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

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Balanced line impedance matching

Is there a way to convert a 100Ω balanced connection to a 200Ω balanced connection without using two baluns? I have a 2.4GHz baseband that I want to attach to a front end, but the baseband ...
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3answers
51 views

Low output impedance vs high output impedance of an amplifier

I read that a low output impedance is desirable for an amplifier. I am unable to understand why from my analysis of the output side of the common emitter amplifier. So looking at the output of the ...
2
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2answers
81 views

Most efficient and rigorous way to calculate input/output impedances (transistor circuits)

I've always had troubles with input and output impedances. It is not very well explained anywhere else I could look on the web so... What is the most efficient and rigorous way to calculate input and ...
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59 views

Adding voltage divider to output of power amp concerns

I have a load box I use to test and burn in analog audio power amplifiers. Each load box is tailored for a specific amplifier circuit and for one of the load boxes I would like to add an LED that ...
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1answer
35 views

Impedance line matching and component value matching

I have the following circuit for the SIM900's antenna connection, using the A10393 antenna from digikey: In closer look: First of all my knowledge on RF design is not great. My questions now are ...
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1answer
42 views

Is RF Transformer Impedance Significantly Affected by Wire Size?

I'm building a Softrock Ensemble III HF Receiver. The online instructions are pretty good, but have a few remnants from an earlier version that no longer apply. So, despite the discussion about the ...
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11 views

Impedance Matching for Amplifier Output [duplicate]

0 down vote favorite I needed some basic advice about impedance matching. I have an RF amplifier with 50 ohm output impedance, capable of generating 400W output power at 500kHz. I am trying to ...
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4answers
123 views

Impedance matching for amplifier output

I needed some basic advice about impedance matching. I have an RF amplifier with 50 ohm output impedance, capable of generating 400W output power at 500kHz. I am trying to deliver this to a 12 ohm ...
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1answer
35 views

Output impedance of a differential line receiver

Let's say I have an INA134 (http://www.ti.com/product/ina134) from Texas Instruments in my design. I want to take the output of that IC and feed it into a resistor network which can have a flexible ...
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1answer
72 views

Does coil require extra resistor before connecting mains?

I am planning to build diaphragm air pump. For this instead of using an AC motor, I am planning to connect an aluminium rod to diaphragm, and put a permanent magnet on it that will be pulled and ...
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3answers
65 views

Simulate RF transmission lines at Low frequencies

I would like to simulate RF transmission lines in how they propagate, and how impedance mismatches at the end of the transmission line cause reflections and power transfer does not work. It would be ...
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2answers
79 views

Question with solving for complex power, S, for each component

simulate this circuit – Schematic created using CircuitLab Hi! So I have a couple questions that I have already tried to solve that I think I am going in a little bit of the wrong ...
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116 views

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
56 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
39 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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38 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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1answer
48 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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3answers
118 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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2answers
57 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
44 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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2answers
128 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
112 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
64 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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139 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
93 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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82 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
78 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 ...
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1answer
131 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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197 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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71 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
70 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
44 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 ...
2
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2answers
146 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
97 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
85 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
61 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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2answers
178 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
230 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
74 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
347 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
142 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
105 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
162 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
181 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
256 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
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
92 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
75 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
65 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
91 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 ...