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Questions tagged [passive-filter]

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2answers
55 views

Modelling 3-phase induction motor and filter for inverter output in LTspice

I am designing an inverter in Ltspice and am looking to have a simple circuit to represent the motor load and filter out the PWM harmonics in order to obtain outputs. The motor characteristics are: ...
0
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1answer
37 views

Unexpected output for a passive filter circuit with low ohm resistor

With a simple filter circuit (either high pass or low pass), I'm seeing unexpected behavior in the o-scope output when I use a resistor with a low ohm value (e.g., 10 Ohms). Since a picture is worth ...
0
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1answer
64 views

Easiest way to find transfer function of a lossless ladder filter after we finish design?

I have completed my Lossless Ladder BPF design, but I don't know how to find the transfer function of the resulting circuit without going through the slow and rigorous process of getting resistances ...
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0answers
50 views

Low power analog timer circuit

How can I achieve the following: When a switch closes momentarily Hold a mosfet switch closed for about 15s. Then gradually reduce power to zero over about 4s Using little-to-no power when not ...
0
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2answers
166 views

Low Pass Filter Wrong Pole Location

I wanted to understand and derive an equation of simple low pass filter that shows the location of pole in frequency response graph (Bode plot). So, here is the derivation: $$V_{OUT}=\frac{V_{IN}*...
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2answers
47 views

How much is the permeability of this attached inductor core?

I want to use this inductor for AC line filter as line reactor. Its inductance value is 6 mH but I don't know the exact value of permeability of the material. It will be used with VFD at the input to ...
0
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1answer
45 views

how to design AC line filter for VFD?

I am working on VFD for single phase induction motor. I am rectifying AC 220V directly to DC link capacitor. There is no LC filter from AC mains. There are harmonics in the AC mains. Can you suggest ...
0
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1answer
38 views

Problem related to the transfer function of RC low pass filter

I have the following question: For the passive RC low pass filter shown below: $$V_S(t)=\cos(t)+\cos(100t)$$ $$V_0(t)=\alpha\cos(t+\theta)+\beta\cos(100t+\phi)$$ (where \$\alpha\$, \$\beta\...
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2answers
174 views

Cutoff frequency of a second order low pass RLC circuit

L = 25 mH, R =1 kOhm, C = 10nF and Vs(t)=sin(wt)V, freq = 500 Hz I am trying to calculate the cutoff frequency of a second order low pass RLC circuit I don't know if I can still apply the formula of ...
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0answers
23 views

Bandpass filter severely attenuating input signal in passband

I've designed a 3rd order chebyshev passive bandpass filter with 10% BW and center frequency of 10kHz. However, when I feed it a 10kHz sine wave to the input, it immediately gets severely attenuated, ...
0
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1answer
52 views

Inductor choice for passive filter

I need to design a band-pass passive filter with pass band 10kHz~150KHz. One of the needed inductor is 2.2mH. I find there are two choice: Axial type or Can type. But it seems they are designed mainly ...
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2answers
269 views

Second Order Passive RC Low Pass Filter Doesn't Have -6dB at cutoff Frequency in LTSpice

For Second-Order RC filter the cutoff frequency is: $$fc = \frac{1}{2\pi \sqrt {R_1C_1R_2C_2}}$$ I have taken R1 = R2 = R = 1K Ohm and C1 = C2 = C= 0.1591 micro Farad. So the cutoff frequency comes ...
5
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1answer
78 views

Design of cavity filter

I try to design a Chebyshev bandpass filter for 6 GHz as a coaxial cavity filter. I know that the filter can be designed with the aid of the coupling coefficients between the resonators and the loaded ...
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1answer
65 views

Where is the dc component?

So a ac filter doesnt allow the dc component to pass through it, so the dc component would take a altetnative path where as the ac component would easily pass through it. My question is, where is dc ...
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2answers
94 views

What does this RC network do in this audio transformer output stage?

This is a relatively well known ABY circuit available on the internet. CLICK HERE, REMOVED IMAGE FOR COPYRIGHT REASONS I have two questions about this circuit : 1) What does the RC network (in the ...
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2answers
58 views

RC Waveform output signal confusion

I've been struggling to understand how filter capacitors specifically low pass filters achieve their output signal waveform. If I take the example from https://www.electronics-tutorials.ws/rc/rc_3....
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2answers
42 views

Transmittance of a capacitively coupled shunt resonator

I have been trying to understand the expression of |s21| for the resonator mentioned in this article. For a circuit similar to the drawn below, in which R1 is used as the temperature sensitive element,...
0
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2answers
86 views

Capacitively coupled shunt resonator

The diagram below shows a capacitively coupled parallel RLC resonator. Through simulations I observe that C2 and C3 influence the resonant frequency . I'd like to obtain the analytic expression for ...
0
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2answers
138 views

Transfer function of a bandpass

i was doing some homework and one thing I had to do was to derivate the transfer function of a given bandPass. I have done it myself but i dont know if it is correct nor if i followed the right path / ...
3
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2answers
197 views

Passive Low Pass Filter

What I want to do is make a low pass filter using a simple RC circuit (first order), or possibly an LC circuit (which would be second order). Right now, I am in the process of determining the values ...
0
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1answer
68 views

Pre-Amplifier Question [duplicate]

back at it again with a problem that I am stuck on and need some clear explanation of. 1/2: I was wondering How those Bass controls work, for example the ones in the car you allow to change the bass ...
0
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4answers
219 views

Chosing R and C values for a given RC filter design

I'm currently into designing passive LP filters such as RC topology and active filters such as Sallen-Key topology. I'm fully aware that what matters in the choice of values for the resistors and the ...
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3answers
134 views

Influence of I/O impedance in Butterworth passive filter design

I'm using a simple online simulator tool to build a passive Butterworth filter. An affirmation made in this page confused me: Enter the filter characteristic impedance. In all cases, unless you ...
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0answers
29 views

Synchronus dcdc converter shunt RC filter design

I'm struggling to find a guide/application note or whatever that explains the calculation, considerations and layout of an RC filter for current sensing on a synchronous DCDC converter (like the ...
0
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1answer
45 views

High power highpass filter

I'm using an audio amplifier to produce a 15-20 kHz, 6 watt sine wave output into a pure resistive load. There are some low-frequency components to this signal that I want to remove (mains frequency ...
1
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2answers
54 views

How can I size the 'supply noise filtering' capacitors at the load end for this scenario?

There is this SMPS dual-power supply which needs to power a load outdoors around 100 meters far away via a 3-wire cable as shown below: simulate this circuit – Schematic created using ...
2
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1answer
314 views

Frequency response of a parallel RC filter (smoothing capacitor in rectifier circuit)

I understand qualitatively and electrically how a smoothing capacitor works in the case of a diode-based full-bridge rectifier but what I am not too certain of is how to describe it in terms of its ...
1
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2answers
64 views

Configuring Frequency Bandwidth and Input Signal for Bandpass filter circuit

How do I set and configure the frequency bandwidth I want the filter to output to a device? I am using a physical passive bandpass filter which I intend to take the signal in and filter it and output ...
0
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2answers
77 views

RC Filter measured response differs from calculated transfer function

I've created a first-order RC filter with R = 68 Ohm, C = 5.0 uF, and I am studying the transfer function of this filter. I have calculated the transfer function to be 1/(1+jwRC), based on the ...
8
votes
1answer
236 views

Parallel RC filter on SCR gate

I came across an old circuit from work that discharges a capacitor (C1) into a step-up transformer to a low-impedance load. This event is triggered by a pulse into an SCR, whom has a parallel RC ...
0
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2answers
276 views

I need to design a bandpass filter by cascading passive high pass filter and passive low pass filter

I have a low pass filter with 3db cut off frequency of 200Hz and a high pass passive filter with 3db cut off frequency of 2kHz. I need to design a cascaded band pass filter which will isolate ...
0
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0answers
65 views

explain 12 pulse rectifier output and filter circuit?

Parameter 3 phase 115/200 volts AC Input 200-amp output Input Frequency is 400 DC output is 28 volts Output ripple is 1.5-volt maximum Question : on transformer secondary side it is star and ...
1
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1answer
112 views

Change in gain and cutoff frequency of 2nd order passive filters due to amplifier circuit

I'm designing an simple equalizer for a first course in Electric Circuits and having some problems. Circuit diagram and AC Sweep Simulation (Multisim 14): Circuit Diagram AC Sweep Simulation The ...
0
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1answer
168 views

Quality factor limit for 2nd order RC passive band-pass filter

simulate this circuit – Schematic created using CircuitLab I'm designing a 2nd Order passive RC band-pass filter and found that the quality factor is given by: \$Q=\frac{\sqrt{C_1C_2R_1R_2}}{...
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0answers
49 views

Butterworth component quality

I'm working my way through Bowick's RF Circuit Design. In the resonant circuit chapter he does a great job of describing how component Q affects circuit Q, and how loaded Q works. There, you set the ...
1
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2answers
148 views

RC Filter Parallel Potentiometer

I am trying to teach myself electronics, namely audio filtering, and I came across this circuit. Now with my limited knowledge the 'volume potentiometer' (that's what it is explained as) seems to be ...
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8answers
3k views

Why, in a passive circuit with a sinusoidal input, do all voltages and currents have the same sinusoidal behavior as the input?

I am familiar that in any circuit composed of linear passive elements and a sinusoidal input, all voltages and currents through and across any element will exhibit the same sinusoidal behavior and ...
1
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1answer
63 views

How to set up signal generator in lab to obtain an output voltage?

In one of my laboratory assignments, I am to study how to work with square signals in RC circuits (low pass filter). Please keep in mind this is an introductory Electronics course. Basically, I am ...
0
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2answers
584 views

Transfer function for a Passive Second order Low-pass Filter and to determine the components values

I am working on an assignment about Passive, second order low-pass filters. Cool little things if you get to know them. We are given the placements of the passive components (Inductor(L1), ...
0
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1answer
45 views

How is the voltage across a capacitor measured in a passive LPF circuit with no ground?

Say we have a low pass filter circuit as the one that follows: If I want to study how the charging/discharging of the capacitor works, I need to apply the universal equation for voltage. However, ...
0
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1answer
52 views

Can't draw bode curve of this zero

I have a transfer function like this: \$H(s)=\frac{s^2+\frac{1}{LC}}{s^2+s\frac{R}{L}+\frac{1}{LC}}\$ I can separate the denominator into an expression of the type: \$(1+s/a)(1+s/b)\$ and then plot ...
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2answers
257 views

DM and CM noise filter

I have this long cable which is carrying two differential voltage signals (around 300kHz maximum frequency) through a very "noisy" environment. I need to acquire this signal through a differential op ...
0
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4answers
152 views

Ladder filter without termination resistor?

I want to drive an ADC with an OpAmp (LT1819). The op-amp is in non-inverting configuration driving the ADC pseudo-differentially. The filter between opamp and ADC should be ("the specs"): passive -...
1
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3answers
260 views

calculating sinewave frequency for a low pass filter with only cutoff frequency, input sinewave amplitude and output sinewave amplitude? [closed]

I have the input and output sinwave amplitudes as well as the cut off frequency how do I use that to calculate the sinewave frequency(Hz) for a low pass filter. I'm unsure of what I need to be a ...
1
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1answer
589 views

Critical damping of SMPS LC filter

I am designing a damping resistor [minimum load of SMPS] in parallel to output capacitor of LC filter. SMPS specs: 1. Vout: 200 V 2. Iout [Max]: 2 A 3. PWM frequency: 50 kHz Output filter specs: 1....
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6answers
707 views

Why we use a 2nd order filter to build a higher order filter?

Why would we use 2nd order filters to build a higher order filter, like a Sallen & Key and others? Is the oscillation problem in higher order filters?
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1answer
262 views

Passive RC Lowpass Filter Effects on DC

Connecting passive low pass filters in series and with a load, reduces the dc voltage. Maybe it is very simple but would you explain a little bit to me about the low pass filter's effects on dc. ...
0
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1answer
42 views

Cutoff frequencies of active this filter?

How can I calculate precisely the roll-off frequencies of this configuration? The passband seem to be between 3.1Hz to 78.1Hz. I tried using the equations for the inverting active bandpass filter but ...
3
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4answers
391 views

100MHz noise filter doesn't attenuate much

I have a switching regulator that puts 100MHz noise onto the power supply that it shares with a microcontroller, and I'm trying to filter this noise to give the microcontroller a clean DC power source....
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0answers
279 views

ESD protection for DC supply line

simulate this circuit – Schematic created using CircuitLab I'm working on a system that will go into ESD testing, The system is powered by an external regulated DC voltage. I'm now using an LC ...