Nicholas23
New Member
Hi everybody.I am new to electronics, and am wondering what the
differance is between GND,0v, and -volts? Any help is wanted.
differance is between GND,0v, and -volts? Any help is wanted.
GRD,0v,-volts
- Thread starter Nicholas23
- Start date
westaust55
Moderator
Voltage Terminology
Hi Nicholas,
Voltage terminology can be a little confusing. Possibly a little more than you asked for but here is my concept:
+V, + or +ve is a positive voltage meaning a voltge above the 0V reference.
VCC = (Common Collector Voltage) is the positive supply voltage as used previously with BJT transistors (comes from NPN transistors) and TTL type integrated circuits such as the 74xx(x) series logic IC’s.
VDD = (Drain Voltage) The positive supply voltage as used typically with FET transistors (which have drain and source connections) and MOS type circuits such as most microprocessors and CMOS IC’s including the 4000 series (CMOS is based on FET technology).
0V is the nominal reference voltage against which other voltages are normally measured.
VSS = (Source Voltage) The “negative” voltage associated with FET transistors and CMOS/MOS type IC’s.. This is normally also at 0 Volts.
VEE = (Emitter Voltage) which is the negative side of BJT (again stems from NPN transistors) and TTL IC circuits. This is normally also at 0 Volts.
Gnd = ground or earth as a reference and often involves a connection to the metal frame/case of equipment. Considered to be a connection to the general mass of earth and an arbitrary zero of potential. This is typically connected to 0V.
-V, - or –Ve is a negative voltage meaning a voltage lower than the 0V reference.
Hi Nicholas,
Voltage terminology can be a little confusing. Possibly a little more than you asked for but here is my concept:
+V, + or +ve is a positive voltage meaning a voltge above the 0V reference.
VCC = (Common Collector Voltage) is the positive supply voltage as used previously with BJT transistors (comes from NPN transistors) and TTL type integrated circuits such as the 74xx(x) series logic IC’s.
VDD = (Drain Voltage) The positive supply voltage as used typically with FET transistors (which have drain and source connections) and MOS type circuits such as most microprocessors and CMOS IC’s including the 4000 series (CMOS is based on FET technology).
0V is the nominal reference voltage against which other voltages are normally measured.
VSS = (Source Voltage) The “negative” voltage associated with FET transistors and CMOS/MOS type IC’s.. This is normally also at 0 Volts.
VEE = (Emitter Voltage) which is the negative side of BJT (again stems from NPN transistors) and TTL IC circuits. This is normally also at 0 Volts.
Gnd = ground or earth as a reference and often involves a connection to the metal frame/case of equipment. Considered to be a connection to the general mass of earth and an arbitrary zero of potential. This is typically connected to 0V.
-V, - or –Ve is a negative voltage meaning a voltage lower than the 0V reference.
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inglewoodpete
Senior Member
When dealing with relatively simple digital circuits, the 3 terms usually mean the same thing. A couple of additional names for the same thing are 'Com' (Common) and 'earth'.
In low voltage digital circuits, the convention is to have the -ve side of the power supply/battery connected to the common rail. Since all other voltages around the circuit can then be compared to the voltage on the 'common' rail, the 'common' is called the 0v rail.
In power (mains) circuits, the reference or common rail is usually connected to the earth via metal plumbing or a metal earth stake. So the terms 'earth' or 'ground' are sometimes used to describe the common rail.
Hmm. Replys from 2 people from Perth at once. Must be lunchtime and too wet and windy to go outside
In low voltage digital circuits, the convention is to have the -ve side of the power supply/battery connected to the common rail. Since all other voltages around the circuit can then be compared to the voltage on the 'common' rail, the 'common' is called the 0v rail.
In power (mains) circuits, the reference or common rail is usually connected to the earth via metal plumbing or a metal earth stake. So the terms 'earth' or 'ground' are sometimes used to describe the common rail.
Hmm. Replys from 2 people from Perth at once. Must be lunchtime and too wet and windy to go outside
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westaust55
Moderator
Symbols and abbreviations
As a adjunct, when using abbreviations for units, under international standards (and I am sometimes guilty of failing myself)
The units have a capital when named after a person otherwise lower case
there is a space between the numeric part of the valve and the units whether as a abbreviation or in full.
Thus as a partial list V, A, Hz, T, W, N, are all capitals as they are named respectively after messers Volta, Ampere, Hertz, Tesla, Watt and Newton. Resistance is named after Mr Ohm though we typically use the Omega symbol (Ω.
But m (metres), g (grammes) , s (seconds), etc, are not named after people
And Yes IWP, it has been pelting down this rain and blowing a gale so indoors over lunchtime or should that be
As a adjunct, when using abbreviations for units, under international standards (and I am sometimes guilty of failing myself)
The units have a capital when named after a person otherwise lower case
there is a space between the numeric part of the valve and the units whether as a abbreviation or in full.
Thus as a partial list V, A, Hz, T, W, N, are all capitals as they are named respectively after messers Volta, Ampere, Hertz, Tesla, Watt and Newton. Resistance is named after Mr Ohm though we typically use the Omega symbol (Ω
.But m (metres), g (grammes) , s (seconds), etc, are not named after people
And Yes IWP, it has been pelting down this rain and blowing a gale so indoors over lunchtime
or should that be 
Peter M
Senior Member
Just to add a little confusion, some systems, such as telecommunications equipment (and some older British cars) use a negative power system, or probably more commonly known as positive earth.
In this system the positive voltage is refered to as earth (and all metal work, coaxial screens etc. are at this potential) and the negative rail is just referred to as the voltage of the system i.e. in telecommunications 50 V.
Just be aware of this... the terminology is not truly correct, but if your talking to someone from the telecommunications industry, when they talk about 50 Volts they are probably talking about negative 50 Volts.
So they use Red as earth and Blue as 50 Volts (actually -50 Volts).
Red and blue being the international standard for +ve and -ve low voltage D.C.
In this system the positive voltage is refered to as earth (and all metal work, coaxial screens etc. are at this potential) and the negative rail is just referred to as the voltage of the system i.e. in telecommunications 50 V.
Just be aware of this... the terminology is not truly correct, but if your talking to someone from the telecommunications industry, when they talk about 50 Volts they are probably talking about negative 50 Volts.
So they use Red as earth and Blue as 50 Volts (actually -50 Volts).
Red and blue being the international standard for +ve and -ve low voltage D.C.
The Kraken Awakes....
I've got nothing to add to WA's description, though I hope all the other Vxx bits, perfectly valid, haven't confused Nicholas. (PS. Nicholas, write them down in your grimoire as you may need this info one day). It can all be very confusing.. especially if it's early in the morning.
Peter: "some older British cars" - older?!? You mean pre 70s if not older? Thats blooming ancient! The last one I remember was my Grandad's Ford Prefect and that was 50s I think.
Grounds,earths - as said is a reference. So regardless of whether it's a negative ground (the usual convention with simple, single rail battery equipment etc.) or positive rail it is still your reference.
So, to cut a long story short:-
"Hi everybody.I am new to electronics, and am wondering what the
differance is between GND,0v, and -volts? Any help is wanted. "
- for a *simple, average, single rail, battery powered or simple psu powered circuit they are the same thing (assuming your "-volts" is referring to the -ve of a standard battery, of course?).
Such that, under normal circumstances, everything else measures positive wrt Gnd/0V/-ve.
To anyone who wants to complicate things with multi-rail, reactive, switched-mode , virtual grounds etc. (yawn): please wait til Nicholas is happy with this bit first - and then you can impress him
* Nicholas. When answering one has to put in all these conditions. If you forget one slightest thing then someone will come flying in to 'demonstrate accuracy'. I've probabaly forgot some little exception now but IDGAD.
I've got nothing to add to WA's description, though I hope all the other Vxx bits, perfectly valid, haven't confused Nicholas. (PS. Nicholas, write them down in your grimoire as you may need this info one day). It can all be very confusing.. especially if it's early in the morning.
Peter: "some older British cars" - older?!? You mean pre 70s if not older? Thats blooming ancient! The last one I remember was my Grandad's Ford Prefect and that was 50s I think.
Grounds,earths - as said is a reference. So regardless of whether it's a negative ground (the usual convention with simple, single rail battery equipment etc.) or positive rail it is still your reference.
So, to cut a long story short:-
"Hi everybody.I am new to electronics, and am wondering what the
differance is between GND,0v, and -volts? Any help is wanted. "
- for a *simple, average, single rail, battery powered or simple psu powered circuit they are the same thing (assuming your "-volts" is referring to the -ve of a standard battery, of course?).
Such that, under normal circumstances, everything else measures positive wrt Gnd/0V/-ve.
To anyone who wants to complicate things with multi-rail, reactive, switched-mode , virtual grounds etc. (yawn): please wait til Nicholas is happy with this bit first - and then you can impress him
* Nicholas. When answering one has to put in all these conditions. If you forget one slightest thing then someone will come flying in to 'demonstrate accuracy'. I've probabaly forgot some little exception now but IDGAD.
Michael 2727
Senior Member
Here's an old version, bit moth eaten and dusty -
http://www.picaxeforum.co.uk/showthread.php?t=4734
http://www.picaxeforum.co.uk/showthread.php?t=4734
Here was where we reproduce Michael's guide.... http://www.minisumo.org.uk/datasheets.phpHere's an old version, bit moth eaten and dusty -
http://www.picaxeforum.co.uk/showthread.php?t=4734
I'm happy to re-edit it... or dare I suggest push it into our wiki!
regards,
Colin
Nicholas23
New Member
Half-way
Thanks everybody. I think I half-way get it. So 0v & GRD are not electrically
charged at all, where as -volts has a negative charge. But that brings up
another question. How come on the picaxe system, where it says 0v, as in
the pinout diagram, when connected to -volts as in a battery it works fine?
This is confussing.
Thanks everybody. I think I half-way get it. So 0v & GRD are not electrically
charged at all, where as -volts has a negative charge. But that brings up
another question. How come on the picaxe system, where it says 0v, as in
the pinout diagram, when connected to -volts as in a battery it works fine?
This is confussing.
Hey, I still have one of those positive common cars from the fifties (1959 to be exact) laying around here somewhere. Came across that issue trying to install an 8-track. Dead serious. Got it to work, too. While there were 8 track tapes...... I don't know about my brother's old British cab, never asked.
Old joke from that era around here (from a friend with an MG TD) - "Know why the Brits drink their beer warm? - they have Lucas refrigerators."
My car was, indeed all Lucas, but, actually, the electricals were pretty reliable until a "specialist mechanic" from the dealer fiddled with them. Never been the same since.Cheers,
Wreno
In this case GND and -Vbat are wired to be the same. It's just a case of what one wants to do with the parts. You could connect +Vbat to GND instead, or have a second battery and connect GND to the middle join between them (Not recommended).
Evan
westaust55
Moderator
Evan,
earth and ground in an electrical power sense at least are one and the same.
Trying to be relatively simple in the following description on how it all works but sure someone will find a flaw:
Here in Australia we have the term earthing, we have an earth grid and each home has an earth stake.
In the U.S. they use the term grounding and it is all for exactly the same thing - a connection to earth (that planet upon which we all live).
The earth/ground stake is driven into the ground for the purpose of achieving a good electrical conenction to the general mass of earth. Any electrical item with a metal housing shall by law (in Australia at least) have that metal housing connected to the earth conductor.
I do know that in New Zealand it is (or at least was) permissible to connect the earth wiring of a house to the reinforcing in the concrete floor slab and no electrical stake was required into the ground.
For single phase power as supplied to most houses (okay some also have 3 phase) there is an active/phase and a neutral conductor.
The neutral is connected to earth (may be at the house and/or down the road at the substation) often solidly but in some installation this may be through an impedance. As such, the earth acts as a reference for the neutral conductor.
When impedance is installed between the earth and neutral, then when an electrical earth fault occurs the neutral will have a voltage relative to earth/ground. The impedance is used to limit the current under earth fault conditions.
For human protection we use residual current devices (RCD's) to detect an imbalance between the active/phase current and the neural current. When an imbalance is detected, there must be current flowing through a fault to earth and this is when the RCD type circuit breaker operates.
At the end of the day, earth and ground are in electrical power terms, one and the same.
earth and ground in an electrical power sense at least are one and the same.
Trying to be relatively simple in the following description on how it all works but sure someone will find a flaw:
Here in Australia we have the term earthing, we have an earth grid and each home has an earth stake.
In the U.S. they use the term grounding and it is all for exactly the same thing - a connection to earth (that planet upon which we all live).
The earth/ground stake is driven into the ground for the purpose of achieving a good electrical conenction to the general mass of earth. Any electrical item with a metal housing shall by law (in Australia at least) have that metal housing connected to the earth conductor.
I do know that in New Zealand it is (or at least was) permissible to connect the earth wiring of a house to the reinforcing in the concrete floor slab and no electrical stake was required into the ground.
For single phase power as supplied to most houses (okay some also have 3 phase) there is an active/phase and a neutral conductor.
The neutral is connected to earth (may be at the house and/or down the road at the substation) often solidly but in some installation this may be through an impedance. As such, the earth acts as a reference for the neutral conductor.
When impedance is installed between the earth and neutral, then when an electrical earth fault occurs the neutral will have a voltage relative to earth/ground. The impedance is used to limit the current under earth fault conditions.
For human protection we use residual current devices (RCD's) to detect an imbalance between the active/phase current and the neural current. When an imbalance is detected, there must be current flowing through a fault to earth and this is when the RCD type circuit breaker operates.
At the end of the day, earth and ground are in electrical power terms, one and the same.
"Thanks everybody. I think I half-way get it. So 0v & GRD are not electrically
charged at all, where as -volts has a negative charge. But that brings up
another question. How come on the picaxe system, where it says 0v, as in
the pinout diagram, when connected to -volts as in a battery it works fine?
This is confus(s)ing."
- Nicholas, read my post #8. Towards the end where I quote your original question. And sort of repeated/reiterated by evanh a few posts later.
charged at all, where as -volts has a negative charge. But that brings up
another question. How come on the picaxe system, where it says 0v, as in
the pinout diagram, when connected to -volts as in a battery it works fine?
This is confus(s)ing."
- Nicholas, read my post #8. Towards the end where I quote your original question. And sort of repeated/reiterated by evanh a few posts later.
??????????- in spite of damper soils here (& also being legally ALLOWED to do simple mains wiring!), NZ mains wiring practices follow Australian standards 100%,hence AS/NZS, & a dedicated electrical earthing stake (which must be accessible for inspection) has long been mandatory. Concrete dwelling floor slabs are usually thermally & moisture insulated by layers of plastic & polystyrene anyway.
The dwelling's galvanized water piping certainly ONCE (pre WW2 era ?) may have double dutied for earthing, & many a plumber can relate hair raising ( & tragic...) tales about this. These usually arise from a loose switchboard neutral then causing the earthing path,instead of the correct M.E.N. (Multiple Earth Neutral),to carry the return current. It's essential to use a clamped bypass bridging cable when cutting such pipes or replacing sections with non conductive plastics. Stan in EnZed
Michael 2727
Senior Member
Dippy, what polarity = wrt ?
westaust55
Moderator
The standard AS/NZS 3000 covers Australian and New Zealand wiring rules. There are some (not many) clauses that apply only to one of the two countries. These are identified by the markings A or NZ against the clauses.
What you say about using metallic water pipes was also true in Australia ONCE almost
beyond my time. As PVC piping came into use, the metallic portions of house plumbing became isolated from the rest of the water plumbing and totally inadequate as an earth.
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inglewoodpete
Senior Member
Some threads have a life of their own, don't they? Phew. Glad I got in early.
PS. The first car I drove was dad's aging Ford Prefect. Yes, yes, that was a long time ago too. Can't remember whether it a positive or negative earth ..er.. ground... I mean chassis. I remember it was only 6volts, so you only got 1 chance to wind it up. After that you had to use the crank handle.
PS. The first car I drove was dad's aging Ford Prefect. Yes, yes, that was a long time ago too. Can't remember whether it a positive or negative earth ..er.. ground... I mean chassis. I remember it was only 6volts, so you only got 1 chance to wind it up. After that you had to use the crank handle.
Michael 2727
Senior Member
Keyboard check Dippy, and "w" is working
hippy
Ex-Staff (retired)
How can ground,- etc. have a voltage less than zero?
For "Negative Earth" as in vehicles, I'd put that down to archaic language and electrician's terminology, short for "a common circuit path ( the chassis ) being connected to the negative side of the battery" which has stuck around.
For everything else you have to define where "zero volts" is, and it can be anywhere of your choice.
For "Negative Earth" as in vehicles, I'd put that down to archaic language and electrician's terminology, short for "a common circuit path ( the chassis ) being connected to the negative side of the battery" which has stuck around.
For everything else you have to define where "zero volts" is, and it can be anywhere of your choice.