How does noise impact the potential measured in a circuit?

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Discussion Overview

The discussion revolves around how noise impacts the potential measured across a point in a circuit, particularly in the context of alternating voltage sources and sensors. Participants explore different types of noise and their effects on voltage waveforms.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant seeks to understand how noise contributes to the potential at a specific point in a circuit, particularly when multiple voltage sources are involved.
  • Another participant notes that there are various types of noise, including thermal noise, external interference, and noise generated by circuits, prompting a request for clarification on which type is being referenced.
  • A participant expresses confusion about the origins of noise and its role in creating potential, indicating a need for further reading on the topic.
  • Specific noise sources are mentioned, such as Schottky noise from charge quantization in low currents and thermal fluctuations in resistors that generate noise voltage.
  • Interference from wireless transmitters and electrical equipment, as well as cosmic microwave background noise, are also identified as potential noise sources.
  • One participant links to external resources for further understanding of sensor noise.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and clarity regarding the concept of noise in circuits. There is no consensus on a specific type of noise or its implications, and the discussion remains unresolved with multiple viewpoints presented.

Contextual Notes

Participants have not settled on specific definitions or scenarios regarding noise, and there are indications of missing assumptions about the types of circuits and noise sources being discussed.

Sahara
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Hello,

I am trying to understand how noise affects the potential measured across a certain point of a circuit.
If we have two alternating voltage sources in a circuit, I understand that the "sum" of the potentials provided can affect the potential at the point of interest. However, I am having trouble understanding where this third form of potential comes from and how exactly it can change the resultant voltage waveform at the point of interest!

Let me know if this is unclear and thank you!
 
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There is a lot of different kinds of noises. There is thermal noise due to random fluctuation of electrons, noise from outside interference, or noise generated by different circuits.

Which noise are you referring to in particular, or is this just a general question?
 
This is just a general question. I'm starting to learn about sensors, but I don't understand the physics behind how potential can be created from noise.
Thank you for your time
 


Your question seems a little vague. This third component (noise) can have lots of sources. Can you give a specific scenario?
 


Well I just learned that noise has an effect on the received signal. I'm not sure what this outside noise component comes from, I actually didn't even know there different categories of sources :S, but my question comes from a demonstration where a signal that is sent from a sender to a receiver is affected by this factor that was called noise.
And I was wondering how this "noise" can create a potential..
Sorry if it's unclear! i think I will read a bit more about it first to see if I can clarify more
 
Sahara said:
Hello,

I am trying to understand how noise affects the potential measured across a certain point of a circuit.
If we have two alternating voltage sources in a circuit, I understand that the "sum" of the potentials provided can affect the potential at the point of interest. However, I am having trouble understanding where this third form of potential comes from and how exactly it can change the resultant voltage waveform at the point of interest!

Let me know if this is unclear and thank you!

welcome to the PF. I googled sensor noise tutorial, and got lots of good hits:

http://www.google.com/search?source...=1T4TSHB_enUS315US316&q=sensor+noise+tutorial

.
 


Two possible noise sources are:
1) The quantization of charge in low currents (1 nanoamp = 6.25 electrons per nanosecond) creates Schottky noise in small signals.

2) Thermal fluctuations in resistors create a noise voltage. See
http://www.sengpielaudio.com/calculator-noise.htm

Also there is the plain old interference from other wireless transmitters and electrical equipment, and the CMB (cosmic microwave background).

Bob S
 
Hello Sahara-
See my answer in your other identical thread
https://www.physicsforums.com/showthread.php?t=367692
Bob S
 
Two threads merged.
 
  • #10
Thank you Bob and others for the reply and links!
 

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