ruffrecords said:
[whinge]
I get confused when different people refer to different things as grounds. Can we agree some common unambiguous terminology?
Mature technology and at least some terminology is defined.
"Ground" is overused and often misapplied. Ground is not a voltage, it is typically a circuit node or path connection.
Safety earth is to stop you electrocuting yourself under fault conditions. I suggest we call this "Earth"
It is already called EGC (Equipment Ground Conductor), at least in the US, by UL and others.
The chassis and some cable screens act as equipotentials and help prevent electrostatic interference reaching signal wires. I suggest we call these "Chassis"
"Chassis ground" is widely used (and typically bonded to EGC so internal fault can trip fuses or breakers or GFCI/RCD ).
The internal zero volts reference for the active electronics is connected to the audio power supply 0V. I suggest we call this "Analog 0V"
I think I call that "Audio 0V", or "audio low", or "local audio ground" depending on the context of how used (breaking my own rule about not calling anything ground, but "local ground nodes" make sense in the context of explaining use of differential circuits to forward and back reference clean audio signals between different "local ground nodes". They can all be connected together but still exhibit different voltage potentials at different locations.
The zero volts reference for the phantom power supply (which may or may not be internally connected to Analog 0V inside the power supply) provides the return path for the 48V phantome supply to external microphones. I suggest we call this "Phantom 0V"
[/whinge]
Cheers
Ian
How about pin 1? .
==
An old analogy I like is plumbing... we have clean and dirty water flows inside our plumbing and we don't want the sewage to corrupt our clean water...
This requires a bit of a mental stretch but try to visualize the currents flowing in conductors (or PCB traces), then think of conductors or traces as resistors with voltage drops (in some cases like high frequency, as inductors).
moamps said:
What about clean and dirt grounds :
?
Back in the early 80s I got in trouble trying to use a parallel redundant "clean" and "dirty" ground system inside a large console. When installed in the main beam of an AM radio transmission tower those two ground networks looked like antennas.
I even recall the frequency of that f'n AM station as my two grounds had a couple volts of 960kHz swinging between them. Of course they were connected together at one common PS ground node, but that was not enough to bond them together at 960kHz several feet away.
I don't share this to scare anybody but to advise caution about over reliance on simple plans.
JR