Questions tagged [noise]
Noise is an unwanted disturbance in an electrical signal. This tag is for questions about sources of noise, noise types, issues caused by electrical noise, or improving the signal-to-noise ratio of an analog circuit.
2,092
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LNA operating in saturation
What happens to an LNA noise figure when operated in saturation? I understand that there will be gain and linearity issues, but what about its noise figure? What is the mechanism which will lead to ...
4
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4
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656
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Can ferrite beads turn high frequency noise into heat?
I understand that ferrite beads provide high impedance for high frequency signals. However, I am very confused on what that actually means. I've been reading in multiple posts and articles that ...
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What happens to noise after crossing through a bypass capacitor?
I understand that bypass capacitors provide a lower impedance path for oscillating noise. However, capacitors aren't able to dissipate energy (apart from their effective series resistance), so all the ...
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2
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How can it be possible that I hear people's voices from my computer speaker? [closed]
I searched on the web and found it can apparently be due to truck drivers communicating on citizen's band radio which is around 20 MHz. Apparently this communication may cause interference with the ...
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1
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Noise during RS-485 operation
I have a switching step-down power supply SCM1301A, from which the entire circuit is powered, namely the microcontroller, op-amp, RS-485. I digitize the signal coming from the microwave module, having ...
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Line Input and dc motor - Noise suppressing capacitors [closed]
I am trying to repair a sewing machine that my mother used for my sister. I have opened the bottom of the machine and there is an obviously blown capacitor - the metal foil and paper is on show and ...
2
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1
answer
84
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Mysterious artifacts in my strain gauge data. Can anyone suggest a possible source? [closed]
I'm working on a project where we are collecting timeseries data from multiple strain gauges. We are seeing a strange pattern of artifacts in our data.
The artifacts appear as sharp 'spikes' with a ...
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2
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70
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Eurorack PSU design and noise
I'm trying to design a cheap way to power my DIY Eurorack modules. I'm trying to use two 15V wall warts to that effect but I'm getting a lot of noise. I've seen a few questions related to noise ...
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Near field probing on a large DUT
I "inherited" a set of boards (it's an elevator controller) that have no 'explicit' EMC countermeasures except a single CM choke for the CAN bus. And, of course, now the whole thing need to ...
2
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2
answers
151
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My First PCB - EMI Problem on Poorly Earth Grounded Test Place
A PCB design amateur here. Stumbled upon a hard problem right at my first PCB design. I have tried to comply with the layout rules of thumb for SI and EMC, but still encountered with strong EMI ...
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Why the induced noise is sometimes additive but sometimes works as a constant?
Why sometimes the noise (e.g., induced 50hz hum) is added to a useful signal (thus increasing its 50hz value), but sometimes it works as a noise floor - has a static value and can be overpowered by a ...
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2
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55
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Ferrite bead on a SMPS output [closed]
Suppose I have an instrument which needs a very clean power supply line. I have an SMPS which outputs 24 V at 3.2 A, which is then cleaned via a LM1084 linear regulator.
Given that the output of a ...
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2
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206
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Trying to record from DIY op-amp results in seldom pops and clicks
I have a 741-based audio amplifier PCB here from the 70s:
When I tried to test it, I powered it with a 24V battery (I tried 12V as well with no difference,) then I shorted pins 15-19, connected the ...
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0
answers
26
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Speaker pop / crackle when SBC connects to WiFi
I'm using a Raspberry Pico to detect movement and play a sound via an amp & speaker. At certain intervals the Pico attempts to connect via WiFi to send and receive data.
However, when attempting ...
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0
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133
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Problem of noisy ground 2
I am new to the forum and am facing the exact problem as described by @gregoiregentil over 10 years ago. I am using the same setup as in the linked question.
I have a circuit board controlling the DC ...
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1
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51
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How to read ripple and noise on a linear power supply using RIGOL DS1202Z-e?
I am new and want to learn the right way to read noise and ripple from a linear power supply. In this case, I measured 5 V DC for a sample. I used 1 channel. I connected the center of the probe to +5 ...
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3
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Lots of electrical noise at boost converter output
I'm trying to implement a boost converter using TI's TPS55340.
After spinning up the design, I have found that the output ripple is almost 8x what I expected to see given my design parameters. First, ...
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Optimal Op-amp circuit for sounder
I'm working on a 40kHz sounder. One pole of the piezoelectric transducer is connected to R3, other pole is connected to GND. OPAMP_OUT goes to STM32 ADC input.
Is this op-amp circuit good enough for ...
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1
answer
64
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Noise in DC supply due to AC track nearby
The RL_NC track in the image will carry 230V AC. Will the EMI noise from this track affect my 9V supply nearby (output of LM7809)?
I use the 9V supply to measure the voltage drop across a conducting ...
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1
answer
119
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Unstable to do resistance measurements due to electric fans
I built a small system to monitor wood drying. The idea is to turn on exhaust or circulation fans (230V-AC) based on the absolute humidity and ambient temperature (respectively) of a small drying ...
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0
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35
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Audio noise when Bluetooth is connected
I'm making a Bluetooth speaker with a rechargeable Li-po battery. I had some noise coming from the speaker that I suppressed connecting a capacitor at the Bluetooth board's power source. Apparently I'...
4
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1
answer
79
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Unknown signal source
Using my oscilloscope near my TV(a Panasonic TH-L42U20A) seems to introduce an unidentifiable source of noise. The scope probe is floating, neither probe or ground clip is connected to anything, ...
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60
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Stepper motor noise
I’m currently developing a belt drive system that uses two separate Nema 42 stepper motors and an htd pulley. Everything is working well except I recently increased the supply voltage from 110 to 220 (...
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2
answers
97
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LM318 strange oscillations
I want to make a 100~200 kHz square wave signal. I tried with a Schmitt trigger oscillator . The circuit below worked well with another op amp but the slew rate was too low so a tried with the LM318 ...
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Control noise in circuit to avoid disturbance in flow sensor reading
I am controlling water pump and electro magnetic flow sensor ( YF-S201 ) by esp32. Flow meter affect while pump running. I disconnected flow sensor in my circuit for testing.
While pump start to ...
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1
answer
66
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USB Audio interface 50Hz + harmonics noise when either laptop or speakers are plugged in
As soon as I plug in either my laptop or my speakers to the wall, I get an unbearable amount of noise in my guitar recording.
Signal chain: Guitar --(1/4 jack)-> Audio Interface --(USB)-> PC --(...
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1
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43
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How do I handle +5V noise and PSU undervoltage due to an OLED module in my circuit?
I am working on a circuit that will use the ADC on an Arduino (Adafruit Feather M4 Express) to measure a small signal, so I want a minimum of noise. Testing the Arduino on a breadboard with a DC test ...
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0
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51
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Software averaging filter for ADC readings in a boost converter application
I'm working on a boost converter using a microcontroller (STM32G030), and I need to measure input and voltages of the converter. But, due to switching noise, the ADC readings become noisy and cause ...
3
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2
answers
178
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SDRAM logic makes noise on ADC readings with FPGA
I am working on a design in which an FGPA reads the output of a 12-bit 40MHz ADC and then stores half of the data on an external SDRAM and the other half on an on-chip BRAM after some averaging.
The ...
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1
answer
53
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Will this electric guitar wiring scheme be noisy?
I want to wire my guitar using two SPDT switches for my pickup selector. This is so I can have four sounds: lower, upper, both in parallel, both in series. I'm concerned that when it's set to use ...
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Why different noise terms are read at specific sampling interval in Allan Variance plot?
I was trying to identify Quantization Noise, Angle Random Walk, Bias Instability, and Rate Random Walk from Allan Variance plot which as Allan deviation on y axis and Sampling Time Interval ...
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1
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105
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Does a single input differential amplifier remove noise?
It is known that the purpose of using a differential amplifier is to remove noise from the input signal, apart from giving some small amplification. To my knowledge, there are two inputs and two ...
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7
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If RF signals require matched impedance to remove reflections, why do approaches to shunt noise need only a “good path to ground?”
From my understanding, for signals to propagate without reflection the impedance of the path must be constant and can be shown via the telegraph equation.
When it comes to noise on the line, for ...
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0
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116
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What is the purpose of these two capacitors?
I came across the schematic shown below. What is the purpose of C22 to C25?
Unless they are used for differential noise, since FL1 eliminates the common mode noise present.
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1
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Powering a NEMA17 stepper motor (DRV8825 driver) with a mt3608 boost converter
I'm encountering a very strange problem at the moment.
In the course of my school project I need to drive a NEMA17 stepper motor with a DRV8825 stepper driver, which is soldered with its breakout on ...
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0
answers
63
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SDM3055 injects 50Hz noise
I am performing some measurements on this circuit (simplified).
Some details:
Power supply is linear
Circuit is mounted on a breadboard
Oscilloscope connected using a ground spring
Oscilloscope and ...
0
votes
1
answer
69
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EMI suppression from vibration disc motors
In my application I'm using 9V (6xAA batteries) to power three vibration disc motors in series (Solarbotics P/N:VPM2,) some LEDs (not shown) and then to a non-isolated DC-DC buck converter. The buck ...
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0
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Why do we get increase in BER with increase in Eb/N0 of the signal?
I'm working on a problem of MSK modulation scheme. I have passed my modulated signal through SUI channel Models and AWGN.
But As I want to do analysis on the performance of SUI channels I'm getting ...
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0
answers
57
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Reasons for lower flicker noise in PMOS vs. NMOS - buried channel, mobility
There have been other questions on the site about why PMOS devices are observed to have less flicker noise than NMOS devices, for example this one, but I'm not sure it's correct.
On mobility - the ...
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0
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81
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Electrical Noise in Raspberry Pi with Multiple USB Connection
I'm currently in the process of creating a mobile robot using a Raspberry Pi. The robot incorporates three devices (ODrive, RPLidar, and UWB), all connected to the Raspberry Pi through USB ports. When ...
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2
answers
94
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Battery in parallel with supply
I´m working on a project to charge a 24VDC lead-acid battery.
As you see, is not the best way to charge a battery. But it has to be like this (if you have any advices to improve the circuit using ...
1
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1
answer
102
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ZVS low noise power supply?
I'm currently looking for low noise isolated DC-DC power supply for analog components. There are different variants available, like SN6501 IC or integrated DC-DC convertors. But I wonder, what if I ...
2
votes
1
answer
53
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Signal not stable on UART Pins of BLDC motor controller PCB [closed]
I am designing a BLDC motor controller PCB based on STM32G030c8t6 microcontroller. But the waveform on UART is not stable. The dashed line is the ground on the following image, but some part of the ...
1
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1
answer
164
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RS232 : dedicated signal ground or common with power ground?
I'm designing the PCB for a robot, where I plan to add some connectors for external RS232 tools (provided by the client).
Each connector will provide power (either 24 or 48V, at 5A max) and an RS232 ...
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0
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36
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System wide noise on high power BLDC controller prototype
I'm designing a highish power BLDC motor diver (120A continuous 48V nominal 90V max) BLDC controller and am having noise issues caused by the mosfet switching.
Basically at the high and low ...
0
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1
answer
52
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Buck Converter : Light-Load Mode : Efficiency vs Audible Noise Reduction : Portable, Handheld Device
Question
I am designing a portable (handheld, battery-operated) consumer electronic. The limited nature of the power source makes high efficiency critical at all loads, but will a lack of an OOA (out ...
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3
answers
90
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Eliminating Noise from Audio Amp Board Input
I made this project by shajeeb (linked below), and I am having trouble with noisy ground lines. The circuit I made is the same as the diagram below except for where I connect the speaker and amplifier ...
0
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2
answers
115
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Noise issue when powering several audio devices from the same power source
I'm working on my portable music production setup and I'm having noise issues due to connecting all my gear to the same power source.
I have three devices (a sampler, a keyboard/synthesizer and a ...
1
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0
answers
54
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Impact of laser current source noise on RIN (relative intensity noise)
I am trying to specify the noise requirements for a constant-current source that would drive a diode laser with a certain relative intensity noise PSD. Lasers typically behave as forward-biased ...
0
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0
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121
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Reduce noise coming from DC brushless fan
First of all, I'm an amateur when it comes to electronics so thanks for your patience!
I have added a fan on a sound processor which tends to overheat but then I discovered I can hear the fan on the ...