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.
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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 ...
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Could dirty power/electricity, EMR or EMP prevent iPad Mini from charging? [closed]
My mother lives at a care home. She has an iPad mini (6th generation) which comes with a 20 W USB charger. One day it stopped charging. I tried changing the charger, USB cable, power outlet. Nothing ...
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SNR simulation and "desired output signal"
I'm simulating an amplifier and want to know if it is possible to define its SNR. A simulation in LTSpice shows that the circuit generates 42nV/Hz, but this value is independent from the input/output ...
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Driving 1602 LCD in noisy environment
My PCB drives a 1602 LCD in 4-bit mode over a 0.5-1m long AWG28 (0.08mm2) ribbon cable. Sometimes I get nibble sync problems. It can be seen on the LCD as strange or garbage characters.
This does not ...
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Placing a comparator below a transformer
I am working on updating an older flyback design. Part of the update is adding a comparator to control a relay through a MOSFET. It's a quasi-resonant flyback so the operating frequency swings between ...
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LED "optical noise" when powered by DC
I am currently designing a circuit where:
An LED driven by a constant current driver shines directly into a photodiode. (I have also tried without the op amp constant current circuit.)
The photodiode ...
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2
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Hum without ground loop
I have an audio measurement system. The system is connected to and powered by a laptop. The system has no other connection to the AC grid. Now, if the laptop is connected to the AC grid and i measure ...
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How can I attenuate noise from synchronous divider and OCXO?
I am experimenting with a square OCXO, dividing its output frequency to 1kHz using a 4017 synchronous counter and feeding the output to a sound card using Spectrum Lab software. I can then record it ...
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Transistor specs in the capacitance multiplier
I'm working on a constant current power supply and as a first step designed the following rectifier with a filter. I know the bottom rectifier is inactive, but with couple of switches the circuit ...
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Why would I use HNM (high noise margin) gate drive over a TTL gate drive for DC motor driving application?
I am making a very simple half bridge DC motor drive using the MAX1760 gate driver. Looking through the datasheet I saw that it offers two types of logic level technologies (if that's the right word?);...
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What are the examples of a high noise enviorment? [closed]
I was reading about the noise margin of different gates and ICs and I came to know about the fact that all the ICs has certain noise margin and in that limit the ICs can function properly. So my ...
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MOSFET parasitic signal? (parasitic triggeried millivolts, can be thermal noise - how to prevent?)
I have a MOSFET that is closed, but even in closed position I sometimes can see some very very small signal from it.
How can I make a barrier to prevent this small signal?
If I put an diode? It must ...
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what causes random (irregular and inconsistent) sound feedback through wires to speakers? [closed]
I have a 3.5mm stereo jack from my laptop to a guitar amp I use as an external speaker. It's not the most ideal set up but sometimes I get feedback, a loud buzz and other times I do not. It runs ...
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HLW8032 energy meter circuit showing power usage at no load
I am designing an AC energy metering circuit. The circuit has to measure voltage, current, power, power factor and energy used for two channels (from the same source). The HLW8032 transmits 24 bytes ...
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1
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64
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EEG instrumentation amplifier stage
I am trying to design an amplifier for EEG SIGNAL using INA 126(gain 6.5). I've included for you the attached schematic diagram. The simulation was working but When I tried to implement the circuit ...
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3
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Noise increases suddenly in op-amp circuit
The circuit is a charge amplifier that connects to a piezoelectric sensor. A buffered voltage divider provides a VDD/2 virtual ground, so the output is in range 0.0V - VDD and oscillates around VDD/2. ...
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Is the noise in current measurements additive to device signal?
I am a chemical engineer, not an electrical engineer, so hopefully this can be explained to me with my still developing knowledge on the matter.
I have been tasked with running current measurements to ...
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If any "antenna" can be impedance matched to the source, can any piece of metal be tuned to perform the same as a physically tuned antenna? [closed]
I have heard online its better to get an antenna physically tuned than a matching network, but I don't understand exactly why. If the matching network would stop reflections and increase power ...
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How to dampen/reduce oscillations from crosstalk in encoder signals
I have two encoders that emit A/B signals for a total of 4 wires. Not sure if this will be relevant but these encoders are not the same and have different output impedances and rise/fall time. I also ...
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Forms of Magnetic Noise Coupling
I was watching a video of Bob Pease discuss magnetic coupling of noise into the ground lead of an oscilloscope probe. See video at 5:40
https://www.youtube.com/watch?v=2vzvWUqUtb8
I noticed another ...
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Bidirectional level shifter (TXS0108E) randomly changing outputs
Circuit and video of weird behaviour.
I am using a TXS0108E 8-channel logic level shifter to convert a 3V3 input (VA) to a 5V output (VB).
According to the datasheet, when there are no inputs driving ...
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Minimizing noise with single-ended opamps
Opamps often get used with one input at a DC voltage, usually the main ground per the standard inverting amplifier example:
For low noise, a BJT input stage like OPA1611's is often chosen for the ...
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Filtering spikes in electric fence energizer
I have designed a 12V electric fence energizer. It works as follows:
A flyback converter charges a 50uF capacitor to 400V. After the capacitor has been successfully charged, a thyristor discharges the ...
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How to eliminate the VFD noise affecting digital sensor reading?
I have a problem getting correct readings from a 5v digital sensor connected to an Arduino Uno board. I get correct reading until I start the VFD that drives a 3-phase motor.
The sensor reading then ...
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Noise spikes with optoisolated circuit driving 12VDC solenoid valve at 6.6 Hz
I have an existing circuit that drives a 12VDC solenoid valve on and off at ~6.7 Hz, 75ms on, 75ms off. This entire system is DC.
The Beagle GPIO logic '1' level is 3.3VDC, and the BeagleBone is ...
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AD711 Noise Figures
I'm looking at the datasheet for the AD711. Why are there several different values for the input voltage noise given without any information to distinguish between them?
Datasheet: AD711
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How noisy is a saturated PNP BJT as a switch compared to a p-channel enhancement mode MOSFET?
I want to switch on phantom power (12V through 680ohm) electronically in order to guarantee simultaneous delivery and not have the comparatively low resistors load the input in case phantom power is ...
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FPGA controlled ADC has undefined data
I have an MAX11116AUT-T ADC Controlled by an FPGA at a 6.25MHz clock.
Once the CS signal is set to low, I can see data being returned by the ADC on the falling edge of the clock.
There is, however, a ...
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Noise floor of an unmatched resistive network thru PSD calculations
I am modeling the PSD of various loads to calculate noise floors. I have various load terminations from 25 ohms to 250 ohms.
Per Johnson-Nyquist, the noise floor on a resistor when load and source are ...
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Transformer-coupled low noise amplifier
A rather common way to make a low noise amplifier with an equivalent input voltage noise density in the range of ~0.1 nV/rtHz, is to take a FET and place a step-up transformer in front of it.
I have ...
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Methods for improving/smoothing the load cell signal
I am using a Delta AS02LC-A cell module and a Zemic 25 kg load cell. Here are some details of the load cell calibration certificate:
And this is the appearance, specifications and wiring diagram of ...
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Can two or more RF noise signals (or noise sources) still be added together if they have been attenuated below the thermal noise floor?
Can two or more RF noise signals (or noise sources) be attenuated below the thermal noise floor, and still add together to be higher than TNF?
If a noise signal experiences path loss or attenuation ...
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SIM800L GSM module humming noise
I am trying to play audio over the call by using SIM800l
I am using this "DFPlayer mp3 module" to play audio and connected its AUDIO OUT to the MIC IN of "SIM800L GSM module" and I ...
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How can we reduce background noise in this system?
We are experimenting with a glucose test strip (below) in our chemistry lab using an electrochemical method where a potential is applied (150 mV) across the working and reference electrodes and the ...
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LM337 Unstable regulation
For an audio project, I need a low noise +/- 12V supply.
I have a linear power supply of +/- 15V and I decided to use the LM317 and LM337 to decrease the voltage to 12V.
The circuit that I use is the ...
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AC adapter interfering with WS2812B LED strip
I have 2 power adaptors connected on same AC line, both grounded.
Power adapter 1:
12V DC 10 A for powering 12 V LED strips, controlled by ESP8266, IRLZ44N MOSFET used to control brightness of the LED ...
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External voltage reference MCU RP2040 - Use of series reference?
I designed a board that uses the RP2040 Pico for its ADC and I/O.
To improve the ADC of RP2040 I wanted to use an external reference. In the past, for other projects, I used as external reference a ...
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Placement of USB/UART converter for robustness and noise immunity: long USB cable or long EIA-422 cable
Consider the very common case of communication between the UART peripheral of a microcontroller and a PC, using a USB-UART converter such as are available from FTDI and others[1].
If there's a non-...
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FFT is not showing noise
I have current values and respective time.
There is noise in the signal. But when I am calculating FFT, it is not showing
I have recorded the values at every 5ms.
below is my code:
...
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Correct way to think about thermal noise?
I have just started learning about thermal noise in op-amps and while studying could not find if the noise given in op-amps data sheets is random sample to sample regardless of the time interval ...
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50 Hz noise on INA125 for Wheatstone bridge application
I am trying to measure mechanical deformations using a full Wheatstone Bridge.
In order to do that, I connected the bridge to an instrumental amplifier (INA125PA).
The amplifier is powered with a dual ...
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2
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How do you characterize the noise in a fluid velocity measurement device?
I have designed and built a measurement device that detects the velocity of a fluid flow (a constant-temperature anemometer). I wanted to experimentally characterize the noise performance of the ...
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Why does this ADC noise calculation divide by 6?
I'm reading an article about ADC noise from ADI:
Seven Steps to Successful Analog-to-Digital Signal Conversion (Noise Calculation for Proper Signal Conditioning)
Let’s assume that we have a sensor ...
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Guitar Pedal Signal Delay and Background Noise
I am designing a guitar pedal for overdrive/distortion from scratch and the circuit creates a lot of noise. The circuit also doesn't immediately start working, there is a delay before the signal makes ...
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Pico / FT232H FIFO bad data
So. I've been trying for several days to get parallel data transfer from a Raspberry Pico through a FT232H to a host computer. I'd like ~25MB/s, which is why I'm trying this route in the first place....
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MAX31865 RTD IC: What is CI's capacitor purpose?
What is the Purpose of CI capacitor? The datasheet does not mention anything for it except its recommended value.
My guess is that it is used to suppress RF noise on the PT100/PT1000 cable. But It ...
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Spectrum Analyzer problem
I am seeing some strange behavior with my spectrum analyzer. It is a Tektronix RSA306B.
I have put a 50 Ω termination at the input of the spectrum analyzer and I am seeing a lot of spurious ...
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Common methods used to reduce op-amps white noise?
I am a beginner learning about op-amps and DSP.
If an op-amp has 1 nVpp of noise/sqrt(Hz), at 1 MHz sampling rate the noise is 1 uVpp. If the sampling rate is quadrupled to 4 MHz, by averaging 4 ...
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Is the noise of op-amps and ADCs Gaussian/mean=0?
I understand that white noise is not always Gaussian. In general, is the Vpp/Vrms noise stated in operational amplifier and ADC data sheets Gaussian/has a mean of 0? Any exemptions to be aware of ...
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Split or not split the ground plane in a low-noise design?
For low-noise design, many component datasheets suggest dividing the ground plane into AGND and DGND and linking them with a star connection.
But my ten years of experience in EMC have shown me that ...
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