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

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Op-amp circuit problem - input impedance and its components

I need help in solving this op-amp problem. For the circuit on picture (op-amp properties:IN impedance is infinite, OUT impedance is equal to zero) determine the input impedance and discuss the ...
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2answers
65 views

How Cropx works?

This company claims that they can determine accurate irrigation patterns on a terrain just by using 3 sensors (https://www.youtube.com/watch?t=80&v=U48XTXXi_MA). They don't talk about the actual ...
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1answer
25 views

Choosing opamp with sufficient output current for Voltage Reference with high impedance load

I am designing a differential sensor that will be placed on the skin to detect biopotentials. Two inputs are fed into an instrumentation amplifier that has a reference set at 1.5 volts (VREF15 in the ...
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48 views

Impedance measurement for open circuit not staying constant

I'm trying to measure all the impedances (Power and critical I/O Pins at a test point) of the board using multimeter. When i measure ground and ground its showing close to zero, which is fine. But for ...
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25 views

Transformer characteristic for impedance matching in RF

In an rf impedance matching circuit it is assumed that transformer is ideal or large enough. I just wanted to know the quantification of "large enough" (which parameter is large with respect to what)
2
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2answers
40 views

Frequency dependent impedance calculation for microstrip

I need a hint. I'm stuck on outer layer impedance calculation for high speed design. Other PCB designers route high speed tracks on inner layers because of not controlled plating thickness on outer ...
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1answer
84 views

Why does cable length matter so much when source is high impedance?

My beginner’s electronics book has now started to teach me about microphones, specifically Electret microphones. While searching the web for more info, I stumbled upon an article where the author ...
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1answer
70 views

Noise Matching transformer

I'd like to use a transformer to improve the performance of our SR5184 preamp. The signal recovery SR5184 is an ultra low noise preamplifier. It has 0.8 nV/ √Hz input noise and a bandwidth of 0.5 Hz ...
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1answer
50 views

Use different footprint for a SATA connector

I am designing an Linux Board which needs a SATA connector. Now im faced to choose between 2.5 HDD SATA connectors and the new mSATA (mini PCI express) connectors. For compatiblity and usuabillity ...
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3answers
153 views

Why do cables have multiple grounds?

Many cables have multiple grounds. Why? For example, according to Wikipedia: The SATA standard defines a data cable with seven conductors (3 grounds and 4 active data lines in two pairs) and 8 ...
2
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2answers
78 views

Difficulties supplying 5V TTLs to 50 Ohm terminated single photon counter

Some background: I am building a confocal fluorescence microscope. Long story short, photons are recorded using a Time Correlated Single Photon Counter (TCSPC). This TCSPC is capable of time stamping ...
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1answer
95 views

Colpitts Oscillator Current and Frequency

Apologies if this has been asked before, but I couldn't find answers to my specific questions. I built a transistor based Colpitts Oscillator and I've been confused by the difference between the ...
2
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1answer
56 views

Impedance of headphones

This is probably the best article for a beginner about impedance with respect to headphones. I haven't managed to find an explanation of why the impedance of headphones is just a single, real number ...
0
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1answer
31 views

Metal Effect on Trace Impedance and Ground

I am working on a project that will have some impedance controlled traces running next to a large metal plate grounded at 1 point. I wanted to confirm that: 1) The metal plate will still impact the ...
0
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0answers
55 views

How do i impedance match two complex impedances?

If i have a source and load both having resistive and capacitive parts to it, what is the best way to go about matching the loads? The source impedance has low resistance around 15ohms but the load ...
0
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0answers
25 views

Measuring AC signal with different input impedances

I measured output voltage of PWM signal from arduino uno's pin 5. I generated 8Mhz fast PWM with the in the following link. http://withinspecifications.30ohm.com/2014/02/20/Fast-PWM-on-AtMega328/ ...
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2answers
58 views

Voltage drops when a signal is fed into op-amp comparator

I have a function generator SFG-2110 from GW Instek. I set it to generate a square wave with max/min of aroudn +- 1 V. And I checked with an oscilloscope. However, when I connected outputs of the ...
3
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3answers
195 views

Adding 90 ohm resistors to DIY USB cable?

I just started with electrics a few months ago, but now I am obsessed but still have MUCH to learn. What I am doing is essentially trial and error. I needed a longer USB cable to a printer so I took ...
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0answers
36 views

How Impedance at Frequencies affect Audio

I am trying to build an isolation transformer for my unbalanced 2 channel audio signal. How is Audio signal affected by different impedance's (of the transformer) over a frequency range? where: ...
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1answer
39 views

Series inductor as discontinuity in transmission line

Dual to this question is the following circuit: simulate this circuit – Schematic created using CircuitLab An infinite transmission line (with characteristic impedance \$ Z_0 \$) ends ...
0
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1answer
65 views

Shunt capacitor as discontinuity in transmission line

As in the following circuit simulate this circuit – Schematic created using CircuitLab suppose that an infinite transmission line (with characteristic impedance \$ Z_0 \$) ends upon a ...
19
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4answers
1k views

Why do characteristic impedances matter only when traces are longer than half a wavelength?

Why are characteristic impedances of traces not considered when the traces are shorter than half a wavelength? I've had the same issue with light diffraction, which happens when pinholes are smaller ...
0
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2answers
83 views

Input impedance of a non-inverting op-amp

From what I've read (and simulated), the feedback loop of an op-amp modifies the input impedance of the non-inverting input. The value specified in the datasheet is the open-loop input impedance, and ...
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30 views

Calculating DC resistance from p.u. impedance

I need to calculate or approximate the DC resistance of a 208.5 km overhead line which has the following information: impedance per unit on 100 MVA base: R = 0.004 X = 0.047 B = 1.049 Is it even ...
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1answer
92 views

What is load impedance?

Like resistance for DC, Impedance is for AC. But what is load resistance. How does it used in a circuit. Had this doubt when reading a line from the book foundations of electronics by D ...
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3answers
66 views

Impedance matching routes in Eagle board

I am making my second board using Eagle CAD. I have different components with a set of different sizes. I set the minimum width for lines to be x. That way, the autorouter creates EVERY line in that ...
2
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2answers
334 views

Why are some common-mode chokes rated in ohms instead of henries?

Some common-mode chokes, including this one, are rated in ohms instead of in henries. Why? Isn't the impedance injected by the common-mode choke entirely frequency dependent? Is there an assumed ...
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29 views

Question about transformer reflected source

The following show the idea how a Thevenin equivalent source is used to replace the primary circuit of transformer. In textbook it is commonly stated that the load impedance sees an equivalent ...
2
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1answer
89 views

Bioelectrical Body Impedance Analysis?

On what principle Bioelectrical Body Impedance Analyzer works? I thought about this many times, and I wanted to know is there really a way to precisely measure all those body parameters with this ...
1
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1answer
91 views

one antenna working as receiver and transmitter

I want to know, if an antenna which transmits and receives the reflected signal can be modeled as an impedance. For example, the antenna is coupled to a Collpits oscillator and sends out an ...
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0answers
41 views

Wideband GHz impedance matching

I'm using an antenna that works in the range from 1 GHz to 3 GHz. I want to match impedances between a cable from the transmitter and the input amplifier and from the output amplifier and the cable to ...
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0answers
73 views

Circuit Impedance

What is the impedance of the following network? My textbook says $$Z = R_i + R + jwL + 1/jwC$$ But I can't seem to make that work.
2
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1answer
34 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 ...
4
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3answers
766 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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70 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
124 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
38 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 ...
0
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1answer
27 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. ...
2
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3answers
74 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
210 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
112 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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2answers
49 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
34 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 ...
0
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1answer
60 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
86 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
327 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 ...
11
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2answers
766 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 ...
1
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1answer
79 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 ...
3
votes
2answers
332 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 ...
2
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2answers
74 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 ...