Questions tagged [filter]
A filter selectively processes input signals in frequency- or time-domain.
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WWVB receiver design advice [closed]
I am completely new to the world of amateur radio and I'm attempting to make a WWVB receiver and antenna. I currently have a large ferrite loopstick antenna built, based on this video.
I got a ...
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Output current of full-bridge rectifier with LC filter
I am learning about the properties of a full-bridge rectifier (with LC filter).
Now, I want to find the output current of the 124 Ω resistive load.
(Vpeak of the AC voltage source is 311 V with no DC ...
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Why does an RLC filter circuit ring?
I have the circuit below.
I understand the concept of time constant in both inductors and capacitors.
The literatures says ringing because the signal resign in the pass band which have slope very ...
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Keysight bandwidth and rise time
According to the following application note from Keysight, one way to know what device to take for measuring a signal is to measure the rise time. Then according to the rise time of the system under ...
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Designing a crossover for dual woofers and a single tweeter
I recently purchased a cheap tower speaker set which has two woofers per channel. This does not have a crossover circuit as i understand and only has a filter capacitor for the tweeter.
Can a three-...
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Are ready made crossover circuits universally compatible?
I am planning on modifiying the crossover circuit in a speaker unit. and after doing some research came across a plethora of ready made crossovers available for purchase on the internet (like the one ...
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Input filter to reduce conducted emissions caused by DC/DC converter
This material from ROHM explains the input filter design for a DC/DC converter.
The filter circuit is given below.
I understood the design of Lf, Cf2, Cd and Rd.
If you see the 3rd page (design of ...
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Transfer function of a 3rd-order high-pass filter
Can we take the transfer function of the below 3rd-order high-pass filter as
$$\left (\frac{R}{R+\frac{1}{j\omega C}}\right )^3$$
?
This circuit is a part of RC oscillator. To calculate the β of the ...
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Calculate the formula of RC low pass filter
In RC filter,
low pass filter formula is
and the absolute vlaue is
To make as the absolute value, Do i need to square to each part(real part and imaginary part) indiviually and then square root of ...
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Filter for high amplitude noise
I need some guidance and pointers for filters which filter out high amplitude noise. I have an analog signal coming from an IR pulse sensor which I would like to amplify further, but certain ...
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How to remove 200 mV ripple from my power supply? [closed]
I am using a step-down-converter to get a variable supply output in the range of 2-4 V from a 5 V input voltage from an adapter.
The problem I am facing is that I get a 200 mV ripple which looks like ...
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Need help with pulse sensor design modification [closed]
So I've got the below pulse sensor design. I don't understand why they filter before they amplify. I'd like to modify it in a way that I amplify the signal first, LPF second, HPF last. For some reason ...
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Square wave (+-15V) to positive DC
How can I convert a square wave signal from -15V to 15V to a positive DC signal?
Here are the details of my problem:
I'm trying to build a duty cycle for a buck converter in the following way: I want ...
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Double Valued Voltage in Rectifier with Capacitor Filter
When a capacitor is charged in a full wave rectifier, as shown below, the load voltage closely follows the AC input voltage, less some 0.7V. When the input voltage falls from its peak, the voltage ...
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Input filtering and protection for instrumentation amplifier (2x ADA4528)
I'm currently trying to measure the load cell output using AD's circuit note CN-0216 "Precision Weigh Scale Design Using the AD7791 24-Bit Sigma-Delta ADC with External ADA4528-1 Zero-Drift ...
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Why Is There a Parasitic Sine Wave at My Signal
I am trying to build an EEG device (following the openEEG open source design). I amplify the small EEG signal with an AD620AN intrumental amplifier, then pass it through a high pass filter to ...
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DC/DC converter pi filter for switching frequency filtering
I am using a DC/DC converter referenced as ECLB75W-24D12 for a product I am designing.
The problem I have is that the switching frequency of 330 kHz is too important on the input and won't pass ...
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Designing an active bandpass filter and selecting R and C values
I have been assigned the task to design an active bandpass filter with a passband of 0.1 to 10 Hz. At these two frequencies, there should be an attenuation of -6dB or more. So far I have selected my ...
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Selecting R and C values for a second-order active bandpass filter
I am using the below second-order active bandpass filter in my breathing rate sensor. I need to have a passband of 0.1 to 10 Hz with -6dB attenuation at these frequencies.
I am not sure what I need to ...
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Weird output when implementing matlab firpm/firls FIR filter in hardware
I suspect it might be something with the way I've implemented by FIR filter in code. The mainloop looks like this
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Identify this component: BEF1592 2143
This component is placed in the signal path next to a multi-band GSM antenna. It seems to have 3 terminals - 1x GND and 2x in signal path. I suspect it is some sort of bandpass filter, but can't ...
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Can you explain this active filter?
I am trying to analyze the open source project OpenEEG's schematics. I came across a filter which supposedly has a 59 Hz cut-off frequency. I could not locate the 59 Hz pole of the filter. Can you ...
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Triggering a relay with a 0.7 - 2 Hz pulsating DC voltage between 0 and 12 V
50% duty cycle. I would prefer if there was a passive solution to this but it's not a necessity. The relay needs to turn on when the signal is pulsating and to turn off when the signal is no longer ...
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First-order filter between sensor and amplifier
I need to sample an analog pressure sensor (TSCDRRN015PDUCV) with very high accuracy. The pressure sensor is currently connected to an instrumentation amplifier (AD623) and then sampled by my MCU's ...
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How do the stages of this high pass filter work?
I am trying to understand exactly how the stages of this Moog high-pass filter work but I still have several things that I cannot quite figure out:
Q13 and Q14 form a push-pull amplifier, and are ...
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Can a modified square wave (average square wave in each discrete time interval) be made from only full bridge inverter without transformer, LC filter?
I'm studying about inverter PWM with textbook.
The similar one with attached figure is in the textbook.
I can understand how the blue chopped square voltage is made.
In the text book, the red curve is ...
user331400
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Ripple rejection of capacitance multiplier when compared to linear regulators
There are some posts and discussions how a circuit popularly called a “capacitance multiplier” could reduce low frequency ripple noise (at 50/60 Hz or 100/120 Hz) and could perform better than common (...
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Input filter transfer function derivation
In the figure above, I am trying to design an input filter that attenuates all switching frequency harmonics from i_sys, such that i_batt is a DC current with vary small ripples.
My approach is to get ...
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Solution of a differential equation of a RC filter (alternating voltage) and graph
I'm trying to solve the differential equation of a circuit on the capacitor for the first half-period (the capacitor is initially discharged):
So far, I have this differential equation:
$$RC_{1}\frac{...
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What is the purpose of these resistors to ground in this EMC filter?
I'm currently using an EMI/EMC filter in my project for the DC output of my HV power supply
(FN2200-75-34 from Schaffner).
I can understand the purpose of the resistors for the Cx capacitors (for ...
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LC transfer function
How would I go about deriving a transfer function or expected cut-off frequencies for this LC moveable bandpass filter (wah-wah effect)?
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Filter design for a bridge rectifier for battery charging
I want to charge a battery bank having voltage 114 V DC. My transformer output is 125 V single phase AC (176 V amplitude) I give this supply to bridge rectifier. Now I don't know how to design an RC ...
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Low-pass filter capacitor configuration for differential output of an amplifier
The diagram below shows the output stage of a bipolar diffential DAC amplifier powered from a dual supply (in my case I won't use an LM324 but an OP484):
The amplifier outputs are fully differential (...
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LTI system: can I infer the system is causal based only on the transfer function without the ROC?
Suppose we have an linear time-invariant (LTI) system which acts on discrete signals. Suppose someone tells us the transfer function is: $$H(z) = \frac{1}{z-2},$$ but doesn't specify the ROC. Now the ...
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Filtering USB +5V and filtering battery (also +5V) before and after LDO
I have a development board project where I want to use USB as the power source when plugged in and then switch off the battery - and vice versa. Then I am running it through a 3.3V fixed LDO (AMS1117-...
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Can Class D output capacitors be placed towards both rails?
Please consider the simplified Class D output stage below. Depending on the half-bridge duty cycle, different output voltages (within the power supply range) can be applied to the load.
simulate this ...
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Filter choice and EMI concerns for 10 A dimmer
I need a power router to divert excess photovoltaic power into a water heater.
Context: Solar panels are connected to a grid-tied inverter. A smartmeter measures how much power the house draws, and ...
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Why do LC filters have 40 dB/decade ripple attenuation at high frequencies?
I am taking an online course on power electronics in which I encountered the following concept which I couldn't understand.
The instructor had the following comment about the following grid interface ...
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USB-C port circuit design: ESD, filtering, short-circuit protection
Below is my first attempt at designing a USB port for a microcontroller board. I am seeking feedback as well as answers to a few specific questions.
Project Parameters
USB bus powered device (dongle ...
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Active notch filter behaves like a low-pass filter
I'm trying to build an active notch filter centered at 50 Hz. I'm trying to wire it using a breadboard but I'm facing some problems with the output signal.
Before wiring the circuit, I tried to ...
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Multiple feedback bandpass filter calculations are wrong when C1 and C2 are different values
I wrote a simple Python program to calculate a single MFB bandpass filter and I am getting different values for Q and bandwidth if the C1 and C2 are totally different values. If I check with a ...
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Analog filter gain in simulation is not as expected
I want to have a 1 stage analog active filter with a cutoff frequency of 26 kHz. I used the MATLAB analog filter design toolbox to create such a filter. The filter that was provided by MATLAB looks ...
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Bessel filter: explicit calculus of the order of the filter
As it is well known Butterworth and Chebyshev filters have explicit ways of calculating the order, derived by its polynomials.
For instance, for Butterworth filters:
$$ n \geq \displaystyle \frac{\log\...
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Why is the filter output not in sin form?
The lowpass filters I created with the Matlab fda tool are different from the sinus form in the simulation.
What could be the reason for this?
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What is the purpose of the resistor in a RC circuit?
I understand that a capacitor can pass high frequencies and block low frequencies, because of its impedance properties.
Now, why do you need to put in series a resistor? Doesn't it already filter ...
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USB 2.0 HS: Common-mode chokes on DP/DM
The USB 2.0 specification seems to discourage the use of common-mode chokes on the D+/D- lines.
For example, in the USB 2.0 DC Resistance Engineering Change Notification (file ...
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USB 2.0 VBUS Filter
I am reading an old (2013) FTDI application note AN_146 about hardware design for USB 2.0. On the subject of VBUS filtering, it says this:
2.4.4 Ferrite bead use and placement – USB peripheral ...
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Regenerative feedback for sensor coil
I'm trying to implement some kind of regenerative feedback in an existing circuit to increase the Q factor of the sensor coil. This sensor is a center-tapped coil with parallel capacitance for ...
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How can I calculate the total impedance of a second-order low-pass filter?
How can I calculate total impedance of this low-pass filter? Also, how can I measure the phase difference?
For example:
L = 12.73 mH
C = 198 μF
R = 8 Ω
F = 100 Hz
Simulators show a graph as top:
...
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LC filter in inverter
I am in the process of creating a high-current inverter, with a current rating of 100A. I have completed the simulation, but am having difficulty finding an inductor with a high enough current rating ...