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

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34 views

What would be the peak voltage value of two combined signals (one noise and one sinusoidal signal)?

As I learned before, the peak voltage value of two combined sinusoidal signals is the sum of the two amplitudes, for example, \$0.6\sin(ax) + 0.8 \cos(bx)\$ can be \$+1.4\$V or \$-1.4\$V. Would it be ...
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1answer
51 views

Is there any offline circuit simulator software that can simulate a noisy power supply?

I have been using Circuit Wizard (Its the only offline program that I can find!). Unfortunately, it is really basic, and I have outgrown it. I need to simulate a 5V circuit with a noisy power ...
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0answers
29 views

Measuring RF Noise of Electric Train

I live near an old electric trolley, and I've noticed that it apparently interferes with RF signals. In particular: I notice that when I drive next to the line my satellite radio drops out. My ...
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2answers
65 views

Ethernet 25 MHz and 50 MHz harmonics cuases radiation emission during the EMC lab test

My PCB has been suffering with 25 MHz and 50 MHz harmonics radiation emission. I am using STM32F207 microcontroller operating with 8 MHz crystal. I am interfacing MAC in microcontroller to PHY ...
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0answers
37 views

Switching Power Supply makes speakers hiss

I have a computer with a 5.1 soundcard, that I'm using to run a standard PC 2.1 setup (Corsair SP2500) on the main audio output, and two rear surround speakers I had laying around. The speakers in ...
2
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1answer
33 views

Difference between SINR SNR

I am bit confused between these two terms. I understand SINR is signal to interference+ noise ratio and SNR is signal to noise but isn't interference noise too? Then why have he segregated these two ...
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1answer
61 views

DIY wifi radio radio NOISE!

I am building a mono, internet enabled, WiFi radio and I have a problem. I am running into what I believe may be a grounding issue. When I turn the system on, I hear all kinds of noise coming from ...
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2answers
98 views

Linear regulated supply from noisy input voltage

I have been working to redesign a faulty circuit board. One of the problems I have identified is the power supply on the board. The input voltage is nominally 13.8V DC from an AC switchmode ...
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1answer
28 views

Noise calculation for ADA4528

I thought I got familiar with noise calculations and RMS nv/rthz conversions, hence I went forward to test my understanding. I am comparing some opamps based on their noise levels. So I wanted peak to ...
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0answers
70 views

Noise-cancelling headphone concept

Inexpensive noise-cancelling headphones use a single microphone located in a little lump between the plug and the earphones. They seem to work fairly well for ambient noises, but not for handling ...
0
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1answer
68 views

Noisy Voltage Rails (Vcc, Gnd) - Noise Isolation for Automotive Circuit

I have an audio (mic, speaker) circuit that I am currently powering off of a 12V car adapter that is fed into a 10V switching DC regulator to power the rest of the circuit. I have noticed a horrendous ...
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3answers
53 views

Correlation and filtering

I am trying to get an understanding of white noise and how it can be filtered out, etc. For that I'd like to understand correlation. What would the autocorrelation of white noise look like? If I am ...
0
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1answer
55 views

50 Hz noise problem in isolated AC-DC power adapter

I have a circuit which is powered using AC-DC 12V wall converter. One of the power supply adapter has ground pin (3 pins) in its input and the other doesn't have (2 pins). The ground pin in the first ...
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1answer
50 views

Decoupling pair of microphones using noisy power source

I currently have a high quality microphone that I am powering from a relatively noisy 8V source, like that shown below. It has a built-in amplifier, and doesn't require any amplification. It just ...
0
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2answers
36 views

Measuring band-limited noise coming from an amplifier

I have a strain gauge amplifier and from my analysis, it will produce a low level of white noise above approximately 1kHz i.e. the power spectral density is flat above 1kHz. If I measure the output ...
2
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2answers
118 views

Issue of power line noise

I am laying out PCB for a stopwatch project that I made couple of months ago. I seem to have taken care of the only sensitive part i.e. crystal, since it is time measuring device. But I also see that ...
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0answers
20 views

What are the major sources of noise in the system

This question is a follow up on the question about the inductor choice for power supply noise filtering. One of the inductor's parameters was frequency response curve. To use this, I would need to ...
4
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2answers
123 views

Inductor selection for obtaining a noiseless analog power rail

I interface an image sensor, and the design schematic for power supply is: How do I choose one from the available 3uH inductors based on the specs? I figured the maximum current and dc resistance ...
4
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3answers
171 views

What causes old power supplies to start humming?

I have a number of mains-powered devices that have begun humming (I assume at 50Hz, though I haven't measured it). These include clock radios, a speaker system, a lamp (20W halogen with a transformer ...
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5answers
103 views

How do metal cases work with connectors & isolation?

I have troubles understanding how do metal cases behave in some cases. Case 1: I made passive attenuation box for amplifier(basically L-pad resistor), simple configuration: Amplifier => attenuation ...
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2answers
143 views

Is my understanding correct in selecting ADC resolution? (Noise analysis)

I have posted a similar question before: ADC resolution, considering DSP. And finally I think I know the answer. Could you please have a check on it? Here is the set up: The input signal of the ...
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2answers
78 views

Determining Bandwidth of any circuit

I am getting familiar to SNR, noise calculations, thanks to this forum, however I often come across Bandwidth of the system to calculate resistor noise, to get rms noise from nV/rt-Hz, etc. I have a ...
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2answers
93 views

How to separate two DC voltages in s dual power supply?

I have a dual power supply (Lacie ACLG-51) that supplies both 12V DC and 5V DC with a common neutral (3 wires) I have used it to drive a little system composed of a Raspberry Pi (5V), USB HUB (5V), ...
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0answers
32 views

Sound Recording Noise and Base Station

I record sounds with the simple same equipment which consist of my laptop and a microphone, both in my home and my office. The sounds are very clear which I record in my office. But, in my home, there ...
3
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1answer
98 views

Understanding source and return current flow on PCBs

I'm looking for advice and tips related to PCB board layout and signal+ground trace/track routing. I'm designing a 2-layer analog-only PCB that has several I/O signals leading to and from other ...
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2answers
70 views

Noise cancellation for electromagnetic signals

I am working in the oil field with tools which I need to connect by cables (which "should be shielded") to computers. Most of the time when I communicate with my tools, I face grounding issues. I ...
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0answers
83 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
738 views

How to route with minimum noise

I'm facing a dilemma on how to route correctly in order to minimize noise on a data signal line. In the example bellow there is a 2-layer flexible PCB (which is very thin). The copper layer is 1OZ and ...
0
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1answer
107 views

Reduce power noise on AVR

I'm working on an AVR computer, everything works fine, except when I tap any ground point with my finger (there are a lot of them exposed), the MCU (an ATMEGA328) hangs for a brief second. I have a ...
2
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1answer
171 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: ...
2
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1answer
68 views

How can I find and remove servo/motor noise from this audio amplifier?

I am troubleshooting an audio noise problem in project which has several components wired together as follows: Overview: The overall project does some motion control with a servo and has an audio ...
4
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1answer
136 views

Get rid of the AC 50Hz noise from circuit

I made a bread board, this board is intended to measure AC 50Hz signal from sub uV to hunderds of mVs. The entire system is floating, powered from a voltage transformer. The front end is like this, P1 ...
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0answers
90 views

Why does a 12V DC applicance generate 50 Hz power line noise in nearby EEG recording

A layman's question: I am recording electroencephalographic signals (EEG) in a shielded cabin. In this cabin, I am also operating an additional electrical device powered by 12V DC (an eye tracker). ...
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1answer
64 views

Suppressing BLDC Motor noise? Is it radiated or a grounding issue? [closed]

I have a BLDC motor that rotates an imaging assembly(ultrasound) and alot of PWM noise can be seen in the resultant image produced. If I play around with the RX line that carries the imaging signal ...
29
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8answers
6k views

How can “purely” electrical circuits emit sound?

Moving membranes or piezoelectric materials obviously produce sound waves, but how can "purely" electrical circuits such as transformers or DCDC choppers (and others) often have an audible noise? Is ...
4
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3answers
129 views

How to isolate processor noise

I'm designing a board that consists of a dspic33F, responsible for running a noise reduction algorithm and compressing audio with a Speex library, and an audio codec connected to an electret ...
4
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2answers
133 views

Do vias introduce more noise to signal

If I have a small signal, does routing it through vias to different layer introduce any significant noise on the signal compared to routing it within same layer without any vias? Considering all other ...
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2answers
78 views

Ideas for troubleshooting a noise generator on a PCB

I am building an electronic "dice" that uses an ATTiny84 to sample avalanche noise from a 2N2222 in reverse-bias and generate random numbers, which are then displayed on 2 7-segment displays. When I ...
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5answers
159 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 ...
2
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2answers
111 views

Inconsistency of ADC output

I am having an issue with my ADC output. I am using: 12-bit ADC integrated in a MCU 3.3V voltage reference. Power supply of MCU, ADC and ADC voltage reference sharing the same voltage rail(3.3V) ...
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1answer
82 views

Homework: Noise in a circuit [closed]

I had this problem in a homework assignment: If the noise in a 5 V voltage line and ground for a five volt circuit is of the order of 10 mV, for a first order system, how many time constants will ...
2
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2answers
85 views

Shielding for Load cells

I am currently having a lot of trouble with noise being picked up by load cells. The strain gauges on the load cell are configured in a full-bridge pattern. In a noiseless environment (ie far away ...
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1answer
54 views

Statistical noise measurement

Is there an accepted measure of noise in a data set? I am taking a series of reading from an ADC, which follow a trend (they are not random data points). However, they generally lie above and below ...
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1answer
166 views

What are these pulses?

To continue of this question... I figured out the main problem and now I have an odd problem. at first, let me to put the codes. "Main.c": ...
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0answers
117 views

Can this op amp circuit easily be modified to provide differential input?

I have a "noisy ground" problem which seems to be essentially the same as the one described in this old post: Ground loop? Switch mode power supply noise The solution (as provided in the answers to ...
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2answers
138 views

Are all USB “audio adapters” DAC's? Can USB ports be used for analog output?

Kind of a weird question.. Background: My motherboard has started producing weird static(buzzing) noises on the audio output(3.5mm jack), it's not noticeable when using headphones, but on speakers it ...
4
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2answers
338 views

Noise at 2^n transitions

I am sampling a video signal from a linear imager. I noticed when the illumination is just at the intensity when the ADC increases by another MSB bit at the output, the noise occurs. That is, when ADC ...
2
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2answers
325 views

I/O series resistor

I've read that digital I/O pins should have a resistor in series in order to limit noise. Should one also use such approach when interfacing with the I/O pins of an arduino, or is that already done on ...
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2answers
97 views

Switching regulator PCB layout

I'm putting together a buck regulator (first time around) based on the lm2374 chip. TI provides gerbers of a recommended layout for this chip family, but my configuration differs a bit. I've read up ...