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

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Impedance matching an RLC circuit (inductor macroscopically drawn on PCB)

Context: I am a physics grad student with basic knowledge of circuits, but impedance matching and RF domain are beyond my normal scope. My PCB is actually copper bonded to a ceramic substrate that is ...
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2answers
49 views

Phototelectric smoke sensor with microcontroller

I am trying to connect a photoelectric smoke sensor with Atmega328. The smoke sensor IC has pin 7 as the I/O pin which gives a 9V when smoke is detected. I have connected this pin to the input pin of ...
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1answer
34 views

Running single-phase through two or three windings of a three-phase inductor; why does the direction of the middle winding matter?

I have a three-phase inductor, MTE RL-00403, nominal 9 mH. I have some experimental results that don't make sense to me, which appear to be related to the fact that all three chokes share a single ...
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35 views

Crystal Oscillator output voltages and power

I have built the crystal oscillator stage to the Pixie 2, a Hartley oscillator, with a 9 volt voltage source. I measured the output with my VOM set to AC 30 volts. It read almost 30 volts. That is ...
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47 views

According to impedance bridging principles, are these results accurate?

Here is the relevant data The setup for this experiment was a Shure SM57 dynamic microphone routed into a Magneto Audio Labs VariOhm, a variable load impedance device, which was then routed into a ...
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112 views

Output impedance refers to open circuit o/p impedance or short circuit o/p impedance?

When we specify output impedance of a two port network, does it imply open circuit output impedance or short circuit output impedance? Wikipedia: output impedance ; Wikipedia: two-port network g22 ...
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55 views

Why is there no voltage drop along a feedline

This page shows a graph of voltage along a transmission line by distance. Considering the case of a simple purely restive feedline of 50 ohms matched to a load of 50 ohms, I would expect the voltage ...
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1answer
35 views

Wien Bridge Frequency Selective Network Frequency Response Proof Exam Question

So this is part of the solution to the proof of what the frequency response on the frequency select section of the Wien Bridge oscillator. What I don't understand is how the answer are equal to ...
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121 views

Calculating Z_T (total impedance)

Using a mobile device so I can't upload a picture. I need to find Z_total in a circuit. I will simplify the circuit description so that its easily pictured. The simple circuit contains The ...
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2answers
106 views

BJT circuit analysis confusion

In the following circuit: Ib is given as: I don't understand how they arrived at this. I thought it would be a voltage divider between Rsig and Rb||Rbase divided by Rbase: Can anyone explain? ...
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1answer
59 views

Output impedance of current series feedback BJT amplifier?

So according to what I've read, in a common emitter BJT amplifier, an unbypassed emitter resistor acts as a current-series feedback path. The gain without feedback is: ...
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133 views

Extremely low output from amplifier

I am unsure what is wrong with my amplifier / microphone coupling. I have read many of the posts on stackexchange including the following: ...
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2answers
73 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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74 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 ...
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1answer
69 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
95 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
123 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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57 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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53 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
40 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
123 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
77 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
84 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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135 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
198 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
62 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
218 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
131 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
90 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
144 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
159 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
237 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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76 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
91 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
74 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 ...
0
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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
90 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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33 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
231 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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49 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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90 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
90 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 ...
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2answers
128 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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173 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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2answers
104 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
80 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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103 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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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
81 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 ...