Questions tagged [impedance]

Impedance defines the voltage/current characteristic of any dipole circuit.

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70 views

Can Network Analyzer measure Impedance, Conductance, Susceptance or is there a device that does all?

I want to measure the impedance, conductance and susceptance of a large metallic object (about the size of a boat), and I want to know if it is possible to measure using Network Analyzer. If yes, are ...
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1answer
39 views

Linear Circuits - Erroneous first order gain observation

At uni, I carried out some lab observations involving a CR circuit (4V AC power source, capacitor, resistor in series, in than order) with the following parameters: simulate this circuit – ...
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2answers
237 views

How to measure the output impedance of a Zener diode in avalanche?

I'm trying to measure (on the bench) the output impedance of this:- simulate this circuit – Schematic created using CircuitLab It's a Zener diode, and the applied voltage is sufficient to ...
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1answer
130 views

“DC” Impedances seen looking into terminals of a BJT

Our professor in college was making us understand the stiff voltage-divider bias concept of a BJT. simulate this circuit – Schematic created using CircuitLab (Ignore the resistor and voltage ...
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1answer
65 views

How to calculate how much high ESR capacitance to smooth impedance spikes?

I am making a 3.7V to 5V voltage booster with 25x 100uF ceramic capacitors on the input and output (with room to add more if needed). I've been warned that having such high capacitance with such low ...
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1answer
82 views

Finding capacitive load driving capability of a Sine wave crystal oscillator

I will be using Crystek CCSS-945X-25-100.000 sine wave oscillator to drive the reference CLKin pins of TI PLL IC LMK04832 This sine wave oscillator will be on a separate PCB which we are calling as "...
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3answers
251 views

Is my understanding of output impedance for this transistor circuit correct?

Im having trouble to understand the meaning of output impedance of an active circuit and in this case the emitter follower. I have read several information but yet failed to get the meaning. Im ...
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2answers
252 views

What does it mean by input and output impedance in a signal generator?

I have a Lock-In amplifier that can generate sinusoidal signals up to 1.5V peak. There is an output port and input port, and I can obviously fix the frequency or amplitude of the signal I am sending ...
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1answer
266 views

Interpretation of scattering parameter

Currently I am (non-engineer) trying to understand the origin of measured scattering parameters with a vector network analyzer and a 2 port system. The second port is terminated with a matched load to ...
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1answer
46 views

Input and Output Impedances of Single to Differential mode converter

I have this circuit that converts a single ended input signal to differential output signal. I want to understand how to calculate or find out its input and output impedances? The two op-amps are in ...
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1answer
45 views

4 Pole Connector and USB cable compatibility

USB 2.0 Cable to pass through enclosure boxes. Are such cables able to be cut and connected (soldered) to the connectors pictured, and used without effect on their performance. Are there specific ...
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100 views

How do I use this impedance converter? (AD5933)

I want to measure a complex impedance with this impedance converter. I have been trying to find out how to use it, and I am confused. I figured I should put my impedance between VIN (5) and VOUt (6), ...
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1answer
370 views

Running a N channel MOSFET from 3.3V MCU

I am trying to run a low side switch with the 3.3V GPIO output of the Raspberry Pi (3.3v MCU), and for the particular transistor I’m using (IRF520) the 3.3V is barely enough to turn it on - is there ...
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185 views

Input and Output Impedances of Differential Amplifier

I have this circuit that is used to convert an incoming analog differential input signal to a single ended signal. The differential input is connected at IN+, IN- and the output is taken from OUT. I ...
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1answer
930 views

Connecting a 75 ohm device to a 50 ohm antenna

I have a device operating at low-frequencies (470 - 790 MHz, Television White Space), which works with a 75 ohm antenna. I want to connect this to a 50 ohm antenna instead. The 75 ohm end has an F-...
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65 views

Circuit Analysis: Difficulty in obtaining a current through a resistor?

I'm solving a problem that requires I compute some impedances, and then the current through a resistor. I obtained some of the impedances*, but don't know how to get the second part (current). ...
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4answers
172 views

Impedance Matching Long 2000 meter Transmission Line

My apologies if this isn't the most appropriate forum to ask this question, but I have found the response from users on this form to be extremely helpful in the past with my electrical questions. I ...
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3answers
838 views

How does Laplace transform include the transient response?

When we provide a sinsusoidal input, the evaluation of the solution of the differential equation head-on becomes horrendous. So we give an imaginary, complex exponential input and solve the ...
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1answer
50 views

Parallel of transformers. Is R/X condition necessary?

Let say I've got two transformer T1 and T2 with both the same voltage ratio. Each transformer has an internal impedance Z1=R1+jX1 and Z2=R2+jX2 respectivley. Also each transformer has a power capacity ...
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110 views

Input Impedance of BJT CE Configuration different from Multisim simulation

So as I derived, my input impedance should be Rb||rπ. But by substituting the value I obtain via the AC analysis from Multsim, I got different values. Tried a few times but still, the input impedance ...
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1answer
39 views

Current when switching on with inductance. Role of Reactance?

When switching on the current through a coil it can be described as: \$ I(t) = \frac{U}{R} \cdot (1 - e^{(-x\cdot R/L)}) \$ For a sinusiodal current the complex resistance for a circuit with ...
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2answers
950 views

Low impedance voltage testing (LoZ)

Is there any issues with using low impedance mode on a multimeter for day to day testing on mains voltage 240Vac or if this mode should only be used when testing for phantom voltage? Is there any risk ...
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3answers
143 views

Impedance match Fishman guitar pre-amp to IRIG2HD

I'm looking for some help in understanding impedance matching. I'm hoping one or more of you technically savvy electronics folks will jump in and give me a simple circuit recommendation. ...
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3answers
2k views

Computing the voltage across a parallel LC component at resonance?

Problem For the circuit illustrated below, I am trying to compute the sinusoidal voltage across resistor \$R_{1}\$ when the parallel LC component is in resonance: I setup my problem with the ...
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1answer
87 views

How to know what this impedance is?

So I'm doing experimental work on an unknown impedance. I used a RLC meter for frequencies of 100, 200, 500, 1k, 2k, 5k, 10k, 20k, 50k and 100k Hz. Now, I think the values I got for each frequency ...
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1answer
178 views

Understanding equation for the quality factor of an RLC circuit?

In my textbook for a course on Circuit Analysis I came across an equation for the quality-factor of an RLC circuit. However, I don't quite understand their reasoning. The explanation that follows is a ...
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3answers
400 views

Dissipation and Impedance

it is known that power losses (which become heat) in circuits are due to resistances, because of Joule Effect. But sometimes I read that dissipation is due to the real part of a certain impedance, and ...
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278 views

Twisted pair with shield and drain wire

Ive been posed with a problem regarding calculating the characteristic impedance of a shielded twisted pair with a drain wire. While I understand how to calculate this for a "normal" shielded twisted ...
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1answer
93 views

Transmission Line Mismatch Simulation

I found an interesting simulator for transmission Lines. I can set a precise value for the load and then see what happens. For instance, let's suppose Z0 = 50 Ohm and let's consider these cases: 1) (...
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2answers
91 views

Confusing equivalent AC circuit (analysis)?

Context I'm doing some analysis on a dummy circuit. I've been explicitly told that the current generated by the source is a sinusoid: $$I_{0} = I_{p} cos(\omega t + \pi/2)$$. It also have been ...
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4answers
96 views

Coax characteristic impedance measurement

How is physically possible to get the value of the characteristic impedance of a certain coaxial cable? Precisely, in my case I have a coax of 50Ohm impedance, and I need to cut it and connect some ...
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2answers
952 views

How to convert capacitor impedance to ESR?

I select an output capacitor for a DC / DC converter (LM2596), it is said that it needs a high ESR (50-60mOhm). In the characteristics of electrolytic capacitors there is no given value, but there is ...
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1answer
212 views

L-Pad Impedance Matching Equation

I've been looking at impedance matching a circuit, but I'm struggling to find an equation for calculating the values of the resistors in the output network. Given this circuit: How are the values ...
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2answers
279 views

How to calculate “effective source impedance” in this audio mixing circuit?

I am new to electronics and have recently been trying to get my head around audio mixing. I stumbled across a helpful introduction by Rod Elliot on passive and active mixers, but I am stuck on a small ...
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5answers
2k views

Does an oscilloscope subtract voltages as phasors?

I want to measure two voltages on an oscilloscope. They are not in phase. I want to know the magnitude of the voltage difference. The oscilloscope has an in-build math function to subtract the ...
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1answer
51 views

Inferring common mode impedance for a given CMRR

In the figure below, the common mode impedances of the line driver and receiver are represented by RCM+ and RC-: (What I understand by the phrase CM impedance is that it is the resistance or ...
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3answers
142 views

Electrical RL circuit problem

So I am given u(t)=325sin(314t+90°)V i(t)=14.14sin(314t+30°)A I have to find the impedance Z∠θ, value for the resistor and inductor, inductive reactance Urms∠θ = 325/sqrt2 ∠90° Irms∠θ = 14.14/...
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1answer
63 views

Should we include Source and Load Impedance while calculating two port parameters?

While calculating the \$Z\$, or \$Y\$ or \$h\$ parameters of a two port network, should we include the source impedance and load impedance or not? In other words, for finding \$Y_{11}\$, we short the ...
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1answer
501 views

How to calculate impedance for reverb tank in a guitar amp

Background: I'm in the process of restoring a HIWATT HI-GAIN 50 COMBO Valve guitar amp and one of the issues it has is that the reverb dial has no effect on the sound. Attempted troubleshooting: ...
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4answers
2k views

Why does the cable resistance jump from a low value to high value at a particular frequency?

I am not well versed with transmission line theory so if you can redirect me to relevant material I'd be grateful. So I used Agilent 4294A to find resistance of a 2 metre long shielded twisted pair ...
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0answers
48 views

Altera Cyclone IV Setting Impedance

I'm trying to learn how to implement a 3V LVTTL interface using a Cyclone IV E (EP4CE10) FPGA. However, I would like to ensure that the input/output impedances of the IO is at 50R. I see that it is ...
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2answers
255 views

Unit of impedance

simulate this circuit – Schematic created using CircuitLab For the circuit above (for steady state I guess, if it is important) impedance of the capacitor is calculated using $$Z_c=\frac{1}{j\...
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2answers
101 views

Do PoE network switches have low output impedance and high input impedance?

I am just curious, and wanted to know if a Network Switches that have PoE ports have low output impedance, and high input impedance?
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1answer
117 views

Laplace Transforms and the imaginary input

When we get an exponential on the RHS of our differential equation (or if we give an exponential input) it's quite easy to solve the equation, but if we provide a sinsusoidal or cosinusoidal input, ...
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1answer
321 views

RF transmission line matching

I'm designing a board which contains an LTE module on it. I am a little confused about designing the trace between module and antenna. As far as I know I need to match these: Impedance of module's ...
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1answer
60 views

How to calculate reactance from an impedance analyzer circuit?

Background I have an impedance analyzer that uses the below circuit: Source One can measure impedance of the device under test (DUT) by using the following formulas: ...
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79 views

How can I view a song from my iPhone jack on an oscilloscope?

I was wondering how to view a song from my Iphone on an oscilloscope. I tried doing it today but got mixed results. I set the horizontal sweep to 1ms/div, the vertical to 1 volt/div and the coupling ...
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2answers
188 views

Why do I need to convert impedance to admittance in this problem

𝐼1 = 18 A, 𝐼2 = 15 A , 𝐼 = 30 A and R2 = 4 Ω. determine 𝑅1 and 𝑋L . This is the picture of the circuit: And this my solution all the way to the point where I have uncertainties: Now I can ...
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2answers
289 views

Is it possible to reduce the resistance of a voltage source (coil)? If yes, how can I do that? [closed]

First, I should inform you that I am a mechanical engineer, so this is an adventure to me. What can sound as basic to you, is like a new discovery for me. Second, I would like to introduce you the ...
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2answers
129 views

How to get phase shift in this task and in general?

So the task says: In the serial circuit connected to the 50 Hz frequency alternating voltage, effective voltage values 𝑈 = 220 V, known voltages 𝑈L = 660 V and 𝑈C = 500 V. The current in ...

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