A filter modifies signals based on their frequency.

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Matched Filter Design

A digital signal is transmitted with the following waveform. s(t) = Acos(omega_ct)*rect(t - (T/2)), bit = 1 0 , bit = 0 , where T=2πK/ωC , K is an integer The ...
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25 views

Radio Frequency and Filteration

So different frequencies are assigned to different radio stations so that we may filter out the required radio station through its assigned frequency with the help of filters ? That is how we select a ...
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3answers
66 views

Understanding Ferrite Chokes

I am looking to clean up the power supplied to a video transmitter on the UAV I am building. The video transmitter consumes about 200mA of current at 16V DC. The 16V line has noise from motors and ...
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1answer
64 views

What is the purpose of resistance & capacitance in parallel to Load ( refer ckt )

What is the purpose of resistance & capacitance in parallel to Load ( refer ckt ) ? As per my understanding these capacitor & resistor is for filtration purpose ( kindly clarify the same) . ...
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1answer
23 views

Cut-off frequencies for common mode and differential mode filter?

Attached is the circuit section for the differential signal amplification. The circuit is comprising of common mode and differential mode filter capacitors.So there will be two different cut-off ...
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31 views

Matlab filter to vhdl

I want to filter a sine wave signal using Altera FPGA(cyclone IV). The sine wave is first converted by an ADC with Fs= 20Mhz, then stored into a register inside the FPGA. The frequency of my signal is ...
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1answer
64 views

What happens if you put two coils in parallel

I want to build an LC-Filter from a tutorial I found (German language, if anyone is interested, I'll add a link). In that tutorial, a 330uH Coil with a max amp of 1A is used. I have some 330uH ...
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1answer
39 views

Uses of Electronic Filters? [on hold]

Can anyone tell the real life examples of electronic filters? Why do we need them ? Whey do we need certain range of frequencies while others are rejected ? Sorry i am new in electronics so please do ...
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34 views

Radio Tuning and Filters [on hold]

Whats meant by tuning a radio ? Does it mean that when we move a tuner it selects one radio channel from many radio channels? Does it mean that channels are different because they have different ...
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1answer
27 views

How can i 4th-order BPF analysis please

How can i calculation center frequency?, and Q-factor and BW? please detail analysis
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1answer
43 views

Can we determine if a filter is butterworth or chebyshev from its physical topology?

Can all analog filters be classified as Bessel, Elliptic, Butterworth or Chebyshev? Given a physical ladder topology of several stages of {L, C or LC} in {series or parallel}, is it possible to ...
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2answers
46 views

Filter design for high power voltages Partial discharge detector

Hell all, I have a signal imposed on a 60Hz 800V AC voltage that I need to retrieve via MCU. The signal is in the range of 10KHz to 50KHz with peak to peak voltage ranging from 5 to 50 volts . The ...
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18 views

Voltage across all the components of a Parallel resonant band-stop filter?

Ive been trying to solve this for a while and i haven't made much progress probably because ive been doing it wrong. given w = 1M i found the reactance of the capacitor and inductor to be = ...
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1answer
73 views

Filtering a frequency and its harmonics (Matlab)

I want to remove all the frequency components from a .wav file except those within \$\pm 25\$ of \$523 \ Hz\$ as well as its harmonics. Attempt: I used a high pass filter first to suppress ...
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2answers
34 views

Band-pass filter with a given impulse response (Matlab)

I am trying to pass a .wav sound waveform through a band pass filter whose impulse response is given by \$ h(t)=50u(t) \exp(-10t) \sin(2 \pi 440t), \$ I have imported the file into Matlab as ...
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1answer
43 views

Best values for an RC low-pass filter

I have a sonic sensor which outputs analog voltage in 0-10V range with some noise on it. The sensor will measure the distance changes so I'm interested in an output signal not more than 40Hz. The ...
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2answers
40 views

implementation different than simulation

I have to build the below series RLC circuit , and output its bode diagram using NI ELVIS Instrument Launcher. It is for a bandpass filter, so the output is taken across the resistor. Before ...
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92 views

How to Filter Very High Voltage Power Supply Noise

Any suggestions of how to filter out this noise? Basic filter math is not working out. I am adapting a cheap commercial HV supply (variable DC voltage up to 40kV at 10mA) for physics experiments. ...
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25 views

Bandpass attenuation does not fit from lowpass transformation

I got a small problem and which I can't solve. I am designing a bandpass filter for use in a compressor, I am using the method of transforming a lowpass filter into a bandpass filter. I First design ...
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1answer
48 views

Missing low frequency tones from bluetooth audio output

Currently I'm working on a project which uses a bluetooth module (Bluegiga WT32i) to get audiostreams from my iphone to a 3.5mm stereo jack input for a car AUX input. The problem now is that I have ...
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1answer
53 views

What's the purpose of this RC filter?

The circuit is the following and i think this RC filter is used for anti debounce purposes but i'm not sure. Is it to prevent the optocoupler and the indicator LED from being "damaged" by the debounce ...
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1answer
69 views

Curve Tracer Power Supply Puzzle

On my continuing odyssey to analyze real-life circuits as a way to expand my knowledge, I'm studying this Heathkit Curve Tracer: IT-1121 Curve Tracer Schematic There are a couple of features about ...
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2answers
55 views

Blocking DC when driving a buzzer with a PWM signal

I am driving a piezo buzzer with a PWM signal (typical freq. 100Hz-1kHz) in order to generate 'beeps'. However due to software constrains (*), when the PWM signal is stopped I can't control if it ...
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1answer
88 views

How to build a circuit that generates a sine wave?

How can I build a circuit to generate sine waves? What I am working on is building a 555-timer circuit that gives 50% duty cycle square wave, then using a low-pass or band-pass filter tuned to the ...
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1answer
42 views

How to protect constant LED current from ripples & clamps?

I need to develope a constant current LED Driver. The product must be portable and as small as possible. So I can not use SMPS, I have use AC/DC adapter as source. This is the AC/DC adapters output: ...
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1answer
35 views

Given input voltage and a set of output voltages of a second order low pass filter, how to calculate the gain of the filter?

I know that voltage gain = 20 log (Vout/Vin) dB, but the slope of the Bode s plot of second order low pass filter is -40dB/decade compared to the first order low pass filter with -20dB/decade. So ...
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79 views

All-Pass Filter that increases phase as frequency increases?

All the all-pass filters I've seen (both lead and lag versions) start at some phase and then lower the phase at some frequency. I need it to increase the phase instead, so instead of having a negative ...
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1answer
34 views

What frequency bandwidth should an accelerometer operate for measuring punching and kicking movements?

I'm trying to choose the bypass capacitors for a schematic circuit that measures the acceleration (in g) for punching, kicking, throwing, etc. But I don't know what to place on the x, y, z output of ...
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1answer
32 views

lead high pass filter and lag low pass filter

I have a question regarding lead high pass filter and lag low pass filter. I do not quite understand the reasoning behind these two special case (when z=0) ? Thanks!
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2answers
61 views

Using a reflective sensor to detect green-

I need to build a circuit that detects whether a green object is in front of it. As I do not need to know which color is in front of the sensor, but only if there is a green object, I thought a ...
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2answers
86 views

Is this an RC filter in the circuit for a nightlight?

So there is this nightlight (a little flower that you plug in directly into a mains socket and switching it on gives you some light to light up your bedroom at night) which I dismantled and tried to ...
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2answers
69 views

Current Generalized Immittance Converter (CGIC) Nodal Analysis

Below shows the current generalized immittance converter. I am trying to derive the transfer function (V3/Vin) of the said filter but I am getting problems in obtaining the voltages at some of the ...
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62 views

Adding Low Pass Filter to Open Collector Hall Sensor

I'm using a gear tooth sensor to create pulses when a metal object passes the sensor. There's a lot of noise on the signal so I decided a simple low pass filter would suffice(f-cutoff = appx.400hz). ...
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41 views

How to calculate the needed order of a LPF?

I am new to filters and am asked to calculated a lot of things for a passive (Butterworth and Chebyshev )LPF. The very first thing asked is to determine the needed order LPF for these specifications: ...
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2answers
61 views

Understand this filter and biasing circuit

Hello I don't have much experience with electronics and I am trying to understand how this circuit works and its effect on AC input signals. My understanding so far is that the circuit acts as a ...
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4answers
63 views

Twin T active notch filter

So I know that this a band reject filter with the quality factor of Q I have two questions: 1-Why in one T the resistance is half the other resistances in the second T. 2- How would adding a ...
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1answer
92 views

Ripple reduction with LC filter

This seems like it must be a common problem but I don't find a clear answer anywhere, maybe my approach is wrong. I have a DC-DC regulator in my circuit, which has a ripple of 50mV at 200kHz, the ...
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44 views

Can I replace this filter with that one?

TL;DR: Can I replace THIS: 0.18uF X capacitor 2500pF Y capacitor 2x3mH inductance 1Mohm resistor 250VAC @ 2A with THIS: ...
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1answer
73 views

IIR filter concerns in PID control systems

The following diagram represents the system: Here comes some more description: The system input (ref or reference is zero). And actually the goal of the controller is to maintain the output of the ...
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4answers
70 views

High Pass filter gain at higher frequency than cutoff frequency

As i know , it's very common easy to find cutoff frequency and calculate gain at highpass filter. This is my circuit; simulate this circuit – Schematic created using CircuitLab My ...
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43 views

Filter design on coax cable

I need to construct a high pass filter to place on a 75 ohm TV coaxial connection. The filter must be filtering on both the ground side and signal side of the coax cable since I have detected noise on ...
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5answers
473 views

What is the best way to get a sine wave from a square wave?

I have square waves of different frequencies (1KHz to 20KHz), and I need to convert them to a sine wave of the corresponding fundamental frequency. A RC ladder Low-pass filter was the first thing ...
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1answer
19 views

Selection of filters (common mode and differential mode)

I am designing a flyback converter that works at an operational frequency of 100kHz. Now, I need 2 levels of filtering at the input phase viz - common mode filter and differential mode filter. The ...
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3answers
121 views

Does Q-Factor matter for low pass and high pass filters?

For band pass and band stop filters, Q tells how sharp the curve is at the centre frequency. I guess in this way it is required to roll-off. However, low pass and high pass filters do not have centre ...
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3answers
79 views

Is there an equation for the cutoff frequency of a chebyshev filter?

I have this circuit here which is a low pass chebyshev filter, I have been asked to find it's cutoff frequency. I have used matlab to plot an output response against angular frequency graph here. But ...
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2answers
38 views

Connecting stages of active filters vs stages of passive filters

Does connecting 2 stages of Sallen Key topology Butterworth characteristic filter only create a 4th order Butterworth filter with same cutoff frequency (-3dB point) but double the roll-off (-40dB per ...
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1answer
54 views

Transfer Function of Notch Filter

I'm looking at designs for notch filters for an audio system. I want to filter out 10kHz and attenuate by 40dB. I found this topology online: I'm unfamiliar with transfer function calculations for ...
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1answer
40 views

RC filter loss amplitude

I made a RC filter with R=200ohm and C= 2.2uF, I want to filter this PWM in the figure with 10k frequency, and get a Sinusoide with 50hz, but in this case I loss amplitude how i can do this???
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1answer
114 views

Low Pass Filter Impedances

I want to design a passive 4-pole low-pass RLC filter for my subwoofer amplifier. So far I found this page: http://sim.okawa-denshi.jp/en/RLClowkeisan.htm But it seems that changing the value of R ...
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1answer
63 views

Why the need for capacitive loads?

Pioneer, Kenwood, Sony, Onkyo, Denon you name it, they all have a similar circuit like this: Why they use C1 and C3 for? Thanks