Electrical Engineering Stack Exchange
Electrical Engineering Stack Exchange

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.

Noise is an unwanted disturbance in an electrical signal.

Occasionally we deliberately generate white noise or pink noise (such as in generators).

In all other circuits noise is a problem we try to minimize.

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Noise and what does V/√Hz actually mean?

Noise figures in (op-amp) datasheets are expressed in V/√Hz, but Where does this unit come from? Why the square root? How should I pronounce it? How should I interpret it? I know lower is better, but will a noise figure that doubles also double the…
jippie
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Loud pop noise while plugging to a headphones jack

I have a Panasonic RX-ES29 boombox with a type C plug (ungrounded). I sometimes hear a relatively loud snap/pop sound in the right speaker of my headphones while I completely plug them into the headphones jack of the boombox when it's on. There's a…
Sepp A
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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 the material microscopically expanding and…
Mister Mystère
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What is "common-mode" noise?

Can someone explain what "common-mode" noise is, and how it can be problematic? I understand "noise" on a signal in general. If I have a "noisy" +5V rail on a circuit board, I'm not going to be getting a constant value of +5, it will be bouncing…
Adam Head
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Identifying Source of Periodic Artifact at Op-Amp Output

My MAX44251 dual op-amp has a very small unwanted 131KHz periodic artifact at the output, seemingly regardless of how it's configured. My assumption was EMI, but I can't see this 131KHz signal on any other part of the circuit. I've also tested this…
Keegan Jay
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Why does GSM cause speakers to buzz?

Based on numerous internet resources, speaker wire acts like an antenna which picks up the transmitted signal of nearby cellphones and causes the speakers to buzz. But I'm not really buying that... A 3.5 mm speaker cable is designed to carry 1 V.…
JSideris
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Why do some EMI/RF shields have holes on the top and some don't?

I am not talking about cutouts for tall components. I don't think they are for ventilation as they are often covered with manufacturer labels.
Dojo
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Noise reduction strategies in electrophysiology

When recording electrical signals from cells (in a dish or inside a living human or animal body), one major problem is to increase the signal to noise ratio. These signals are usually in the 10uV to 100mV range and are generated by very low power…
Ali
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Why is it good to slow down digital lines with resistors?

I've heard that sometimes it is recommended to "slow down" a digital line by putting a resistor on it, let's say a 100 ohm resistor between the output of one chip and the input of another chip (assume standard CMOS logic; assume the signalling rate…
Alex I
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How to disable a single op-amp in dual packaging?

I am using a dual op-amp package in a circuit, however I only need to use one. Is there anyway to disable the other op-amp so it doesn't inject electrical noise in my circuitboard? I think grounding the positive input and setting the op-amp into…
user1207381
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Is it possible to receive information if the received power is below the noise floor?

This relates to my previous question, which I think I have asked in the wrong way: How to insert background EM noise into pathloss equation? I wasn't really interested in detectability of the signal, and I have phrased that question very…
David K.
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Why are high impedance circuits more sensitive to noise?

Why are high impedance circuits being more sensitive to the noise? They have less current flowing through them, but how is that related to noise, since external noise becomes voltage on the wires, and then current proportional to resistance?
1p2r3k4t
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Is twisting a single ended signal with its own GND really useful?

I know that the most robust way of transferring an analog signal over long distances is via differential pairs which are twisted together and then shielded (shield grounded at one end only). But sometimes, we have to make do with single ended…
user42875
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Via fences for noise reduction of a chip antenna?

I'm working on a 4-layer PCB that has a wifi module and a chip antenna, the antenna is placed at the corner of the PCB and the copper beneath it is removed, I see that via fences are used on the breakout board of the same module, but the reference…
mux
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How to clean up a noisy signal?

I'm controlling a 4-pin PWM PC fan from a PIC16F684 with the fan speed driven from an ADC reading of a proximity sensor. This all works ok. I wasn't originally planning to use the tachometer output from the fan, but as it's available I been…
Roger Rowland
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