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

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26 views

Impedance Matching a switching Circuit

I'm trying to mathematically model a Class E amplifier in the hopes of deriving a relationship between the input and output (Transfer Function). One particular difficulty i'm facing is impedance ...
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3answers
251 views

What does it mean for reactive power to be delivered / consumed?

Real power makes sense since there is actual consumption, but regarding reactive power; what is consumed / delivered? And how does the circuit change once this happens?
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66 views

Average alternating power

"For each of the values calculate P and Q" (average) V = 250 \$\cos (\omega t +45)\$ I = 4 \$\cos (\omega t -30)\$ The way I would try solving this would be by converting to phasors, taking the ...
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3answers
39 views

Impedance matching for a guitar pedal

So it's me working on a pedal again. I would like to add some equalizer effects on the pedal and found a fascinating circuit "Smash Drive": As far as I know, maximum power with lowest effect is ...
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1answer
36 views

adding parallel Impedance 1

A homework problem tells me to find the equivalent impedance, so I added the series and parallel impedances just like I would a resistor; however, I don't understand how does one go from ...
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1answer
21 views

How to test for Bioelecetrical impedance in an body fat analysier

I have an interesting project for school. I want to test these body fat machines for consistency between different brands. Ultimately to see if a cheaper brand is as good as an expensive one. ...
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3answers
63 views

Back reflections at low frequency?

Say I have a signal driver operating at 50 ohm output impedance, driving something with high (hundred kilo-ohm) input impedance. If the wavelength I'm using (a few kilohertz) is much longer than my ...
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2answers
168 views

Schematics: Effect factor and impedance

I have a questions regarding a simple schematic. I would like to calculate the total angle (φ) and power factor (cos φ) of this circuit and the total impedance (Z). -- Not using the complex-method ...
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3answers
82 views

Op-Amp based guitar direct box

I successfully built an active DI box using this circuit (image posted below), everything went fine and I'm happy of the result. Parts List ...
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32 views

Operational Transconductance Amplifier Input Configurations

I recently purchased several OTAs (Lm13700) but have had quite a bit of trouble using them. Going through the TI datasheet and a Nuts & Volts tutorial it's occured to me that transconductance amps ...
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1answer
32 views

How do you account for receiver sensitivity in tranceiver half wave dipoles?

if you are to design 2 halfwave dipoles, both can transmit to each other using 3 watts and have receiver sensitivity of -80dbm (a picowatt). Suppose they are 800m and have same height from ground. How ...
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1answer
31 views

Boost Converter High output impedance

at no load my boost converter, will be the same as in the photo. I'm thinking without a load at the end of the boost circuit the output impedance will be very high which will make the potential ...
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3answers
82 views

Frequency response of a complex circuit

I am interested in finding the impedance as a function of frequency of the \$n^{th}\$ circuit in this series: simulate this circuit – Schematic created using CircuitLab (By request: this ...
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2answers
91 views

Calculating resistance and reactance of an coil (motor winding)

I want to find out the resistance and the reactance of an motor coil. I can measure the magnitude of the current through the coil using a DMM. For example, If the voltage across the coil is 230v ac ...
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2answers
627 views

Should each trace carrying RF be 50Ohm in characteristic impedance? How?

I have to translate a VHF (160MHz) receiver schematic into a PCB. After looking here and there, I am a bit confused. It seems like the main issues with RF are to avoid stray inductors and ...
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1answer
60 views

Interfacing a GPRS chip (WISMO218) with an RF antenna. Calculating line width for the right impedance

I want to interface the WISMO218 GPRS chip with an antenna. The antenna lines on the PCB board have to be very specific, otherwise the system won't work. I have uploaded the part of the datasheet that ...
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2answers
287 views

Finding the schematic of a black box with unknown impedances

I'm struggling with trying to understand a piece of homework in Electrical Engineering that I'm really trying to solve on my own but now I'm basically stuck. The assignment is to find the schematic ...
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2answers
47 views

Solving for the impedance and phase shift in a series-parallel AC RCL Circuit with Complex Numbers

Having a lot of trouble working through an AC circuit, asking for some help. The circuit is relatively simple - I have a capacitor of capacitance \$C\$ and resistor of resistance \$R\$ hooked in ...
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1answer
49 views

Why does ceramic capacitor ESR change with frequency?

In most datasheets, I see a typical table which shows that ESR of ceramic capacitor changes with frequency. I understand that impedance of every kind of capacitor must have a minimum due to its ...
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3answers
74 views

What is Source Impedance?

I was going through data sheets of op amps and saw that bias currents usually add unwanted voltages due to voltages generated from the bias current flowing through the source impedances. What exactly ...
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187 views

How do utilities calculate transmission lines impedance?

I'm an electrical engineering student getting into Transmission Circuit Analysis, and a question came out to me: How do utilities measure their transmission lines impedance? Do they use special ...
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1answer
62 views

Matching the impedance of a filter?

Currently designing a circuit consisting of 50 Ohm rated ICs. Between two ICs (switches), I will place a BP-filter made out of discrete components (high-Q inductors and capacitors). The filter will ...
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2answers
89 views

Output Voltage Swing vs. Load Resistance of an Op Amp

What does the "Output Voltage Swing vs. Load Resistance" signify? Lets say I want to get a gain of 400 from an op-amp. I can use any one of the following combination Gain = -(R2/R1) Case 1: R2 = 400 ...
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3answers
90 views

How do I find the input impedance a common emitter amplifier?

How do I find the input impedance of this common emitter amplifier? \$V_{CC}\$ is supposed to be at the top of \$R_5\$. I forgot how to do the analysis to find the input impedance. The input goes ...
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4answers
99 views

What is an impedance in AC circuit? (Preferred simple answer) [closed]

Can someone please help me understand what an impedance in AC circuit, please? I have read so much about it still I having time understand it. How does it affect the circuit, is it good or bad for ...
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1answer
71 views

Question regarding electrical resonance/impedance [closed]

Me and my friends are currently working on a project where we have basically soldered a microphone unto a circuit with a small laser pointer. We have a reciever circuit consisting of a photo resistor ...
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3answers
231 views

How can I analyze an op-amp based negative impedance converter in a circuit?

I am thinking of the circuit pictured below, which, while the op-amp is operating in its linear region, gives rise to the relation $$ v_0 - v_1 = -i_0 r , $$ where the direction of positive current ...
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2answers
96 views

Wind high impedance transformer at home

Suppose I need to make transformer at home, but I am unable to wind 100k turns obviously, then can I just connect a resistor in series with a winding to achieve desired impedance? Will it have serious ...
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2answers
157 views

Output Impedance of BJT/Mosfet amplifiers

I have heard in lectures that the desired output impedance for the BJT/Mosfet Amplifiers is LOW. But these transistors are Transconductance amplifiers 'by birth'. I mean they give output current ...
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2answers
82 views

What is the 'characteristic frequency' of a certain impedance?

I'm not familiar with that term. Could somebody explain it to me? Is it the frequency at which the phase of the AC current running through the impedance goes to zero? Edit: Here is the context in ...
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1answer
58 views

impedance matching single vs series capacitor

Im looking at a impedance matching circuit on a schematic that shows a .75pF capacitor pulled to ground. With my current board design I have a 1pF and a 3.3pF on the board already so I am thinking ...
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92 views

From RLC prototype to signal flow graph

This simple 3rd order low-pass circuit simulate this circuit – Schematic created using CircuitLab can be described with the following 3 equations: $$-V_1 = \displaystyle \frac{-1}{sC_1} ...
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2answers
241 views

How to measure trace impedance?

I have seen that trace impedances in PCB's are maintained 50 ohm & so on. How to measure this impedance using a simple multimeter?
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109 views

Why is power reflected when there is an impedance mismatch? [duplicate]

I understand that when there is an impedance mismatch between an output stage, for example from an amplifier, and an input stage, for example, a transducer; power is reflected. I would like to know ...
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118 views

Op amp circuit design

I am having trouble with understanding how to design circuits involving op amps. I need to design a circuit using as less op amps as possible which has the following characteristics: high input ...
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1answer
39 views

How to determine the minimum proximity of magnet to an AC line for no electrical impedance?

As the title says, I am wanting to calculate the minimum proximity for a magnet to be near a AC line for no electrical impedance. My scenario is this: I have a theoretical device like MagSafe ...
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3answers
269 views

Do I really need the open loop output impedance of an op amp?

There are several answers on the internet and here on how to calculate the output impedance of the opamp with a given feedback. My intention, though, is to find this value with an open loop ...
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1answer
77 views

Estimating the schematic of a black box using the measured impedance curve

I need to estimate/predict the circuit design of a black box using the measured impedance at the output of this box. The only hint I have is that the circuit inside the box is a demodulator. Is it ...
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2answers
92 views

OUTPUT Impedance

I wish to find the output impedance of the circuit in the attachment. I have drawn the AC Equivalent of the circuit but I don't know how to come out with the Formula for the Output Impedance. I would ...
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1answer
341 views

Differential pair impedance calculation

I'm having troubles calculating the characteristic impedance of USB/Ethernet traces for a pcb. The Saturn PCB design program calculates values where I'm not sure if they are correct. I want to use a 4 ...
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0answers
46 views

2SC1970 input impedance

Looking at this circuit, it says the base impedance is 12 ohm, so he used a 2:1 transformer to match to the input 50 ohm. Now in the spec of 2SC1970, base impedance is 10.4-15.3j ohm, but why did ...
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6answers
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How does Ohm's law extend to Z if Z is complex?

We know that impedance, Z, is complex. I'm told that $$V = IZ$$ But that rearranges to $$Z = \frac{V}I$$ But both voltage and current are real numbers, so how can a real number divided by another ...
2
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2answers
129 views

50 ohm output impedance

I saw some circuits that uses a emitter follower as a buffer for output. The emitter resistance is 470\$\Omega\$. The author says that, since the ac emitter resistance is very small, he put a ...
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1answer
63 views

MHz oscillator probe impedance?

I find something weird going on in my 100MHz oscillator probe. I always thought the probe has a resistance of 1M ohm, but apparently at 13MHz, when I put a 2.2k ohm resistor in series with the probe, ...
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2answers
56 views

How differential pairs should be called out on fabrication print?

I have a design that the diff-pairs (100 Ohm impedance) and single-ended (50 Ohm impedance) are routed on the same layer. To specifying the impedance, on the “Lamination Stack-up”, I am going to add ...
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40 views

Reaction vs Rotary torque sensor for force/impedance control

I am working on a robotic system that is requiring a torque feedback from a rotational (single axis) joint for a force or impedance control loop. When researching the available torque sensors I've ...
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1answer
71 views

Replace crystal earpiece in bat detector circuit

I've been following the instructions on http://pw1.netcom.com/~t-rex/BatDetector.html which includes the following schematic for a Frequency Division Bat Detector circuit: The instructions clearly ...
2
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1answer
72 views

Impedance of waveguides shorter than 1/10 of wavelength

I read already several times that it is a common rule of thumb, that matching the impedance of a waveguide to the external network impedance is only necessary for waveguides longer than 1/10 of the ...
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1answer
104 views

Sinusoids and Phasors AC circuit impedance

Hello. I've been doing problems, and transforming from time domain to phasor domain to find input impedances seems simple enough But I've come across a circuit with a dependent voltage source, as ...
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1answer
97 views

Impedance Matching of Antenna and Amplifier

I've been doing a lot of research on impedance matching and I am just having a hard time understanding some of the specifics and I was wondering if someone here could help me out. I have a 50 Ohm ...