Questions tagged [passive-filter]

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Trouble getting measurments of my circuit

I'm trying to turn the first image in a multisim circuit but i can't get the right measurements. I have tried a vcc power source but i still can't get the right result in the oscilometer can anyone ...
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3answers
104 views

Calculating the frequency of a sinewave with the cutoff frequency, the input and output amplitudes of the sinewave?

simulate this circuit – Schematic created using CircuitLab I know there's a question similar to this on the website but that wasn't solved as not enough details were given. It is a first ...
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2answers
100 views

RC Analog Filter Component Selection

I have a question regarding RC filter designs. I have a system that picks up an analog signal at 200Hz and I'm passing the signal through a two stage low pass filter and then a two stage high pass ...
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1answer
101 views

Topology for ideal cutband response (-20dB per decade per order) for passive, low pass, constant output impedance filter

I am trying to develop a low-pass constant output impedance filter. The output impedance must be within ±10% of 5Ω from DC up to 1GHz. The filter is driving an open load (>10M) and must filter current ...
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4answers
2k views

Active low-pass filters — good to what frequencies?

Appendix E of The Art of Electronics, 3rd Edition (LC Butterworth filters) starts by saying that "active filters are convenient at low-frequencies but impractical at higher frequencies". They go and ...
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2answers
101 views

Transfer function and cut-off frequency of cascoded RC-LRC filter

At the moment I'm struggling with the problem, i can calculate the transfer function of the following circuit, but not the cut-off frequency. The transfer function is in my case: $$H(s)=\frac{1}{s^3\...
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0answers
46 views

What capacitor to use for high voltage & high current filter application

I am designing a filter that needs a capacitor. I am not allowed to paste the schematic here, so only the maximum voltage at and current through the cap, pasted from the spice simulation: (voltage is ...
2
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1answer
86 views

Is using passive anti-aliasing filter with its transfer function instead of an active filter common or reliable?

I need to ask this general question with an example for clarity. Imagine I have to measure a signal with BW of 5kHz and I need to make a unity gain active anti-aliasing filter with a steep roll off ...
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1answer
94 views

DC Filter for DC free transmitting

I have a sine signal with Vpp = 5V, DC Offset = 2.5V. Now I am asking myself how to remove this offset in order to have a DC free transmission.
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1answer
101 views

Difference between simulated and constructed filter

I recently designed a passive RL ladder filter to obtain certain specifications for anti-aliasing purposes (circuit shown below and simulated in LTSpice). The response I got in LTSpice was very ...
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2answers
100 views

Band pass filter bandwidth problem

I am trying to design a band pass filter that allows frequencies between 16,384Hz and 32,768Hz. Firstly I tried to make it using a passive RC band pass filter: Using the formula fc = 1/2πRC, the ...
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1answer
70 views

Filter transfer function

I've the following filter circuit: simulate this circuit – Schematic created using CircuitLab The transfer function can be written as follows (I think): $$\frac{\frac{1}{\text{sC}}}{\frac{1}{\...
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1answer
34 views

Inductance value of PI-filter connectors?

I find myself in the situation of being forced to use filter connectors to solve an EMC issue very late in the project. Normally, this should of course be solved in circuit design, but as projects and ...
1
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1answer
135 views

Filter load transient from power rail

I have a 12.3V power rail, which is sourced from a 2A 12V AC wall adapter. The 12.3V rail supplies a 3A 4V SMPS, which sometimes sees large load fluctuations from almost 0A through to 2A ...
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3answers
857 views

How do I implement a feedback to keep the DC gain at zero for this conceptual passive filter?

Regarding an example passive LC ladder filter, when I sweep the source resistance, Rs, the filter characteristics changes as follows as expected: On the other hand, if I sweep the load resistance, ...
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4answers
144 views

How do you pick component values for a debouncing filter?

I bought an incremental/quadrature rotary encoder for a project I'm working on. The specs: https://www.bourns.com/docs/Product-Datasheets/PEC12R.pdf They provide a diagram of a suggested filter ...
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3answers
160 views

How to combine a LPF and a Voltage divider?

I have to connect a 5V analog signal to a 3.3V MCU analog GPIO input as shown in the attached image. I wonder if its possible to combine the 2 blocks of voltage divider and RC-LPF into a single block? ...
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2answers
110 views

Filter capacitors to avoid pop when hitting footswitch

This is an audio circuit question. I have two line level signals going into two DIs going into a PA. I want to craft a custom passive mute switch, sometimes when debugging feedback when performing ...
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1answer
57 views

What is the purpose of the upper inductor in this speaker diagram?

What is the upper inductor symbol in series with the woofer used for in the below diagram? It seems the tweeter and the woofer are both I guess 8 Ohm and that's why the 4 Ohm parallel equivalent ...
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1answer
136 views

Why did C2 fail?

I'm trying to run a Raspberry Pi as a remote controller and timer for a diesel water pump but it keeps rebooting when the engine cranks. I checked and the supply doesn't drop below 10.5V during ...
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0answers
70 views

PWM to sinusoid with LC filter

I am studying a three-phase inverter with output LC filter (as shown). I want to get 12VAC 50Hz sinusoidal wave at output of LC filter (at load) Vdc=48V fs=10kHz switching freq. Load=13.8 ohm ...
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6answers
682 views

RC Lowpass Filter between Amplifier and ADC input

I have sensors (pyranometers that consist of thermopiles and measure sun irradiation) that ouput a low voltage signal so I need to amplify them using an instrumentation amplifier. I have chosen the ...
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0answers
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When is a differential choke preferred to an LC filter and vice versa?

Both single LC and differential choke are used for attenuating differential mode noise. I only know that LC filter has resonance issues. Is that the only reason a differential choke is preferred? ...
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0answers
62 views

What are the important specs for inductor in passive tone control?

I'm pretty much an electronics newbie. I'm working through some circuits in "Electronic Projects for Musicians". It has a "Passive Tone Control" which seemed like an easy start. Unsure if I can ...
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2answers
53 views

How to smooth changes in *current* in a current meter?

I have a milliammeter I'd like to debounce with an \$f_c\$ of say 0.1 Hz (10 s) to where it reads a mean average rather than however fast the needle moves, dampened only by physics. Vcc is about 8-9 V ...
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2answers
137 views

Is this symbol for common-mode choke or usual inductor?

In the below circuit from this datasheet, I think L1 represents common-mode choke; but what does L2 represent? And in this datasheet for a similar filter, I don't see any difference between the ...
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1answer
201 views

Input impedance of low pass filter on LTspice must be constant in it's pass band?

I have single supplied sallen-key filter more that have nice 3MHz flat LPF response. I tried to compute the resistance directly by dividing the input voltage by input current which is the voltage and ...
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2answers
231 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
54 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
76 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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2answers
226 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
56 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 ...
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1answer
58 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 ...
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1answer
107 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
1k 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 ...
0
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1answer
56 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
950 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 ...
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1answer
192 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
86 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
119 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
80 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
47 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,...
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2answers
112 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 ...
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2answers
376 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
381 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 ...
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1answer
72 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 ...
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4answers
959 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
286 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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1answer
51 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 ...
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2answers
67 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 ...