debating the labels used in positive ground boards ;)

[ulysses]

hey all,

i have seen a bunch of people label positive ground as (-9, ground) and others label them (+9 ground, 0V)

imo it is pretty stupid to use the labels (-9, ground) when calling a board "positive ground" as neither (-9, ground) are "positive".

anyone want to make a good argument for the labelling a positive ground board (-9, ground) in philosophy of language debate?

[alanp]

No argument from me. It's as daft as talking about the "positive leg" of a diode.

[antonis]

Why not establish something like "positiver ground" in stomboxology vocabulary..??

Or maybe a label depicting GND making some immodest gestures to 9V..??

[samhay]

It depends as all voltages, including ground, are relative.
In isolation, your preferred nomenclature makes some sense. However, I quite like to plug stuff into my stompboxes.
If you connect* you circuit to the outside world, then it makes sense (at least to me) for all points with the same name - e.g. 'ground' - to be at the same voltage.

Thus, I vote for ground and -9V.

* this assumes you have some DC connection somewhere. This is almost always the case with your 'ground', which is connected/shared via audio jack and/or daisy chained power supply.

[TejfolvonDanone]

Isn't it because "the positive terminal of the battery goes to ground" got shortened to "positive ground"?
Or at least that's how i think about this.

[anotherjim]

If supply positive is connected to 0v/ground/chassis then it really shouldn't be called anything but 0v or ground or chassis.
That leaves the negative supply to be called -9v or whatever.

I know what positive ground means, it's an ancient terminology with good historical reasons for its usage, but personally, I prefer to say "This uses a negative power supply".

[digi2t]

Why not establish something like "positiver ground" in stomboxology vocabulary..??

Or maybe a label depicting GND making some immodest gestures to 9V..??

How about 9V, +9V, and ++9V then?

[ulysses]

I know what positive ground means, it's an ancient terminology with good historical reasons for its usage, but personally, I prefer to say "This uses a negative power supply".

for me, the confusion comes in because people go to use a power supply a certain way. they know their wall wart has +9 and -. they expect to use the product this way. so if we say to the consumer "you need to use this product backwards" that breaks a fundamental design rule "don't break convention". "dont use a pull handle on a push door"

for me, even if a circuit is "positive ground", the labels for design should still be "+9 and 0V". if you want, "+9 ground and 0v"

peace

[karbomusic]

hmm... as someone who doesn't come from a formal electronics background, positive ground still made perfect sense to me since polarity is a binary choice.

[greaser_au]

From an engineering perspective, in this context "ground" refers to a circuit  "counterpoint" or a zero reference (a local zero volts point), that all measurements of other points in the circuit are referred to. The logical conclusion is that "-9V" and "ground" is correct terminology and very clear when referring to a "positive ground" circuit - which infers "power supply positive is connected to ground".

david

PS I had three positive ground cars, I switched them to negative ground at the first opportunity 

[antonis]

I had three positive ground cars, I switched them to negative ground at the first opportunity 

DON'T do it or you'll have major corrosion (rust) problem due to electrolysis oxidation.. 

[greaser_au]

I had three positive ground cars, I switched them to negative ground at the first opportunity 

DON'T do it or you'll have major corrosion (rust) problem due to electrolysis oxidation.. 

No worries there, Mate...  I had an Energy Polariser*....       

david

* (a box of snake oil promoted by a former #1 racing driver in Australia)

PS apologies to ulysses for hijacking the thread!

[Kipper4]

Let's not get all non binary.....

[antonis]

To stay on Father of Telemachus spirit..
(we don't want the son of greatest archer to get angry..)

Would anyone be satisfied with a label of two electrons (one big & one small) indicating the voltage difference..??


edit: Bad idea because there will be some confusion about conventional and actuall current flow..

[ulysses]

The logical conclusion is that "-9V" and "ground" is correct terminology and very clear when referring to a "positive ground" circuit - which infers "power supply positive is connected to ground".

and see this is the problem for philosophy of language for me "power supply positive is connected to ground" --> "this is a product where you have to have to put the battery in backwards". but this goes against all design rules -- (and when i say design, im talking industrial design ie, dieter rams, or https://www.amazon.com/Design-Everyday-Things-Revised-Expanded/dp/0465050654)

the customer should never know about connecting things back to front. the customer should be expected to act in the way he/she has always acted -- connecting + to + and - to -. therefor for the labels should be +9v and 0V. the labels should represent the connection on the source. the battery is labeled (+9v, -) the wallwart is labeled (+9v, -). the product should indicate +9v.

also, can i reiterate the other problem, you cant call something "positive" and then insist all voltages running through the circuit are "negative". thats just backwards.

i appreciate technically, it is -9v, but the colloquial terminology should not reflect his.

peace

[greaser_au]

and see this is the problem for philosophy of language for me "power supply positive is connected to ground" --> "this is a product where you have to have to put the battery in backwards". but this goes against all design rules -- (and when i say design, im talking industrial design ie, dieter rams, or https://www.amazon.com/Design-Everyday-Things-Revised-Expanded/dp/0465050654)

the customer should never know about connecting things back to front. the customer should be expected to act in the way he/she has always acted -- connecting + to + and - to -. therefor for the labels should be +9v and 0V. the labels should represent the connection on the source. the battery is labeled (+9v, -) the wallwart is labeled (+9v, -). the product should indicate +9v.

OK, I thought we were talking about labelling the board for offboard wiring.  Not something a non-technical customer should be needing to access.

If you are talking about an untrained non-technical person connecting some power source to a complete assembly, the argument for ANY use of a "0V"/"ground"  label anywhere is just too silly for words - any more "+/0" vs "-/0"  argument is absurd in this context (phone and UPS systems are not within context of this discussion).

For the untrained, external connections should be either obvious, or impossible to get wrong.  For example :
* The 2.1mm DC connector should be labeled in an obvious manner,  e.g. the  very standard "pin-in-circle" diagram with polarity shown as "+" and "-" (and the voltage/current).   
* It's not possible to connect a PP3 9V battery snap backwards (well it is, but then  maybe that  user had better take a good long hard look in the mirror!).
* If it's a native  'positive ground' effects pedal with no internal polarity inversion or inverting PSU, in addition it better say "battery/isolated supply only".
* Maybe: "No user serviceable parts inside...  Only use recommended power supply - warranty void otherwise..."

If the user CAN get it wrong, they will!   I'd offer I'm not alone when I say "I looked at the wallwart and the device markings  and still got it wrong". If you look back over my post history you'll see  I recommend the use of 16VAC1A transformer wallwarts as an easy way to use mains power supply - but I suggest use of a different plug...

However, if we ever get to the situation where the label has to say "put the battery in backwards"  the designer and/or builder had better take a good... long... hard... look in the mirror.

also, can i reiterate the other problem, you cant call something "positive" and then insist all voltages running through the circuit are "negative". thats just backwards.
i appreciate technically, it is -9v, but the colloquial terminology should not reflect his.

This is electrical/electronic engineering and the language *IS* different and often needs explanation (if think you dislike this language form, wait until you hit AC theory ).  Like many things in life there are a number of conventions that are assumed, and are needed so that we all get along, though some of them may, at first view, appear backwards until explained- just like the '+' next to the diode cathode. Pretty much all of physics understanding requires a reference frame.

* For the readings on a basic multimeter (set to volts)  to make sense, the black lead is the zero reference and for a positive reading, the red lead must be more positive than the black- this is by convention.
* While unconnected, the terminals of (say) a PP3 battery are positive and negative _relative to one another only_  and have no real reference to anything else.
* Once you connect the battery to the multimeter, you have to choose which terminal you are making the "zero reference" and  connect the black lead to that. 
* If you choose the "+" terminal, you have made the "+" terminal the "zero reference" (by convention "positive ground").
* if you connect the red lead there also, the meter reads 0V.
* You now connect the red lead to battery "-"  and your meter will read close to "-9V". 
* If instead you choose battery "-" as the zero reference you are by convention "negative ground" and the + terminal will read +9V.

There's no escaping that conventional usage.  If you try to label it some other way, you are implying a different frame of  reference, and it's going to confuse everybody.

It's a very simple example, but the point is that the circuit has a zero reference, and that is best chosen at the beginning of the design. With very few exceptions, a circuit designer using mainly NPN/N-channel devices or valves(tubes)  will generally  use negative ground and mainly PNP/P-channel designs will use positive ground. One has to have some agility in their thinking, and be able to look from both directions.  Have a look at the MN3002 datasheet. note the voltage specifications, the pin names, and the fact  that is a P-channel process chip, yet you'll usually find it in negative-ground circuits (even in the datasheet reference circuit).  The chip has a *very local* positive ground!

The 'colloquial' language user should never have to deal with this, but still,  people with almost no electrical knowledge deal quite happily with the concept of positive earth vehicles.

I think it's a bizarre convention that people would drive on the right side of the road or flick a switch UP for on. However, if I ever visit the US, I'm going to adapt, mainly for my own safety...
However, I reckon I'm going to stub my toe in the dark for  the first  few of those 3am comfort stops,  though  (and do it again when I get home!).  I'd also  bet the same applies in reverse for our friends in the US    
Hey - we've recently made the 'Pittsburgh left' rule legal at some intersections over here!!!!!

david 

edit: expanded on mn3002