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Questions tagged [noise]

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

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1answer
58 views

Noise Temperature of Antenna

A microwave receiving antenna on a satellite is pointing towards the earth . The antenna beamwidth is 50 degrees, the earth subtends 5 degrees at the satellite. What will be the noise temperature of ...
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1answer
49 views

Prevent small signal with noise

I am designing a Conductivity Meter by using Arduino. I used ad9850 to generate a sin wave with 1khz and peak to peak 20mV. but there is a bit of noise with my output Signal and after the voltage ...
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2answers
43 views

Bose QC20 in-ear headphones 50Hz buzzing noise on PC

When I plug my Bose QC20 on the PC, I hear a low volume 50Hz buzzing noise. Some interesting facts: When I touch a metal part (PC case, keyboard) the noise is gone. I have this noise on all USB ...
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1answer
45 views

What's the source of this noise in my Arduino oscillator?

I've been experimenting with techniques to rapidly switch on and off the digital output pins in an Arduino. This is the code I use: ...
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2answers
47 views

Troubleshooting TL071 to TA8207 100 Hertz hum

I worked out to build a pre-amplifier connected to a power driver in a single setups(a pcb). Problem arises when it's powered up. here are a few questions. Setup has a TL071CP as preamp with a unity ...
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0answers
69 views

How can I eliminate the noise in this case?

As a part of a big system Arduino is being affected from a switch outside(so the spike is not always there only when an outside switch or surge happens ect.) and I guess through its USB producing ...
4
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1answer
81 views

How to reduce noise in SMPS (Switching mode power supply) circuit

I am just using a reference design of SMPS (from Microchip) to boost input voltage from 12V to 90V as the image below: It's working normally but the problem is the noise at the output of 90V. I ...
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1answer
36 views

How can I model a circuit for this noise coupling phenomenon

A shielded Wheatstone type force transducer FT is mounted on a metallic structure and through its cable is connected to an industrial amplifier module Amp(I gave the names in the below illustration). ...
0
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1answer
46 views

How phase modulation changes spectrum?

I'm studying amplitude,frequency and phase modulations for an exam. I just studied amplitude and frequency modulations, however i didn't succeed in understanding how the phase modulation changes the ...
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1answer
49 views

Splitting an Analog Signal Without Adding Noise

I am trying to take a current measurement, run it into a PCB that splits the signal, and then output the signal in two places. One of the destinations is a RIO being used for feedback control, the ...
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0answers
50 views

SMPS secondary rectifying diode placed on GND instead of Vcc [closed]

I have designed a SMPS (low noise) and diode is placed on GND instead of normal Vcc . Is there a benefit having the diode placed there instead of Vcc from a noise perspective ? Is it possible that I ...
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0answers
19 views

smps power plane

I am designing an ultra low noise SMPS with 4 layer PCB. On the first layer I have components and power traces. On the second layer I have a whole GND plane. My question is: for the 3 plane (power ...
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0answers
46 views

Identifying Noise in 12AU7 Based Headphone Amplifier

I've been working on making a tube based headphone amplifier as a fun personal project. The amplifier is based around this 12AU7 vacuum tube. The project for the most part is following this existing ...
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3answers
41 views

Inherent DC Bias in ADC sampling

I was just simulating the quantization behavior of ADCs of different bits, on data sampled by a 24-bit ADC. What I noticed that as we go towards ADCs with less bits a DC bias in the signal becomes ...
4
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2answers
50 views

Sampled Noise Amplitude

I am trying to understand how an arbitrary noise spectrum is sampled by an ADC. Let the broadband noise floor be, for example, \$e_n\$ = 5nV/√Hz @ 1kHz and the 1/f noise be \$E_{1/f}\$ = 2 μV peak-...
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0answers
30 views

Stepper Driver signal noise problem (Ground Loop)

I have an BluePill board (Arm Cortex M3 Dev. Board). Also a a4988 stepper motor driver. BluePill is powered from usb of my PC. Stepper motor driver is powered by external power supply which is 220V -> ...
1
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3answers
121 views

Is there a practical way to create/inject some visible interference into a nearby AC mains?

I have this 230 to 6V rms step-down transformer. I use it to observe the mains voltage. But recently I needed to create some interference or spike in the mains. So I first tried the following: I ...
0
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1answer
401 views
+100

What could be causing this interference and how to eliminate it?

(update: Please also see the major edit at the end) A sensitive electronic equipment Device 1 below is basically composed of a power line EMI filter at the mains entry, an SMPS power supply which ...
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2answers
24 views

Determining equivalent resistance to find the cutoff frequency

I am designing a low noise circuit for a precision application and require a stable voltage supplied to the circuit. I have determined that the MAX6250 voltage reference best suits my circuit. A ...
1
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1answer
44 views

Voltage Divider with low noise?

I'm working with a nano scale motion stage with high precision. To move the stage I supply Sinusoidal wave using (Agilent Keysight) function generator. This F-gen, goes as low as \$20mV_{pp}\$ in ...
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0answers
51 views

How to remove PWM noise from my speed sensor wires?

I'm driving a brushed DC motor via PWM at 5kHz. I'm also measuring the speed of the motor. When I try to sample the speed, sometimes I'm getting a value of 5kHz, which is exactly my PWM frequency. ...
3
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2answers
77 views

Changing noise level with 24-Bit A/D Converter

I work on a 8 Channel 24-Bit A/D-Converter. I have an issue with the noise level of this converter. There are some "quiet" periods where the noise is low and acceptable and there are other times where ...
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0answers
23 views

Inductive spikes and noise in a hand prosthesis circuit

I am designing a circuit for a hand prosthesis. The main part of it is as follows (connections via pcb): Since it is meant to be as robust as possible, while keeping it low-cost and affordable (thus ...
0
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1answer
61 views

Good PCB Design - Single Power Plane with 2 Power supplies (+ve & -ve)

Recently I've taken over a project which requires low noise but the design given to myself does not meet the requirements. I noticed on the PCB design It has a single Power Plane with 2 separate ...
0
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1answer
35 views

Amplifying noise floor

Let's say you have -120Db noise floor on an amplifier circuit. You feed this noise into an ideal noiseless amplifier with an Av=25. What is the new noise floor? Proper equation?
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0answers
52 views

RS485 Waveform while Receiving Data

I was testing the RS485 Circuit, below is my circuit and I connect J5 to my PC using another RS485 to USB converter. In PC through Modscan software I was monitoring the polling and response, a twisted ...
0
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1answer
32 views

Hall sensor for slowly varying magnetic fields

I am trying to measure the change in the field of a permanent magnet (at about 50 mT) due to temperature fluctuations at room temperature (timescale ~ mins to hours). The sensor I am currently using ...
1
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1answer
41 views

SMPS and pcb layers

I am trying to design a ultra low noise SMPS with 20 W output (85 V to 220 V) and need to make a choice between 4 layers PCB and 6 layers. On the 4 layers we plan on having components on both sides ...
1
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1answer
47 views

Does impedance balancing in the far end make no sense?

Below shows a conversion of unbalanced line to a balanced one: My question is about: if the unbalanced line is very long which means the signal source and the isolation amplifier is apart from each ...
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0answers
50 views

MEMS Microphone noise floor power level & audio noise spikes measurement

I have a circuit with a MEMS microphone and would like to be able to measure the audio noise spike contents and check the noise floor power level in the audio circuit. My intention is to connect the ...
0
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1answer
19 views

Relation between bandwidth, response time and disturbance rejection for a control system

I read the following line in a control system book: Higher bandwidth corresponds to better command following, disturbance rejection and sensitivity to parametric variations. On the other hand, ...
0
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0answers
47 views

OPA Noise Calculation

This question is somewhat general but I will ask in terms of an example. Following is the general noise calculation for a noninverting negative feedback amplifier with the corresponding transfer ...
0
votes
1answer
45 views

Noise spikes caused by external AC switching

I have built a circuit that measures time between two 5V pulses. It works good but I'm having problems with voltage spikes that comes from the AC mains. And it triggers the interrupt pin on the PIC. ...
0
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1answer
61 views

“Creating” a ground pin for my laptop

I am building a sensor using an Arduino connected to a laptop; I noticed that the readout is much more noisy when I use a non-grounded laptop (either running on battery or connected to a power socket ...
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2answers
92 views

What is the application of capacitor between Vcc and GND [duplicate]

This is a schematic mo ATmega328P used circuit. It has paralleled two 100nF capacitors between Vcc and GND. (C8 and C9) What is the function of this two capacitors and why they are paralleled?
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1answer
46 views

Protect signal from noise in Arduino

I am trying to send a signal from the Arduino to a relay to open a switch. My problem is that my Arduino will be near the AC power lines. I searched for how to prevent the noise to ruin the signal ...
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0answers
40 views

How to calculate circuit noise in dB from measurement

I've never quite understood how to calculate the noise in dB from an analog circuit at the output of the ADC. This is my measurement: It is a 16bit ADC, as we can see there is roughly a +/-1 bit, or ...
0
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1answer
32 views

add different current loads to test noise on DC-DC converter

I want to test the LTM8021 DC-DC converter (using an eval board I bought - schematic for it is below) for noise output at varying current loads (10mA, 100mA, 200mA, 450mA) and still fairly new to this....
2
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0answers
36 views

What is the signal-noise model of laser induced fluorescence?

The following image is an example of a fluorescence signal trace from the photomultiplier tube detector (PMT). Each spike represents one fluorescently labeled cell. This signal model is definitely ...
0
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1answer
47 views

In which way could this noise be coupling?

In a data acquisition system, a single ended earth grounded daq board has inputs from many force transducers and some transducers types. Daq basically has a common ground for all inputs and ...
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1answer
52 views

Data acquisition wiring - How to deal with extreme noise?

Hi all, I'm trying to build a portable data acquisition system to gather readings really close to high voltage powerlines. I was hoping to get some advice on how to achieve the best noise immunity. ...
0
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2answers
42 views

Confused with understanding the text about high input impedance and coupled noise for an electret microphone

I have a problem with understanding a text's paragraph about the use of FET as a preamplifier. It claims that it reduces the coupling noise for an electret microphone before it is amplified in the ...
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0answers
38 views

Noise in BLDC motor with 32kHz PWM

I built a controller with FOC for BLDC motors and it works well for most motors I tested so far, but as it comes to motors with low resistance and inductance, I hear a noise, that sounds like water in ...
4
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2answers
1k views

Long wires causing Raspberry Pi to die?

I've been working on a simple project involving a Raspberry pi and some switches. I would never thought I would have any problem for something as simple as a switch, but here I am. The 2 wires from ...
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3answers
65 views

Shield grounding for analog sensor

I have an analog sensor, a resistance temperature thermometer, which is essentially just a resistor (~50 Ω) which I apply a constant current to (10 mA) and measure the voltage of in order to ...
0
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2answers
38 views

noise comparions between Schottky and MOSFET

I have a circuit that uses a Schottky diode to provide reverse voltage protection. However, the diode chosen is on a long lead time and an alternative that is immediately available is required. I've ...
2
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0answers
56 views

Noise immunity of single ended analog voltage signal

I want to use a sensor with analog output in my design. The output of the sensor is a low frequency traingular wave (less than 300 Hz) and voltage vetween 0 - 5V. I need to carry the sensor signal to ...
2
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0answers
52 views

What is the reason for high frequency noise when amplifier is powered with battery?

Hi I made a small headphone amp and powered it using lipo battery.voltage is stepped up to 5v.everything is working with direct supply (ie., while charging battery)but as soon as I unplug the charger ,...
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1answer
33 views

Termination method of a connector pins and noise

In applications like a 24V transducer to be powered and its signal to be delivered to an enclosure ect. I mean low power electronics sometimes cable mount or panel mount connectors needed. Im ...
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2answers
112 views

What is the easiest way to add noise to a circuit?

I'd like to have a sinousid wave with some noise. Then use that signal as input for an arduino, visualize that signal in Matlab and use a simple filter (moving average, for example) to remove the ...