water analogy- a simple calculator

[John Larkin]

On Tue, 11 Jan 2011 09:13:31 -0600, John Fields
<jfields@austininstruments.com> wrote:

On Sun, 09 Jan 2011 15:36:16 -0800, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Sun, 09 Jan 2011 05:56:29 -0600, John Fields
jfields@austininstruments.com> wrote:

On Fri, 07 Jan 2011 20:29:09 -0800, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Thu, 06 Jan 2011 13:12:39 +0100, tuinkabouter
dachthetniet@net.invalid> wrote:

Op 6-1-2011 10:49, F*cking French schreef:
Hello,

I'm a designer, and I don't know much about electronics and water
analogy...
But I was wondering if a very basic calculator could be made with
water.

Lets say a circuit able to + and - numbers and display them.

I have no idea how complex such a circuit would be.

There is no analogy between electronics and water.
The only analogy i know is teh analogy between water and electricity.

Pressure is voltage.
Flow is current.

It's a weak analogy, because the equations don't match. You can't
apply Ohms-law type reasoning to fluid flow because pressure drop is
nonlinear on fluid flow.

John

---
So what?

It's still an excellent way of introducing someone unfamiliar with the
concepts of voltage, current, and resistance to their fluid analogs of
pressure, flow, and pipe diameter.

Except that most people don't understand the fluid situation to start,

---
Really?
Got a reference?
---

and lots of people don't do these sorts of physical analogies very
well.

---
Bullshit.
---

I find it easier to just explain the electricity.

---
Because, since it's convenient for you, you don't have to bother
constructing an analogy which might get the newbie over the hump, and
you get to demean anyone who doesn't understand how things work
according to his highness' high-handed "teaching" strategies.
---

And, as far as Ohm's law goes, if pressure (voltage) increases while
resistance (pipe diameter) remains constant, then current (flow) will
increase, so the _reasoning_ is the same in either case regardless of
the equations.

As I said, it's a weak analogy.

---
As _you_ said?

That's just more of your posturing and is supposed to conjure up the
image of you being incarnate and your word being incontrovertible.

Contrary to your statement, it's a very strong analogy, qualitatively,
and readily lends itself to a newbie's being able to grasp the
concepts of voltage, resistance, and current as analogies of fluid
characteristics which are palpable.
---

You have to misunderstand fluid flow for it to even sort of work.

---
Well, then, since you stated earlier:

"Except that most people don't understand the fluid situation to
start",

it shouldn't be much of a stretch to leave what doesn't matter out of
the water analogy and use what's salient to explain the basic concepts
of electricity.
---

I've never liked using plumbing to explain electronics.

---
You don't like _anything_ you disagree with,

Of course I don't. People disagree with things because they don't like
them, because they think they're wrong. Duh.


and have demonstrated

time and time again that you'll lie and cheat in order to keep from
having to admit that what you disagreed with was right.

---
JF

I've taught basic electricity, electronics, and programming to lots of
people. They generally say that I make it very clear. I make sure
everybody gets it before I move on. I don't invoke plumbing. There's
no hydraulic equivalent of an electric or magnetic field, and fields
are where teaching electricity starts.

I did teach one course on simulating dynamic systems with computers.
One assignment was to simulate a toilet tank filling up, graphing
level versus time. Everybody got it right.

John

 

[Rich Grise]

F. Bertolazzi wrote:

George Herold:

Hmm that's not easy to do... Water spraying out the end of the hose
looks like a circuit spitting electrons....

Wait! Who sys that water is similar to electrons?

I was talking about electric current, that flows from a high reservoir
potential to *ground* potential, throung an acqueduct and hose that have a
fixed resistance and a variable thumb

Electrons, by the way, go the other direction.

I could never understand how, in a CRT, the current knows exactly which
pixel to leap off of to go exactly through the deflection circuitry, to end
up at the cathode.

Clairvoyance? ;-)

Cheers!
Rich

 

[Rich Grise]

John Larkin wrote:

OK, what's the electrical equivalent of the finger-on-the-hose thing?
Schematic, please.

Okay:

Supply ------------+
[hose Bibb] |
|
[R] <-- hose
|
|
[rheostat] <-- thumb
|
|
Ground <-- literally! ;-)

Hope This Helps!
Rich

 

[Rich Grise]

John Larkin wrote:

A true anology uses the same equations, with the same solutions.

No, that's an identity.

An analogy is like, "time flies like an arrow." ;-)

Cheers!
Rich

 

[John Larkin]

On Tue, 11 Jan 2011 14:50:56 -0800, Rich Grise
<richg@example.net.invalid> wrote:

John Larkin wrote:

A true anology uses the same equations, with the same solutions.

No, that's an identity.

An analogy is like, "time flies like an arrow." ;-)

Cheers!
Rich

Generalizations don't mean much.

John

 

[F. Bertolazzi]

John Larkin:

On Tue, 11 Jan 2011 06:11:41 +0100, "F. Bertolazzi"
TOGLIeset@MAIUSCOLEtdd.it> wrote:

Michael A. Terrell:

John Larkin wrote:

OK, what's the electrical equivalent of the finger-on-the-hose thing?
Schematic, please.

A transformer: High flow at low pressure is transformed into low
flow at high pressure.

Humm. Maybe John is right.

HA!

No, I did not mean to imply that *you* are stupid.

 

[F. Bertolazzi]

John Larkin:

I've taught basic electricity, electronics, and programming to lots of
people. They generally say that I make it very clear.

Yes, that's the point. It is, at the end of the lesson, or, better, it
seems to be. But, a few months later...

 

[F. Bertolazzi]

John Larkin:

Right. I can't think of an electrical analogy to friction.

Uh?

 

[John Fields]

On Tue, 11 Jan 2011 14:02:09 -0800, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Tue, 11 Jan 2011 09:13:31 -0600, John Fields
jfields@austininstruments.com> wrote:

I've never liked using plumbing to explain electronics.

---
You don't like _anything_ you disagree with,


Of course I don't. People disagree with things because they don't like
them, because they think they're wrong. Duh.

---
I think, in your case, that you don't like things you disagree with
because you're afraid that they might prove you wrong, and in that
vein, do whatever you can can to try to kill the messenger.
---

and have demonstrated
time and time again that you'll lie and cheat in order to keep from
having to admit that what you disagreed with was right.

---
JF

I've taught basic electricity, electronics, and programming to lots of
people. They generally say that I make it very clear. I make sure
everybody gets it before I move on. I don't invoke plumbing. There's
no hydraulic equivalent of an electric or magnetic field, and fields
are where teaching electricity starts.

---
I've done all of that as well and, unlike you, instead of browbeating
students into submission, used hydraulic analogies to get the "AHA!!!"
look in the eyes of the ones who needed a little more help than the
others.
---

I did teach one course on simulating dynamic systems with computers.
One assignment was to simulate a toilet tank filling up, graphing
level versus time. Everybody got it right.

---
So, since

Vcc
t = RC ln -----------,
Vcc - Vth


they all came to the conclusion that it would take forever for the
tank to fill up?

---
JF

 

[F. Bertolazzi]

John Larkin:

Generalizations don't mean much.

Things you can't feel and touch don't mean anything, after few months (or
days or even hours).

If, after a Larkin's lectio magistralis you don't touch and feel it by an
oscilloscope or a meter, you're going to forget it, unless you already
wandered about what you touched and felt.

With an ammeter or a wet brother.

 

[F. Bertolazzi]

Rich Grise:

I could never understand how, in a CRT, the current knows exactly which
pixel to leap off of to go exactly through the deflection circuitry, to end
up at the cathode.

Kicks in their butt and being... charged on the side

Clairvoyance? ;-)

LOL.

 

[Rich Grise]

John Larkin wrote:

Right. I can't think of an electrical analogy to friction.

This is a joke, right?

Personally, I don't see what a dashpot does, but damp (much like a
snubber). The only analog to an inductor I can think of would be
a positive-displacement turbine (like a gear pump) and a flywheel.

Thanks!
Rich

 

[Rich Grise]

John Larkin wrote:

On Tue, 11 Jan 2011 14:50:56 -0800, Rich Grise
John Larkin wrote:

A true anology uses the same equations, with the same solutions.

No, that's an identity.

An analogy is like, "time flies like an arrow." ;-)

Generalizations don't mean much.

Yes, and 96.4% of statistics are made up on the spot. ;-)

Cheers!
Rich

 

[Rich Grise]

F. Bertolazzi wrote:

John Larkin:

Generalizations don't mean much.

Things you can't feel and touch don't mean anything, after few months (or
days or even hours).

If, after a Larkin's lectio magistralis you don't touch and feel it by an
oscilloscope or a meter, you're going to forget it, unless you already
wandered about what you touched and felt.

With an ammeter or a wet brother.

Confucius taught: ?I hear and I forget. I see and I remember. I do and I
understand.?
--- google ;-)

Cheers!
Rich

 

[John Larkin]

On Wed, 12 Jan 2011 01:46:59 +0100, "F. Bertolazzi"
<TOGLIeset@MAIUSCOLEtdd.it> wrote:

John Larkin:

Right. I can't think of an electrical analogy to friction.

Uh?

Uh? Can you?

John

 

[John Larkin]

On Tue, 11 Jan 2011 21:27:19 -0500, Jamie
<jamie_ka1lpa_not_valid_after_ka1lpa_@charter.net> wrote:

Rich Grise wrote:

John Larkin wrote:

Right. I can't think of an electrical analogy to friction.


This is a joke, right?

Personally, I don't see what a dashpot does, but damp (much like a
snubber). The only analog to an inductor I can think of would be
a positive-displacement turbine (like a gear pump) and a flywheel.

Thanks!
Rich

Eddy current?
Drop a PM down a non-magnetic conductible tube and see it drop
slowly.


Jamie

Friction results in zero motion until some threshold amount of force
is applied. And sliding friction drag mostly depends on normal force
but not velocity. I don't know of any electrical phenom that behaves
like that.

The PM in the tube thing is more like viscoscity; no force threshold
for motion, and drag increases with velocity.

John

 

[Jamie]

Rich Grise wrote:

John Larkin wrote:

Right. I can't think of an electrical analogy to friction.


This is a joke, right?

Personally, I don't see what a dashpot does, but damp (much like a
snubber). The only analog to an inductor I can think of would be
a positive-displacement turbine (like a gear pump) and a flywheel.

Thanks!
Rich

Eddy current?

Drop a PM down a non-magnetic conductible tube and see it drop
slowly.


Jamie

 

[John Larkin]

On Tue, 11 Jan 2011 18:58:58 -0600, John Fields
<jfields@austininstruments.com> wrote:

On Tue, 11 Jan 2011 14:02:09 -0800, John Larkin
jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

On Tue, 11 Jan 2011 09:13:31 -0600, John Fields
jfields@austininstruments.com> wrote:


I've never liked using plumbing to explain electronics.

---
You don't like _anything_ you disagree with,


Of course I don't. People disagree with things because they don't like
them, because they think they're wrong. Duh.

---
I think, in your case, that you don't like things you disagree with
because you're afraid that they might prove you wrong, and in that
vein, do whatever you can can to try to kill the messenger.
---

and have demonstrated
time and time again that you'll lie and cheat in order to keep from
having to admit that what you disagreed with was right.

---
JF

I've taught basic electricity, electronics, and programming to lots of
people. They generally say that I make it very clear. I make sure
everybody gets it before I move on. I don't invoke plumbing. There's
no hydraulic equivalent of an electric or magnetic field, and fields
are where teaching electricity starts.

---
I've done all of that as well and, unlike you, instead of browbeating
students into submission, used hydraulic analogies to get the "AHA!!!"
look in the eyes of the ones who needed a little more help than the
others.
---

I did teach one course on simulating dynamic systems with computers.
One assignment was to simulate a toilet tank filling up, graphing
level versus time. Everybody got it right.

---
So, since

Vcc
t = RC ln -----------,
Vcc - Vth


they all came to the conclusion that it would take forever for the
tank to fill up?

---
JF

They start filling linearly, until the level hits the float and the
feed valve starts to close. Then, with the simplified model I gave
them, the fill becomes exponential forever, asymptotic to the line on
the inside of the tank. It's a nice exercize, because everybody can go
home and flush and see it happen.

John

 

[John Larkin]

On Wed, 12 Jan 2011 01:46:57 +0100, "F. Bertolazzi"
<TOGLIeset@MAIUSCOLEtdd.it> wrote:

John Larkin:

I've taught basic electricity, electronics, and programming to lots of
people. They generally say that I make it very clear.

Yes, that's the point. It is, at the end of the lesson, or, better, it
seems to be. But, a few months later...

Of course most people will forget the basic lessons if they don't use
it regularly. But then, they may as well. No point cluttering your
brain with stuff you don't intend to use. They made me study French,
which I forgot as soon as I could.

The point of introductory EE is to get people doing the math from the
very start. Because they will be helpless if they can't do the math.
Analogies don't help there.

John

 

[Phil Hobbs]

Rich Grise wrote:

John Larkin wrote:

A true anology uses the same equations, with the same solutions.

No, that's an identity.

An analogy is like, "time flies like an arrow." ;-)

Cheers!
Rich

"And fruit flies like a banana."

(http://preview.tinyurl.com/27jchnw)

Cheers

Phil Hobbs





--
Dr Philip C D Hobbs
Principal
ElectroOptical Innovations
55 Orchard Rd
Briarcliff Manor NY 10510
845-480-2058

email: hobbs (atsign) electrooptical (period) net
http://electrooptical.net