Questions tagged [noise]

About issues caused by electrical noise, or improving the Signal/Noise ratio of an analog circuit.

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Are there serial coils for corona ignition?

I did the 50kV power frequency high voltage test for a 22.9kV transformer. We have three types of HV tester. All RMS and peak of output voltages are the same, but the corona ignition voltage is not ...
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Waveform acquired from scope, what is the sample rate for post processing?

I want to make a noise measurement with my scope, but I need it to be band-limited. I am using a Tektronix TBS1102, which allows me to save to a USB flash drive an Excel/CSV file with the X and Y ...
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Reduce or filter DC spike and noise

Goodmorning, I have a small voltage drop (about 20-25 mV, DC) on a sense resistor (0.180 Ohm) and I need to amplify this with an op-amp to reach 2-3 V (DC). The signal is not clean and the noise, with ...
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How to find noise sources from noise figure data?

An amplifier datasheet provides noise measurements that show it has a noise figure of 3dB for R_s = 100Ω and R_s = 10kΩ (same noise figure for both values of R_s) at T=300K and f=10kHz. I need to ...
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Mechanical relay Noise [closed]

what is generating noise in the mechanical relay and where it can propagate or spread, as when I am using this as a normal switch for switching purposes. please explain me in detail Thank you,
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Which noise sources dominate in a receiver?

For a radio receiver that digitizes over-the-air RF signals (such as an SDR), my assumption (as a DSP guy; pardon my hardware ignorance!) has been that thermal noise dominates total receiver noise, ...
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How to reduce or eliminate inductor sound noise in a buck SMPS?

I use this circuit as my device power supply: Here I have R2=5.6K as my SMPS load but at this load I have about 10KHz switching frequency which leads to an annoying audible noise, probably from L1 (...
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Noise of low-frequency RC high pass filter preamplifier circuit with LT1028

I want to build a low-noise and low-frequency preamplifier with the first-stage opamp of type LT1028 offering an input-referred voltage noise density of about \$2~\mathrm{nV}/\sqrt{\mathrm{Hz}}\$ at \$...
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Motor driver blanks out AM/FM radio reception

Story I do many restorations of 'boomboxes' (70s/80s/90s) especially the decks inside these units. Next to the common problems with belts, gears, pinch rollers, rubber rings etc there is another issue ...
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What is the tradeoff in decreasing the frequency bandwidth when reducing noise of a resistor?

A resistor's Johnson (Inherent) noise can be modelled as an RMS voltage in series with the resistor: $$ e_{rms}\triangleq\sqrt{4kRT\Delta f} $$ where k is Boltzmann's constant, R is resistance, T is ...
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Identifying EMI on I2C Bus

I am using an RPi to interface with a micro controller which, in turn, controls a motor. I am struggling with bus errors when the motor is enabled. The motor draws ~1A. All boards are connected to a ...
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CD4051 noise measurement

I am using a CD4051B for multiplexing 8 inputs into one according to 3 control bit A, B, C. Below is my schematic: My problem is : The input of the MUX (in_mux) is quiet disturbed on my PCB board ...
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Audio noise when transmitting radio packets using the ESP32

I am building a sort of walkie-talkie using an ESP32 WROOM chip. I use the internal ADC to sample the microphone and the internal DAC to power small headphones. This all works OK, not the highest ...
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LDO units for noise [duplicate]

In this Link, on page 6,they have mentioned the LDO noise in terms of uV/(sqrt)Hz. Can someone tell me what does this unit mean and how to understand this unit?
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What is the core material being used in CMC (Common mode choke) and DMC (Differential mode choke)?

The core symbol in below diagram indicates that it is an iron core material but Iam not sure whether it is correct. I see the same representation in many other circuit schematics as well. Below ref ...
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Would noise in general mean AC components only ? Is DC noise possible?

Noise refers to the unwanted disturbance in an electric signal. Would there be a DC Common mode noise? I guess it is not possible to have DC common mode current, let alone noise, as it doesn't have ...
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Power supply noise reduction

I am new to electrical Engineering and would like to know wich noise reduction filter ist better for use in audio equipment. Some decalcifications: VBUS --> 5V from usb-port GND --> Ground from ...
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How to avoid noise on serial connection?

tldr: How can I prevent noise on a short (30cm) serial line? I'm trying to connect a Jetson Nano to a Sabertooth motor driver via UART (I'm using their "packetized serial" mode, but I don't ...
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Hamming code error correction multiple bits

If we send a message from a sender and the noisy channel produces 2 bits with error can we detect both bits using hamming code or is it just for 1 bit?
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How to calculate the noise root-spectral-density of below switched-capacitor circuit?

I have the following question: How the noise density of below circuit with output node “out2” is calculated? How the simulator came to a value of “-178.3 dBVrms/sqrt(Hz)”? For me is clear, for the ...
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Stove spark igniter make the touch switch off/on

I've made a capacitive touch/on (currently on bread board) with TTP223 touch IC on active low mode and used 74HC74D as output flip flop. When I use this board near stove and power up the stove spark ...
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EMI analysis for low power low voltage AC/DC

I've designed an 80W 220V-IN 400V-OUT PFC Boost converter in order to analyze its conductive EMI and design the proper active EMI filter for it. but as this is my first implementation project, working ...
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How to prototype with sensitive electrical components without a PCB?

Right now I'm trying to get consistent radio operation with an NRF24L01+ and a Teensy 3.6, however in my experience working with radios they have extremely inconsistent connectivity when using ...
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How to determine noise power and SNR from extinction ratio?

I have a pulse train signal with infinite extinction ratio (ER). I want to add a white gaussian noise to my signal to get ER=15 (dB). I know that ER=P1/P0, i.e., the power level with the light source ...
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Audio noise on output of PCM1789

I am developing a Bluetooth adapter to be able to listen to music from my phone in my car. I am doing that with ESP32, from which the audio data is sent to PCM1789 which converts it to the analog ...
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3 votes
1 answer
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Noise of a precision/active rectifier

I am trying to build a precision rectifier circuit to implement AM demodulation in a sensor signal chain. For now I have calculated the sum RMS noise of the total signal chain except that of the ...
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Spark plug noise on power supply

I am working on a motorcycle diagnostic tool. Everything works fine except for the fact that when the engine is turned on, in some motorcycles spikes start appearing all over the circuit, and the ...
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ECG artifacts and two electrode ECG without a driven electrode (AD8232 analogue front-end)

I am using the SparkFun Heart Rate Monitor which contains the AD8232 front-end chip. I want to use only two electrodes (LA and RA) without the RLD driven electrode. I am aware that this question has ...
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1 vote
2 answers
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Mixed signal PCB components placement

I'm designing a PCB that contains digital and analog parts. I'm thinking of placing the digital parts closest to the source and analog parts farther from the source and after the digital parts. The ...
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ADC signal noisy

I have an Adafruit KB2040 μcontroller, which is based on the RP2040 chip from the rPi PICO. The Adafruit max9814 microphone hooked up to the ADC0 channel gave me a very noisy signal. So instead, I ...
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Receiver stage of single ended signal impedance

I have buffered RC filter feed by single ended signal from 5m wire. Since we can scale impedances without frequency characteristic change, I now we can opt between input resistor of filter being small ...
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Non-polarised capacitor (polarity when installed)

I was watching a youtube video in which it was explained that even non-polarised capacitors (mylar, polyester etc.) have to be installed with the "external plate" of the capacitor connected ...
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AC adapter makes high pitched noise when a notebook is turned off or asleep

When I put my notebook into sleep mode or turn it off the notebook's AC adapter starts making a high pitched noise. When the notebook is on the adapter doesn't make any noises. Could anybody explain ...
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LDO PSRR Value Problem

I am searching a LDO for my design but I have a problem. Some of the LDOs don't have PSRR value. So, I can not compare these LDOs then others for noise feature. For example here are 2 LDO. Why these ...
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4 votes
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Is it ordinary that near-field probes do not detect EM noise?

Last week we did a pre-certification test with a device and it failed. Description of the device: It is powered from Li-ion battery. It integrates a BQ24090DGQT which is a Li-ion battery charger, the ...
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noise based dimming of an LED

I am thinking about building a dimmer for an LED that does not use PWM. My idea is to use a white-noise-signal and switch an LED on (or off) depending on whether the signal is above or below a certain ...
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VCO generating a lot of electrical noise, picked up by ultrasonic transducer

In my setup, I have a VCO CD4046 Phase Locked Loop IC generating a square wave, and an ultrasonic transducer set that transmits and receives that setup. You can imagine it looking something like this. ...
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1 vote
3 answers
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Is chopping used for the the most precise voltmeters?

Are the most precise nanovoltmeters (e.g., Keithley 2182A) for 1 Hz sampling (i.e., measuring the average over each second) chopping the input stage? I can't tell from datasheets and am curious how ...
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Why might my rack chassis have ground leakage?

I have a metal rack that contains a single item: A Samson S Patch Plus Patchbay. The patchbay is well isolated from the rack using nylon shoulder insulating washers, and I've thoroughly tested this ...
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1 vote
2 answers
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PC emits buzzing sound when nearby welding machine is on

A desk computer is making odd buzzing sound exactly when welding machine in other room is being used. Is it because they share same electrical grid?
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50 Hz noise from mains plug even though it isn't connected to a power source

I am developing a front-end for a smart meter and I'm trying to measure the mains by using a power lead with the other end spliced to connect it to the front-end. I firstly powered the setup with a ...
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1 vote
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Help with providing a ground to an external circuit without compromising shielding

As per my previous post, I am attempting to use a lock in amplifier to detect changes in impedance across a small wire gap (probe) boxed with a dotted line as shown in the drawing below. I would like ...
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1 vote
1 answer
55 views

ADC susceptibility to EMI from cellphone source

I'm having trouble with EMI induced noise in my prototype ADC project. The ADC functions well in all tests but my (admittedly unscientific) test of placing my cellphone beside the PCB or the power ...
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2 votes
1 answer
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Am I calculating/considering linear regulator voltage ripple correctly?

I need a clean and power efficient -1.22V supply for a ADC driver fully-differential op-amp, the main power source will be a Lipo battery cell. I'm considering ADM8828 followed by a LT1964. The LT1964 ...
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Op-amp weird noise (asymmetric) [closed]

I have a discovery board and an ADA4528-2 op amp. These are connected together. PCB and schematic are in later. Acquired data from MCU ADC of stm32f746 is on the picture below. As you see the signal ...
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ADC channels of STM32f746G-Discovery noise

Two channels of arduino pin-headers a0 and a1 are monitored through ADC and both are floate, I've connected channel 1 ([0]) to 3.3, through capacitor, the secound channel ([1]) still is float and the ...
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A question about BW term in thermal noise of a resistor

Following example shows how to calculate the spectral density of the noise of a 10k resistor: Now if we have the following opamp(at 25C°) where R1 is 10k and overall gain of the opmap is 5 how can we ...
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SNR (Signal noise ratio) calculation (RC filter)

I would like to know how to calculate the SNR after a RC filter (let's say 1k-100nF as example). My input signal is 0.5Vrms, and the noise of the signal is 1mVrms, that's give me SNR = 54dB. But what ...
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Understanding noise in transimpedance amplifier

So I've been studying on TIAs for the last days and understood everything except the term of "noise". Let's take this TIA as an example: https://www.ti.com/lit/ds/symlink/opa380.pdf?ts=...
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Help with comparing opamp noise specs [closed]

I need a DIP package quad opamp which has better output noise than LM324, anything less than 5mV output noise floor would be great. I could only come across with the following: LM324: https://www.ti....
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