Dobar dan i vama!!!
I read a lot of stuff these days and i found that is ok to have two star grounds.Star of stars they call it.
But only one is Main audio ground and all other(star of stars)must be connected to MAG.
Here is example.
Some of the links in post #520 take some serious reading and thought. Here are some easier audio oriented papers.
*********************************
2012
"An Overview of Audio System Grounding and Interfacing"
by
Bill Whitlock, President
Jensen Transformers, Inc.
Life Fellow, Audio Engineering Society
Life Senior Member, Institute of Electrical & Electronic Engineers
http://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf
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Power and Grounding For Audio and Audio/Video Systems -- A White Paper for the Real World
http://www.audiosystemsgroup.com/SurgeXPowerGround.pdf
*********************************
Middle Atlantic's
"Integrating Electronic Equipment and Power into Rack Enclosures"
'Optimized Power Distribution and Grounding for Audio, Video and Electronic Systems'
White Papers
*********************************
2012
"An Overview of Audio System Grounding and Interfacing"
by
Bill Whitlock, President
Jensen Transformers, Inc.
Life Fellow, Audio Engineering Society
Life Senior Member, Institute of Electrical & Electronic Engineers
http://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf
********************************
Power and Grounding For Audio and Audio/Video Systems -- A White Paper for the Real World
http://www.audiosystemsgroup.com/SurgeXPowerGround.pdf
*********************************
Middle Atlantic's
"Integrating Electronic Equipment and Power into Rack Enclosures"
'Optimized Power Distribution and Grounding for Audio, Video and Electronic Systems'
White Papers
I do think that the issue of grounding and signal return is the most important part of an electronic/electrical design and requires serious study, and especially Henry Ott. There is no easy route to understanding for this, neither is there one magical cure. The links were also all audio based.
Star grounding referred originally to star points where different grounds were connected, these spiders legs grounds that have developed have no advantage on a PCB over correctly implemented ground planes, and in todays RF rich world can be detrimental to preventing and removing high frequency noise. There are many papers and designs regarding high definition analogue designs, but we will save them till the basics have been discussed.
This is another (simple) document that is very relevant today:
http://www.x2y.com/filters/TechDay0...log_Designs_Demand_GoodPCBLayouts _JohnWu.pdf
Star grounding referred originally to star points where different grounds were connected, these spiders legs grounds that have developed have no advantage on a PCB over correctly implemented ground planes, and in todays RF rich world can be detrimental to preventing and removing high frequency noise. There are many papers and designs regarding high definition analogue designs, but we will save them till the basics have been discussed.
This is another (simple) document that is very relevant today:
http://www.x2y.com/filters/TechDay0...log_Designs_Demand_GoodPCBLayouts _JohnWu.pdf
This is one of the most important messages that seems to go straight over the heads of nearly all our Members.
SIGNAL RETURN !!!!!!!!
Understand that all circuits have a Flow route and a RETURN route and you are half way there already.
I my opinion using the term "GROUND" is the most confusing word in electronics.
There are two things to grasp:
- flow and return, as you say - this is about currents which always need a loop
- voltage reference, as there is no such thing as "a voltage" - voltages always need a reference
Get these two clear in your mind and much of the problem disappears. Thoughts of 'ground' as some bottomless sink of current and equipotential surface then fade away, as they should.
- flow and return, as you say - this is about currents which always need a loop
- voltage reference, as there is no such thing as "a voltage" - voltages always need a reference
Get these two clear in your mind and much of the problem disappears. Thoughts of 'ground' as some bottomless sink of current and equipotential surface then fade away, as they should.
i don't understand electronics one bit but, i always think of Earth as something that goes to 'Mother Earth' and is always for safety (run to mummy coz i hurt myself), Ground i think of as a 'shield' to protect from unwanted signal, Positive i think of as 'power in' and Negative i think of as 'power out'.
where i get confused is COM. is it a ground or is it a negitive. i do know it's 0v but where does it go.
where i get confused is COM. is it a ground or is it a negitive. i do know it's 0v but where does it go.
Safety ground does not have to go to 'Earth' but merely establish a roughly equipotential environment. This is how PME works (I believe). If all exposed metalwork in your house is correctly bonded together then you can't get an electric shock.
A shield (or screen in British English) may be connected to ground or some other point used as the voltage reference.
Power flows from a power supply into a circuit through both cables, positive and negative.
COM may mean Common, which may be a voltage reference or a current return path or both.
There is plenty on the web about grounding, and other basic electronics. Some of it is correct and helpful.
A shield (or screen in British English) may be connected to ground or some other point used as the voltage reference.
Power flows from a power supply into a circuit through both cables, positive and negative.
COM may mean Common, which may be a voltage reference or a current return path or both.
There is plenty on the web about grounding, and other basic electronics. Some of it is correct and helpful.
The 1983 Henry W. Ott magazine article:
"Ground - A Path For Current Flow"
http://www.hottconsultants.com/pdf_files/ground.pdf
"Ground - A Path For Current Flow"
http://www.hottconsultants.com/pdf_files/ground.pdf
Dear Kevin I just downloaded all the information that you kindly linked anyway like the previous by marce and many more that I have in my files, today was a hard day, I like to understand this infused and tedious phenomena related to Ground-Shield-earth-Com and galvanic currents.
I must study a little more. But I need time to cover the abstraction that mean this part that is "ennuyeux" or in better English "boring" theme.
I must study a little more. But I need time to cover the abstraction that mean this part that is "ennuyeux" or in better English "boring" theme.
The term ground and earth are interchangeable in electronics, (in Australia anyway). Com is Common and by definition is referring to the reference point for the measurement.
Shield - this depends on whether the circuit is balanced or unbalanced. Unbalanced (RCA leads) the shield forms part of the signal return. I'll use the term shield to refer to the signal return and ground to refer to power ground/earth.
The shield can be connected to ground, which is quite common in a lot of audio design, or it can be isolated (guarded) from ground, this is where the shield and ground are separate. in otherwords the signal and power return paths are kept separate.
I work in the repair section of a Standards Calibration Laboratory we repair and calibrate a lot of highend Fluke and Agilent test equipment. Grounding and guarding is a very complex issue and one which we often struggle with in the Lab. When you are measuring microamps with ± a couple of nanoamps tolerance proper grounding is essential. If you do not the guarding and grounding correct you end up with stray current that can be high enough to effect the measurement.
I will say it is impossible to totally eliminate these stray currents all that can be done is to minimise them. A good way to do this is to use a single power source for ALL audio gear (a single power board) we have one that has been modified with very large copper braid connecting all of the earths in the board this braid is then used as a STAR ground for all of the guards/shields connecting the different equipment.
In Australia Safety ground must go to earth, every house has an earth stake. If it does not then there is nothing stopping the house ground from floating at Mains.
In the old days electricians often used the steel water pipe to connect the house ground, if the earth stake or some other connection ended up bad then the taps in the house became LIVE, a few people were electrocuted this way.
dear dady, sarcasm is the lowest form of wit my friend and i find it strange that a Spaniard could be capable of it, but i like your style of trying. amateurs like myself struggle to understand because of people like yourself, just remember that everyone is good at something and we all need others to help.
thanks everyone. i knew i was wrong so i'll do as suggested and go looking on the net to TRY and understand a bit more.
thanks everyone. i knew i was wrong so i'll do as suggested and go looking on the net to TRY and understand a bit more.
In the UK there are two systems widely used. The older system uses earth (usually from the conductive outer of the incoming cable) as the reference. The newer(?) system uses neutral as the reference, but this will be grounded at the substation so it will usually not be too different from local earth. In either case it is rare for a house to have its own earth stake. Either system is fine for audio. The latter raises problems for radio enthusiasts.warrjon said: