Holy Moly -- Residual Electricity????

[Prisoner at War]

Is there some such concept as "residual electricity"???

There was a problem with a computer at work...it's a new Dell running
WinXP Pro...everything's fine, I go to lunch and come back to a blank
screen that won't wake up from power-save/sleep mode!! I do the
obvious and check connections, making sure they're secure and
whatnot. I turn off the computer and turn it back on a few times, to
no effect!

Tech Support suspects some kind of a "power management" issue --
whatever that is -- and suggests that I leave the system off for a few
minutes, literally, to let things "clear"...whatever that means. Sure
enough, however: it works!

So now I'm here asking, because Tech hasn't the time to puzzle over it
with me, WHAT HAPPENED??? And how come shutting off power for a few
seconds isn't comparable to leaving power off for a few
minutes????????????

TIA!

 

[jimp]

Is there some such concept as "residual electricity"???

There was a problem with a computer at work...it's a new Dell running
WinXP Pro...everything's fine, I go to lunch and come back to a blank
screen that won't wake up from power-save/sleep mode!! I do the
obvious and check connections, making sure they're secure and
whatnot. I turn off the computer and turn it back on a few times, to
no effect!

Tech Support suspects some kind of a "power management" issue --
whatever that is -- and suggests that I leave the system off for a few
minutes, literally, to let things "clear"...whatever that means. Sure
enough, however: it works!

So now I'm here asking, because Tech hasn't the time to puzzle over it
with me, WHAT HAPPENED??? And how come shutting off power for a few
seconds isn't comparable to leaving power off for a few
minutes????????????

TIA!

Capacitors.

 

[Gordon]

Capacitors.

capacitors usually discharge when the current is switched off - their main
job is to smooth current, not to store volts....

 

[Unknown]

When you turn it off and leave it off for a few minutes, it allows the
capacitors in the power supply to discharge.
With the power supply caps discharged, you in effect are guaranteeing a good
power on reset when you power on.

 

[Jupiter Jones]

They discharge, but it can take some time depending on the capacitors.
A few minutes is not at all unusual.

 

[Lem]

capacitors usually discharge when the current is switched off - their main
job is to smooth current, not to store volts....

True, but they don't discharge instantaneously. Ever hear about the
"time constant" of an R-C circuit?

T = R × C
where:
T = time constant in seconds
R = resistance in ohms
C = capacitance in farads

The time constant is the time taken for the charging (or discharging)
current (I) to fall to 1/e of its initial value (Io).

After each time constant the current falls by 1/e (about 1/3). After 5
time constants (5RC) the current has fallen to less than 1% of its
initial value and we can reasonably say that the capacitor is fully
(dis)charged, but in fact the capacitor takes for ever to (dis)charge
fully!

--
Lem -- MS-MVP - Networking

To the moon and back with 4KB of RAM and 72KB of ROM.
http://en.wikipedia.org/wiki/Apollo_Guidance_Computer
http://history.nasa.gov/afj/compessay.htm

 

[Pegasus \(MVP\)]

capacitors usually discharge when the current is switched off - their main
job is to smooth current, not to store volts....

Capacitors don't store "volts" - they store "Coulombs".
Volt is a measure for "voltage" (or "electrical tension").
Coulomb is a measure for electrical charge. The main
purpose of a capacitor is not to smooth current but to
keep the voltage constant, regardless of the current
supplied or drawn.

 

[Tom Lake]

They discharge, but it can take some time depending on the capacitors.
A few minutes is not at all unusual.

You can get some nasty burns from a TV that's unplugged due to those
things!

Tom Lake

 

[Gordon]

Capacitors don't store "volts" - they store "Coulombs".
Volt is a measure for "voltage" (or "electrical tension").
Coulomb is a measure for electrical charge. The main
purpose of a capacitor is not to smooth current but to
keep the voltage constant, regardless of the current
supplied or drawn.

I did Physics A level in 1973!

 

[Androcles]

: : >
: > Capacitors.
: >
:
:
: capacitors usually discharge when the current is switched off - their main
: job is to smooth current, not to store volts....

That shows how much you know -- which is zilch.

 

[Gordon]

: : >
: > Capacitors.
: >
:
:
: capacitors usually discharge when the current is switched off - their
main
: job is to smooth current, not to store volts....

That shows how much you know -- which is zilch.

Well rooty toot to you.

 

[Androcles]

: : >
: > : > : : > : >
: > : > Capacitors.
: > : >
: > :
: > :
: > : capacitors usually discharge when the current is switched off - their
: > main
: > : job is to smooth current, not to store volts....
: >
: > That shows how much you know -- which is zilch.
: >
: >
:
:
: Well rooty toot to you.

That shows just how childish you are.

 

[Gordon]

: : >
: > : > : : > : >
: > : > Capacitors.
: > : >
: > :
: > :
: > : capacitors usually discharge when the current is switched off -
their
: > main
: > : job is to smooth current, not to store volts....
: >
: > That shows how much you know -- which is zilch.
: >
: >
:
:
: Well rooty toot to you.

That shows just how childish you are.

Sod you you arrogant ignorant moron.
Capacitors ARE used to smooth current so just crawl back under your slimy
rock...

 

[Pegasus \(MVP\)]

I did Physics A level in 1973!

Then you need to be careful with capacitors, to avoid
getting zapped!

 

[Jim]

I did Physics A level in 1973!

Well, I studied College Physics in 1949, but I still know that a capacitor
stores energy not voltage. Coulomb is a measure of electrical energy.

Jim

 

[Bill Sharpe]

I did Physics A level in 1973!

I'm way ahead of you. Physics 1 in Fall 1949, Physics 2 is Spring 1950,
grades D and A respectively. And, no, I don't remember what we covered
in each semester...

Bill

 

[Pegasus \(MVP\)]

Well, I studied College Physics in 1949, but I still know that a capacitor
stores energy not voltage. Coulomb is a measure of electrical energy.

Jim

Nope. Coulomb is a measure of electrical charge. Joule (or Watt-second)
is a measure of electrical energy.

 

[Androcles]

: : >
: > : > : : > : >
: > : > : > : > : : > : > : >
: > : > : > Capacitors.
: > : > : >
: > : > :
: > : > :
: > : > : capacitors usually discharge when the current is switched off -
: > their
: > : > main
: > : > : job is to smooth current, not to store volts....
: > : >
: > : > That shows how much you know -- which is zilch.
: > : >
: > : >
: > :
: > :
: > : Well rooty toot to you.
: >
: > That shows just how childish you are.
: >
: >
:
: Sod you you arrogant ignorant moron.
: Capacitors ARE used to smooth current so just crawl back under your slimy
: rock...

That shows just how stupid you really are, you don't even know
the difference between voltage and current.
HAHAHA!

 

[Guest]

Technically, caps store electricity and discharge it, at a specified rate.
and yes they can store it like a battery.

 

[Guest]

I'm sure you guys have heard of starting caps???
used when you have a high horsepower electrical motor that needs a high
surge just when starting?? like motors used in freezers, or heat pumps, same
concept.
can we save the insults, and have a regular discussion, not an arguement.