Understanding Grounds in Schematic Diagrams

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Discussion Overview

The discussion revolves around the concept of "grounds" in schematic diagrams, focusing on their purpose and implications in circuit design. Participants explore the meaning of ground symbols, their practical applications, and the distinctions between different types of grounding in various contexts.

Discussion Character

  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • One participant expresses confusion about the role of ground symbols in schematic diagrams, particularly regarding their placement in circuits.
  • Another participant explains that ground typically signifies points that can be safely connected or touched without affecting circuit operation, except in specific cases like radio devices.
  • It is noted that ground may refer to a substantial area of metal used for bypassing, which can be a metal case or a section of a printed circuit board.
  • There is mention of the negligible resistance between different areas of ground, allowing them to be treated as the same point in most circuits, although high-frequency circuits may require consideration of inductance.
  • In portable battery-operated devices, the metal area does not need to be connected to actual ground, while mains-powered devices must adhere to wiring regulations for grounding.
  • One participant emphasizes that voltage is relative and that ground serves as a base reference point.

Areas of Agreement / Disagreement

Participants present various perspectives on the concept of ground, indicating that while some aspects are clarified, there remains a degree of confusion and differing interpretations regarding its application in different contexts.

Contextual Notes

The discussion does not resolve the complexities of grounding in high-frequency circuits or the specific regulations governing mains-powered devices, leaving these areas open for further exploration.

john ross
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Im very confused when I see schematic diagrams with ground symbols. In my understanding, those ground symbols are placed in the negative connection in the circuit . Can someone explain me what are "grounds" for?
 
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Unless it is a radio device where the real ground makes a difference, "ground" really just means that these points can be joined together or touched by humans without affecting the circuit operation (or the humans).

Normally, there will be a substantial area of metal which is used for bypassing purposes.
This may be an actual metal case or it may be a portion of a printed circuit board copper coating which has not been etched.
Incoming shielded cables would have their shield connected to this "ground" and pins of ICs etc that were marked as "ground" would be connected to this area as well.

Because the different areas of this ground have negligible resistance between them, they can be regarded as the same point for most circuits. For very high frequency circuits, the inductance beteen various points on the "ground plane" have to be allowed for in the circuit layout.

In portable applications such as battery operated equipment, this metal area does not have to be connected to the actual ground or even to a mains supply ground.

If the apparatus was mains powered, this metal case would have to be grounded in accordance with wiring regulations.
 
Just remember that voltage is relative and ground is used as a base reference so to say.
 
ok thanks for the brief explanation
 

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