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

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47 views

How does Altium Designer's “impedance constraint” feature work?

Altium has a design rules option for setting a track width constraint according to line's impedance (e.g.; 50\$\Omega\$). How do I use it? Please give me instructions or a link to an online tutorial. ...
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71 views

Why Inductor reactance 180 ohms?

Why is the inductor reactance 180 ohms for designing Voltage controlled Oscillators ( or oscillators maybe ?) I came across a few resources for designing oscillators, colpitts and hartley ...
4
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1answer
55 views

What does 100Ohm @ 100MHz exactly mean in ferrite beads?

I am trying to understand the parameters of ferrite beads and having trouble in understanding the impedance vs frequency parameter. What does 100Ohm at 100MHz exactly mean? Does it mean that the ...
4
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1answer
65 views

Calculating differential PCB traces - Edge-Coupled Microstrip

I finally have the microstrip characteristic impedance thing figured out. But now, of course, I need to learn about differential signalling on PCB traces. I've spent some time researching. Here is ...
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1answer
37 views

Coplanar waveguide for differential trace calculator

Although there are plenty of free impedance calculators out there, I'm struggling to find one that can solve impedances for a differential pair using coplanar waveguide. Anyone know of any free ...
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0answers
43 views

Calculating Voltages in phases when a neutral fails

In the above star-connected three phase circuit the neutral is floating. I need to find the voltage across each load and which voltages are higher than 240 (Assuming the Line-to-line voltages are ...
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2answers
41 views

Finding the Average Power Loss in a Series RL Circuit

Question : A current \$I=3\sin(400t)\$ amperes in a series RL circuit in which \$L=1mH\$ and \$R=100Ω\$. What is the average power loss? Answer : $$ APL = 450 \space W $$ My Steps : ...
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1answer
37 views

dual piezo pickup

I experimented with different types of piezoelectric disks as double bass pickups and found two that picked up different parts of the frequency spectrum decently. The specification of the two piezos ...
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2answers
84 views

Using audio amplifier speaker output to drive an electromagnet

My first time here as a poster so forgive me if I make a misstep... I am building a coil (22swg enameled copper wire, about 500 ft), some 4in inner diameter of the bobbin, 1" wide, will have ~ 450 ...
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1answer
58 views

Why do we use S-parameters for High frequency signals?

I have read at numerous places that S-parameters are used for analyzing systems which deal with high frequency. But why only high frequency? From what I have read, I have understood the following ...
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1answer
78 views

Line-out: why is there no impendance issue when plugging an amp rather than headphones?

Given that the input of an amplifier has very high impedance, while headphones have very low one, why can I plug either one or the other on the audio-out plug of my computer? Even with a degree on ...
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1answer
60 views

Calculating the current of an AC circuit

My goal is to calculate the current i(t) up in the right corner. Using the formula $$ Z_{total} = \left( U\over I\right), I = \left( U\over Z_{total}\right) $$ Given values are $$ R_{1} = 1k ...
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98 views

Multimeter input impedance and its effect on the measurement of charged capacitor's voltage?

while experimenting with capacitors, I charged a 15pF cap through a resistor to the voltage of a 1.5v battery. Then when I disconnected the capacitor and tried to measure its voltage with a 10Mohm ...
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3answers
177 views

Electrical issue with USB ? Hi-speed device not working on own design

Disclaimer, I'm a SW guy, so please don't take anything for granted, and I would appreciate explanations in layman's terms :) We have a custom design based on ...
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2answers
56 views

Measuring Load Capacitance and resistance of 4~20mA transmitter

In order to make a spec sheet on a loop powered 4~20mA product, we need to measure the Device Capacitance and Device Resistance. Is there any standard procedure for measuring such parameters?
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1answer
137 views

Definition and Explanation of Insertion Loss and Return Loss

I'm trying to understand the physical meaning on Insertion Loss and Return Loss on a transformer, specifically RF transformers. The values are often quoted as figures of merit in datasheets, but I'm ...
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4answers
126 views

How can I minimize the variance in voltage drop across transistors - or eliminate transistors from this design?

I have a fairly simple circuit that I'm using with an arduino to measure the impedance on a very low-resistance circuit. The user plugs in a device at A and B and the arduino can compute the ...
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4answers
73 views

High input impedance devices - induced noise sensitive

I am currently reading about 4-20mA current loops and the reason we use them .As stated there , using voltage to transmit signals we get voltage drops over long cables due to cable resistance. We ...
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3answers
127 views

Voltage output from a tank circuit

I have the following tank circuit. Now at resonance of about 50.054 MHz, the output voltage should be same as input, as the tank circuit would have a high resistance. I have calculated the ...
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2answers
126 views

Selecting different impedances then 50 ohm in DDR3

I've worked with DDR2 and DDR3 memories and usually stuck to 50 ohm impedance for traces. But i do see that SoCs and DDR2/3 memories seem to support other impedances such as 30, 60 and 150 ohms. ...
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3answers
209 views

Required output impedance for ADC input?

On the Atmel AVR 328P on the Arduino Uno, the ADC's an R(ain) value is 100Mohm - which I assume is the ADC input impedance? However, in the datasheet it says "The ADC is optimized for analog signals ...
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2answers
74 views

Solving three impedances in series

I have a circuit of two capacitors and three resitors, where two pairs of the components are in parallel combinations: I'm trying to calculate the total impedance. Since \$C_1\$ and \$R_1\$ are in ...
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1answer
86 views

How to realize a zero at infinity ? RC synthesis

I'm just trying to synthesize this bellow pole-zero map. Since now I have come up with the following equation. $$Z(s) = \frac{(s+1)(s+3)}{(s+2)(s)} $$ But I have no idea about how could I ...
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1answer
70 views

Input impedance of a transistor amplifier from an example

Going on reading "The Art of Electronics", I am still stuck on another input impedance calculation for a transistor amplifier. This is really something I should overcome, maybe your explications will ...
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1answer
63 views

Impedance Matching Resistor

I'm working on a high speed ADC/DAC board. I saw some reference designs for the device, there are matching series resistors connected between output digital pins & controller. Though, resistor ...
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1answer
84 views

Microphone output resistance, why this value?

I would like to sample the output of a microphone. I am using the following set-up in order to tune the DC offset at the microphone output. simulate this circuit – Schematic created ...
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31 views

Picking the right tool to trust for impedance calculations

I'm having a dilemma, when I'm creating layer stackup for my boards I'm in a situation where my tools (Altium, ICD stackup planner, online calculators) and even my PCB manufacturer do not necessarily ...
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3answers
221 views

Input resistance of a transistor circuit

I have a question from the razavi's microelectronics book: I'm puzzled because in the solution provided, the first line states that: "We know that the input resistance Rin = R1||R2||\$r_π\$." ...
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45 views

Impedance problem (polar to rectangular)

Having a little problem understanding why this example converted polar to rectangular form to get Z. What is wrong with just leaving it in polar form and doing the algebra to get the value for Z
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79 views

Xilinx Spartan3-E FPGA input impedance and input leakage current for the GPIO pins

I am trying to use one of SPARTAN3-E FPGA GPIO pin as an input to ADC. I want to know the input impedance and the leakage current for GPIO? Should I just connect my circuit's Vout to GPIO pin or ...
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2answers
86 views

Door phone audio signal to pc soundcard

I need to interface door phone system to a pc soundcard to listen and talk to the external unit. The door phone to interface is an as yc/200 of BPT and its a classic analog 4+n wires Door phone ...
2
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2answers
117 views

Does impedance discontinuity distance matter?

I'm not remembering my education very well. I know when a signal encounters an impedance discontinuity there will be some reflection, I just want to know if in my case that is a practical concern. I ...
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147 views

Automatic impedance matching in microwave waveguides

I am trying to building a magnetron plasma using microwave magnetron. I now need to build magnetron to antenna link using rectangular waveguide, WR-340. I then found out that it needs to be tuned ...
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103 views

Take the voltage out of a voltage divider with no distortion

In the (simplified) schematics below, I would like to measure the voltage at point A with an instrument that I have to plug at point B. The problem is that if I simply add a wire between A and B, ...
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1answer
73 views

Why single-ended pcb trace impedance is fixed to 50ohms [duplicate]

Why is the trace impedance of a single-ended trace on a PCB fixed to 50 ohms or 75 ohms (for video signals)? Why can't it be fixed to any other impedance values?
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91 views

Voltage Reference Output Impedance

Relevant Datasheets: AS431 Voltage Reference INA126 Instrumentation Amplifier I am designing a circuit which will amplify a few millivolt input (~+/-10mV full range) to a few volts (~0-8V output, ...
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24 views

Influence of a Capacitance Matrix of a voltage measurment

I am having a problem in understanding how, in a multiconductor system, the Capacitance Matrix influences the measure of voltage between two electrodes. In the case that interest me we have 4 ...
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2answers
76 views

How to set the input impedance of an inverting amplifier

I want to Design an op-amp inverting amplifier circuit with Closed-loop voltage gain = -10 and Input impedance = 10k Since the it's an inverting amplifier then the Closed-loop voltage gain =-Rf/Rin ...
0
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1answer
105 views

Is it possible to design this circuit with a single potentiometer (L-pad)?

I'm designing an L-Pad for my speakers. They attenuate the signal while keeping a consistent effective impedance, which is necessary for the amplifier and crossover circuits. Typically, these values ...
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3answers
115 views

The contradictions in relation between current and voltage with regards to power and impedence

What happens in a house if there is a change in voltage due to voltage fluctuations? assume voltage decreases from its normal value case 1) V = I*Z Z does not change unless there is a change in ...
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434 views

How is xΩ impedance cable defined?

This is probably a really simple question, but I can't seem to find a definite answer anywhere. I'm guessing 50Ω cable means 50Ω per unit length. What unit length is this? If this is not how its ...
4
votes
3answers
155 views

How to measure headphone impedance for a target cut off frequency?

Lets say I have an audio signal with a DC offset and I want to use my earplugs to listen it clearly. Since I'm a human my hearing range is 20Hz to 20kHz. It means I need to filter very low frequency ...
2
votes
1answer
150 views

Linear Transformer and Ideal Transformer: electric circuit question

The question is to determine k in so that no current flows in Zx. I literally have no clue how to start. If there is no current in \$Z_x\$ that would make it an open circuit, so for it to be ...
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2answers
102 views

Why does this parallel->series rewrite change my AC simulation results a little?

Here are two circuits I've simulated. Both have a current source of \$\sin(\omega t)\$ mA with \$\omega=1000\$. They should be equivalent but give different simulation results. Here are the ...
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4answers
1k views

How are speakers matched with audio amplifiers? (avoiding overloading either)

I know a similar question title has been asked, but I believe that does not answer my question (and I couldn't think of a better way to phrase the question). I'm a bit confused by how exactly an amp ...
2
votes
2answers
123 views

About impedance matching for high frequency and divider effect

----- 2013/11/08 modify my question I have an 'A' source has 5 MHz signal (0-5 V square wave) without knowing input impedance and a receiver 'B' has 75 ohm input impedance. As I know I have to match ...
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2answers
143 views

What does it mean for an input impedance to be “differential”?

In a specs of a data acq. device the input impedance is shown as "20 MΩ differential". Does that mean the measured impedance in diff input case? If so how can I calculate the input impedance for ...
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2answers
115 views

Correct calculation of conductance/susceptane and from there to admittance, impedance, resistance and reactance.

I am sending a sine wave through a unknown RC circuit. At the other side I have a current-to-voltage converter (transimpedance amplifier) measuring the current indirectly as voltage. I am using IQ ...
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1answer
78 views

Designing a purely reactive circuit with the following requirements

how would you design a purely reactive circuit with: Infinite impedance in f = 0 Hz and f = 800 Hz Zero impedance in f = 5000 Hz and 11000 Hz At 7000 Hz, has a reactance of 181.85 Ohms How to proceed ...
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1answer
121 views

Calculating voltage in RLC circuit

Well I think the prof has made a mistake in one of his exercises, though asking here to be sure, The question is to calculate the supply voltage in the system below. simulate this circuit ...