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a question about resistors in an arc experiment

S

Spehro Pefhany

Jan 1, 1970
0
John Larkin said:
John Devereux wrote:

John Devereux wrote:
[...]
Here's a minus one ohm resistor:

. 1 ohm
. ___
. .---|___|-.
. | |
. -1 ohm --> | |\| |
. o--------o--|-\ |
. | >---|
. .--|+/ |
. | |/| |
. | ___ |
. o---|___|-'
. | 1 ohm
. .-.
. | |1 ohm
. | |
. '-'
. |
. ===
. GND
[...]
It's incomplete. It has no power supply.

Hi Silvia,

You can use a battery.

Which is significant. You cannot simulate a negative resistance
without a power supply, because it is an energy source.

Of course, the energy comes from the supply.

The fact that it needs a power supply emphasises the fact that it
only simulates a component with negative resistance. It isn't a real
negative resistor. The highly desirable real negative resistor, were
one to exist, would function indefinitely. A simulation can only
function as long its energy reservoir lasts.

But it is nevertheless a negative resistor / resistance during that
time IMO. Put it in a box with a bettery and bring out the input
terminal and GND. It's a negative resistor - i.e. a two terminal
circuit with negative resistance. It will have limits of operation
determined by the components used (but so does a "real" one).

That's the circuit I used, in a box with two 9-volt batteries, in my
class project ca 1968. I used a 709 opamp, as I recall. It was fun,
plugging negative numbers into all the classic circuit equations and
seeing the actual waveforms.

Sylvia should try it.

There's (at least) one nice direct application of this idea -
compensating for the winding resistance in a DC motor speed
controller.

<http://focus.tij.co.jp/jp/lit/an/sboa043/sboa043.pdf>

This is SOP in brush DC motor drives. It is called "IR Compensation"
in the industry.
 
S

Spehro Pefhany

Jan 1, 1970
0
OK, I apologize for the incorrect claim that "nobody was confused by
that", since it's obvious that you'd be confused.

John

Too bad. I was hoping to connect it to the mains and get 14kW out of
it.
 
R

Rich Grise

Jan 1, 1970
0
On Thu, 15 Jan 2009 17:29:20 -0800, Archimedes' Lever


Kilovolts? Where do the kilovolts come from, and when?
From the negative resistor, of course. As the current approaches zero,
the voltage approaches infinity. ;-)

Hope This Helps!
Rich
 
S

Sylvia Else

Jan 1, 1970
0
John said:
When we (engineers who design electronics) draw opamps, we don't
always show the power supplies, because we all know that opamps need
power supplies to work. And we don't always insert every adjective and
every qualifier into a sentence where we know other circuit designers
will perfectly understand our intent. And most of us take conservation
of energy for granted.

Usually, when an electronics engineer draws an opamp, he's not trying to
pass the circuit off as something it isn't.

Sylvia.
 
M

MooseFET

Jan 1, 1970
0
Right. When an EE says "negative resistance" he generally means some
negative slope on the I:E curve. Things like "negative resistance
region" and "negative resistance oscillator" are common. Phil Hobbs
recently noted here that one can linearize a platinum RTD by
connecting it across a negative resistance, and nobody was confused by
that.

Most of us know that there are few true negative resistors in the
Mouser catalog.

You need to look in McMaster for them. Shunt connected generators are
negative resistors.
 
P

Phil Allison

Jan 1, 1970
0
"John Larkin"
Sylvia Else
If you visit SED to lecture us on how we should be what we are, and
how we should talk to each other, you won't make a lot of friends. I
don't know if that matters to you.


** Of course not - Sylvia is a notorious usenet TROLL.


By my standards, the opamp thing has a negative resistance at its
terminals. And a tunnel diode is a negative-resistance device.

Post some circuits you've designed and we'll take a crack at them.


** Sylvia has zero electronics knowledge.

Here is her pic:

http://www.onlineopinion.com.au/author.asp?id=3937

NLP = Naturist Lifestyle Party ( a nudist party, now defunct).

Sylvia was the secretary of the party and stood for election to the NSW
upper house a couple of years back.





...... Phil
 
S

Sylvia Else

Jan 1, 1970
0
Software engineering.

It doesn't matter what a software engineer designs, because his/her
manager will invariable pass it off as something it isn't.

Sylvia.
 
J

Jasen Betts

Jan 1, 1970
0
These drawings always look wrong in my newsreader, Free Agent. Does
it require a specific font or something?

any font with all the characters the same with.
"courier" is one candidate.
"terminal" is another.

cut-and-paste into notepad is an easy way to "decode" them
 
S

Sylvia Else

Jan 1, 1970
0
John said:
Sylvia Else said:
John said:
John Devereux wrote:
Sylvia Else <[email protected]> writes:
[...]
One could qualify comments about resistance by observing in each case
that the resistance is positive, but since resistance is never
negative, that would be redundant.
Here's a minus one ohm resistor:

. 1 ohm
. ___
. .---|___|-.
. | |
. -1 ohm --> | |\| |
. o--------o--|-\ |
. | >---|
. .--|+/ |
. | |/| |
. | ___ |
. o---|___|-'
. | 1 ohm
. .-.
. | |1 ohm
. | |
. '-'
. |
. ===
. GND
.

(created by AACircuit v1.28.6 beta 04/19/05 www.tech-chat.de)

That won't work.
Really? What's wrong with it?
It's incomplete. It has no power supply.

Hi Silvia,

You can use a battery.
Which is significant. You cannot simulate a negative resistance
without a power supply, because it is an energy source.

Of course, the energy comes from the supply.
The fact that it needs a power supply emphasises the fact that it
only simulates a component with negative resistance. It isn't a real
negative resistor. The highly desirable real negative resistor, were
one to exist, would function indefinitely. A simulation can only
function as long its energy reservoir lasts.

But it is nevertheless a negative resistor / resistance during that
time IMO. Put it in a box with a bettery and bring out the input
terminal and GND. It's a negative resistor - i.e. a two terminal
circuit with negative resistance. It will have limits of operation
determined by the components used (but so does a "real" one).

Yes, though now we're getting down to an argument about the meaning of
words, which admittedly I started. Given the overall context of this
thread, I think I was justified in objecting to the circuit being
described as a negative resistor, even though it's easy enough to see
that it behaves like one, within limits, as long as its energy source lasts.

Faced with black box with that behaviour, and asked what it is, few
people would characterise it as a negative resistor, in the passive
component sense, simply because such a device violates conservation of
energy. Presumably most would quickly conclude that the black box
contains some sort of active circuit.

And no one would suspect it contained an electric arc.

Sylvia.
 
S

Sylvia Else

Jan 1, 1970
0
Phil said:
"John Larkin"
Sylvia Else



** Of course not - Sylvia is a notorious usenet TROLL.





** Sylvia has zero electronics knowledge.

Here is her pic:

http://www.onlineopinion.com.au/author.asp?id=3937

Are those two comments related?
NLP = Naturist Lifestyle Party ( a nudist party, now defunct).

Sylvia was the secretary of the party and stood for election to the NSW
upper house a couple of years back.

I never stood for election, Phil. Try to get your facts right.

Sylvia.
 
P

Phil Allison

Jan 1, 1970
0
"Sillier than Anyone Else" "
Are those two comments related?


I never stood for election, Phil. Try to get your facts right.



** Oh dear - seems I gave Sylvia far more credit than she deserved.

The " Naturist Lifestyle Party NSW Inc " was never any more than an
incorporated association - ie a tiny private club.

It FAILED to ever get enough members to become a legal political party.

Wot a hoot !!!!!

But Sylvia was a founder and public spokesperson for the handful of wankers
involved - so it was her intention to become a candidate for the NSW upper
house.

So now the totally mad bitch just haunts usenet with her demented thinking.




...... Phil
 
Pity; arcs can be interesting.

I have a nice explanation of arc negative-resistance behavior in my
copy of Morecroft's great "Principles of Radio Communication", 2nd
edition, 1927. I could post it if anyone were seriously interested.
Negative-resistance Poulson arc transmitters were being built up to
the megawatt level.

ftp://jjlarkin.lmi.net/Poulsen.JPG

A Poulsen arc transmitter in Pearl Harbor was the only reliable means
of communicating to US submarines during WWII.


I'm sure that MiniProng has no interest in things like this.

John
I probably knew what VLF was before you did.
 
A

Archimedes' Lever

Jan 1, 1970
0
You sound like a leftie weenie, telling me what *I* can believe,
DimBulb.

You obviously didn't get it. Bwuahahahaha!
 
A

Archimedes' Lever

Jan 1, 1970
0
OK, I apologize for the incorrect claim that "nobody was confused by
that", since it's obvious that you'd be confused.

John

That is not the statement to which I refer, you confused fucking
retard. And yes, you ARE a fucking retard, because you knew exactly what
I meant.
 
A

Archimedes' Lever

Jan 1, 1970
0
John Larkin said:
On Fri, 16 Jan 2009 12:38:22 +0000, John Devereux


John Devereux wrote:

John Devereux wrote:
[...]

Here's a minus one ohm resistor:

. 1 ohm
. ___
. .---|___|-.
. | |
. -1 ohm --> | |\| |
. o--------o--|-\ |
. | >---|
. .--|+/ |
. | |/| |
. | ___ |
. o---|___|-'
. | 1 ohm
. .-.
. | |1 ohm
. | |
. '-'
. |
. ===
. GND
[...]

It's incomplete. It has no power supply.

Hi Silvia,

You can use a battery.

Which is significant. You cannot simulate a negative resistance
without a power supply, because it is an energy source.

Of course, the energy comes from the supply.

The fact that it needs a power supply emphasises the fact that it
only simulates a component with negative resistance. It isn't a real
negative resistor. The highly desirable real negative resistor, were
one to exist, would function indefinitely. A simulation can only
function as long its energy reservoir lasts.

But it is nevertheless a negative resistor / resistance during that
time IMO. Put it in a box with a bettery and bring out the input
terminal and GND. It's a negative resistor - i.e. a two terminal
circuit with negative resistance. It will have limits of operation
determined by the components used (but so does a "real" one).

That's the circuit I used, in a box with two 9-volt batteries, in my
class project ca 1968. I used a 709 opamp, as I recall. It was fun,
plugging negative numbers into all the classic circuit equations and
seeing the actual waveforms.

Sylvia should try it.

There's (at least) one nice direct application of this idea -
compensating for the winding resistance in a DC motor speed
controller.

<http://focus.tij.co.jp/jp/lit/an/sboa043/sboa043.pdf>

You can do that in power supplies, too, to make up for wire resistance
to a remote load. A lot of hysteretic buck switchers have inherent
negative output resistance, for reasons I don't know.

John
The term for the day is 'feed forward'.
 
A

Archimedes' Lever

Jan 1, 1970
0
Well, the point is to have fun with whatever anybody posts, isn't it?

John


Except that you're not FUn... You're FUcked... in the head.
 
M

MooseFET

Jan 1, 1970
0
Here's a minus one ohm resistor:
I'm going to modify it slightly:
.                       1 ohm
.                        ___
.                   .---|___|-.
.                   |         |
. -1 ohm -->        |  |\|    |
.          o--------o--|+\    |
.                      |  >---|
.                   .--|-/    |
.                   |  |/|    |
.                   |    ___  |
.                   o---|___|-'
.                   |   10K
.                  .-.
.                  | |10K
.                  | |
.                  '-'
.                   |
.                  ===
.                  GND

The polarity on the op-amp and the values of the resistors are now
more like I would do it.
 
S

Sylvia Else

Jan 1, 1970
0
Phil said:
"Sillier than Anyone Else" "



** Oh dear - seems I gave Sylvia far more credit than she deserved.

The " Naturist Lifestyle Party NSW Inc " was never any more than an
incorporated association - ie a tiny private club.

It FAILED to ever get enough members to become a legal political party.

Wot a hoot !!!!!

Phil, did you never try something as an experiment, knowing full well
that it might not work, but also knowing that if you didn't try, it
definitely wouldn't happen?

Sylvia.
 
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