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Questions tagged [impedance]

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

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40 views

Can I connect a 16 ohm output signal to a line input if I use a resistor in series?

newbie here. I have a Hi-Fi system and I wish to connect its output to a line input in another system while still being able to hear through the Hi-Fi´s original speakers. If I use the Headphone ...
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2answers
51 views

Low-impedance tap in this oscillator circuit

Here is the schematic of Michigan Mighty Mite, a popular transmitter circuit design. It seems to be quite close to a regular feedback oscillator, with a few peculiarities. What puzzles me is the ...
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1answer
37 views

How to quantify the cable impedance for common mode voltages?

Since a coaxial cable is not twisted, in the case of a common-mode interference the positive and negative lines will pick up different voltages. This unbalanced impedance nature of the cable can be ...
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2answers
94 views

Controlled Traces Length in SD card

I my new design I need to use SD card communication. I would like to match all the impedance traces and control the length of the traces. Regarding the controlled length, is there a rule of thumb to ...
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1answer
80 views

Induction heating

I was reading the working principles of induction heating and I think I understand the basics. Out of curiosity, I searched the Internet for a schematic and found one. However, the thing that confuses ...
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2answers
46 views

Problem understanding impedance measurement device accuracy format

I am reading the datasheet of an impedance measurement device. Its accuracy is listed as '±0.4% rdg. ±8 dgt.'. What does 'rdg.' and 'dgt.' mean? And how should I interpret the accuracy? The device is ...
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21 views

Input and Output Impedance of a SAW Filter

I am reading the datasheet of a SAW Filter B39162B4348P810. The datasheet doesn't say much about impedance of Input and Output ...
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0answers
28 views

HB100 microwave sensor impedence question

The patch antenna on these are minimal. I would like to cut the feed point and tap it with a short length of UT141(?) to feed two 10 GHz horns. Does anyone have a guess as to the feed point impedance? ...
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45 views

Difference between horn and power resister?

I have a circuit where my microcontroller is turning off and on a heavy load using a power mosfet (I've also tried it with a mosfet and a relay which yielded the same results). When I use a power ...
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1answer
26 views

LVPECL termination impedance

I'm designing a level converter PCB using a LVPECL driver (ADCMP573) and a LVPECL-to-LVTTL translator (SY89323L). I'm reading a document about LVPECL termination schemes and there's something unclear ...
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3answers
119 views

Determining Impedances of an Op-Amp Circuit

I'm trying to review some old concepts, and thus far, there was one that I couldn't really understand: impedance of circuits involving op-amps. Assuming an ideal op-amp, it has infinite input ...
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47 views

How to read high impedance on pin Arduino?

The goal is to catch an AC leak. For these purposes, I use a measuring transformer (RCMB121). When there is no leakage, the output contacts are low (GND). If an accident occurs, the contacts go into a ...
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51 views

Finding input impedance of the circuit

I'm having difficulties finding complex impedance of the following circuit: What I did first is find the impedance of \$C\$ and \$R\$ in parallel, which is: $$\underline{Z}_{CR}=\frac{R}{1+j\omega CR}...
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72 views

How to design an impedance meter?

I am designing an impedance meter with NI devices. I am applying 0-20 uA current signal to an RC circuit and measuring the voltage. Impedance is calculated by dividing Vp-p by Ip-p. I am controlling ...
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28 views

AC signal for impedance meter design

I am designing an impedance meter with NI current output device and voltage input device. I am applying a current signal, measuring the voltage response and dividing Vp-p of voltage and current to get ...
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22 views

ngspice .measure syntax in AC + par()

Why do the two netlists give totally different output impedance values ? Netlist 1: ...
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18 views

Impedance equivalent model of electrolysis process

I am measuring impedance between two electrodes and trying to model the equivalent circuit. Do I have to consider electrode/electrolyte interface of both electrodes in my equivalent circuit like the ...
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1answer
62 views

Ideal Transformer Theory Question

I have some questions regarding ideal transformers, similar to the one seen below: When talking about 'ideal transformers', can I calculate the current on the primary side by finding the complex ...
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1answer
45 views

Is 'R' in impedance equation an AC or DC resistance?

I am using an impedance meter to measure impedance in complex form (R-jX) and an RLC meter to measure R & C values in an RC circuit. The value of DC resistance is equal to the R value in impedance ...
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34 views

Electrical Impedance change with respect to measuring electrode pair distance in saline solution

I’m measuring impedance between electrodes in an electrode array. My impedance decreases with increase in distance between measuring electrodes. However, I don’t have ground to back this finding. In ...
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1answer
26 views

Confusion with output impedance using h parameters

Regarding the below liner circuit model, as far as I understand to find the output impedance the input current Ib is set to zero and the output resistance is calculated as Vc/Ic. I think this way of ...
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1answer
43 views

Why the input resistance of a common emitter amplifier is like this?

I am trying to find the input resistance of this BJ common-emitter amplifier: I replace the transistor with the hybrid-pi model It appears clear to me that the input impedance will be \$ R_{in} =...
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1answer
107 views

Maximum via frequency

I am designing a 18 layer, 2.5mm board using the material FR408HR and I am wondering about maximum via frequency, because I should use them for PCIe 2.0 (5 Gbps). I have not found a specific ...
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1answer
46 views

Admittance of the impedance of R and C in series?

I have a resistor \$R=150\$ and a capacitance \$C=\frac{1}{750\omega}\$ in series: \$ Z=R-jX=R-j\frac{1}{\omega C}=150-j750 \$ If I take the admittance I have \$Y=\frac{1}{Z}=\frac{1}{R-jX}=\frac{...
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49 views

What is a high impedance low level signal?

What is a high impedance low level signal? (I'm reading the circuit designer's companion by Peter Wilson)
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36 views

Analog Switches for decoupled Signal

I am currently working on a small board just for learning about PCB-Design and some analog stuff. Hence, I am pretty much a noob in this domain. I want to measure the impedance of a device, however ...
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42 views

Calculating the off impedance of a relay output by a multimeter

I'm trying to calculate the output OFF impedance i.e. the impedance caused by its RC snubber of this SSR. So I perform the following test: Zc is the relay's OFF impedance and Zv is the fluke 114 ...
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1answer
118 views

Is it possible to realize an 1:16 impedance ratio Transmission Line Transformer on a single core?

I would like to build a wideband amplifier with a 1:16 impedance ratio Transmission Line Transformer (TLT) at the output. The input port of the TLT accepts a differential signal and provides a ...
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1answer
126 views

Why it is necessary to put two 120 ohm termination resistors at each end of CAN transmission line respectively? [duplicate]

Why it is necessary to put two 120 ohm termination resistors at each end of CAN transmission line respectively? Does it make an equivalent resistance of 60 ohm? (parallel resistors). Is it OK to put ...
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0answers
40 views

Do Germanium BJTs have lower impedance than Silicon BJTs?

What brings this up is the fact that Germanium has a higher electron mobility than Silicon(as well as lower barrier potential) and does that translate to greater admittance(including susceptance)?
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1answer
53 views

Does impedance balancing in the far end make no sense?

Below shows a conversion of unbalanced line to a balanced one: My question is about: if the unbalanced line is very long which means the signal source and the isolation amplifier is apart from each ...
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5answers
138 views

Output impedance of STM32H743 MCU?

How do I find the output impedance of the STM32H743 (and potentially other similar devices)? I've looked through the datasheet (DS12110 Rev 5) and the reference manual (RM0433 Rev 5) however haven't ...
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0answers
7 views

SPD type 3, L-L protection mode, and Impedance computation

Many think a Surge Protector Device MOV (Metal Oxide Varistor) simply shunt or throw the current to ground or neutral during surges lowering the voltage. That is why they can't comprehend how it can ...
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2answers
63 views

measuring output impedance of op-amp

I've just took for granted the fact that the input impedance of op-amp is high and output impedance is low. I was reading "the art of electronics" lab book and there is an exercise that asks you to ...
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43 views

In Impedance track algorithm, How is resistance is related to soc(state of charge)?

In impedance algorithm for battery capacity, why we are calculating impedance and why it important to know impedance for SOC(state of charge)? 2.I doing some research on algorithms which we have,so,...
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3answers
35 views

Contact pressure vs contact area

I'm learning to weld. I've realised my earth clamp is limited. The spring is weak and its contact area is small as it's tooth shaped. Researching better clamps, I see clamps which have threaded bolts ...
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0answers
72 views

Contact a very small area (impedance matched)

In my current project, I want to apply a voltage to a capacitor (top electrode on a thin film heterostructure) very rapidly. Since capacitors have their own charging rate \$(\tau = R \cdot t = R \cdot ...
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1answer
58 views

Output impedance for microcontroller minimum 5kOhm

So I'm looking into the stm32f469 series of chips (datasheet here), and see if I can play good audio with one with the build in DAC. To my knowledge, the built-in ones on chips usually aren't that ...
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2answers
58 views

Collisions of Thermal Impedances

As shown in the picture below, thermal impedances of an IGBT device depends on the temperature. However, there is a strange phenomenon as follows. While with increasing the temperature, steady-state ...
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1answer
74 views

RLC Impedance Calculation

Sorry, will provide more information now. I am working through this question from an all about circuits webpage (See attached webpage link) and have having trouble seeing how they calculate an ...
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1answer
90 views

Impedance matching a capacitor load

I am currently trying to impedance match a capacitor as a load. In detail, it is an insulating thin film grown on top of a conductive layer (grounded). We now sputtered small Pt electrodes on top and ...
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2answers
47 views

Does the value of opamp input impedance have direct effect on the amount of noise measured in this scenario?

Regarding noise added on a signal during transmission i.e. along the long wires between the source and the amplifier, Im wondering whether in a single ended system does the input impedance of the ...
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2answers
46 views

Confused with understanding the text about high input impedance and coupled noise for an electret microphone

I have a problem with understanding a text's paragraph about the use of FET as a preamplifier. It claims that it reduces the coupling noise for an electret microphone before it is amplified in the ...
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44 views

How do I refer an impedance from the delta side of a transformer to the WYE side?

My question is regarding the simple arrangement below: It is simply a three phase source feeding a load through Z1, followed by an ideal WYE DELTA transformer, followed by Z2. My question is how do ...
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2answers
181 views

Which is broken, the amp or the driver of this subwoofer?

My subwoofer (with an internal amp) is showing difficulty reproducing low frequency sounds (sine 30Hz ~ 70Hz). As I lower the frequency, around 70Hz, I start hearing very slight distortion (hint of ...
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1answer
89 views

Microstrip and CPWG transitions on PCB

I've been doing some simple RF boards as part of an internship in a lab, mainly to test particular ICs and prototyping, and mainly using coplanar waveguides. I've now been tasked with designing a ...
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0answers
112 views

Parallel transmission lines impedance

I just want to know the correct way to calculate \$Z_{in}\$ in this network. It's very simple but I think I might be doing something wrong. Is it ok to calculate the impedance over one line and get \$...
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1answer
68 views

Is Current Transformer secondary current independent of load impedance? and How to find voltage of CT Secondary side?

i am trying to figure out a CT (Current Transformer) which is installed in my device of analysis. This CT has Two wires passing through its center hole (one is phase/red wire of single Phase AC supply ...
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1answer
45 views

Ultrasonic transducer for NDT short circuit

i have bought several transducer for NDT test from some manufacturers, but before i tried them, i checked that the impedance between the positive and negative transducer just around 2 Ohm, and it didn'...
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2answers
293 views

Why is the transformer impedance given in percentage?

I have just talked to an Electrical Engineer and he referred to the impedance of a 3 phase transformer/rectifier with line reactors as 41% (8% transformer and 33% reactor). I asked him what these % ...