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KILOWATT

Posted: Fri Feb 02, 2007 5:16 pm

Guest

Hi... thanks for your attention.

I just wish to know the precise reason why for example, a digital counter
may count many pulses on it's clock input when the clock is feed via a non
noise-free source like a mechanical switch. It is because when the contacts
makes/breaks, arcing (i've read somewhere that there can be a possibility of
arcing even at low voltage) occurs, or if it's because of the very rough
surface (microscopically-speaking) of the switch contacts, were the metal
molecules grinds (and possibly flexes) together, during switch activation?
TIA for your reply.

--
Alain(alias:Kilowatt)
Montréal Québec
PS: 1000 excuses for grammatical errors or
omissions, i'm a "pure" french canadian! Smile

(If replying also by e-mail, remove
"no spam" from the adress.)

default

Posted: Fri Feb 02, 2007 6:03 pm

Guest

On Fri, 2 Feb 2007 16:16:44 -0500, "KILOWATT"
<kilowatt"nospam"@softhome.net> wrote:

Quote:

You got it - on a microscopic level the metal contacts will create
high frequency noise (a good scope may be necessary to see it). Some
reed switches were produced that eliminate the bounce by using
electrodes with a mercury coating in an inert gas capsule.

Ironically, they were also used with mechanical actuators to produce
fast rise time pulses to test semiconductors. Nothing says "on" like
mercury coming together.

Some dry switches deliberately induce a wiping action on the contacts
which prolongs the switch life, but creates more noise.

The clock input of logic circuits is fast enough to count the
transitions.
--

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http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups
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John Larkin

Posted: Fri Feb 02, 2007 8:00 pm

Guest

On Fri, 2 Feb 2007 16:16:44 -0500, "KILOWATT"
<kilowatt"nospam"@softhome.net> wrote:

Quote:

Bouncing means bouncing. When contacts collide, they, well, bounce,
like a ball hitting the floor. Multiple contacts are made and unmade
until it settles down. This is quite visible on an oscilloscope.
Small, low mass contacts have a higher mechanical resonant frequency
so tend to have higher bounce rates and settle faster. Mercury-wetted
contacts don't bounce at all.

There's no significant arcing contribution at low voltages.

Incidentally, for both wet and dry contacts, the initial electrical
connection can have sub-nanosecond risetime.

John

Jon Slaughter

Posted: Sat Feb 03, 2007 4:13 am

Guest

"KILOWATT" <kilowatt"nospam"@softhome.net> wrote in message
news:45c3aa6d$0$31564$c3e8da3@news.astraweb.com...

Quote:

Hi... thanks for your attention.

I just wish to know the precise reason why for example, a digital counter
may count many pulses on it's clock input when the clock is feed via a non
noise-free source like a mechanical switch. It is because when the
contacts
makes/breaks, arcing (i've read somewhere that there can be a possibility
of
arcing even at low voltage) occurs, or if it's because of the very rough
surface (microscopically-speaking) of the switch contacts, were the metal
molecules grinds (and possibly flexes) together, during switch activation?
TIA for your reply.

The atoms of the two materials are not configured in such a way that there
is complete contact. If they were then the materials would be fused. Since
there are not fused and they slide there is friction involved and this
friction causes the contacts to move farther a part and then closer
together. So the average distance between the constants is changing
significantly campared to when is not moving and they are making good
contact. So now the electric field is changing because of the distances
changing between the contacts. As the contacts move farther away the field
becomes weaker but now we have a capacitive effect. This effect creates a
force between the contacts that attract them. One now has a kinematic force
pulling the contacts away(so it can slide), one of friction that wants to
stop the slide, and one of capacitance that is attractive(I'm sure there are
more too).

Anyways, So there are all these forces that are interacting and the end
result is this oscillation of the contacts moving toward and away from each
other. One always gets "arcing" but thats kinda relative turn. (In some
sense all electronic flow is "arcing".) Generally this term is used when
there is significant macroscopic arcing and this requires much higher
voltages than the microscopic arcing that always happens. (Its just a matter
of degree). This oscillation that happen is called bouncing and the net
effect is to increase and decrease the resistance but with a trend towards
increasing it(which happens very sharply when the contacts finally break
away).

When a switch bounces it does turn on and off instantaneously a few times
then finally settles on off. Nothing is every instanenous in the real
world. The net resistance is dependent on many factors and one of them is
the distance between the contacts. Theres a point where the distance becomes
so great that microscopic forces do not have any significant effect. The
bound that you see on an oscilloscope occurs right at this point where D
becomes more significant and the other forces do not. This point has to do
with how much of the two contacts are actually in contact although it
happens over the whole surface since some points on the contacts are more in
contact than other points. In this case we have an average that approximates
the whole surfeces very well unless the contacts are very distorted.

I guess ultimately the effect I'm talking about is sorta middle ground
between the atomic and the macroscopic. Whats really important here is what
happens when the two contacts are about to completely leave each other and
not what happens before(although it could be significant it is just a
smaller version of the main one). Once you understand this then its not
hard to see that it happens many times before but just on a smaller and
smaller scale. (One could say that bouncing is always happening so its just
a matter of degree).

Anyways, I'm kinda rambling there but maybe it will shed a little light on
your problem.

Jon

Ben Jackson

Posted: Sat Feb 03, 2007 5:30 am

Guest

On 2007-02-03, John Larkin <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

Quote:

Incidentally, for both wet and dry contacts, the initial electrical
connection can have sub-nanosecond risetime.

I knew I shouldn't have paid a premium for these "high speed digital
buttons"!

--
Ben Jackson AD7GD
<ben@ben.com>
http://www.ben.com/

John Fields

Posted: Sat Feb 03, 2007 8:33 am

Guest

On Fri, 02 Feb 2007 16:00:30 -0800, John Larkin
<jjlarkin@highNOTlandTHIStechnologyPART.com> wrote:

Quote:

Incidentally, for both wet and dry contacts, the initial electrical
connection can have sub-nanosecond risetime.

---
Contrary to popular belief, a 'dry' contact isn't a contact that
carries a small current, it's a contact that never does any hot
switching.

--
JF

John Larkin

Posted: Sat Feb 03, 2007 2:40 pm

Guest

On Sat, 03 Feb 2007 08:13:46 GMT, "Jon Slaughter"
<Jon_Slaughter@Hotmail.com> wrote:

Quote:

"KILOWATT" <kilowatt"nospam"@softhome.net> wrote in message
news:45c3aa6d$0$31564$c3e8da3@news.astraweb.com...
Hi... thanks for your attention.

I just wish to know the precise reason why for example, a digital counter
may count many pulses on it's clock input when the clock is feed via a non
noise-free source like a mechanical switch. It is because when the
contacts
makes/breaks, arcing (i've read somewhere that there can be a possibility
of
arcing even at low voltage) occurs, or if it's because of the very rough
surface (microscopically-speaking) of the switch contacts, were the metal
molecules grinds (and possibly flexes) together, during switch activation?
TIA for your reply.

The atoms of the two materials are not configured in such a way that there
is complete contact. If they were then the materials would be fused. Since
there are not fused and they slide there is friction involved and this
friction causes the contacts to move farther a part and then closer
together. So the average distance between the constants is changing
significantly campared to when is not moving and they are making good
contact. So now the electric field is changing because of the distances
changing between the contacts. As the contacts move farther away the field
becomes weaker but now we have a capacitive effect. This effect creates a
force between the contacts that attract them. One now has a kinematic force
pulling the contacts away(so it can slide), one of friction that wants to
stop the slide, and one of capacitance that is attractive(I'm sure there are
more too).

Sorry, but that's all nonsense. At low voltages and currents, switch
contacts bounce for purely mechanical reasons.

If your field theories were true, the applied voltage would radically
change the bounce waveform. It doesn't. Try it.

Quote:

Jon Slaughter

Posted: Sat Feb 03, 2007 5:58 pm

Guest

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message
news:kcl9s21bv0ulr6m2sdjlnkffdftp8mh68c@4ax.com...

Quote:

On Sat, 03 Feb 2007 08:13:46 GMT, "Jon Slaughter"
Jon_Slaughter@Hotmail.com> wrote:

"KILOWATT" <kilowatt"nospam"@softhome.net> wrote in message
news:45c3aa6d$0$31564$c3e8da3@news.astraweb.com...
Hi... thanks for your attention.

I just wish to know the precise reason why for example, a digital
counter
may count many pulses on it's clock input when the clock is feed via a
non
noise-free source like a mechanical switch. It is because when the
contacts
makes/breaks, arcing (i've read somewhere that there can be a
possibility
of
arcing even at low voltage) occurs, or if it's because of the very rough
surface (microscopically-speaking) of the switch contacts, were the
metal
molecules grinds (and possibly flexes) together, during switch
activation?
TIA for your reply.

The atoms of the two materials are not configured in such a way that there
is complete contact. If they were then the materials would be fused. Since
there are not fused and they slide there is friction involved and this
friction causes the contacts to move farther a part and then closer
together. So the average distance between the constants is changing
significantly campared to when is not moving and they are making good
contact. So now the electric field is changing because of the distances
changing between the contacts. As the contacts move farther away the field
becomes weaker but now we have a capacitive effect. This effect creates a
force between the contacts that attract them. One now has a kinematic
force
pulling the contacts away(so it can slide), one of friction that wants to
stop the slide, and one of capacitance that is attractive(I'm sure there
are
more too).

Sorry, but that's all nonsense. At low voltages and currents, switch
contacts bounce for purely mechanical reasons.

Um, and you seem to think that mechanical bouncing is some real thing. Its
an abstract concept. There is no real think as bouncing. When a ball bounces
you think that the surfaces are idealized. No, they are governed by quantum
mechanics. Believe it or not, doesn't matter ot me.

Quote:

If your field theories were true, the applied voltage would radically
change the bounce waveform. It doesn't. Try it.

hmm. so the waveforms are exactly the same? They do not scale with voltage?
You seem to think that ohms law doesn't apply here? V = IR or did you not
learn that? What do you really think these waveforms will look like? Do you
think they will be perfect unit step functions? Get into the real physics
of it and stop trying using idealized descriptions of the behavor.

http://www.ece.uci.edu/rfmems/publications/papers/mems/C021-EUMTT99.pdf

http://www.scienceprog.com/dealing-with-switch-bounce-problem/

Do you really think that the effects I'm talking about are going to
radically change the macroscopic scale? The time scale is femto or less and
the forces are fN or less. (although the above analysis are still idealized)

Your logic is like saying a resistor behaves exactly the same no matter what
conditions. Your a bafoon in thinking that everything is some simple
mathematical equation that you learned in cal 101.

You think that a resistor doesn't change its "waveform" with voltage? R =
V/I. What happen when V is very low? what about when V is very high? What
about most of the time? Most of hte time R is the APPOXIMATELY constant.
THATS RIGHT!!! A resistor doesn't change its "waveform"(which is wrong way
to put it as switches and resistors are not waveforms) for a wide range of
voltages. If this what the case then they would be practically useless.

Did you ever take quantum mechanics 101? Hell, even basic physics supplies
an approximately correct answer. Coulomb's law for the contacts state
something like

Sum(k*Qi*Qj/r_ij^2,i=1..N)

(this is better described in a statistical quantum fashion but I don't want
to confuse your little brain)

Do you think that distances in this equation have some special meaning
between when a switch is open and not? Sure there is a point where the
strenght of the field drops off almost to 0 but it is not instantaneous.

The OP asked for the microscopic answer and not something you read out of an
electricians manual.

(BTW, show me some waveforms's from two different switches using the same
voltage and lets see if they are even close. Hell, show me two waveforms
from the same switch using the same voltage and lets see if they are even
close.)

Quote:

Anyways, So there are all these forces that are interacting and the end
result is this oscillation of the contacts moving toward and away from
each
other. One always gets "arcing" but thats kinda relative turn. (In some
sense all electronic flow is "arcing".)

Metallic conduction is not "arcing." Arcing is gaseous conduction.
Vacuum tunneling happens too, but the range is just on the order of an
atomic diameter, not important for things like switch contacts.

So we cannot have an arc in a vacuum without any gas? Hmm, can you prove
this? I think this would go to explaining a lot about vacuum tubes(I guess
they don't "arc" or must contain a gas(a significan't amount to explain the
arcing)).

It may not be significant to you but you are not the genius you think you
are. People like you are satisfied with any explaination that doesn't
confused them people like the KILOWATT want to know the real reason why
things work. You take it on faith(sure, you might look at a few switch
characteristics using an oscilliscope but then you do not care to go
farther) while he wants to know the real reasons. The difference is one of
religon and one of science.

The same factors that cause friction are at work with a mechanical switch.
You can ignore this all you want and thats fine. But don't try to act like
the world is some idealized place that is perfectly described by few simple
mathematical equations. (all equations are wrong to some extent and some are
better than others. Usually the better equations are more complicated).

Your logic is like "A diode is a switch" while mine is "A diode is a device
that can behave like a switch but this is because of the properties of the
material. (then I'd have to talk about doping, holes, drift, junctions,
valence electrons, pauli exclusion principle, etc...). Rarely is any simple
explination the full explination.

If he asked what was switch bounce then your answer is good enough. What he
asked was what was the microscopic reason for switch bounce. Now I didn't
talk about quarks because obviously that level is to low and there is no
need(as far as we know). Even the theory of friction at the atomic level is
not know that well. But this is the best level to explain it because you
get at the heart of the reason. Now my explinations might not be perfect but
just because you think they are wrong doesn't mean they are. I also never
said the effects were significant, but there is a macroscopic effect.

Its fine if you want to act like the world is not made up of atoms and
idealize everything. I have no problem with that. But when someone else
wants to know more then don't try to make them believe what you believe.
Only thing I can think of is that your afraid that if they go and explore
that they might prove you wrong. So you care more about looking right than
being right.

Did you factor in resistance into your switch? Didn't think so. Do you know
that resistance depends on voltage? (doesn't matter how, just that there
exists two different voltages that produce two different values of
resistance). You know that voltage and heat are related? (Even directly.
Not that its significant. Even absolutely zero cannot stop an atom from
moving.)

Anyways...

John Larkin

Posted: Sat Feb 03, 2007 6:56 pm

Guest

On Sat, 03 Feb 2007 21:58:27 GMT, "Jon Slaughter"
<Jon_Slaughter@Hotmail.com> wrote:

Quote:

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message
news:kcl9s21bv0ulr6m2sdjlnkffdftp8mh68c@4ax.com...
On Sat, 03 Feb 2007 08:13:46 GMT, "Jon Slaughter"
Jon_Slaughter@Hotmail.com> wrote:

"KILOWATT" <kilowatt"nospam"@softhome.net> wrote in message
news:45c3aa6d$0$31564$c3e8da3@news.astraweb.com...
Hi... thanks for your attention.

I just wish to know the precise reason why for example, a digital
counter
may count many pulses on it's clock input when the clock is feed via a
non
noise-free source like a mechanical switch. It is because when the
contacts
makes/breaks, arcing (i've read somewhere that there can be a
possibility
of
arcing even at low voltage) occurs, or if it's because of the very rough
surface (microscopically-speaking) of the switch contacts, were the
metal
molecules grinds (and possibly flexes) together, during switch
activation?
TIA for your reply.

The atoms of the two materials are not configured in such a way that there
is complete contact. If they were then the materials would be fused. Since
there are not fused and they slide there is friction involved and this
friction causes the contacts to move farther a part and then closer
together. So the average distance between the constants is changing
significantly campared to when is not moving and they are making good
contact. So now the electric field is changing because of the distances
changing between the contacts. As the contacts move farther away the field
becomes weaker but now we have a capacitive effect. This effect creates a
force between the contacts that attract them. One now has a kinematic
force
pulling the contacts away(so it can slide), one of friction that wants to
stop the slide, and one of capacitance that is attractive(I'm sure there
are
more too).

Sorry, but that's all nonsense. At low voltages and currents, switch
contacts bounce for purely mechanical reasons.

Um, and you seem to think that mechanical bouncing is some real thing. Its
an abstract concept. There is no real think as bouncing. When a ball bounces
you think that the surfaces are idealized. No, they are governed by quantum
mechanics. Believe it or not, doesn't matter ot me.

If your field theories were true, the applied voltage would radically
change the bounce waveform. It doesn't. Try it.

hmm. so the waveforms are exactly the same? They do not scale with voltage?
You seem to think that ohms law doesn't apply here? V = IR or did you not
learn that? What do you really think these waveforms will look like? Do you
think they will be perfect unit step functions? Get into the real physics
of it and stop trying using idealized descriptions of the behavor.

http://www.ece.uci.edu/rfmems/publications/papers/mems/C021-EUMTT99.pdf

That paper describes a simulated mems switch that is electrostatically
operated and *never* makes electrical contact. That's not very
relevant to a conventional mechanical contact that is mechanically
driven and *does* make electrical contact.

Get an oscilloscope, a toggle switch, a power supply, and a resistor.
Set up to observe the bounce waveform. See if changing the applied
voltage changes the nature and timing of the bounce waveform, which is
must if electrostatic forces are significant. Of course the voltage
will change when you change the voltage; I won't argue that point.

This is real physics: try it.

Quote:

http://www.scienceprog.com/dealing-with-switch-bounce-problem/

That says nothing about the physics. And it's actually easier to
"debounce" a pushbutton: just read it every 50 milliseconds and accept
what you see.

Quote:

Your logic is like saying a resistor behaves exactly the same no matter what
conditions. Your a bafoon in thinking that everything is some simple
mathematical equation that you learned in cal 101.

No, I'm an engineer who knows how real parts actually behave.

Quote:

Vacuum tubes don't arc in normal operation; thyratrons do. Arcing is
plasma (ionic) conduction. Vacuum tubes operate by electron-only flow.
Metals conduct through movement of conduction-band electrons.

John

John Fields

Posted: Sat Feb 03, 2007 8:52 pm

Guest

On Sat, 03 Feb 2007 08:13:46 GMT, "Jon Slaughter"
<Jon_Slaughter@Hotmail.com> wrote:

Quote:

---
That's not true.

When the contacts come to rest after the bouncing period is over
they will either be in intimate contact or they will be completely
separated.
---

Quote:

If they were then the materials would be fused.

---
Which, indeed, they are until the coil is de-energized and the
return spring exerts force on the armature, breaking the microscopic
weld(s) and allowing the contacts to open.
---

Quote:

Since there are not fused and they slide there is friction involved
and this friction causes the contacts to move farther a part and then
closer together.

---
No. The friction you're talking about is only about the contacts
rubbing against each other when they're making or breaking and is a
second order phenomenon compared to bounce, which occurs when the
contacts alternately make and break when the coil is energized.
Bounce also occurs when the armature is de-energized, but to a
lesser degree, and is caused by the moving contact skipping across
the stationary contact when the coil is de-energized.
---

Quote:

---
No. The high-level bouncing behavior is due only to the gross
mechanical characteristics of the contacts and has vanishingly
little to do with the microscopic effects, which are at least six
orders of magnitude smaller than the mechanical effects, I'd guess.

Do you have some hard numbers which would prove otherwise?

--
JF

John Fields

Posted: Sat Feb 03, 2007 9:43 pm

Guest

On Sat, 03 Feb 2007 21:58:27 GMT, "Jon Slaughter"
<Jon_Slaughter@Hotmail.com> wrote:

....

Quote:

Anyways...

Why are you being so angrily defensive?

Contact bounce is nothing more than a spring-loaded screen door
bouncing back from the jamb when it's let go early.

--
JF

Jon Slaughter

Posted: Sun Feb 04, 2007 10:00 am

Guest

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in message
news:jp3as21pt9disdg31cs1ap3vgmbleghqfk@4ax.com...

Quote:

On Sat, 03 Feb 2007 21:58:27 GMT, "Jon Slaughter"
Jon_Slaughter@Hotmail.com> wrote:

"John Larkin" <jjlarkin@highNOTlandTHIStechnologyPART.com> wrote in
message
news:kcl9s21bv0ulr6m2sdjlnkffdftp8mh68c@4ax.com...
On Sat, 03 Feb 2007 08:13:46 GMT, "Jon Slaughter"
Jon_Slaughter@Hotmail.com> wrote:

"KILOWATT" <kilowatt"nospam"@softhome.net> wrote in message
news:45c3aa6d$0$31564$c3e8da3@news.astraweb.com...
Hi... thanks for your attention.

I just wish to know the precise reason why for example, a digital
counter
may count many pulses on it's clock input when the clock is feed via a
non
noise-free source like a mechanical switch. It is because when the
contacts
makes/breaks, arcing (i've read somewhere that there can be a
possibility
of
arcing even at low voltage) occurs, or if it's because of the very
rough
surface (microscopically-speaking) of the switch contacts, were the
metal
molecules grinds (and possibly flexes) together, during switch
activation?
TIA for your reply.

The atoms of the two materials are not configured in such a way that
there
is complete contact. If they were then the materials would be fused.
Since
there are not fused and they slide there is friction involved and this
friction causes the contacts to move farther a part and then closer
together. So the average distance between the constants is changing
significantly campared to when is not moving and they are making good
contact. So now the electric field is changing because of the distances
changing between the contacts. As the contacts move farther away the
field
becomes weaker but now we have a capacitive effect. This effect creates
a
force between the contacts that attract them. One now has a kinematic
force
pulling the contacts away(so it can slide), one of friction that wants
to
stop the slide, and one of capacitance that is attractive(I'm sure there
are
more too).

Sorry, but that's all nonsense. At low voltages and currents, switch
contacts bounce for purely mechanical reasons.

Um, and you seem to think that mechanical bouncing is some real thing. Its
an abstract concept. There is no real think as bouncing. When a ball
bounces
you think that the surfaces are idealized. No, they are governed by
quantum
mechanics. Believe it or not, doesn't matter ot me.

If your field theories were true, the applied voltage would radically
change the bounce waveform. It doesn't. Try it.

hmm. so the waveforms are exactly the same? They do not scale with
voltage?
You seem to think that ohms law doesn't apply here? V = IR or did you not
learn that? What do you really think these waveforms will look like? Do
you
think they will be perfect unit step functions? Get into the real physics
of it and stop trying using idealized descriptions of the behavor.

http://www.ece.uci.edu/rfmems/publications/papers/mems/C021-EUMTT99.pdf

That paper describes a simulated mems switch that is electrostatically
operated and *never* makes electrical contact. That's not very
relevant to a conventional mechanical contact that is mechanically
driven and *does* make electrical contact.

Get an oscilloscope, a toggle switch, a power supply, and a resistor.
Set up to observe the bounce waveform. See if changing the applied
voltage changes the nature and timing of the bounce waveform, which is
must if electrostatic forces are significant. Of course the voltage
will change when you change the voltage; I won't argue that point.

This is real physics: try it.

Electrostatic forces? No one said anything about electrostatic forces. That
is kinda irrelevant too as electrostatic forces are forces generated by
charges not in motion. When charges in motion one has electodynmaics which
is a completely different phenomena(which is not decribed in parameterized
way on time because it would not explain the magenetic fields created.

What your thinking is that these minute forces some how change in a way on
voltage that is not linear. This is true but only in a certain range of
voltages. Just like a resistor is "linear" but actually this is not true at
all. its an apporoximation that in no way explains the true mechanisms of
resistance. If you could see the true "waveform" then every one would be
different even for the same resistor. Its more like a stochastic brownian
process and you see its statistical average. I doubt a 1GHZ scope could even
capture those subtle effects.

My original point to you was that even though these interatomic forces are
"random" doesn't mean the macroscopic behavor is random or even close. Just
like gravity of the earth is extremly complicated and due to an extremly
large number of small forces we can still describe it by g at the surface
and it is quite accruate. In some sense the large number of "random"(not
truely random but best described by random processes) events have a simple
non-random macroscopic effect. One even can have an effect that is simply V
= IR. The microscopic behavor is extremly complex and somewhat random but
its pretty much perfectly described by that equation.

Quote:

http://www.scienceprog.com/dealing-with-switch-bounce-problem/

That says nothing about the physics. And it's actually easier to
"debounce" a pushbutton: just read it every 50 milliseconds and accept
what you see.

Yes, I was only showing it because of the waveform which I believe is the
tyep of waveform that you think real switches actually exhibit.

Quote:

Your logic is like saying a resistor behaves exactly the same no matter
what
conditions. Your a bafoon in thinking that everything is some simple
mathematical equation that you learned in cal 101.

No, I'm an engineer who knows how real parts actually behave.

Really? Do you know that all materials are made up of atoms and atoms are
quite random(Stochasic is a better term). That is, trying to describe the
motion of any one atom/electron is impossible(not even because its hard but
becaues of the uncertainty principle) but all the atoms of a material taken
together exhibit a property that is independent of any single atom. If this
were not the case we could not have any simple laws describing those
macroscopic properties(cause they would change so easily and we could never
do any experiments with them).

What your trying to do is talk about engineering when teh OP wanted to know
about the physics. Engineer's could care less about what causes the
properties but only care about the dollar.

Quote:

Metallic conduction is not "arcing." Arcing is gaseous conduction.
Vacuum tunneling happens too, but the range is just on the order of an
atomic diameter, not important for things like switch contacts.

So we cannot have an arc in a vacuum without any gas? Hmm, can you prove
this? I think this would go to explaining a lot about vacuum tubes(I guess
they don't "arc" or must contain a gas(a significan't amount to explain
the
arcing)).

Vacuum tubes don't arc in normal operation; thyratrons do. Arcing is
plasma (ionic) conduction. Vacuum tubes operate by electron-only flow.
Metals conduct through movement of conduction-band electrons.

Ok, then maybe I'm not using some technical definition of arcing. If arcing
must involve a plasma to be called arcing then thats fine. I was wrong. I
normally just think of arcing as electronic flow. I could say that any time
an electronic flows through a material it is arcing from one atom to the
next. In some sense this still works with your definition since the
conductor could be though of a plasma but ofcourse this is wrong by the
defefinition of plasma. Ofcourse when electricity arcs in air we don't
normally think of it as creating a temporary plasma(that only lasts for
probably a ms at most) but we still say it arcs? Or do you just call this a
electron flow.

When the electrons flow in a flow the tube they do flow without ionization
because there is no gas in the tube to interfer with the flow. Put a gas in
the tube and you get ionization and if there is enough then a plasma. While
not technically correct, to me this seems to say that arcing is more matter
of degree than just a simple black and white definition.

I think here that arcing and electric flow are very similar and overlap.
Ionization usually happens(if not always) when there is electric flow.
Metalic conduction is just electric flow because the metal atoms are so
easily ionized while in ionizing a gas tends to be a lot harder(more work
for the electrons to flow until it is already ionized).

Anyways, doesn't matter so much as thats not what the OP asked about.

The main point I'm trying to make to you is that your ideal view of how
things work is not how they work. Maxwell's equations do not govern true
electronic flow. It assumes that the current density is continuous and this
is far from the case. It works because on such a macroscopic scale one does
see what looks to be a continuous medium. If you only ask about what
happens on that scale then the equations are valid(Similar to Newton's law
and the speed of light). But to describe what happens at the microscopic
level you have to use quantum mechanics. If you want to know how total
macroscopic effect of a contact switch then Maxwell's equations along with
classical dynamics work just fine. If you want to know what really happens
you'll have to bring in QED and QM. Its just that simple. Classical physics
was not formulated at the level of QM and it was only important for
macroscopic purposes(Not that this didn't stop them from hypothesizing at
the atomic level). QM is formulated on the atomic level(and some of it at
the sub-atomic). It has proven that when its laws are taken in a statistical
sense on the macroscopic level they reduce to the classical formulations.

http://en.wikipedia.org/wiki/Friction

Try reading that and you'll see that they do bring in EM a little but there
equations or not formulated on EM. The reason is simply that the macroscopic
effect can be described in such a simple fashion and this is how they were
found. Those that discovered these "laws" didn't start with the atom but
started with the macroscopic effects and tried to formulate descriptive
mathematics out of it.

Jon Slaughter

Posted: Sun Feb 04, 2007 10:16 am

Guest

"John Fields" <jfields@austininstruments.com> wrote in message
news:1vdas29f4io4odpptfbg3fkup2mpdpopso@4ax.com...

Quote:

On Sat, 03 Feb 2007 21:58:27 GMT, "Jon Slaughter"
Jon_Slaughter@Hotmail.com> wrote:

...

Anyways...

Why are you being so angrily defensive?

Contact bounce is nothing more than a spring-loaded screen door
bouncing back from the jamb when it's let go early.

Because you guys always seem to think that your way is the right way. I know
you guys are not stupid but it seems that you take a simple view of the
world and if someone else wants more info then you act like they are stupid.
You think, say, that if you measure the V-I curve on a resistor and see that
it looks like a perfectly straight line then it must be.

You neglect all the other factors involved. This is fine if you don't care
about them but if someone else does then you tell them what you have
observed and that is what they should believe.

To me, its like your trying to tell someone the world is flat. Now because
it you believe it you don't doubt that it is. It must be. It sounds as if
you think you know everything. And while you guys may not be wrong in most
cases in some way or another, usually you have an idealized or even a narrow
minded view of things. If you never experienced it then it must not be
possible.

Usually when someone asks something one doens't get a response like "In my
experiences I have no had this happen" but instead "It can't happen". Now
the problem with the second is that history should have taught you that
nothing is impossible but if you really believe it then you should have good
reasons. So just state them. "It can't happen and heres why...". Better
yet, "I don't think it can happen and heres my reasoning...". The first
sounds like an arrogant fool while the second one sounds like a rational
human being. Ofcourse maybe you can convince most people with the
"authority" loic but its wrong and should specially not be used in a
scientific place.

If you disagree with something then just explain why. Don't act like you
know everything about everything because you could be wrong(not saying
you/they do this all the time but it happens to much in this NG).

I could be wrong on many things I say. I'm not perfect and I do not know
everthing. But I try to rationalize everything with proof. Sometimes my
logic is faulty and sometimes I use bad evidence. I will admit when I'm
wrong if there is good counter logic involved(and not the authoritative
logic). Maybe you guys were kings in another life and are used to having
everyone do what you say no questions asked?

Actually any reasonable person who has a desire for knowledge would love for
everything they say to be questioned because it gives them a chance to
understand explain to others and reinforce there own understanding(or change
them if necessary) there view. Many times when I have "argued" with others
I have come up with a better understanding of my own point of view.
Sometimes I have also realized that my original logic was quite shakey or
even wrong. This has happened to help me be self-analyzing on much a
greater scale than most. Although in the last couple of years I've lost
almost all that ability as I do not hang around with any intelligent people
any more. Maybe thats why I get defensive, I don't know. I guess I just see
this arrogance everywhere and I feel that it does no good for humanity. (Its
getting so bad that eventually everyone will not care what others think and
believe they are kings)

Anyways...

Jon Slaughter

Posted: Sun Feb 04, 2007 10:25 am

Guest

"John Fields" <jfields@austininstruments.com> wrote in message
news:g99as2pkr9ugvcobb2r7upq2ck7f50v71j@4ax.com...

Quote:

On Sat, 03 Feb 2007 08:13:46 GMT, "Jon Slaughter"
Jon_Slaughter@Hotmail.com> wrote:

"KILOWATT" <kilowatt"nospam"@softhome.net> wrote in message
news:45c3aa6d$0$31564$c3e8da3@news.astraweb.com...
Hi... thanks for your attention.

I just wish to know the precise reason why for example, a digital
counter
may count many pulses on it's clock input when the clock is feed via a
non
noise-free source like a mechanical switch. It is because when the
contacts
makes/breaks, arcing (i've read somewhere that there can be a
possibility
of
arcing even at low voltage) occurs, or if it's because of the very rough
surface (microscopically-speaking) of the switch contacts, were the
metal
molecules grinds (and possibly flexes) together, during switch
activation?
TIA for your reply.

The atoms of the two materials are not configured in such a way that there
is complete contact.

---
That's not true.

When the contacts come to rest after the bouncing period is over
they will either be in intimate contact or they will be completely
separated.
---

If they were then the materials would be fused.

---
Which, indeed, they are until the coil is de-energized and the
return spring exerts force on the armature, breaking the microscopic
weld(s) and allowing the contacts to open.
---

So can you shear a part a solid piece of metal with a spring? Its a matter
of degree. If the contact interface was completely "fused" then thee would
not be any contact interface(assuming the same material is used for both
contacts).

Quote:

Since there are not fused and they slide there is friction involved
and this friction causes the contacts to move farther a part and then
closer together.

---
No. The friction you're talking about is only about the contacts
rubbing against each other when they're making or breaking and is a
second order phenomenon compared to bounce, which occurs when the
contacts alternately make and break when the coil is energized.
Bounce also occurs when the armature is de-energized, but to a
lesser degree, and is caused by the moving contact skipping across
the stationary contact when the coil is de-energized.
---

The friction is due to electrical forces. There are only 4 known
forces(well, 4 main ones) in the world. Gravitations, Electrical, Strong and
weak. Gravitational is like 10^(-40) smaller than electrical. The strong
and weak work only as a sub-atomic level.

So are you saying there is some other forces involved?

Quote:

So the average distance between the constants is changing
significantly campared to when is not moving and they are making good
contact. So now the electric field is changing because of the distances
changing between the contacts. As the contacts move farther away the field
becomes weaker but now we have a capacitive effect. This effect creates a
force between the contacts that attract them. One now has a kinematic
force
pulling the contacts away(so it can slide), one of friction that wants to
stop the slide, and one of capacitance that is attractive(I'm sure there
are
more too).

---
No. The high-level bouncing behavior is due only to the gross
mechanical characteristics of the contacts and has vanishingly
little to do with the microscopic effects, which are at least six
orders of magnitude smaller than the mechanical effects, I'd guess.

Sure, but we are not talking about high level. The high level is strictly
due to the averging of the microscopic. See above about the forces.

Quote:

Do you have some hard numbers which would prove otherwise?

Yes I do. 4 forces, 1 is too weak to be of any use for this problem, the
other 2 are too weak at the distances we are discussing.

Here, I'll even get you a link with some pretty pictures:

http://hyperphysics.phy-astr.gsu.edu/hbase/forces/funfor.html

How do you explain yourself out of this one? Just cause you have a quarter
doesn't mean the quarter is smallest denomination. (Ok, stupid analogy but
works).

All of reality is based on these 4 forces(at the present understanding of
reality). You can ignore that fact and just look at the infituide of
outcomes that these forces produce but you are then neglecting what really
happens. Its even much more complicated than this but these are adaquate for
the OP's problem. He asked what was happening at this level and these are
the tools one has to use to explain it. You cannot explain something at a
lower level higher level tools(ok, maybe a little but theres no guarantee
that it will work).

John Fields

Posted: Sun Feb 04, 2007 12:59 pm

Guest

On Sun, 04 Feb 2007 14:16:42 GMT, "Jon Slaughter"
<Jon_Slaughter@Hotmail.com> wrote:

Quote:

"John Fields" <jfields@austininstruments.com> wrote in message
news:1vdas29f4io4odpptfbg3fkup2mpdpopso@4ax.com...
On Sat, 03 Feb 2007 21:58:27 GMT, "Jon Slaughter"
Jon_Slaughter@Hotmail.com> wrote:

...

Anyways...

Why are you being so angrily defensive?

Contact bounce is nothing more than a spring-loaded screen door
bouncing back from the jamb when it's let go early.

Because you guys always seem to think that your way is the right way. I know
you guys are not stupid but it seems that you take a simple view of the
world and if someone else wants more info then you act like they are stupid.
You think, say, that if you measure the V-I curve on a resistor and see that
it looks like a perfectly straight line then it must be.

---
To a first approximation, it is, and for the purposes of this
newsgroup that's good enough most of the time.
---

Quote:

You neglect all the other factors involved. This is fine if you don't care
about them but if someone else does then you tell them what you have
observed and that is what they should believe.

---
Yes. And rightfully so. In the absence of a specific request for
the microscopic, the macroscopic explanation will generally suffice.
If it doesn't, then the onus is on the querant to ask for more
detail. You seem to think that everyone wants to know the minutiae
of "why", and that's just not the case. In this instance the OP
asked for an explanation of why a noisy switch causes a counter to
count falsely, and the answer is: "Because the switch contacts make
and break many times before they settle down, causing multiple
transitions at the counter's clock input."

This can be shown to be true by using a mercury-wetted reed relay or
switch in place of a conventional switch. Doing that will result in
precisely one count made for each make-break cycle of the switch.

That suggests, to me, that the reasons you cited for the miscounts
(the electric field attracting or repelling the contacts, for one)
are flawed, since the very mobility of the mercury film would
certainly cause it to be more affected by that field than a big mass
on the end of a spring would be.
---

Quote:

To me, its like your trying to tell someone the world is flat.

---
It is, in places, so why shouldn't I tell them that if the micro
view is necessary?

You seem to be saying that when it's convenient for you to use the
macro view you will, but that no one else is allowed to.
---

Quote:

Now because it you believe it you don't doubt that it is.
It must be. It sounds as if you think you know everything.
And while you guys may not be wrong in most cases in some
way or another, usually you have an idealized or even a narrow
minded view of things. If you never experienced it then
it must not be possible.

---
Don't you think that lumping us all together as "you guys" is taking
a narrow-minded view of things? That is, you're doing exactly what
you say it's wrong for us to do.
---

Quote:

Usually when someone asks something one doens't get a response like "In my
experiences I have no had this happen" but instead "It can't happen". Now
the problem with the second is that history should have taught you that
nothing is impossible

---
Can you uncook an egg?
---

Quote:

but if you really believe it then you should have good reasons.
So just state them. "It can't happen and heres why...". Better
yet, "I don't think it can happen and heres my reasoning...". The first
sounds like an arrogant fool while the second one sounds like a rational
human being. Ofcourse maybe you can convince most people with the
"authority" loic but its wrong and should specially not be used in a
scientific place.

---
Sounds to me like you're getting a little authoritarian there.

In the first place, If I want to make an all-encompassing statement
and not back it up with proof, that's my business. I'm certainly
not bound by _your_ rules, and if you have a problem with the
statement, then the burden of proving it false is on you.
---

Quote:

If you disagree with something then just explain why.

---
Exactly.
---

Quote:

Don't act like you know everything about everything because
you could be wrong(not saying you/they do this all the time
but it happens to much in this NG).

---
Well, the very act of disagreeing with someone is saying: "I think
you're wrong" or just plain old: "You're wrong", which means that
you think you know more about it than they do, so if you disagree
with the way people post in this newsgroup that means that you know
better than they do about how they should post. Don't you agree?
---

Quote:

I could be wrong on many things I say. I'm not perfect and I do not know
everthing. But I try to rationalize everything with proof. Sometimes my
logic is faulty and sometimes I use bad evidence. I will admit when I'm
wrong if there is good counter logic involved(and not the authoritative
logic).

---
"If there is good counterlogic involved" means that you get to be
the judge of what is and what isn't good counterlogic, so you get to
be in the favorable position of deciding whether you're right or
wrong by deciding whether your opponent's logic is good or not
regardless of whether your opinion is right or wrong. Handy, no? Wink

---

Quote:

Maybe you guys were kings in another life and are used to having
everyone do what you say no questions asked?

---
Maybe.
---

Quote:

Actually any reasonable person who has a desire for knowledge would love for
everything they say to be questioned because it gives them a chance to
understand explain to others and reinforce there own understanding(or change
them if necessary) there view.

---
Not true. I wouldn't love being questioned in a hostile manner by a
person who is frustrated by his inability to understand the answer
to the question and is trying to prove me wrong because of his
inability to admit to being wrong.
---

Quote:

Many times when I have "argued" with others
I have come up with a better understanding of my own point of view.
Sometimes I have also realized that my original logic was quite shakey or
even wrong. This has happened to help me be self-analyzing on much a
greater scale than most. Although in the last couple of years I've lost
almost all that ability as I do not hang around with any intelligent people
any more.

---
What're we, chopped liver? Wink

---

Quote:

Maybe thats why I get defensive, I don't know. I guess I just see
this arrogance everywhere and I feel that it does no good for humanity. (Its
getting so bad that eventually everyone will not care what others think and
believe they are kings)

---
We _are_ all kings. Some of us just have bigger kingdoms.

--
JF

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