D
David
Energy= 1/2(C*V^2)Jim said:
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G
Gerald Newton
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!
Yes,To the moon and back with 4KB of RAM and 72KB of ROM.
So why can't some one harness nuclear fusion for our energy needs?
H
HeyBub
Bill said: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...
Semester 1: Mechanics
Semester 2: Heat, Light, Sound
Semester 3: Electricity & Magnetism
No, wait...
H
HeyBub
Prisoner said: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????????????
You're going to get a lot of theory here, but the real answer is: The power
supply's broke.
?
=?iso-8859-1?Q?_db_=B4=AF`=B7.._=3E=3C=29=29=29=BA
Well,
when the pc is powered down
it is important to wait for
the disks inside the hard drive(s)
to stop spinning before powering
them up again. Usually 20 seconds
is good waiting period before
powering your pc up again.
This helps prevents a surge
and reduces the wear and tear
on those tiny little motors.
As for the residual electricity
it depends on what kind of
capacitors they are.
They are designed with different
specifications. Some hold large
charges of electricity and some hold
miniscule amounts. Some are designed
to release their charges frequently
while others are designed to hold
them until something or someone
grounds them.
However the above on
residual electricity is only
a consideration when accessing
the internals of pc.
Electronics are not unlike
light bulbs, in that they can
handle being turned on and off
frequently. However, the
motors need time to
slow down and stop before
powering them again.
--
..
when the pc is powered down
it is important to wait for
the disks inside the hard drive(s)
to stop spinning before powering
them up again. Usually 20 seconds
is good waiting period before
powering your pc up again.
This helps prevents a surge
and reduces the wear and tear
on those tiny little motors.
As for the residual electricity
it depends on what kind of
capacitors they are.
They are designed with different
specifications. Some hold large
charges of electricity and some hold
miniscule amounts. Some are designed
to release their charges frequently
while others are designed to hold
them until something or someone
grounds them.
However the above on
residual electricity is only
a consideration when accessing
the internals of pc.
Electronics are not unlike
light bulbs, in that they can
handle being turned on and off
frequently. However, the
motors need time to
slow down and stop before
powering them again.
--
db ·´¯`·.¸. said:<)))º>·´¯`·.¸. , . .·´¯`·.. ><)))º>`·.¸¸.·´¯`·.¸.·´¯`·...¸><)))º>
..
A
Androcles
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_Computerhttp://history.nasa.gov/afj/compessay.htm
Yes,To the moon and back with 4KB of RAM and 72KB of ROM.
So why can't some one harness nuclear fusion for our energy needs?
1) Don't need to, your energy needs are really your energy wants.
Mankind can survive without the inefficient use of energy and has
done for millions of years, as do all other species on this planet.
There is a huge difference between need and want.
2) The equations are wrong, the fools are fiddling with Einstein's
relativity and it doesn't work.
So why can't *you* harness nuclear fusion for *my* energy wants?
U
Unknown
No it's not!
HeyBub said:You're going to get a lot of theory here, but the real answer is: The
power supply's broke.
U
Unknown
GREAT spoof!
db ´¯`·.. > said:Well,
when the pc is powered down
it is important to wait for
the disks inside the hard drive(s)
to stop spinning before powering
them up again. Usually 20 seconds
is good waiting period before
powering your pc up again.
This helps prevents a surge
and reduces the wear and tear
on those tiny little motors.
As for the residual electricity
it depends on what kind of
capacitors they are.
They are designed with different
specifications. Some hold large
charges of electricity and some hold
miniscule amounts. Some are designed
to release their charges frequently
while others are designed to hold
them until something or someone
grounds them.
However the above on
residual electricity is only
a consideration when accessing
the internals of pc.
Electronics are not unlike
light bulbs, in that they can
handle being turned on and off
frequently. However, the
motors need time to
slow down and stop before
powering them again.
--
.
T
Tony Harding
Gordon said:capacitors usually discharge when the current is switched off - their main
job is to smooth current, not to store volts....
But it's not instantaneous, which can be seen easily by turning off your
computer, unplugging it from the wall/USP and pressing the computer's ON
switch. What you're doing is bleeding off the charge left behind by the
Instant On feature (keeps the mobo hot). This bleeds off pretty quickly
on its own.
IIRC I've seen big warning stickers on TVs/monitors warning of 1,000 of
volts if you go poking inside.
http://icrontic.com/forum/showthread.php?p=241556
?
=?iso-8859-1?Q?_db_=B4=AF`=B7.._=3E=3C=29=29=29=BA
Well,
when the pc is powered down
it is important to wait for
the disks inside the hard drive(s)
to stop spinning before powering
them up again. Usually 20 seconds
is good waiting period before
powering your pc up again.
This helps prevents a surge
and reduces the wear and tear
on those tiny little motors.
As for the residual electricity
it depends on what kind of
capacitors they are.
They are designed with different
specifications. Some hold large
charges of electricity and some hold
miniscule amounts. Some are designed
to release their charges frequently
while others are designed to hold
them until something or someone
grounds them.
However the above on
residual electricity is only
a consideration when accessing
the internals of pc.
Electronics are not unlike
light bulbs, in that they can
handle being turned on and off
frequently. However, the
motors need time to
slow down and stop before
powering them again.
--
..
when the pc is powered down
it is important to wait for
the disks inside the hard drive(s)
to stop spinning before powering
them up again. Usually 20 seconds
is good waiting period before
powering your pc up again.
This helps prevents a surge
and reduces the wear and tear
on those tiny little motors.
As for the residual electricity
it depends on what kind of
capacitors they are.
They are designed with different
specifications. Some hold large
charges of electricity and some hold
miniscule amounts. Some are designed
to release their charges frequently
while others are designed to hold
them until something or someone
grounds them.
However the above on
residual electricity is only
a consideration when accessing
the internals of pc.
Electronics are not unlike
light bulbs, in that they can
handle being turned on and off
frequently. However, the
motors need time to
slow down and stop before
powering them again.
--
db ·´¯`·.¸. said:<)))º>·´¯`·.¸. , . .·´¯`·.. ><)))º>`·.¸¸.·´¯`·.¸.·´¯`·...¸><)))º>
..
L
Leythos
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????????????
The issue is with a cheap motherboard that doesn't properly recover from
Power Management settings.
Yes, capacitors have to be drained down over a couple minutes in some
cases, but they are not the symptom of the real problem - the real
problem is a crappy APM or motherboard.
--
Leythos
- Igitur qui desiderat pacem, praeparet bellum.
- Calling an illegal alien an "undocumented worker" is like calling a
drug dealer an "unlicensed pharmacist"
(e-mail address removed) (remove 999 for proper email address)
U
Unknown
Another spoof!
Leythos said:The issue is with a cheap motherboard that doesn't properly recover from
Power Management settings.
Yes, capacitors have to be drained down over a couple minutes in some
cases, but they are not the symptom of the real problem - the real
problem is a crappy APM or motherboard.
--
Leythos
- Igitur qui desiderat pacem, praeparet bellum.
- Calling an illegal alien an "undocumented worker" is like calling a
drug dealer an "unlicensed pharmacist"
(e-mail address removed) (remove 999 for proper email address)
J
John
Gordon said:capacitors usually discharge when the current is switched off - their main
job is to smooth current, not to store volts....
What utter crap.
John.
J
John
And failed by the sound of things.Gordon said:I did Physics A level in 1973!
John.
A
Androcles
: Gordon wrote:
: > : >> Capacitors.
: >>
: >
: >
: > capacitors usually discharge when the current is switched off - their
main
: > job is to smooth current, not to store volts....
: >
: >
:
: What utter crap.
:
: John.
Not only is it utter crap, the arrogant little prick gets bent out of
shape when you call him on it.
: > : >> Capacitors.
: >>
: >
: >
: > capacitors usually discharge when the current is switched off - their
main
: > job is to smooth current, not to store volts....
: >
: >
:
: What utter crap.
:
: John.
Not only is it utter crap, the arrogant little prick gets bent out of
shape when you call him on it.
T
**THE-RFI-EMI-GUY**
It was just before the end of the tech support guys shift and he wanted
enough time to escape from your call back if it didn't work!
enough time to escape from your call back if it didn't work!
--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©
"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."
"Follow The Money" ;-P
enough time to escape from your call back if it didn't work!
It was just before the end of the tech support guys shift and he wanted(snip)
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!
enough time to escape from your call back if it didn't work!
--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©
"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."
"Follow The Money" ;-P
L
Leythos
Another spoof!
Not at all, if the system won't come out of suspend properly, since it's
not a Windows issue, it's almost always the result of bad quality of the
motherboard / BIOS. Seen it hundreds of times, and that's one reason to
not buy cheap crap.
--
Leythos
- Igitur qui desiderat pacem, praeparet bellum.
- Calling an illegal alien an "undocumented worker" is like calling a
drug dealer an "unlicensed pharmacist"
(e-mail address removed) (remove 999 for proper email address)
N
nottoooily
:: >
: > 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.
He's right. In a computer that's what they're for. Sure they can still
store charge without any current flowing, but that's not their
intended purpose. Many of them will automatically discharge straight
away into the heavy loads they're connected to. But in the power
supply are capacitors which do retain their charge after switching
off.
Not sure what this has to do with stopping the computer from working,
clearly there's an actual problem that should be fixed to prevent it
happening again.
U
Unknown
No he's not. Capacitors do NOT smooth current. They reduce or eliminate
voltage fluctuations.
voltage fluctuations.
U
Unknown
What spoof!
db ´¯`·.. > said:Well,
when the pc is powered down
it is important to wait for
the disks inside the hard drive(s)
to stop spinning before powering
them up again. Usually 20 seconds
is good waiting period before
powering your pc up again.
This helps prevents a surge
and reduces the wear and tear
on those tiny little motors.
As for the residual electricity
it depends on what kind of
capacitors they are.
They are designed with different
specifications. Some hold large
charges of electricity and some hold
miniscule amounts. Some are designed
to release their charges frequently
while others are designed to hold
them until something or someone
grounds them.
However the above on
residual electricity is only
a consideration when accessing
the internals of pc.
Electronics are not unlike
light bulbs, in that they can
handle being turned on and off
frequently. However, the
motors need time to
slow down and stop before
powering them again.
--
.
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