A filter modifies signals based on their frequency.

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1answer
52 views

Send digital data over same wire as analog data

I am trying to modify an existing circuit that I am able to send another digital signal over the same connection. My circuit is a so called "Partyline Intercom" which is based upon the schematics of ...
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2answers
194 views

Anti-aliasing filter closer to amp or ADC?

I'm designing a board with several amplified analog signals being fed into the internal ADC of a PIC DSP (dsPIC33FJ256GP710). Because of the board size/shape restraints, the analog buffers can't sit ...
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0answers
58 views

Low-pass filtering a 120 volt AC line to remove noise

I have active monitors (speakers) plugged into a 120 V line and they are picking up 120 Hz noise being generated by the TRIACs of the Lutron light dimmers in my house. The dimmers are on different ...
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2answers
56 views

Singnals, filters and power output

I have couple of questions: A square signal goes through a low pass filter and in the output of a circuit we get a sine. What happens there? Give a scheme? This is really weird, because, from what ...
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0answers
45 views

Empty Cylindrical Housing for homemade low-pass filter [on hold]

I am looking for a manufacturer that provides cylindrical housing units (preferably with BNC Male and Female ends) so that I can open it up and insert my own circuit in it (one input, one output). It ...
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0answers
63 views

Combining LC filters

I would like to add an EMI filter to a high power LED driver. The datasheet of the driver suggests an LC filter for the power line as shown below. However I would like to use more than one driver ...
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1answer
33 views

Design steps for a choke inductor

I want to filter out high frequency noise on my power line. At first, I was considering to use an LC filter on the line; but then, I learned about choke filters are used exactly for this purpose. ...
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3answers
32 views

Transient analysis of filters inside allowed band

I understand that a zone pass filter will cut off portions of the signal in the cutoff zone, and allow or amplify the frequency parts of the signal in the allowed zone. Now lets assume a signal that ...
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2answers
81 views

Why should Q not exceed 1/2 on a 2-stage filter?

I am just starting on filters. I've seen on a tutorial that says 2-stage RC filter Q could not exceed 1/2. Could someone give some explanation?
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2answers
107 views

Generating a variable DC signal with PWM

I need to generate a variable DC signal from a given PWM signal. I read that this can be done by using first a low pass filter + op amplifier. The picture in the link can explain what I want ...
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2answers
48 views

Bandwidth of low pass filter

Say I have some low pass filter of the form: $$G(s) = \frac{a}{s+b}$$ How do I find the bandwidth? I know for example that with bandpass filters it's the difference between +-3dB of the cutoff ...
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2answers
68 views

High pass filter Using Inductor or a capacitor?

So I was thinking about making a basic Highpass filter. I was wondering if there was any reason to use an RL configuration as opposed to a CR configuration.
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1answer
100 views

How to make power supply to 434MHz receiver module more stable on RC car?

Following the recommendations I got on my last question about troubleshooting communications in my RC car, I probed the +5V power pin of my RF 434MHz receiver module with my oscilloscope. Below is a ...
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6answers
264 views

Cutoff frequency: exactly -3 db of power

I have a question which may sound strange, but still I'd like to ask community to explain that. Hope other people may find it interesting aswell. As we know, cutoff frequency is the one frequency ...
2
votes
1answer
112 views

USB 5v power filtering

I am creating a pcb that splits a single USB input into 3 outputs (one with data/power carried, two with just power), and I was wondering what is the best way to reduce noise on the power line as this ...
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6answers
1k views

What is the physical/electrical limit of audio quality?

A few days ago I was in a class about electronics on my study. The first lesson was an introduction into the main subject, bits, analog signals, conversion, etc. An example was asked by the teacher: ...
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3answers
93 views

Low-DC-resistance inductors?

simulate this circuit – Schematic created using CircuitLab I have a 5V DC source that passes AC noise (alternator whine, spark plug discharge through the smoke-lighter-to-micro-USB ...
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1answer
48 views

Integrated RC Filter Chip [closed]

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 ...
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2answers
38 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 ...
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1answer
63 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 ...
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1answer
32 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: ...
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5answers
127 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
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0answers
33 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 ...
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2answers
74 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 ...
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1answer
531 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
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1answer
185 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 ...
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0answers
89 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 ...
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3answers
62 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 ...
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1answer
44 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 ...
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1answer
37 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 ...
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2answers
55 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
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1answer
91 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 ...
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1answer
94 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 ...
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5answers
157 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 ...
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0answers
34 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 ...
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0answers
61 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 ...
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1answer
49 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 ...
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2answers
81 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 ...
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2answers
44 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 ...
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1answer
33 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
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1answer
60 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 ...
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3answers
41 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
37 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 ...
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votes
3answers
89 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
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1answer
147 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
82 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
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0answers
62 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
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1answer
38 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?
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1answer
78 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 ...
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3answers
125 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 ...