A filter modifies signals based on their frequency.

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Effect of AC coupling on DC signals

I am currently trying to amplify a very small AC signal that is riding on a high DC offset. In order to amplify the signal (using a simple op amp circuit), I obviously need to remove the DC offset to ...
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0answers
10 views

Sigma-Delta RC Filter

I am using a MSP430F427A to measure the voltage across a current shunt for coulomb counting stage of charge monitoring. Just looking at what kind of filter to put at the input of the SD16 ADC, and the ...
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32 views

Matlab filter function used to convolve [on hold]

It is asked to compare the method using conv() and filter() with n<=15 ...
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5answers
444 views

How can I read the graph of a low pass filter

Given information I have the following circuit, and frequency graph. The capacitor is connected to ground at the bottom. Unfortunately the graph is in dutch, but it won't matter much. Just understand ...
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1answer
53 views

MOSFET Circuit: Bypass capacitor

Does anyone know how a Bypass Capacitor work in it's physical operation? How does a bypass capacitor filter out the ac signal in the device structure and physical operation?
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0answers
23 views

Understanding Baxandall's tone control ckt

I am learning to understand and design filters.. I was unable to design a ckt to control bass as well as boost (passive)... which would have transfer function (for boost) H(s) = (s+k)/s I came ...
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2answers
30 views

Problem with simulating LC filter with N channel MOSFET used for PWM

I'm trying to simulate an LC filter for a PWM output and I'm having problems with MOSFET used for controlling the voltage. I'm using LTSpice for simulation. When I filter the PWM output directly, it ...
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4answers
169 views

Transfer Function for a combination of filters

simulate this circuit – Schematic created using CircuitLab I am currently working on trying to determine the transfer function for the audio tone circuit pictured. $$R_1 = t \times ...
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4answers
87 views

Practical Considerations of a Butterworth Filter

I'm trying to design/implement a low-pass filter for the amateur 2M band (144-148 MHz). To meet FCC regs, I need harmonics to be at least 40dB down, so I calculated a 7-stage Butterworth Filter with ...
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0answers
46 views

Inductance to capacitance ratio in LC filter for PWM

When using parallel LC filter for smoothing out PWM, I'm using the following equation to calculate its frequency: F\$_C = \dfrac{1}{2\pi\sqrt{LC}}\$ Here is a schematic of an LC filter I'm talking ...
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1answer
32 views

Limiting wired low frequency signal transmission

I'm now considering TDA5051A to transmit information over the 230VAC power network. To avaid any interference between neightbours I will need to stop transmision beyond the appartment electrical ...
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0answers
12 views

Summer in MF-10 not working

I am using MF10 to make a filter. So can we use the summer provided in the IC as a opamp? I have made an inverting amplifier with gain = 1 using the summer, but the output of the summer is just a ...
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1answer
28 views

Audio High Pass Crossover Question

I'm doing a sound system for\with a friend of mine (I've done many, many before).... In the past I've done either simple L\C or LC crossovers, but I've been looking around for something I can build ...
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1answer
36 views

Controlling the current through a Diode Bridge VCF

I'm investigating different analog low pass filter circuits and came across this Yamaha patent which ingeniously utilizes a diode bridge as a variable resistor. It takes some reading but in short: ...
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2answers
67 views

Voltage Controlled Second Order Low Pass Filter

First time poster. Please be kind! I'm working on an analog synthesizer project and recently started looking at Voltage Controlled Filter designs. I've scoured the internet for a low pass ...
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1answer
61 views

EEG amplifier circuit low and high pass filters. Oscillations, noise, etc

I designed a EEG amplifier circuit for for EEG signal amplification and filtering. Because I never had any experience in filters, It would be highly appreciated if someone could check my design. In ...
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1answer
27 views

resistor values of a 4th order bessel high pass filter

I have a question about cascading the 2nd order bessel high pass filter to form a 4th order bessel high pass filter, I have an equation to solve for R1 and R2, will the same equation be used to solve ...
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0answers
25 views

Implementing biquad filter using MF10

I am trying to implement biquad filter shown in this image I wanted to implement this circuit using commercially available Universal Switched Capacitor filter IC (MF-10 by Texas Instruments). Note: ...
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1answer
55 views

Low Pass Filter calculation

I am designing a circuit which reads a analog signal(DC - Response from a photo-diode exposed to tungsten lamp) to a 12 bit ADC. The ADC is MCP3202 running at 1Mhz speed and uses 16 input bits to get ...
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1answer
42 views

Biquad bandpass filter IC?

Is there an IC that will enable us to have biquad filter given in this PDF? Thanx..:)
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1answer
45 views

Can a crystal oscillator be used instead of a ceramic filter?

For my FM radio circuit i require a 10.7 MHz ceramic filter. When i asked for it in a shop he gave me a crystal oscillator of 10 MHz value. Can i use the oscillator instead of the filter in my ...
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0answers
26 views

Reducing noise from an input using an FIR in VHDL

I have a non digital input I want to read in my VHDL file but it has sooo much noise that I would like to filter out using a digital filter that would sample the signal and allow pulse levels that ...
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1answer
37 views

Why does my bandpass RF filter complain about Ts in Simulink?

I am doing a basic amplitude modulator, and I'm using as input signal for now a Gaussian noise generator, then I modulate it with a carrier fc=2e9Hz. When using Simulink along with a RF bandpass ...
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1answer
34 views

Size of inductors in passive filters

I was reading about why we need active filters even when we have passive filters with us. I got to know that one of the main reasons for doing so, is that at lower frequencies the size of the inductor ...
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1answer
62 views

Cancelling gain from a filter

I have a bandpass filter with tunable central frequency but the problem with this filter is that as I tune the central frequency its gain for different central frequencies is different. Is there a way ...
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1answer
161 views

Input impedance of PIC32 ADC pin

I want to measure temperature of an oven using a thermocouple. The maximum change in the temperature will be 1oC/s. The amplifier section will already contain a low pass filter, but I want to put an ...
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1answer
107 views

Finding Q for filters

Given the transfer function for a given filter, how can I find a value for the q-factor? For example, I have this transfer function for a Sallen-Key lowpass filter \$ H(s) = ...
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1answer
99 views

30 capacitors in parallell?

I can't find any uF valued capacitor with a high Q-rating (~150) for my required frequency (~100 MHz). I need a 3 uF capacitor of this kind to realize my filter. I have found a good capacitor that ...
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2answers
75 views

Active narrow bandpass filter with variable center frequency

I want to make bandpass filter with its center frequency variable(range 50Hz to 5kHz), bandwidth the smaller the better but not less than 50Hz.The bandwidth to be same across the range should be same. ...
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0answers
30 views

Passive harmonic filter: Why Immensely Hot and Humming

I encountered a passive harmonic filter, PHF with highly non linear loads, i.e. variable frequency drive, VFD (most of the time running 50Hz) serving an induction motor. I believe that it is a ...
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1answer
94 views

LM386 and low-pass filter

First time here, so here I am with an electronic-related question. Please note that altough I have a scientific background, I'm quite new to electronics. Setup I'm trying to build a small audio amp ...
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2answers
43 views

Will an impedance matching network also act as a filter?

Will a matching impedance network also act as a filter? I'm using a pi network and am wondering if I should also add a filter. I designed the pi network by using the program SimSmith and it consists ...
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2answers
48 views

Low-pass filter for high power application

I'm designing a LP filter that should be used for a load of up to 2000W. I want to filter the AC voltage that supplies a controlled heater which uses a TRIAC for control. I've tried one approach but ...
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2answers
47 views

Band Pass Filters for MHz

I have come across the following site: Passive Band Pass Filter - Electronics Tutorials. It is a tutorial about band passive filter circuits. The following formular is given with: $$ C=\frac{1}{2 ...
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2answers
79 views

If the High Pass Filter is a differentiator, what's the analogy for Low Pass Filter?

I have seen many times the analogy that the High Pass Filter (HPF) is a differentiator, something that explains some interesting facts, like that a non-negative signal might have negative components ...
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2answers
65 views

PWM + LC filter - voltage value non linear with duty cycle

I'm experimenting with PWM and LC filter and I think it works correctly when it comes to smoothing signal, but for some reason voltage on the output is not linear with duty cycle. I use 56uH inductor ...
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1answer
48 views

What does this LC circuit do

Can someone explain what does it circuit do? Is it some kind of filter? Thanks.
0
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1answer
65 views

RC low pass filter PCB layout limitation

I have an RC low pass filter for debouncing a GPIO pin. Do I have to place the resistor and the capacitor close to each other? Currently the capacitor is near the GPIO pin, and the resistor can be ...
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1answer
53 views

Matching the impedance of a filter?

Currently designing a circuit consisting of 50 Ohm rated ICs. Between two ICs (switches), I will place a BP-filter made out of discrete components (high-Q inductors and capacitors). The filter will ...
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2answers
27 views

Frequency design parameter for DC signals

I have been using some online tools to design a circuit to amplify photo-diode current. I have understood that all such tools needs a frequency/bandwidth to drive the calculations. For example, a Low ...
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0answers
15 views

Multiple active filtering or single active filtering

I am using an op amp(Inverting configuration) to get a gain(V) ranging from 20 to 160 using a multiplexer to choose a different R2 value. R1 is a 1K pot which is set to .5K and the MUX has 8*10K ...
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3answers
182 views

Where to put low-pass filter on the analog signal path?

I want to test my basic pH sensor circuit to find if there is a need for a low-pass filter. How I can test it? The signal pathway is: Sensor probe---> Buffer op-amp circuit ---> ADC ---> MCU So is ...
0
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1answer
30 views

What is the pinout on my K F455P 7An filter?

I have a ceramic filter that I'm using for an AM receiver, but I don't know the pins for it. The lettering on it says K F455P 7An. I know that it's a 455 kHz signal filter and I think that it has a ...
0
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1answer
67 views

Simplest method to filter a PWM'ed sinusoid?

I am using PWM to dim a bulb and was wondering how I could restore the chopped waveform to a sinusoid whose amplitude varies with the duty cycle. The switching frequency is 25Khz and the line ...
0
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1answer
52 views

Help understanding 60 Hz low pass filter behavior in oscilloscope

I have been testing this circuit in simulation which is supposed to be a low pass 60Hz filter, as far as i am concerned the simulation works as intended in simulation starts filtering frequencies ...
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6answers
151 views

Analog filter design

I have designed my analog low pass filter using LM358 op amp. I used r1=r2=330 Ohm and c1=c2=100nF. The cut off frequency =4.8 KHz. But i dont know where its going wrong , my attenuation which should ...
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1answer
41 views

Transfer function of a cascaded passive + active filter

How do I get my H(s) transfer function from this circuit? If there was infinite impedance between the two filters, I'd just do H_LP (s) * H_HP (s). However, we are assuming that the input/output ...
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1answer
99 views

Simple Power Line Communication

I'm working on a remote (wirless) door opener and I need to install a device (just in the opener) at the entrance of a building where there is an electric opener. The problem is i can not install ...
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0answers
40 views

Infrared filter on CMOS single package sensor

I am trying to recognize infrared-reflectors with a CMOS module. The ideal would be to use an IR filter to get rid of everything else and only have the trackers (reflectors) on the picture. I found ...
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1answer
32 views

Filter Analysis using Audio Analyzer

I have a RC low pass and ferrite bead cap filter combination on my circuit board. I am trying to use Audio Analyzer U8903 to analyze the gain response of the filter. I see quite different result in ...