Main Question or Discussion Point
I feel as if the difference between grounding in a circuit and grounding in mains power is not very clear. So my questions are, what does a ground do in circuits and is it necessary?
I think some data is omitted. It says it is a neutral reference point, but what does that mean? It also refers to signal grounding, which it explains in context of grounding in a circuit. Could you please explain this?
Ground is a reference - in some cases (AC Mains), ground is actually the GROUND. Neutral is often connected to ground outside your house to provide a consistent voltage reference.Voltage is a differential quantity. To measure the voltage of a single point, a reference point must be selected to measure against. This common reference point is called "ground" and considered to have zero voltage. This signal ground may not actually be connected to a power ground. A system where the system ground is not actually connected to another circuit or to earth (though there may still be AC coupling) is often referred to as a floating ground.
Why would you expect more than the momentary equalisation current you get whenever you touch two pieces of metal?if I were to hook up the positive terminal of a battery to a ground (such as one used in AC mains), would there be a current?
Suppose you have a microphone running off a 1.5 volt battery feeding a preamplifier, running off a 15 volt supply, driving a power amplifier running off a 60 volt supply.What purpose does a circuit common/0V reference provide?
Suppose you have a microphone running off a 1.5 volt battery feeding a preamplifier, running off a 15 volt supply, driving a power amplifier running off a 60 volt supply.
You would designate (in this case) the negative terminal of each supply as the 'common' and call the common value zero.
This way you could measure voltage from common to any point in any of the parts and get a consistent set of readings.
This is using the common as a reference.
Sometimes we designate the high side of the supply as reference.
I see....sorry, I was misreading your response. You were supplying an answer to the question about what the common is. It is the point where you can measure voltage relative to other components of the circuit.No I didn't mention ground and I said use the negative in this case.
go wellAn earth is a body whose potential does not alter, regardless of the current flows into or out of it, within the design limits of the system.
As far as I am aware the term earth is synonymous with ground - One is basically UK usage, the latter US.
Isn't the white neutral the power supply return?In house wiring that bare wire is regarded as "Circuit Common" because it is power supply return.
I think this has already been said, but I'll say it again another way...I feel as if the difference between grounding in a circuit and grounding in mains power is not very clear. So my questions are, what does a ground do in circuits and is it necessary?
Thanks EBThanks Jim. Nice write up... One question:
Isn't the white neutral the power supply return?
In this case the transformer is the power supply and everything (120V anyway) is "returning" on the center-tapped neutral, correct?
EDIT: I just realized you're talking about the large bare wire between transformer and service entrance. Not to be confused with the bare (sometimes green) wire in the branch circuits of your house. My apologies...
I was going to be a wise guy and ask if the L1 and L2 leads of the transformer were 180 degrees out of phase with each other, but I decided against it ;-)
Two solutions:well i just lost a half hour's typing due to that %#@^%&%(@U(*QRT!!!~~*** login gauntlet.
This is a good question.Potential with respect to what?