A filter modifies signals based on their frequency.

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2
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3answers
53 views

Low-DC-resistance inductors?

I have a 5V DC source that passes noise (alternator whine and spark plug popping getting through the smoke-lighter-to-microUSB port). The device it powers needs under 100mA (bluetooth ...
-2
votes
1answer
43 views

Integrated RC Filter Chip [on hold]

I need an 100 tımes RC Low pass filter(6MhZ) for an application. There lots of another component in my layout. Do you know any RC low pass filter 'array' or similar chip ? update : I have 100 Ouptuts ...
0
votes
2answers
35 views

How to filter out everything except the laser light using linear array sensor

I use iC-LF1401 to capture line 128 x 1 in horizontal position. Parallel to this linear sensor, I've mounted linear laser (vertical light). How can I filter out linear sensor output, clear all except ...
0
votes
1answer
46 views

Filtering voltage spikes caused by slow SMPS output regulation

I have a 48V 50A SMPS driving a fairly erratic load. The load varies wildly between 1 and 10A and can suddenly drop from full load to low load. I don't have an oscilloscope at hand, so these are ...
0
votes
1answer
24 views

How to simulate an AC line filter in LT Spice

I'm fairly new to LT spice and am trying to simulate an AC line filter, but it keeps giving me the error K1: coupling to shorted out (ignored) inductor L1. What am I doing wrong? Here's the circuit: ...
0
votes
5answers
109 views

Can a proximity sensor read through fabric?

I am trying to build an arduino project with the following requirements: Proximity sensors detect human presence and its distance The sensors are hidden behind fabric Range has to be 1-3 meters or ...
0
votes
0answers
23 views

Electret Microphone Breakout bandpass filter RC or Op AMP

I'm using this Electret Microphone Breakout from Sparkfun https://www.sparkfun.com/products/9964 I want to do a bandpass filter, so I can determine the frequency of a musical note sample and ...
1
vote
2answers
69 views

Designing a Filter

I am trying to design a filter which has the following Bode plot, So according to this site I designed the filter as shown below, As the two cross over frequencies are f1 = 50 Hz and f2 = 200 ...
4
votes
1answer
514 views

What does this symbol in the schematic represent?

I know the symbol at the bottom is ground, but I can't get what the other symbol is. It can be a single symbol of two arrows pointing at each other, or two symbols each one a arrow. I also have the ...
4
votes
1answer
145 views

What is the transfer function for a first order active high-pass filter

What is the transfer function for the below circuit? simulate this circuit – Schematic created using CircuitLab Since the op-amp has unity gain, the transfer function should be the same ...
1
vote
0answers
75 views

BLDC motor control PCB

I am trying to make a PCB to control a Sensorless Brushless motor. I just wanted to know if it looks right. The IC I am using is a TB6588FG it has a 2.5A peak output current. I want to use it with ...
0
votes
3answers
56 views

RC filter on a clamping circuit

I have designed a clamping circuit to protect pins of my microcontroller and I have to add a low pass RC circuit at the microcontroller end to filter out the high frequency noise. My circuit analysis ...
0
votes
1answer
36 views

FWHM of something which does not reach half of maximum?

There is some curve for which I have find FWHM. But the curve does not reach half maximum i.e., its maximum is 1 and it only reaches .7 (but it does have the bell curved shape the filters have). Right ...
0
votes
1answer
35 views

How to solve transfer function of a bandpass filter with Butterworth approximation?

How can I calculate the transfer function of this bandpass filter characteristic with Butterworth approximation? \$A_{max}\$ = 0,9 dB \$A_{min}\$ = 6,5 dB \$\omega\$3 = 100 \$\omega\$1 = 300 ...
0
votes
2answers
49 views

FIR filter output result Interpretation While input is taken from ADC161S626: 16 bit

I have implemented a 20 order FIR Low pass filter, 1000 HZ cutoff frequency on Sparten - 6 FPGA. First I calculate the coefficients in Matlab, Then I directly put them in vhdl code. Here are my ...
0
votes
1answer
86 views

Low-pass filter for digital input

I made a digital input circuit to convert a 120Vac waveform into a digital 2.3V signal. I would like to add a "low-pass" filter at the output to get a low level for higher frequencies than 1kHz. I ...
1
vote
1answer
72 views

Why would a current transformer act like a high pass filter, how can I estimate the low frequency cutoff?

I am struggling to wrap my head around this. I understand that a transformer is not going to pass DC, and that every current transformer (CT) has some pass band. But what properties drive the high ...
1
vote
5answers
153 views

How to generate Red light from a Blue-Dominated Spectrum

I have a white LED light source, the spectrum of which looks as follows --- want to filter out red light from this white LED source. But as you can see the spectrum dwindles in the red zone. And ...
0
votes
0answers
29 views

Analytical design of bandpass filter: MATLAB function documentation

I am trying to "design" a blackbox bandpass filter (butterworth or chebyshev) based on parameters such as \$f_{min}\$, \$f_{max}\$, bandwidth(BW)/Q-factor, and etc, using Visual Basic. However I am ...
0
votes
0answers
56 views

Why does this State-Variable low pass filter overheat when turning up resonance?

I am trying to build an audio-frequency state-variable resonant filter. Power supply is ±15V. The circuit contains three TL072 op-amps and three LM13700 OTAs. It receives audio input from -2.5V to ...
1
vote
1answer
42 views

Electret microphone filtering

I am coupling an electret microphone to the input of an audio codec which does all the amplification, so all I need is biasing and filtering. I picked up the circuit from a colleague and I'm having ...
1
vote
2answers
73 views

Phase Shifter: why is simple RC circuit's output 0 when phase is 90 deg?

I am rereading an electronics book (Fundamentals of Electric Circuits; Alexander) that says that the circuits or have the total impedance Z = R + jXc and that the phase shift is given by ...
1
vote
2answers
41 views

Why would an 8-order LPF switched capacitor has a least steep roll-off curve (max7405)?

As far for my understanding, a higher order LPF will have a steeper roll-off curve. Something like below would happen if we increase the number of order for the LPF: Normal LPF frequency response ...
0
votes
1answer
31 views

How to calculate the oscillator capacitor value for a switched capacitor (MAX7405)?

I would like to use an 8-order LPF switched capacitor: MAX7405 datasheet The cut-off frequency can be set by simply connecting an external oscillator capacitor, Cosc. I would like to design a 50Hz ...
0
votes
1answer
56 views

Why is the cut summed in a graphic equalizer?

I would think a basic graphic equalizer could function as such: a bank of filters, each with their own connection through a potentiometer to a summer (such as an op-amp summer). However, I've run ...
1
vote
3answers
39 views

Need help deriving cutoff frequency of output (collector) RC network

According to the book I'm studying, the cutoff frequency for this circuit is given by $$f_c=\frac{1}{2\pi(R_C+R_L)C_3}.$$ I tried to derive it by solving for the frequency at which \$V_{out}\$ is ...
0
votes
1answer
29 views

EMC/ Mains line filtering

I have an application which uses a PCB to control a big AC fan (approx 1300VA) and a cartridge heating element. Since the application will be operated on regular mains, there needs to be some form of ...
2
votes
3answers
80 views

Op Amp : Gain Bandwidth Product and LP Filter

What will happen if I use an op amp as a buffer amplifier for signals with frequency greater than Gain Bandwidth Product. More specifically : 1) Say I have a signal with 2 frequencies : a) 2 MHz and ...
0
votes
1answer
133 views

Switched capacitors using MOSFETs in filter design

I'm designing a State Variable Filter design using switched capacitors to control cut-off and resonance. Simulating this using idealized switches yields excellent results. See attached schematic ...
1
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2answers
77 views

Differential filter design

simulate this circuit – Schematic created using CircuitLab I have faced a problem in understanding, the following circuit. But after deep search, I expect to be Differential Low Pass ...
0
votes
0answers
61 views

State Variable Filter analysis

I'm in the process of making my own adaptation of the classic State Variable Filter (SVF) in the analog domain. Reading up on this article. I discovered that they use superposition to get the ...
0
votes
1answer
36 views

Bandpass Filter Balanced Ports?

I have a question regarding bandpass filter. What is unbalanced port and balanced ports? I noticed that outputs of balanced ports are connected to RF_P / RF_N of Zigbee IC. What are RF_P / RF_N?
-2
votes
1answer
77 views

What signal will come in?

I have a simple setup as shown, I would like to know what kind of RF signal will come in? Since the filter is configured around 2.4GHz, will all ISM (WiFi, Bluetooth, Zigbee, etc.) come in? The ...
4
votes
3answers
104 views

Active Band Pass Filter Design

I'm repairing some instrumentation equipment and I've come across a filter I do not fully understand. It seems to be a band pass filter and the only documentation that came with this device was an old ...
1
vote
1answer
116 views

Switch mode power supply connected to the diesel generator makes bad voltage oscillation

GEKO diesel generator has 60 kVA electric power. Our switch mode power supply connected to this generator via passive filter DL-50EA3 and 6-pulse bridge rectifier (see the schematic). In this ...
4
votes
3answers
183 views

How to know whether the bandpass filter is stable

I am designing a bandpass filter using MFB. However, I do not know whether my filter is stable or not. Can anyone give me some criteria or methods to evaluate the stability of the filter design?(still ...
0
votes
0answers
56 views

Twin T Network to equivalent T or Pi Network

How do I convert this Twin T network to Equivalent to T or Pi network? I tried using the star delta conversion but just get confused with nodes and loops.
1
vote
1answer
190 views

Voltage drop in RC filter

There is something I'm struggling to understand about passive RC filters: When considering a simple low pass RC loop, what exactly is the gain/output at DC and low frequencies? I've been assuming two ...
0
votes
0answers
56 views

8 IR sensors and 74HC4051 multiplexer where to place low pass RC filter?

So I've got 8 IR sensors like these Then I connect them to multiplexer. And arduino will run mux's selectors through the loop.. Something about 5-10 times per second(read every sensor 5-10 times ...
1
vote
0answers
47 views

Görtzel in VHDL?

I would like to detect dtmf signals with görtzel in VHDL. I couldn't find any examples written with VHDL, would you give me some tips? Where shall I start looking for, is there already an existing one ...
2
votes
1answer
158 views

How to calculate voltage divider time constant?

A cheap and easy way of interfacing a 5V device with a 3.3V device is to use a simple voltage divider. I've read using a voltage divider to convert a fast-changing signal (such as serial lines) can ...
0
votes
2answers
38 views

Guitar Tube Amp RC Filter frequency fluctuation

In a simple LP or HP RC filter, is there a scenario where the centering frequency can fluctuate? So say the filter is a low pass and its set to pass everything up to 800hz, is there a situation where ...
2
votes
2answers
112 views

How can I keep my sinusoid in phase with its input after filtering?

A section of a circuit I'm working with makes a sinusoid from a square wave by passing it through an 8th order filter (MAX293). Up until now, everything was ok, but I was told recently that the input ...
0
votes
2answers
99 views

RC Low pass filter [closed]

I have a question in my EC subject like: Assuming there is a series RC circuit connected to a sinusoidal voltage source with a peak-to-peak value of 8V & frequency of 10kHz and a DC offset of 2V, ...
1
vote
2answers
112 views

Why does my Inductor Get Warm? (Inverter Output Filter)

I have a H-Bridge based Inverter that modulates a 350VDC source into 220V RMS @ 50 Hz. Right now I'm working at just 70VDC but my output inductor is getting quite warm. Here is a schematic: The ...
1
vote
0answers
106 views

LM13700 OTA VCF resonance

I built a variable state VCF from Ray Wilson's book on analog synths. It works well except the resonance: turning it up should yield oscillation, instead it just doubles the gain of the output signal ...
4
votes
1answer
294 views

-3dB on filters, just approximated?

I have been told that -3dB is when you get half the power or equivalently the original voltage divided by the square root of 2. Nonetheless, doing the calculations I get 3.01029dB. I figure this is ...
1
vote
2answers
144 views

High pass filter seems not to work

I have designed this basic RC high pass filter circuit in LtSpice IV: It should have cutoff frequency around 10 kHz. When I perform the ac small signal analysis the output is as expected. But if ...
9
votes
2answers
418 views

Why should I use digital filters for bandpassing rather than simply manipulate signals in frequency domain and then recover them into time domain?

I'm quite a novice for signal processing and I know this question may be too broad. But I would still like to hear hints from experts. I was taught to use butter ...
1
vote
2answers
105 views

Reducing jitter and improving speed of accelerometer output

I'm not sure if this is an EE question or a StackExchange question due to the programming involved, but anyway here goes: I just built a tilt sensor for my tractor's front loader. I wanted something ...