Questions tagged [passive-networks]

Use this tag for circuits that only contain passive components, such as resistors, capacitors, and inductors. This includes RC, RL, LC, and RLC circuits.

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Thevenin's theorem for Voltage divider bias

I am calculating the base current of transistor Q1. To simplify the circuit equations, I applied the Thevenin's theorem and converter V1 and R1, R2 into Vth and Rth as shown in the image. Vth= V1x(R2/...
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Is the resonant frequency as defined for a second order transfer function same as the frequency at resonance in a second order electrical circuit?

When I studied second order system and thus natural, damped and resonant frequency I wondered if the resonant frequency I find using the formula \$ w _ { r } = w _ { n } \sqrt { 1 - 2 D ^ { 2 } } \$ ...
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Modelling a single trace PCB?

I am trying to model a PCB trace as a R, L, C circuit. Assumption: My PCB has a a single trace running through it. Just giving input from one side and taking output from other. There is not even a GND ...
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How do you derive an expression for the output voltage of a ladder network of N sections?

I am really stuck with a result from a circuit lecture slide. I understand how the thevenin equivalent circuit for this section shows the general result. But I am stuck on how to prove it generally ...
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State-Space Model of Resonant Circuit

I am trying to determine the state-space model of the circuit shown below. Also shown are the KH equations. Those equations I put in a Solver (Mathcad), however the result does not seem correct. For ...
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Parallel RLC Circuit with DC voltage source input

I am new to LTSpice and I am trying to simulate an RLC parallel circuit with a DC source. The ideal switch is initially open and then closed at t=0+. The input is an ideal DC source with 1V. I have a ...
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Question on RC circuit.(Texas Instruments interview)

I have confusion in this circuit. I know at t=0 both capacitor charges instantly. and voltage divided between both capacitors equally. but after some time output loop start active and capacitor C1 ...
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I designing a pulse generation circuit using capacitor and resistor but my output is not coming as expected

I am designing a pulse circuit which I will be feeding to a comparator. I am using a combination of resistor capacitor and diode for generating positive edge triggered pulse as shown in the below ...
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Which of the following is LC lossless function?

Which of the following is LC lossless function and why? Pick one of the valid LC lossless functions and realize it using Foster-I and Cauer-I form. I have been trying to solve this question for ...
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Confusion with determining lossless function

Why is not a valid lossless function? Below condition 1, 2, 7 or 8 constitute the sufficient conditions for being a lossless function, but I am confused why is this not a valid lossless function. ...
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Differential equation of a LC circuit in series with a parallel RLC circuit

I have the following RLC circuit. I am having trouble finding an expression for the natural response of this circuit. I found a similar question, but I was unable to simplify exactly like was done in ...
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How is energy conserved in an LC tank with voltage offset?

Consider an ideal LC tank oscillator offset by an ideal battery*: The core question is this: is the energy balance here maintained by the charge-voltage relationship of the battery? Energy seems to ...
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How to simplify matching network LC circuit

I'm relatively new to RF design, and trying to implement a Micrel reference PCB antenna design (Heli-2). I am using a MICRF113 RF transmitter at 315MHz to transmit digital data using ASK (OOK). Here ...
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Capacitor current in parallel network with ESR and parallel resistance

So this might be a very simple question and I've got a knot in my brain but I've been at this for days and don't see how I could solve this problem. I'm trying to find the solution for both ucA, ucB(t)...
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Differential stripline characteristic impedance measurement

How would you measure the characteristic impedance of a differential pair (stripline) if you don't have access to a Vector Network analyzer? I have access to an oscilloscope and a signal generator. ...
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Laplace Transformation: Determine the current through the inductor versus time i(t)

simulate this circuit – Schematic created using CircuitLab I am trying to find the current through the inductor versus time i(t) using Laplace transform. Converting everything into the s-domain: ...
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Phase of grid current is not varying in the simple RL circuit

I am trying to implement the following circuit: Circuit parameters are as follows: R1 = 2 ohms L1 = 10mH V_inverter = 28.175V (peak) V_grid = 200V (peak) I want the grid current to vary in full ...
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How would you find the quality factor of this RLC circuit?

I have been trying to find the quality factor of this RLC circuit for some time now. My method is trying to find the equivalent series RLC circuit and calculate the resonant circuit. When I work ...
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LT Spice: parallel RLC circuit resonator giving weird frequency response?

I am trying out the following parallel RLC circuit configuration: On trying out other similar parallel circuits (like with an RL coil in parallel with C or with RC and RL branches in parallel) I got ...
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How to find nature of RLC circuit?

If a resistance value, XL value and XC value are given, how do we determine the nature of the circuit (whether it's capacitive, resistive or inductive)? The only thing that comes to my mind looking at ...
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2 votes
1 answer
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On the topic of Quality factor in arbitrary RLC resonance circuits

In question Quality factor in arbitrary RLC resonance circuits, the OP asks about the Q of more complex circuits other than simple series or parallel RLC topologies. The responses I read, in ...
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How to determine the time constant from an RL circuit graph?

I have an RL circuıt and this is the RL circuit's input and output graph. How can I fınd the time constant in the graph using the cursor?
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RLC circuit as an average filter

I have simulated a buck converter in LTSPICE, and below is the switching signal (red )that goes into an RLC filter( vout as green). The filter does not average the switching pulses, So I believe the ...
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Measuring inductor current with oscilloscope in a parallel RLC circuit

How can I obtain the inductor current waveform on the oscilloscope? If L=1 henry then integral of voltage across the inductor can give me the current but if the oscilloscope can't take the integral ...
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3 answers
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Signals and systems - Find the inverse Fourier transform of a RLC circuit

I was analyzing the following RLC circuit: And applying the Fourier transform on the circuit, I ended up with the following transfer function: $$ H(\omega)=\frac{V_c(\omega)}{V_i(\omega)}=\frac{1}{1+...
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How to find optimal resistant value to dissipate energy from RLC circuit?

This is my personal problem not any acadamic or homework. Given this circuit We will charge the capacitor with V1 until it fully charge then switch to RLC circuit at, t = 0 simulate this circuit &...
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How exactly does the inductor in an LC filter reduce motor noise?

I'm currently working to quiet down the emissions from a stepper motor drive circuit. The motor drive frequency is 22kHz, and there is significant 60MHz noise that comes ONLY from the 36V side as ...
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2 answers
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How to compute S21 when port 1 and port 2 reference impedance (Zo) are different

The attenuator given in the figure is a 6 dB attenuator when both port 1 and 2 have a reference impedance of 50 Ω. Then, their S-parameter matrix (when port 1 and 2 have 50 Ω reference impedance) ...
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RL-circuit using Laplace

I have a series RL circuit (with zero initial conditions) and I want to find the voltage across the inductor. The formula I got is: $$\text{V}_\text{L}\left(t\right)=\int_0^t\text{V}_\text{in}\left(\...
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2 votes
2 answers
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MC34063 inductor current peak does not match calculations

I am trying to design a voltage inverter based on old/cheap/jelly bean parts. I wanted to use the MC34063. Mostly for learning purposes, so I don't look for easier parts to use for now. I run the ...
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1 answer
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Damping Ratio Implications for an Increasing Resistance In an RLC Circuit

I have managed to derive the 2nd order ODE for a simple RLC circuit (this circuit is part of a booster dc-dc converter). I derived an expression for the damping ratio of the circuit and fact checked ...
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The circuit modeling a surge test [closed]

In the surge test as far as I know, a capacitor is charged to a high voltage and is discharged via an RL load. The voltage is a decaying sinusoidal across the capacitor. This is the general picture I ...
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RLC bandpass filter transfer function

I've been tasked with finding the transfer function of the RLC filter shown below. I converted to the S-domain and used the voltage divider rule to find the output, and came up with: $$H(s) = \frac{R}{...
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1 answer
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Making a DC to AC converter at home

My idea was to build a DC to AC converter, and I want to make sure it's feasible: simulate this circuit – Schematic created using CircuitLab A supercapacitor has very low voltage operating ...
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3 answers
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Finding the current through an inductor in a second order circuit?

Assume that the circuit has reached a steady state. I'm trying to find the current through the inductor at some time, t, which should be a function of t. I'm having trouble creating a system of ...
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3 answers
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If all the resistances inside a passive resistive network is multiplied by some factor, what will happen to the thevenin resistance?

Lets imagine an arbitrary passive resistive network, a black box. Let its Thevenin equivalent resistance across some terminals \$a,b\$ of the network be \$R_{th}\$ ohms. Now lets imagine another ...
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LC filter for TEC (Peltier)

I am designing TEC controller which both COOL and Heat. This will be control with PWM from microcontroller. I have two questions: Spec: TEC will be run between 6V-12V max current 2.5A What type of ...
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How to include an independent source in two-port theory

how does one include an independet current or voltage source as a two-port. With ABCD matricies it's easy to cascade multiple networks together. So let's assume we have a two port connected to a ...
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3 answers
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How to communicate short-distance (under sea) using induction?

I need a bite-throttle on my scuba-regulator to wirelessly control my foot-mounted thrusters, which are about 1.5meters distant from my transmitter. I need only "1 bit" (on or off) right ...
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1 answer
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Can you measure or estimate antenna reflection back into freespace caused by a freespace impedance mismatch?

Consider an antenna as a 2-port reciprocal network such that you may have S11 reflection at the feedpoint, but also S22 reflection back into freespace. S11 is well understood and measured because that ...
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Can port parameters in one representation (mag-angle, decibel-angle, or real-imaginary) be converted to the other?

I'm trying to figure out what network parameter data would be "best" to use when generating a Touchstone file, or if the different data representations are equivalent in terms of the ...
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Can an antenna be modeled as a 2-port passive network?

I've been using xnec2c to model antenna characteristics in Linux and the latest version is able to create a CSV by frequency of SWR, Zr/Zi, dB gain, and other metrics. I was thinking it would be neat ...
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Second order transfer functions, intrinsic time constants and responses

Say I have the following circuit: - simulate this circuit – Schematic created using CircuitLab This circuit has the following transfer function \$H(s) = \frac{V_o(s)}{V_{in}(s)} = \frac{\frac{1}...
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Measuring and connecting a parallel LC circuit

I have built an LC circuit at 3.4 MHz and measured it's resonance with a VNA as schown in this picture and described here: The parallel LC circuit is connected to the output of the VNA and is open, ...
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Too high frequency when building an LC circuit

I am trying to build an LC oscillator for a thesis at my university. I'm aiming for ~3.5 MHz, I would a Helmholz pair with 30 windings each coil and a radius of 1.5 cm, which I calculated to have ...
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Calculate capacitance given I and V graphs

There's this question which asked us to find the capacitance value give both (v-t) and (i-t) graphs for capacitor. Here are the graphs: This is how I calculated the capacitance: It was obvious from ...
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How to use an LC stage as a voltage amplifier?

What I have done From my simulation here, I have tried using a parallel LC stage as a voltage amplifier at resonance. $$f = \frac{1}{2\pi\sqrt[]{LC}}$$ $$L = 0.001$$ $$C = 10 \cdot 10^{-6}$$ $$\...
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LC filter synthesis, given transfer function (by expressing driving point impedance as continued fraction)

I want to know how to synthesise a passive LC circuit to implement an arbitrary known transfer function. (I understand that not all functions are suitable, so let's assume \$T(s)\$ is a positive real ...
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Jump in RC current response to a square wave

Periodic square wave feeding an RC circuit: I am currently studying RC filter response to a square wave input with a period of \$ T_1 + T_2 \$. I have understood about voltage expressions and current ...
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RL Transient Analysis confusion

simulate this circuit – Schematic created using CircuitLab When I am using Thevenin's circuit and deriving inductor currents equations i am getting different Time constant \$ \tau\$ from what I ...
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