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# Questions tagged [impedance]

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

204 questions with no upvoted or accepted answers
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432 views

### I need help understanding the total impedance in a delta connection

I'm trying to upskill by teaching myself electrical engineering. I already have a degree in theoretical physics and pure mathematics so I don't mind math-heavy answers. While I don't find the maths ...
47 views

### Amorphous Silica Electrical Impedance Tomography

I would like to see if the idea I have for an experiment is even worth the effort and money to perform. I would like to use electrical impedance tomography to image a developed thin layer ...
2k views

### How important really is the impedance of an USB 2.0 signal line?

The USB 2.0 specs requires a differential impedance of 90 Ohms and a common mode impedance of 30 Ohms (with some tolerance). This, by definition, gives a target of an odd mode impedance of 45 Ohms and ...
125 views

### Electrical circuits homework

I am pretty new to circuits analysis and I have the following problem as homework: ig2(t) = 4sin(ωt + π/4), e3(t) = 12sin(ωt + π/4), R1 = 10 Ω, ωL1 = 4 Ω, ωL3 = 3 Ω, 1/(ωC2) = 6 Ω I have to calculate ... 74 views

### Are there measured values for the resistance contribution of vias of different diameters and depths?

I'm interested to know if there are real-world measurement values available for the resistance contribution of vias (or plated through holes). Sure - there is no widespread definition of what a ...
2k views

### Output impedance of a series shunt feedback amplifier

I am trying to find the output impedance of a series shunt feedback amplifier by converting it to a two port network. I know the input impedance: Ri=ri*(1+A.β) But I dont know how I should find ...
10k views

### How do I convert S-parameters for impedance matching?

How do I derive the Z-parameters to calculate a matching network for a device? I'm not sure what terms to even search for as I get all sorts of information I am not familiar with. My task is to ...
744 views

### Connect speaker directly to Samsung Galaxy S6. Minimum impedance accepted

I want to connect an external (passive) speaker (3W/16 ohm) directly to my Samsung Galaxy S6 using the headphone jack. I want to do this on my bicycle using the smallest space possible. Connecting the ...
73 views

### Two-Way Speakers & First Order Butterworth Crossover

I live in the Upper Hunter of NSW and my knowledge of electronics is rudimentary. Recently I found a pair of two way bookshelf speakers. The cabinet of both speakers had been opened up and the wires ...
257 views

### How to calculate the output impedance of an oscillator?

Is it possible to approximately calculate the output impedance of an oscillator if the rise/fall times at a given load capacitance are known, simply by using the formula for the RC time constant T = R ...
141 views

### Small signal output impedance for a circuit with bipolar transistor?

For the following circuit, I need to find the small-signal impedance looking into the collector of the transistor at terminal X, not taking the load resistance Z into account: My attempt at a SSM is: ...
202 views

### How would you design a power divider with 50-Ohm unbalanced input and 4x 100-Ohm balanced output impedances to send RF down a CAT6 cable?

A CAT6 cable has 4 balanced pairs, each at 100 Ohm. I'm wondering if I can make a 50-Ohm coax unbalanced input and split the power to 4x 100-Ohm balanced output (and then merge it back together the ...
261 views

### Why the capacitive divider in this output stage?

I have this output driving stage, reverse engineered from a generic Chinese mist generator: The goal is to drive the piezo transducer with a given frequency (more or less 1.7MHz or 2.4MHz depending ...
93 views

### Common term for Resistance and Conductance?

Simple question; Impedance and Admittance are complementary quantities, and can be described by the common term "Immittance". Likewise Resistance and Conductance are complimentary quantities,...
70 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). ...
564 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 ...
488 views

### How does at low power factor impedance (p.f=R/Z) (if R is constant ) increases while current also increases?

Impedance is equivalent resistance of circuit having resistive and reactive components so if we keep R constant and increase inductance than Z will increase and power factor will going to decrease as ...
773 views

Admittance is the reciprocal of impedance. But: 1) Susceptance is the reciprocal of reactance, or the imaginary part of admittance ? 2) Conductance is the reciprocal of resistance, or the real part ...
61 views

### Calculating the off impedance of a relay output by a multimeter

I'm trying to calculate the output OFF impedance i.e. the impedance caused by its RC snubber of this SSR. So I perform the following test: Zc is the relay's OFF impedance and Zv is the fluke 114 ...