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Old 2nd April 2006, 08:13 PM   #1
Khron is offline Khron  Romania
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Default 1R resistor

I'm just curious... What exactly is the purpose of a 1 ohm resistor between the input ground and the "ground star" (as seen, for example, in the MyRef gainclones) ???
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Old 2nd April 2006, 08:26 PM   #2
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Supression of ground loops....
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Old 2nd April 2006, 08:29 PM   #3
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!). Would act as a protection fuse to save the PC board from massive destruction in the case of the ground of the attached component becoming hot to the mains.

2). Would help reduce magnetically induced hum in the unbalanced signal conductor along the length of the shield in the interconnecting coaxial cable resulting from any AC mains current flowing as a result of voltage differential in the earth of the chassis of various system components.

3). In extreme cases will inspire a user who is not as brain dead as most, to think about it's purpose and perhaps even ask others "Why?"
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Old 3rd April 2006, 12:17 AM   #4
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Quote:
Originally posted by rcavictim
!). Would act as a protection fuse to save the PC board from massive destruction in the case of the ground of the attached component becoming hot to the mains.

2). Would help reduce magnetically induced hum in the unbalanced signal conductor along the length of the shield in the interconnecting coaxial cable resulting from any AC mains current flowing as a result of voltage differential in the earth of the chassis of various system components.

3). In extreme cases will inspire a user who is not as brain dead as most, to think about it's purpose and perhaps even ask others "Why?"

I feel rather stupid asking this, but what exactly is a star ground? I'm familiar with the signal ground and power ground, but not the star ground.

Also, if I'm not mistaken, the speaker ground is connected to power ground, yes?
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Old 3rd April 2006, 02:04 AM   #5
poobah is offline poobah  United States
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It might make more sense the call it asterisk ground rather than star ground. It is the practice of bringing ALL ground connections to a single physical point.like a lug or a terminal. All ground connections "lead out" in a star configuration to the individual circuits.

It is done to prevent the small resistances and inductances in the ground connections from cross coupling (talking to each other). To see the problem more clearly; take a schematic and replace every ground connection with a small resistor... see what a mess things became??

It's not so hard to do but often misunderstood... post a schematic and people can tell you how to do the "star"

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Old 4th April 2006, 09:40 PM   #6
CJ900RR is offline CJ900RR  Sweden
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You can clearly see the "star" at this picture of one of mine boards, http://www.leetmaa.se/diy/PICT0503.JPG
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Old 6th April 2006, 04:24 AM   #7
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Originally posted by poobah
It might make more sense the call it asterisk ground rather than star ground.

Hmmm... and what is the root of the word asterisk? Hint: it's also in astronomy and disaster.
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Old 6th April 2006, 05:08 AM   #8
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Quote:
Originally posted by Stephen Morgan



Hmmm... and what is the root of the word asterisk? Hint: it's also in astronomy and disaster.

Besides J.P. Morgan didn't Tesla get some funding from a dude named "aster" representing considerable "risk"? Spelling stretch notwithstanding to promote joke value.

The connection to a good ground was well appreciated by Tesla BTW.
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Old 6th April 2006, 06:04 AM   #9
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Another example of star grounding....
Attached Files
File Type: pdf sr-buf634_dps#1.pdf (57.2 KB, 133 views)
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Old 6th April 2006, 06:05 AM   #10
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And detail...
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File Type: pdf sr-buf634_dps#2.pdf (40.6 KB, 103 views)
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