Reducing 30amps to 1amp - Page 2

GooSE · 8th October 2007, 10:35 AM

What the shit is with anyone calling current amperage? I'm not having a go at the OP as he probably doesn't know any better, but fuck it pisses me off.

Whoever coined the term should be shot.

Spoiler below, highlight to read:
That's my daily rant over

Odje · 8th October 2007, 12:06 PM

Quote:

Originally Posted by GooSE

What the shit is with anyone calling current amperage? I'm not having a go at the OP as he probably doesn't know any better, but fuck it pisses me off.

Whoever coined the term should be shot.

Spoiler below, highlight to read:
That's my daily rant over

Just to piss you off, Incorrect terminology is appearing on products now. If you have one of the GPO power meters from Jaycar that everyone has bought, have a look at the compliance label. Notice the word "wattage" on it.

LethalCorpse · 8th October 2007, 4:34 PM

Quote:

Originally Posted by Odje

Just to piss you off, Incorrect terminology is appearing on products now. If you have one of the GPO power meters from Jaycar that everyone has bought, have a look at the compliance label. Notice the word "wattage" on it.

That really just gives me angerage.

Symon · 8th October 2007, 7:10 PM

Quote:

Originally Posted by 2xCPU

That's not very meaningful.
You can have a very high voltage with little or no current ('flow').
You can also have a low voltage and very high current.

If you want an analogy to 'flow', it would be power.

You have NFI do you?

Gives me the shitsage.

The water analogy is fine, there is a reason why it's still being used in teaching classes.

There are limits to the analogy, but none of them justify it being called 'bad'.

You can have a very large pump, but very low water flow, just as well as you can have a small pump and a large flow. Your example above doesn't justify it as a 'bad' analogy. And the 'flow' is the flow of electrons, not power, so it ties nicely with water flow.

Anyways, read up on it http://en.wikipedia.org/wiki/Hydraulic_analogy and http://hyperphysics.phy-astr.gsu.edu...c/watcir2.html before your next dribble.

underskore · 8th October 2007, 7:19 PM

i love the hydraulic analogy, specially how it relates to inductors, capacitors and diodes.

(anyone know why Heaviside didnt like it?)

LethalCorpse · 8th October 2007, 9:00 PM

I've never much liked the fluid flow analogy, as I find it gets in the way of understanding what's really going on. Sure, helps to explain it conceptually to people who don't actually have to use it, but if you really need to understand it I think it's best to approach it from physics and chemistry. More pain initially, but ultimately gives you a better understanding.

Symon · 8th October 2007, 9:38 PM

For basic systems it's hard to beat, even for us dumb arse sparkies

2xCPU · 9th October 2007, 12:45 AM

Quote:

Originally Posted by Symon

You have NFI do you?

Gives me the shitsage.

The water analogy is fine, there is a reason why it's still being used in teaching classes.

There are limits to the analogy, but none of them justify it being called 'bad'.

Perhaps it would be best if the OP says weather (s)he now understands. If the answer is yes, then the analogy can be considered adequate.

2.

nux · 9th October 2007, 12:56 AM

Quote:

Originally Posted by 2xCPU

That's not very meaningful.
You can have a very high voltage with little or no current ('flow').
You can also have a low voltage and very high current.

Yes its very meaningful.

High voltage (Pressure) with low current (Flow, being the amount of water passing per time) occurs with a high resistance (works for water as well).

Low voltage/pressure with high current/flow occurs with a low resistance.

V = I*R <<==>> Pressure = Flow * Resistance

http://hyperphysics.phy-astr.gsu.edu...ic/watcir.html

2xCPU · 10th October 2007, 10:45 PM

Ok, I concede the point.
Perhaps you could enlighten us as to how the analogy works with a compressible fluid?

2.

nux · 10th October 2007, 11:28 PM

Why would it need to..?
Yes, the analogy cannot 100% explain it all or work in all cases. However the pressure, flow and resistance terms transfer very well for electrical circuits.

underskore · 11th October 2007, 12:18 AM

Quote:

Originally Posted by LethalCorpse

I've never much liked the fluid flow analogy, as I find it gets in the way of understanding what's really going on. Sure, helps to explain it conceptually to people who don't actually have to use it, but if you really need to understand it I think it's best to approach it from physics and chemistry. More pain initially, but ultimately gives you a better understanding.

well i did hear about it in high school science, and occasionally in first year physics and now i dont know whats going on :'(

edit: no but seriously it is great as a conceptual aid when learning the very basics but after that it should be thrown away.

2xCPU · 11th October 2007, 12:26 AM

Quote:

Originally Posted by nuxie1

Why would it need to..?
Yes, the analogy cannot 100% explain it all or work in all cases. However the pressure, flow and resistance terms transfer very well for electrical circuits.

Quote:

Originally Posted by dakiller

You have a tank at 100bar, that's high pressure but it isnt going anywhere so there is no flow
The atmospheric pressures across the earth only change by a few thousandths of a bar, yet how much volume of air gets moved around?

(not my proposal)

2.

dephilile · 11th October 2007, 9:15 PM

The analogy works fine for incompressible fluids such as water.

Anyway. It’s not meant to be 100% correct. It’s a learning tool.

ojk007 · 11th October 2007, 9:41 PM

Quote:

Originally Posted by 2xCPU

Perhaps it would be best if the OP says weather (s)he now understands. If the answer is yes, then the analogy can be considered adequate.

2.

he*

Yeah it was answered a little while ago actually.

Quote:

Originally Posted by Menthu_Rae

A PSU can *provide* 30A if required. It doesn't send that much current to the device.

Think of current as the *amount* of water in a river. Voltage is how fast/strong the water flows, and resistance is equivalent to things like eddies/currents in the water that stop the flow from going as fast as possible.

If you shove a straw into this river, you can suck all you want - but the full amount of water isn't going to go into your mouth. Think of your sucking power as current draw for the speakers in question.

They will only use 1A of the available 30A, so there is no need to step it down.

notice my reply

Quote:

Originally Posted by ojk007

very informative, answered my question.

Thanks
oj

i stopped looking at this thread, assumed it was finished but theres been a nice little flamin here

8th October 2007, 9:00 PM	#21
LethalCorpse Member Join Date: Mar 2003 Location: Harris Park, NSW Posts: 3,799	I've never much liked the fluid flow analogy, as I find it gets in the way of understanding what's really going on. Sure, helps to explain it conceptually to people who don't actually have to use it, but if you really need to understand it I think it's best to approach it from physics and chemistry. More pain initially, but ultimately gives you a better understanding. __________________ Sig Of Shame removed.

8th October 2007, 9:38 PM	#22
Symon (Plugging your Socket) Join Date: Apr 2002 Location: Brisbane QLD Posts: 2,826	For basic systems it's hard to beat, even for us dumb arse sparkies __________________ DISCLAIMER - The mindless babble of this post does not constitute professional advice. I will not be held responsible if you choose to act on this advice. Unless I tell you to eat jellybeans, everyone likes jellybeans OCAU's self-appointed electrical safety expert - Founder of the bakasan Technical College - enrollments welcome. -- My Web Server in a Box

10th October 2007, 10:45 PM	#25
2xCPU Member Join Date: Jan 2005 Location: melb Posts: 2,395	Ok, I concede the point. Perhaps you could enlighten us as to how the analogy works with a compressible fluid? 2. __________________ If "building a computer" doesn't involve powertools, you're just assembling spare parts. ---- The universe is made up of atoms and empty space, the rest is mere opinion. Democritus, 400 BC.

8th October 2007, 10:35 AM	#16
GooSE Member Join Date: Jun 2001 Location: Sydney Posts: 6,428	What the shit is with anyone calling current amperage? I'm not having a go at the OP as he probably doesn't know any better, but fuck it pisses me off. Whoever coined the term should be shot. Spoiler below, highlight to read: That's my daily rant over

8th October 2007, 7:19 PM	#20
underskore Member Join Date: Nov 2002 Location: 3122 Posts: 3,936	i love the hydraulic analogy, specially how it relates to inductors, capacitors and diodes. (anyone know why Heaviside didnt like it?)

10th October 2007, 11:28 PM	#26
nux Member Join Date: Jan 2002 Location: Melbourne Posts: 16,790	Why would it need to..? Yes, the analogy cannot 100% explain it all or work in all cases. However the pressure, flow and resistance terms transfer very well for electrical circuits.

11th October 2007, 9:15 PM	#29
dephilile Member Join Date: Jun 2006 Location: Daejeon - South Korea Posts: 944	The analogy works fine for incompressible fluids such as water. Anyway. It’s not meant to be 100% correct. It’s a learning tool.