electronics question

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antispatula

antispatula

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can someone please explain to me what ground is and why it's used and how it hooks up to a circuit and how it effects the flow and path of electron flow. I'm having a hard time getting this. Thanks!
 
Well I'm certainly no expert, and I don't understand everything about it, but ground is basically an electrical reference (to '0' per se). What ground actually is is, well, a path to earth, or the ground. Electricity always follows the path of least resistance, so in the case of an excess of electricity, such as a surge, or just overloaded circuits, the electricity will drain by following the ground to .. the ground. You can get some nasty shocks by touching an ungrounded piece of equipment and a grounded piece at the same time o_0.

Occasionally, grounds can cause problem when not observed. The path from equipment to earth generaly goes through the ground wiring in the equipment or instrument, to the ground in the cable, to the mixer or whatever the cable is plugged into, then down the power cord into the wall using the third ground prong. And from there it goes through the building's internal electricity until it reaches the stake and disperses into the ground. The problem lies when there are multiple grounds present - in other words you have lots of gear with plenty of interconnecting wires, and more than one thing is plugged into the wall and grounded. This means electricity doesn't "know" where to go in excess, and it can cause hum, whether it be subtle, almost inaudible, or quite obnoxious and very obvious.

Those kinds of incidents are called ground loops. This is why most DI's have a ground lift switch, which basically just disconnections the ground when passing through to prevent ground loops (if, say, you had a guitar running through powered effects modules, then through a DI and over to the soundboard. Or if you had a grounded keyboard in the same situation)

Hope this helps some. Like I said I'm no electrician, but that's what I do know about the subject.
 
antispatula said:
can someone please explain to me what ground is and why it's used and how it hooks up to a circuit and how it effects the flow and path of electron flow. I'm having a hard time getting this. Thanks!

Hey neighbor - That's a bit of a question! Hmmm, how to approach this without delving into the physics?
Ground gets it's name, literally from the ground, and the third pin on a grounded plug, the ground pin, actually connects to an earth ground. Think of ground as having zero potential, a sort of reference point for all positive and negative voltages. Current will want to flow between these potentials and ground, and if we provide a conductive path for them to do so, we can make the resulting electron flow do work for us.
In an electronic circuit, ground may or may not actually be tied to earth ground, but it becomes the common reference point of the circuit, and is therefore sometimes referred to as common, or common ground. It's common because all branches of the circuit share this common return path. Problems can develop in a circuit when this common ground isn't really common. Even a wire has some resistance, and hooking up a daisy chain of ground wires can result in varying points in the circuit having slightly different ground potentials....that's bad. A good quality PCB has a ground plane, a sheet of copper, either inside the laminate (internal ground plane), or on the bottom of a 2 layer board. This keeps the entire circuit ground at the same potential. In a hand wired circuit, instead of a daisy chain ground, you should use a star ground, where all the branches of the ground are conected to one point. This gets closer to a proper ground plane and reduces ground currents that can cause noise and instability in a circuit.
Ground is a quiet place, a place where matter is all at the same potential, and at rest. This quiet can be extended as a shield against intrusion of stray EMFs into our circuits by encasing our circuits in a grounded chassis, and by encasing our cables with grounded foil or braided wire.
I'm out of time now, and probably not doing a great job of this, but it really is a deep subject, so I've tried to generalize to the practical. Maybe someone else can contribute? Are you studying electronics, or is this to better understand your gear and wiring?
Peace, gotta eat.
 
here it is in a nutshell

electrons flow between voltage and ground

through stuff

and between stuff



think of ground as a big reservoir of electrons

they flow into it from a negative voltage

and out of it to a positive voltage

(current is electron flow, but by convention is opposite in direction)



voltage (potential difference)

it the "pressure" that

drives the electrons in one direction

or another
 
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here's a diagram
 

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give it some familiar names
 

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ground can be an actual copper pipe

driven into the ground

(or attached to your house's water pipes)

or just a common connection between several circuits

for instance, if they're all battery powered

and never "plug in" to the mains
 
antispatula, that's a good question. i've been trying to learn more about electronics for a while now and that very question still lurks in the back of my mind. i've read many explanations of what ground is and it can be a confusing concept. it's the concpet of zero, negative, and positive voltage that confuses me. i just try to look at it as a zero voltage reference so that i can get on with other things. good luck with making heads or tails out of it.
 
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