, The impedance of the series and parallel RLC circuit both tend to R near the resonant frequency (one is a min/ one is a max) so if I expand the frequency around this point I should be able to show they are the same for \delta \omega small right? For some reason I can't get it to work. Any...

Hi there, I have a circuit in which consists of a resistance (rs) in series with parallel combination of capacitor and resistance(rc). I want to calculate value of rs. So i did this by calculating total impedance Ztotal which is V/I and then substracting impedance of parallel rc circuit...

I'm looking for references or some place where i can find the calculations that impedance plethysmography is based on.

Hello, I wonder if there's any difference between the "impedance matching" and "maximum power transfer" criterion? I assume in both cases, one impedance should be designed to be the complex conjugate of the other. Thanks.

Homework Statement Hi. Just like the title says, why is the output impedance of an op-amp so small? (as in physically, I understand why a low output impedance is a desirable characteristic)

I need to make an impedance matching circuit using microstrip lines. Zin --> MATCHING CIRCUIT --> ZL The input impedance (Zin) is 50Ω. The impedance at the load is 50 - j 500Ω. Design frequency of 900MHz. The board I am required to use is the Taconic RF-35. It has a thickness of d = 1.524mm...

Homework Statement Hi! We have a parallel circuit on 230V, 60Hz voltage. One of the parallel's has a 0.0768H coil, the other has a 50 Ohm resistance on it. The question is: What is the effective I in the main current? Homework Equations Z = Lw The Attempt at a Solution OK, so I...

Homework Statement The following three impedances are connected in series across a 100-V, 20-kHz supply: (1) a 12-Ω resistor, (2) a coil of 100 μH inductance and 5-Ω resistance and (3) a 390-nF capacitor in series with a 15 Ω resistor. Sketch the circuit diagram, impedance diagram and the...

How do you determine the output impedance of cmos gates?

I'm a bit lost on this one. Also, what formula do I use for impedance? http://i111.photobucket.com/albums/n149/camarolt4z28/2010-09-19202315.jpg?t=1284947003 http://i111.photobucket.com/albums/n149/camarolt4z28/2010-09-19202817.jpg?t=1284947014

Good Morning can anyone help explain what this statement really means, when referring to a npn transistor in common mode, as an amplifier. "The collector is a high impedance when compared to the emitter" what's the pratical implication of this statement thanks David

Homework Statement In a circuit consisting of a capacitor (Voltage across is 3.2V) and a 47\Omegaresistor (Voltage across is 4.65V), with a current of 0.0989A and a phase difference between the two voltages being 90', what is the complex impedance for the circuit? Unsure of how to work this...

Hello All, I have been doing some experiments with inductors of various sizes and inductances. I was wondering if anyone here knows of any suppliers out there that sell high impedance air-core inductors (a few thousand turns of high gauge wire (30 gauge or so)) that can be purchased off the...

[Moderator note: This is an old thread from 2010. But it sounds like a good question, so I moved it here and bumped it to the top.] Hello, this is my first post to PF. I've been trying to find out my answer in similar posts (resistance of a disk, ...) with no luck. So I would really appreciate...

I have a question about impedance matching with transformers. If I have a source impedance of 20 K ohms, to step up the voltage does the primary have to match 20K ohms with a secondary of 40K ohms for a step up of 1:2. Or can I change it so the primary is 50 Ohms with a secondary of 40K ohms...

Impedance -- Current phasor In a series circuit of two elements, the voltage and current, for w = 2000 rad/s, are V = 150|-45° and I = 4,74|-116,6°.That variation in the frequency of the source would result in a phasor current of 6 amps? Assuming an unlimited variation in the frequency, what is...

Hallo, i'm trying to implement a comsol simulation of a impedance spectroscopy experiment. But unfortunatly I'm an absolut beginner in Comsol and i have many problems with this work. First of all i want to say that I'm using the AC/DC module, more precisely the transient analysis. At the...

what are the methods of improvement of surge impedance loading

For the circuit attached, I'm first asked to find I_1, I_2, V_1, V_2 by using the appropriate loop equations. I got these answers (which I checked and are correct): \overline{I_1} = 1.556A\angle61.4^\circ \overline{I_2} = 1.111A\angle-100.25^\circ \overline{V_1} = 3.92V\angle139.8^\circ...

If I'm not wrong, empty space (vacuum) has the greatest impedance amongst any material. Because \eta = \frac{1}{n} \sqrt {\frac{\mu _0}{\epsilon}} if I'm not wrong and n=1 (smallest value possible) for free space. What does this mean that free space has a big impedance? It makes the greatest...

Homework Statement A 25-Ω resistance is connected in series with a 30-mH inductance and a 12-µF capacitor and are connected to a 90-V (rms) ac. If the frequency of the ac source is 500 Hz, calculate (i) the current in the circuit. (ii) the voltage across each element (iii) the phase...