fibre washers
The little lost angel
<day_t...@REMOVEyahoo.com> wrote:
>Unless your ohm meter can read inductance, what might be the point of your
What is this inductance thingy?
I've been trying to figure this out but searches just makes it more
confusing, from inductance I end up with inductive reactance, which
seems like resistance except it isn't and works only on AC? *confused*
What exactly is the practical difference between low inductance
resistor and a high inductance resistor?
Thanks! :D
Grasso
>I've been trying to figure this out but searches just makes it more
>confusing, from inductance I end up with inductive reactance, which
>seems like resistance except it isn't and works only on AC? *confused*
(Although Keith may want to correct me):
Resistance is the real part of impedance while reactance is the
imaginary part of impedance. For an understanding of real and
imaginary values look up "complex numbers". Often people use the word
resistance also for the norm of the impedance vector.
A coil is an inductance. It´s magnetic. If you turn on a power source
on a coil (i.e. apply a pulse), the current lags after the voltage.
A cap is an capacitance. It´s electrostatic. If you turn on a power
source on a cap (i.e. apply a pulse), the voltage lags after the
current.
>What exactly is the practical difference between low inductance
>resistor and a high inductance resistor?
The latter has a higher resistance for high frequencies than the
former.
The problem Eric talks about is that modern PC mainboards contain a
switching power supply for CPU core voltage and another one in the
PSU. They operate at high frequencies, hence serial impedances in
power supply wires can cause error voltages which in turn can lead to
data corruption. Any electronics designer can confirm that noise
caused by digital circuits tends to leak into everywhere, also
degrading performance of analogue circuits (soundcards, RAMDACs). In
times when a i386 used no more than 1W this problem was hardly
existent, but today it can be very bad. CRT monitors also contain a
switcher and can make a PC crash if badly designed.
I claim that due to such HF issues (see also low-quality caps, cheap
PCB layout, lacking termination resistors, parasitic capacitances, AGP
woes, i820 MTH bug, KT133 133MHz startup failure, wrong RAM timings,
etc.) a third of all sold PCs face frequent data corruption.
Uli
--
------- http://grassomusic.de -------
R. Anton Rave
> What exactly is the practical difference between low inductance
> resistor and a high inductance resistor?
With non-inductive resistors, I was unable to destroy all the output
transistors in my homemade audio amplifier, but with the other type it
was easy.
But for uses where induction won't be a problem, inductive resistors,
which are usually wire wound, can be more reliable, accurate,
temperature stable, and cause less noise than composition resistors.
I don't know how they stack up against metal film resistors (they can
be inductive, too, because of the spiral cut), but wire wounds are
still more common for high power.
Ralph Wade Phillips
"The little lost angel" <a?n?g?e?l...@lovergirl.lrigrevol.moc.com> wrote in
message news:3d27de56....@news.pacific.net.sg...
> On Sat, 06 Jul 2002 19:08:24 -0400, daytripper
> <day_t...@REMOVEyahoo.com> wrote:
> >Unless your ohm meter can read inductance, what might be the point of
your
>
> What is this inductance thingy?
It's the measure of how much reactance an inductor has.
Look at it this way - If you coil up wires, DC goes through it just
fine, but the higher the frequency, the more the coil resists the changing
voltage. That's inductance. How much it impedes the voltage is impedance.
Hence the "8 Ohm Impedance" rating on speakers ...
> I've been trying to figure this out but searches just makes it more
> confusing, from inductance I end up with inductive reactance, which
> seems like resistance except it isn't and works only on AC? *confused*
Why confused? A coil of wire has a DC resistance, and at higher
frequency, resists AC better and better as the frequencies get higher and
higher.
>
> What exactly is the practical difference between low inductance
> resistor and a high inductance resistor?
You'd not want to use either as an output in an RF-sensitive curcuit
<grins>
RwP
Eric
> What is this inductance thingy?
> I've been trying to figure this out but searches just makes it more
> confusing, from inductance I end up with inductive reactance, which
> seems like resistance except it isn't and works only on AC? *confused*
Inductance is the resistance that a wire or circuit has to a *change* in
current flow. Resistance is basically a steady state DC term. Inductance
is an AC or pulsing DC term. Because of the changing voltage of high
frequency noise, the inductance of the wire it traverses must be low.
Think of a hose that will not allow sudden increases in water flow,
but will accept the increased flow gradually. That hose has a high
"inductance", yet a low resistance.
> What exactly is the practical difference between low inductance
> resistor and a high inductance resistor?
A high inductance resistor is typically wire-wound, and a low inductance
resistor is generally carbon or carbon fibre. Low inductance wire-wound
can be made (and are) but are wound specially to keep inductance low.
High inductance resistors should not be used if the current through
them changes at high frequencies. In such cases, the instantaneous
impedance of that resistor is higher than the DC resistance. Again,
think of the hose analogy.
--
Better than hearing "Lady Day", or checking in at Monterey...
[Remove bodies from address for email.]
Keith R. Williams
gras...@hotmail.com says...
> >What is this inductance thingy?
> >I've been trying to figure this out but searches just makes it more
> >confusing, from inductance I end up with inductive reactance, which
> >seems like resistance except it isn't and works only on AC? *confused*
>
> (Although Keith may want to correct me):
Nope. Only ignore you. You have nothing to say, but you'll
wander off anyway.
>
> Resistance is the real part of impedance while reactance is the
> imaginary part of impedance. For an understanding of real and
> imaginary values look up "complex numbers". Often people use the word
> resistance also for the norm of the impedance vector.
>
> A coil is an inductance. It´s magnetic. If you turn on a power source
> on a coil (i.e. apply a pulse), the current lags after the voltage.
>
> A cap is an capacitance. It´s electrostatic. If you turn on a power
> source on a cap (i.e. apply a pulse), the voltage lags after the
> current.
>
> >What exactly is the practical difference between low inductance
> >resistor and a high inductance resistor?
>
> The latter has a higher resistance for high frequencies than the
> former.
>
> The problem Eric talks about is that modern PC mainboards contain a
> switching power supply for CPU core voltage and another one in the
> PSU. They operate at high frequencies,
Yep, wandering again. This has nothing to do with the issue at
hand. One word: "capacitors".
> hence serial impedances in
> power supply wires can cause error voltages which in turn can lead to
> data corruption. Any electronics designer can confirm that noise
> caused by digital circuits tends to leak into everywhere, also
> degrading performance of analogue circuits (soundcards, RAMDACs).
Are we in Kansas yet?
> In
> times when a i386 used no more than 1W this problem was hardly
> existent, but today it can be very bad. CRT monitors also contain a
> switcher and can make a PC crash if badly designed.
Nope, Toto! ...there is nothing like home, there is nothing like
home, there...
> I claim that due to such HF issues (see also low-quality caps, cheap
> PCB layout, lacking termination resistors, parasitic capacitances, AGP
> woes, i820 MTH bug, KT133 133MHz startup failure, wrong RAM timings,
> etc.) a third of all sold PCs face frequent data corruption.
Yawn! What's this got to do with the price of oats? Please try
to stay on subject! I know even you can do it, if you truly
*believe*.
----
Keith
Jack
news:MPG.179410458...@enews.newsguy.com...
: In article <01tfiu0iale1odrpt...@4ax.com>,
: gras...@hotmail.com says...
: > >What is this inductance thingy?
: > >I've been trying to figure this out but searches just makes it more
: > >confusing, from inductance I end up with inductive reactance, which
: > >seems like resistance except it isn't and works only on AC?
*confused*
: >
: > (Although Keith may want to correct me):
:
: Nope. Only ignore you. You have nothing to say, but you'll
: wander off anyway.
<snip>
: Are we in Kansas yet?
:
: > In
: > times when a i386 used no more than 1W this problem was hardly
: > existent, but today it can be very bad. CRT monitors also contain a
: > switcher and can make a PC crash if badly designed.
:
: Nope, Toto! ...there is nothing like home, there is nothing like
: home, there...
Correction: There's **no place** like home, there's no place like home...
:
: > I claim that due to such HF issues (see also low-quality caps, cheap
: > PCB layout, lacking termination resistors, parasitic capacitances, AGP
: > woes, i820 MTH bug, KT133 133MHz startup failure, wrong RAM timings,
: > etc.) a third of all sold PCs face frequent data corruption.
:
: Yawn! What's this got to do with the price of oats? Please try
: to stay on subject! I know even you can do it, if you truly
: *believe*.
Ha ha ha....ya think? ;-)
J.
Keith R. Williams
> "Keith R. Williams" <k...@attglobal.net> wrote in message
> news:MPG.179410458...@enews.newsguy.com...
> : In article <01tfiu0iale1odrpt...@4ax.com>,
> : gras...@hotmail.com says...
> : > >What is this inductance thingy?
> : > >I've been trying to figure this out but searches just makes it more
> : > >confusing, from inductance I end up with inductive reactance, which
> : > >seems like resistance except it isn't and works only on AC?
> *confused*
> : >
> : > (Although Keith may want to correct me):
> :
> : Nope. Only ignore you. You have nothing to say, but you'll
> : wander off anyway.
> : >
> <snip>
>
> : Are we in Kansas yet?
> :
> : > In
> : > times when a i386 used no more than 1W this problem was hardly
> : > existent, but today it can be very bad. CRT monitors also contain a
> : > switcher and can make a PC crash if badly designed.
> :
> : Nope, Toto! ...there is nothing like home, there is nothing like
> : home, there...
>
> Correction: There's **no place** like home, there's no place like home...
In the pursuit of (non political) correctness, honesty, and
objectivity, correction noted and accepted. ;-)
----
Keith