A filter modifies signals based on their frequency.

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High-Pass Filter Volume Control

I have designed a basic active high pass filter, the amplifies and audio signal. Is there a way to implement a form of volume control, to reduce the volume to zero. I was thinking of using a ...
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26 views

How to detect ripple in a specific frequency range on a power rail?

I'm struggling with a circuit that should monitor the ripple between 1000 Hz and 4000 Hz of a power rail (48 V). It must be able to detect if the peak to mean ripple is larger than 2 V. My first ...
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1answer
28 views

High side and low side driver

Is there a specific design for filter capacitors other than selecting a voltage value higher than the supply value,and choosing an appropriate capacitance value??
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2answers
50 views

Building a distributed low-pass filter with cutoff frequency of 1hz but the highest frequency of 10^13 hz

How does one build a distributed low-pass filter with cutoff frequency of 1hz and highest frequency of 10^13hz (or arbitrarily high)? In case of lumped circuits, this is easy to do, but in case of ...
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0answers
35 views

How can I calculate the noise in a simple RC high-pass filter?

How can I calculate the noise in a simple RC high-pass filter? (Assuming very low input impedance and very high output impedance.) I know the Johnson noise in the resistor should be 4kTR, but I'm ...
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4answers
812 views

Why don't decoupling/bypass capacitors need resistors to perform their function, like regular filters?

Why don't decoupling/bypass capacitors need resistors to perform their function, like regular filters? Is it because the stray resistance of copper traces is enough to filter, along with the ...
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2answers
48 views

Adapting 120VAC High Pass Filter to UK 240VAC

I am looking to build a analog high pass filter with a cutoff frequency of 5.3 kHz. I have found a design which suits my need but I would like to adapt it from the 120V AC, 60Hz and a cutoff frequency ...
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3answers
42 views

Quasi-elliptical vs pseudo-elliptical filters vs Chebyshev Type 2 filters

Are quasi-elliptical or pseudo-elliptical and Chebyshev Type 2 filters the same filter response? Quasi-elliptical or pseudo-elliptical filters appear to be defined as "... filters with finite ...
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2answers
320 views

Using PC audio to listen to electrical noise on power line?

I have done a bit of research on digital filtering and I was wondering if it would be possible to use the audio hardware of my computer tu listen to the electrical noise on my powerline ? If it is ...
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1answer
56 views

Filter behaving as oscillator

I've built a state-variable filter, to this schematic: R6 and R7 are a dual gang potentiometer (with the 3rd terminal unconnected, so variable resistor), and R2 is a single gang potentiometer ...
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1answer
29 views

What is a Thresh filter?

I was looking at this site and saw the term. While I'm a bit familiar with some DSP terminology, I have never heard of this before. Google did not really help at all. From what the site explores, it ...
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3answers
112 views

Ignore Pulses Less than a Given Width in a Pulse Train

Let's say I have a 5V pulse train that varies between 0 and 75000 pulses per second. Pulse width, let's say, is 5 microseconds. How could I calculate or determine the best way to filter out all pulses ...
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25 views

Wave Digital Filter (Basic)

DOWN wave is the reflection, am I right? And is D considered as reflection-free (rf) in dtyeh's illustration? Because the root of the tree is D, there should not be rf on D and since there is no rf ...
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1answer
34 views

Active Bandpass Filter Design Issues

I am trying to design a bandpass filter that would have cutoff frequencies at 150Hz and 500Hz. The main purpose of this will be filtering notes played on a piano (or generated pure tones) that are ...
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3answers
104 views

Passive filter design, transfer functions and loading

I have been playing around with some basic passive filters (first order), really just to try and get a better understanding of the equations and transfer functions. I was talking to someone about ...
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1answer
48 views

Diagnosing not-working filter circuits

I'm trying to build a state variable filter, to this circuit diagram: All resistors are \$1k\Omega\$ and both capacitors \$1\mu F\$. I've constructed it on a breadboard: But the output I get, ...
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1answer
58 views

Audio Spectrum Analysis without uC

I have to design a spectrum analyzer that takes a normal audio input and creates a 4 band spectrum display. My current plan to accomplish this task is to construct 4 band pass filters centered around ...
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1answer
49 views

Twin T notch filter vs RC HPF for 120 Hz sinusoid

I am sending a data with On-Off keying over the air using an LED and receiving it with photodiode. A figure below is a stream transmitted (blue) and a stream received (yellow). A symbol rate of this ...
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3answers
69 views

Electrical noise sources in farms

I am designing the data logger of a solar-powered automatic weather station that will be installed in farms. It's used to gather data from environmental sensors (wired) and send it to a host using the ...
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1answer
75 views

Distinguishing between FIR and IIR filters from transform function

I was good at this but unfortunately I have forgot almost everything... So the question is what are the steps to tell if a transform function is for IIR or FIR filter: $$H(z) = ...
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0answers
23 views

Return Loss \$ (S_{11} ) \$ Equation for a nth-order Chebyshev Type 2 Filter [duplicate]

I need an closed form equation for the return loss \$ S_{11} \$ of an n-th order Chebyshev Type 2 low-pass prototype filter. I am designing a high power RF (lumped element) n-th order Chebyshev Type ...
0
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1answer
34 views

Return Loss \$ (S_{11}) \$ Equation for a nth-order Butterworth Filter

I need a closed form equation for the return loss \$ ~S_{11}~\$ of an n-th order Butterworth low-pass prototype filter. I am designing a high power RF (lumped element) n-th order Butterworth bandpass ...
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2answers
57 views

How to measure cutoff frequency of a low pass audio filter?

I've built a low pass filter for use in a synthesizer and would like to measure the cutoff frequency compared with various different control voltages to profile its characteristic. I have access to a ...
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1answer
80 views

Low Pass Filter For Square Wave Through An Optoisolator

I've got a higher voltage square wave input that I'm feeding through FOD817B Optoisolator. The square wave frequency is in the range of 30 to 300 Hz. The Circuit is like this: simulate this ...
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1answer
58 views

which of these is more efficient for AC coupling

In the beginning I was using the circuit (at the bottom) to separate the AC from the DC ( the second order filter ) which in fact is just a second order high pass filter and the DC is a zero Hz ...
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0answers
32 views

IIR filter: why always a0=1

I have worked with IIR filters for some time and always assumed a0 (absolute part of the recursive path) to be one. I know this allows me to get my output y(n) out of the equation without having to ...
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1answer
72 views

Does position error from accelerometer still build up quadratically when using Kalman filtering?

I want to implement an inertial navigation system that uses a basic IMU for indoor position tracking. From all the things I've read you need to assist the IMU with something like GPS or other means of ...
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1answer
74 views

Cut Off Frequency in three phase LC filter

Good afternoon all My question is what will be the formula to calculate cut off frequency of attached LC filter. Its a three phase LC filter. \$(L1=L2=L3= 6.1 \mathrm{mH}) \;\mathrm{and} ...
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1answer
79 views

How to determine the value of a decoupling capacitor across a Peltier device?

I have a TEC device (Thermoelectric Cooling device/peltier device), and I have seen several datasheets recommend placing a bypass capacitor across the TEC device (i.e. parallel to the TEC, and in ...
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3answers
67 views

Calculating Fc (cutoff) of series to RC to ground on inverting input of non-inverting amplifier

Regarding the chosen answer for: How does this OP-AMP non-inverting amplifier work? The following circuit is given, and it says that $$F_c = \frac{1}{2\pi R_1C_1}$$ simulate this circuit ...
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3answers
135 views

Using wxMaxima to obtain a transfer function from T-twin filter & op amp

I'm trying to get the transfer function from this circuit using wxMaxima So first using the ideal op amp model I know Vx = Vy and I can know Vy from that voltage divider from Vo Now I solve this ...
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0answers
31 views

Results analysis of the sequential filter and strength-reduced filter in frequency domain

I realized two low-pass filters by Verilog. The filter can be represented as following equation: 1. Sequential filter with 32 stages. For saving the multipliers, I only use one multiplier and do ...
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6answers
362 views

Capacitor selection for filtering of low level signal

I am currently dealing with low level signal(voltages in milli-volt from the sensors) for the first time. I was advised to use filtering circuit moreover RC filtering which I have already implemented. ...
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1answer
70 views

What is the harmonic content of a PWM signal?

Suppose I'm using a 3.6 kHz carrier to reproduce a 60 Hz sine wave. To properly design a filter for this application to hit a specific harmonic distortion target, I need to know the harmonic content ...
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2answers
72 views

Solving RC filter by differential equation

I'm trying to solve the differential equation of a simple RC filter. What i got so far is: $$CRV'+V=V_0\sin(\omega t)$$ Solving i get: $$V == \frac{V_0 \sin(\omega t)}{1 + R^2C^2 \omega^2} - ...
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0answers
57 views

How to discharge a capacitor quickly…(filter of an H-bridge/inverter)

I have used four IGBTs to build an H-bridge… the inputs of the h-bridge are SPWM and are programmed in a way as shown below: The output of the H-bridge is a three level pwm(as expected), and then its ...
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0answers
18 views

What is pulse train filter in the context of a control system?

I have recently seen some code written in modelling tool like Simulink, ASCET which uses PT1 filter? Why do we use a pulse train filter? What is the difference between FIR, IIR, Chebyschev, ...
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1answer
22 views

Finding the system function of a digital filter

I am studying for exams and I need help with a question I came across in a textbook. Given a digital filter $$y_n = a(x_{n-1} + x_{n+1}) + bx_n$$ find the system function of this filter and the ...
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2answers
42 views

What is the filter and the transfer function that shown below?

May i know above is below to which type of filter? is it a low pass filter? and what is the transfer function for the circuit, may i know the step to drive it? Thank you
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2answers
263 views

Filtering Capacitors before the fuse or after the fuse while limiting inrush current?

There are basically two questions I have for this circuit. 1) Which capacitor configuration is good? before fuse or after fuse 2) How do I limit my inrush current? My thoughts: I am confused ...
5
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1answer
112 views

How do I properly size components for an EMC filter for a variable frequency drive power supply?

One of the products my company designs is, essentially, common bus power supplies for variable frequency drives (VFDs). Thus far we have only sold into the United States. We are considering selling ...
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2answers
67 views

Anti Aliasing Filter and the bandwidth selection

I am currently analyzing the raw measurements of a sensor with the sampling frequency of 400[hz]. According to Nyquist theorem, the bandwidth must be less than a half of the sampling frequency, which ...
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2answers
58 views

RC network (Filter) output calculation

I have an RC circuit with a transfer function $$ h(s)=\frac{1}{1+0.0033s} $$ Is it possible to calculate theoretical output of this network for a set of input voltages? For this how do I solve this ...
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1answer
32 views

Input and out put SNR of Low pass filter

A low pass filter has L=20mH and C=0.0012F .the input signal amplitude is 2V peak to peak and its frequency is 5k Hz .An unwanted noise input is also prsent with amplitude of 0.2 V peak to peak and a ...
16
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2answers
695 views

Why are caps configured this way in EMC filters?

Every EMC filter I've seen has capacitors between the AC lines and earth, configured like this: simulate this circuit – Schematic created using CircuitLab Why are the caps not configured ...
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4answers
389 views

Rc network placing R before C vs after

simulate this circuit – Schematic created using CircuitLab Using a rc network to smooth a PWM signal from a microcontroller, to a true analogue voltage. What will be the effect of having ...
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2answers
48 views

Best Filter Type

I have a sine wave (uV level) that is in varying frequency (1kHz to 8kHz). I like to design a band pass filter that attenuates the other frequencies while amplifying my target frequencies and this can ...
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2answers
63 views

Determining the frequency response of an audio crossover (something seems off)

I'm in the process of putting together an audio crossover. I finished assembling the components, and I though it would be neat to do a frequency sweep on the filters. When I inspected the tweeter ...
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53 views

Is there any way to reduce THD for low pass filter?

I got low pass Sallen-Key filter for 8 kHz corner frequency but I still got too high THD for 8 kHz frequency and 10V output amplitude. THD I would like to achieve is less than 0,2% but now I got more ...
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3answers
282 views

Why are high values of capacitance in low pass active filters not recommended?

I am designing low pass active filter (Sallen-Key structure) and I have come to a point where I have to decide what should be the value of C (C1 = C2 = C) and then calculate values of resistances. I ...