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

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Question regarding electrical resonance/impedance

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 ...
2
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2answers
113 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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24 views

Use of hpcompac desktop computer internal speaker for mobile phone audio output [on hold]

My hpcompac desktop computer is dead but internal speaker is working I want to use this speaker to listen songs on my mobile phone, any suggestions?
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0answers
76 views

Power circuit analysis [closed]

2 questions 1) does anybody on this website have any knowledge of transformers and power system? (just to make sure i'm not on the wrong site) 2) can someone explain how to draw a transformer ...
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0answers
38 views

Transformer equivalent circuit [duplicate]

If anybody has any experience with practical transformer schematics and analysis techniques, could you please explain how to solve this question, i have looked all over multiple websites and there is ...
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1answer
45 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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61 views

transformer (no load test)

If anybody has any experience with practical transformer schematics and analysis techniques, could you please explain how to solve this question, i have looked all over multiple websites and there ...
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2answers
60 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
66 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
45 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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0answers
47 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
85 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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2answers
93 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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2answers
94 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
34 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
161 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
48 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
87 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
205 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
38 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
971 views

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 ...
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2answers
97 views

50 ohm output impedance

I saw some circuits that uses a emitter follower as a buffer for output. The emitter resistance is 470 ohm. The author says that, since the ac emitter resistance is very small, he put a 50 ohm ...
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1answer
60 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, ...
2
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2answers
54 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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27 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
59 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
49 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
70 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 ...
2
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1answer
81 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 ...
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1answer
61 views

How does one calculate the voltage ratio V+/Vo for this circuit?

I can understand the first case above, that seems simple as I can simply measure across the ground and V+, but I am getting very confused for the second case. Is the capacitor and the resistor in ...
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1answer
53 views

How do I wire speakers in multiple rooms to one amp? [closed]

I would be happy if anyone can help me with the following project I wish to build : I have an old amplifier 4ohm impedance with A and B zones, support for mono and stereo and playing both A and\or B. ...
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1answer
74 views

How to calculate theoretically Output Impedance of a Linear Voltage Regulator

I am trying to calculate the output impedance of the following circuit, a linear voltage regulator. What is confusing me is the feedback coming from R1 and R2. I used R4= 500 ohms, R3 = 1K , R1= 25k ...
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2answers
161 views

What is the output impedence of this RC Circuit

I have this simple circuit. And from what I calculated the output impedance seen from the OUT node comes to about \$138.765 \Omega\$. $$ X_c = \frac{1}{2\pi * 890*10^3 * 10^{-9}} = 178.8257\Omega $$ ...
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1answer
105 views

Placing Via's on PCB

I'm designing a PCB for USB 3.0, the specifications for Differential impedance comes at 90 ohms with a tolerance of +- 5 ohms. I've used different calculation tools but when I have to hold these ...
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4answers
462 views

How is it possible to have a 5W transmitter driving 50 ohms with a 12V supply?

So let's say you have a circuit, which generates a carrier wave at some frequency (let's say 27MHz) and it's connected to a 50 ohm dummy load (which I gather is equivalent to an antenna for circuit ...
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4answers
85 views

Current Source Circuit Internal Impedance

So I've been learning about current source circuits - this one in particular. I'm told that an ideal current source should give out the current no matter what happens to the load. But it should also ...
10
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2answers
344 views

Why does ST recommend 100nF decoupling caps for a 72MHz MCU? (And not 10nF)

I've been reading about decoupling caps, and I can't seem to understand why ST recommends 100nF decoupling caps on a 72MHz arm mcu. Usually 100nF decoupling caps are only effective up to about ...
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3answers
124 views

Recognising output impedance of an amplifier though inspection

The output impedance of FET amplifiers seem to be a hit and miss affair when I try to find it just through inspection. For example, sometimes it's easy to predict, whereas some other times I have to ...
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32 views

How does the impedance of the source effect the positive sequence impedance measurements of distance relays?

How does the impedance of the source effect the positive sequence measurements of distance relays in relation to power system protection? I wrote that increasing the source impedance decreases the ...
2
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2answers
85 views

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 ...
2
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3answers
138 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
185 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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2answers
93 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 ...
0
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1answer
67 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 ...
2
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1answer
127 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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0answers
44 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 ...
0
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4answers
197 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
52 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 ...
0
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1answer
89 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
104 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 ...