A filter modifies signals based on their frequency.

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How to determine if this filter is stable

Hi I have a filter which has the following transfer function: H(z) = (z^2 + 0.04)/(z^2 + 3.24) for which i need to determine whether this is stable or not. I'm not sure how to attempt this, but I'm ...
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33 views

Filters in IR alarm circuit

Electronics student here, so i'm printing a IR receiver for a project of my school. I'm trying to understand the filtering part of the circuit. The signal is received through the BP104 photodiode ...
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38 views

What should be the source impedance and load impedance in LC filter design?

My aim is to generate analog signals with class-D amplifier. For that I am using the following configuration: Class-D-->Low-pass filter(LC)-->load(complex, real+imaginary) class-D amplifies my PWM ...
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2answers
309 views

Obtain an accurate DC value in an AC+DC signal

Background: My goal is to use an Arduino with two proximity probe sensors to achieve some output. It is worth mentioning that the output of the proximity probe has two components: DC output that ...
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32 views

Superposition on a circuit with just one source

I'm trying to analyse this circuit (state variable filter): All the places on the web I've found solve it first using superposition, creating an equation of the form \$ V_2 = kV_1 + kV_4 + kV_3 \$. ...
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25 views

How do I decide upon the order of SINC filter for sigma delta modulator?

I have simulated a first order sigma delta modulator im Matlab simulink. The clock frequency of the modulator is 20Mhz (oversampling frequency). Now I am trying to convert a sine waveform (50Hz) to ...
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26 views

Drop on high pass filter measure

So I'm implementing an analog control scheme, and one important component is a first-order high pass filter. The source signal is the output of a shunt monitor (INA138 - in the circuit below the ...
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21 views

DWDM filter response

I have been trying to find an analytical expression of the frequency response of a DWDM filter, say at 40 GHz bandwidth. Any help would be much appreciated.
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61 views

Inverting Opamp on Noisy Ground. Would an LC filter help?

Alright, say I have this Inverting Opamp, but it so happens the positive input to ground is also connected with another sub-circuit that happens to produce a lot of noise (no pun intended): ...
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45 views

Filtering the output of an H-bridge

What's the best way to filter the output of a H-bridge? I have a PWM output at +/- 20 V and I want to get a 10V RMS sine wave out at 50hz Also is there a way to do it without inductors?
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37 views

Capacitor quenching circuit across Brush and Commutator of DC motor

To reduce the spark between brush and commutator segment there is capacitor and resistor spark quenching circuit is placed between each commutator segments. please find below images for detail idea ...
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59 views

Changing LC filter passband width

I am building a circuit that uses an LC bandpass filter (with the inductor and the capacitor in parallel between the signal and ground lines). However I am having a problem in that there is no way ...
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64 views

Calculating resistance and capacitance given the time constant

I'm currently conducting an experiment where I need to determine what a black-box component consists of. After measuring input and output voltage for various frequencies I have so far determined that ...
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48 views

EMI filtering at end of a long copper wire transmitting high DC power

I have a long (20 - 50 m) copper wire for supplying DC power. One one end there is a AC-DC converter supplying 600W-1000W of power at 60V output. At the other end I have a switching type (100-140 kHz) ...
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3answers
81 views

How to calculate resistors and capacitors values for analog RC filters?

How to calculate resistors and capacitors values for band-pass RC filters based on LM348 operational amplifier? In this example, 3.2KHz, 4.3KHz are standard center frequencies, that are individually ...
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1answer
46 views

Input RC filter design for analog pin of ADC

I am implementing ADC filter for AD7705 ( Sigma Delta ADC - Analog Devices Chip ). Input to ADC is constant DC voltage. So, what will be cut-off frequency I should consider to implement RC filter at ...
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1answer
61 views

Digital Low-Pass Filter When Oversampling Audio

The human ear can hear sounds up to ~ 20KHz. Some ADC's oversample. For example, to capture frequencies up to 20KHz, an ADC converter might sample at 160KHz. The steps are: 1. Filter the audio with ...
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64 views

High pass filter for I2C

I am building a gimbal and passing I2C through sliprings. Right now I have 1.6Vpp spikes at about ~32kHz on the i2c bus. (The spikes are harmonics from motors which are driven at 16~17kHz). The i2c ...
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52 views

Sallen-Key filter using LM358 doesn't act as supposed to when fed a 31.25 kHz PWM

I want to create an Analog Voltage by filtering a PWM signal. After some googling, I found an active low pass filter topology with -40db/decade called the Sallen-Key topology. I tried implementing a ...
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1answer
55 views

Function of Glass bead on EMI Filter Legs

I am looking at a PCB that has tiny glass beads on the input and output legs of an EMI filter. The middle pin goes to GND. What is the purpose of the glass beads? Couldn't get the focus quite right ...
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36 views

current feedback design

How do I select the current sensing resistor \$R_{56}\$ with following details: Feedback threshold voltage is 0.5V. DC input voltage 400V. AC output voltage 230V. output power is 500W. operating ...
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75 views

Filters responses

I got a filter and I want to examine whether it is stable or not. My system has the following TF $$H(s) = \frac{0,0001s^4 + 10s^2}{0,0001s^4+0,05s^3+10s^2+s+1}$$ So after plotting the zpmap (shown ...
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45 views

Filtering noise off of PWM signal

I am trying to measure the resistance of a nichrome wire that has a PWM (1000Hz and different duty cycles between 0 and 100%) voltage applied to it from a 5.0V regulator. The setup I have in mind ...
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44 views

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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21 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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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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72 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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29 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
55 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
179 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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93 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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59 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
38 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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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
30 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
43 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
88 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
83 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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28 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
68 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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52 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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50 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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29 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
57 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
37 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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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
194 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
116 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
102 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 ...