uf, pf, mfd???
Watts
What is the difference between uf, pf, and mfd? Are they
convertable between one and other, or are they all totally different
measurements?
Jason
anthony kelly
In article <4uss9o$q...@sjx-ixn4.ix.netcom.com>, wat...@ix.netcom.co
says...
capacitance. However a farad is quite a large capacitance, for example a
parallel plate capacitor with two plates of 100cmē seperated by 1mm would
have a capacitance of around 80 pf.
The 'p' and 'ĩ' before the 'f' are called Standard Decimal
Prefixes which are abbreviations to create sub-units.
'pf' = pico-farad = 10Ŋđē = 0.000000000001 farad.
'ĩf' = micro-farad = 10^-6 = 0.000001 farad
Please note that since I don't know how to get small numbers on the
screen I am using the following notation -
10^2 = 10ē = 10 to the power of 2
10^3 = 10ģ = 10 '' 3 etc..
The ones I remember are
Prefix Abbreviation Multiplier
tera T 10đē
giga G 10^9
mega M 10^6
kilo k 10ģ
hecto h 10ē
deka da 10đ
deci d 10Ŋđ
centi c 10Ŋē
milli m 10Ŋģ
micro ĩ 10^-6
nano n 10^-9
pico p 10Ŋđē
femto f 10^-15
atto a 10^-18
I don't recognise 'mfd'. Perhaps if you put it into context it
might be recognisable.
Regards
Anthony ;o]
Paul Maurer
Watts wrote:
> What is the difference between uf, pf, and mfd? Are they
>convertable between one and other, or are they all totally different
>measurements?
>
>Jason
I am assuming you are talking about capacitors.
uf = microfarad (actually the similar looking greek char instead of u)
pf = picofarad
mfd= millifarad (I think)
They are simply a difference in order of magnitude, kind of like the
difference between a centimeter and a millimeter. A pf is one million
times smaller than a microfarad which is 1000 times smaller than a
millifarad (one thousandth of a farad). In other words 1x10^12 pf = 1x10^6
uf = 1000 mfd = 1 farad.
The basic unit of capacitance is the farad, a very large amount.
Capacitance is determined by the amount of static charge it can hold per
unit of electromotive force. One farad is equal to a coulomb per volt
(F=C/V).
--
Paul Maurer
maur...@pgh.net
Michael W. Moran
I've seen "mfd" used quite often where the context made it obvious
that the proper unit was microfarads.
Hopefully not too far off-topic, I'm curious to know why there seems
to be such an aversion to the unit "nanofarads" here in the U.S. It's
commonly used elsewhere, but when I've included it in schematics the
reactions have ranged from puzzlement to outright annoyance.
We have no problem stopping at K's on the way between ohms and megs,
so why do "1000 pF" or ".001 uF" seem to be preferable to the simple and
logical "1 nF"?
Maybe this is related to the similar aversion to the "4K7" notation
which also, at least to me, makes a great deal of sense.
Daniel Tavares
Paul Maurer wrote:
>
> Watts wrote:
>
> > What is the difference between uf, pf, and mfd? Are they
> >convertable between one and other, or are they all totally different
> >measurements?
> >
>
>
> uf = microfarad (actually the similar looking greek char instead of u)
> pf = picofarad
> mfd= millifarad (I think)
>
(micromicrofarads or mickey-mikes) which is now called picofarad.
Dan T
Jeff Gruszynski
Paul Maurer (maur...@pgh.net) wrote:
: uf = microfarad (actually the similar looking greek char instead of u)
: pf = picofarad
: mfd= millifarad (I think)
Well, actually not, but it should be. :-)
mfd is *micro*farad. Yes, it is *not* following the prefix convention
properly, but it's from the time before that kind of stuff was
standardized by international convention (like when people used
"megacycles" instead of "megaherz"). You'll typically see "mfd" on
older radio equipment capacitors (like those big-old paper or
electrolytic capacitors) and/or older schematics.
Minor point: farads is always 'F', and not 'f'. (uF, pF, nF)
Jeff
--
=============================================================================
Jeff Gruszynski Any Standard Disclaimers Apply
Test & Measurement Webmaster
Hewlett-Packard Company
=============================================================================
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Richard Steven Walz
In article <32129D...@cts1.internetwis.com>,
Well it does have to do with the cultural inertia of 250 million
people who speak the same language and won the biggest war ever, but
the nano- prefix was simply not well known here till more recently.
Being both holdouts on the metric system and on its prefixes, we had
adapted them for physics/electronics ONLY, for a while. The use of
milli was older, and the use of micro was older than the Metrique or
the SI system more recently, and they were a part of our language for
quite a while. Microscope, micrometer, etc. even though things like
that were in inches!! But the vague idea was about, that milli meant
1000, and micro was a bunch smaller, so they became 1/10^3 and 1/10^6,
respectively. And if things had to be smaller, we concatenated them,
such as micro-micro-Farad, writtem mmF for a long time. And they saw a
number on the little disk caps, but they saw no "p", so they just knew
those were "mickey-micks", the jargon for pico at the time. So, as you
see, there was just no natural place to introduce the nano- prefix.
Americans had rejected the attempt to metricize, and so now their
children or their children WILL finally get it. The prefix on the
placeholder's spot for the decimal just looked like mixing factor
labels and quantities too much to Americans, who were used to those
being perfectly separated. If Americans had learned more scientific
notation, this would not have been a problem, but there IS an
anti-intellectual streak in Americans, so that some would almost
rather pretend ignorance than admit they knew more than the guy next
to them. It was an anti-classist American ideal, but it is a dumbing-
down force in American life. The two things you mention are a little
different, but they irritate Americans because we wish to feel that we
are the most powerful cultrue on earth. It might be true, and IF so, we
see no reason to accept new ways from ANYONE who might be from a "lesser"
civilization. I don't think this way, mind you, but many Americans DO!
But physics has pretty firmly adopted the SI, and so, sooner or later,
the metric SI will have a larger label on the package and the english
will be the smaller. And a couple generations will simply have to die
off to allow its acceptance commonly! It will happen, as they use
mostly metric with kids in school now. As you bend the sapling so
grows the tree.
-Steve Walz rst...@armory.com http://www.armory.com/~rstevew/
--
-Lots of New FTP Electronics Stuff!! 500 Files/27 Dirs (Full Mirror ==> *)
-Steve Walz rst...@armory.com ftp://ftp.armory.com:/pub/user/rstevew *
Italy: ftp://ftp.cised.unina.it:/pub/electronics/mirrors.ftp.armory.com *
USA: ftp://ieee.cas.uc.edu: Don't bother! Not keeping up their Mirroring!
Gary Morris
Watts wrote:
>
> What is the difference between uf, pf, and mfd? Are they
> convertable between one and other, or are they all totally different
> measurements?
>
Anthony Kelley posted a reply addressing uf and pf.
"mfd" is an older term that means exactly the same as "uf." That is,
"mfd" stands for "micro farad." My guess is that "mfd" was replaced by
"uf" to make a clear distinction in view of the standard use of "m" to
mean "milli" or .001.
"mmfd", meaning micro-micro farad was once in common use, also, and
means the same as pf, In other words, mmfd = pf = .000000000001 farad.
--
Gary Morris
gmo...@gv.net
pspray
> What is the difference between uf, pf, and mfd? Are they
>convertable between one and other, or are they all totally different
>measurements?
The basic capacitance measurement is the farad (F). This is the value of a
capacitor that would show one volt across it if it held a charge of one
coulomb. That means that if you shoved one ampere into it for one second,
it would build up to one volt.
Unfortunately, the farad is a *large* unit - working with it is like trying
to measure your neck for a shirt with a tape measure marked in miles.
So, we use the metric prefixes to get us smaller units, just like
millimeters and centimeters. All of our electrical quantities are metric to
start with, so there's no conversion required.
What you show as uF should really be the Greek letter mu in front (can't do
a mu on the Net since that character is not in the 7-bit ASCII set and
standard 7-bit ASCII is what the Net runs on). The prefix means one
millionth, or 10^(-6) of whatever the unit that it is in front of is.
In a lot of the old literature you would see mfd, which means the same
thing, one millionth of a farad. The other one, pF, means a millionth of a
millionth, or 10^(-12). The old literature would sometimes use mmfd for
this, but good metric usage discourages "stacking" prefixes.
The other one you will see in recent literature is nF, which is 10^(-9) of a
farad.
So, 1.0 F = 1 000 000.0 uF
1.0 uF = 1 000.0 nF
1.0 uF = 1 000 000.0 pF
1000 pF = 1.0 nF
etc...
-- pHil
David Gibson
wat...@ix.netcom.com(Watts) wrote:
> What is the difference between uf, pf, and mfd? Are they
>convertable between one and other, or are they all totally different
>measurements?
>Jason
Jason,
mfd and uF are the same, both 'microfarad'. A uF is one millionth of a
Farad.
pF is a millionth of a uF, sometimes referred to as uuF or
'micro-mike'
In between you have nF (nano Farad) which is a billionth of a Farad.
The prefixes are the ones common in scientific terminology:
milli = 1 E-3
micro = 1 E-6
nano = 1 E-9
pico = 1 E-12
femto = 1 E-15
Read E-3 as 10 to the power -3 i.e. 0.001 etc.
David Gibson
Microconsultants http://www.microconsultants.com
Makers of SPLat easy to use programmable controller
Visit our site for free software for SPLat
and Statistical Process Control
anthony kelly
In article <4v0q1e$s...@services.arn.net>, psp...@arn.net says...
>
>What you show as uF should really be the Greek letter mu in front (can't
do
>a mu on the Net since that character is not in the 7-bit ASCII set and
>standard 7-bit ASCII is what the Net runs on).
Hey look at this
ตตตตตตต and even ตตต and so on
Regards
Anthony ;o] ต
Ireland
Michael W. Moran
STEVE:
Well put, and I think (unfortunately) pretty accurate. Stubbornness
is one of our (speaking as a US citizen) less admirable traits in these
areas. I guess we'll have to be patient with our less-enlightened peers
(excuse me for a moment whilst I don my flame-resistant suit), keep
using the units we think make the most sense, and let the industry sort
things out.
Mike
Scott Hinman
Paul Maurer wrote:
>
> Watts wrote:
>
> > What is the difference between uf, pf, and mfd? Are they
> >convertable between one and other, or are they all totally different
> >measurements?
> >
> >Jason
>
>
> pf = picofarad
> mfd= millifarad (I think)
>
> difference between a centimeter and a millimeter. A pf is one million
> times smaller than a microfarad which is 1000 times smaller than a
> millifarad (one thousandth of a farad). In other words 1x10^12 pf = 1x10^6
> uf = 1000 mfd = 1 farad.
>
> The basic unit of capacitance is the farad, a very large amount.
> Capacitance is determined by the amount of static charge it can hold per
> unit of electromotive force. One farad is equal to a coulomb per volt
> (F=C/V).
>
> --
>
> Paul Maurer
> maur...@pgh.net
Actually, mfd in electonics is microfarads, the same as ufd, even thoug
the prefix "m" does indicate milli in almost every other discipline.
Its curious how this came about.
Cheers, Scott
Sam Goldwasser
> I am assuming you are talking about capacitors.
> uf = microfarad (actually the similar looking greek char instead of u)
> pf = picofarad
> mfd= millifarad (I think)
mfd may simply be another abbreviation for uF as in MicroFaraD.
In general:
p=pico=10E-12
n=nano=10E-9
u=micro=10E-6
m=milli=10E-3 (but may not apply in this case).
--- sam
> They are simply a difference in order of magnitude, kind of like the
> difference between a centimeter and a millimeter. A pf is one million
> times smaller than a microfarad which is 1000 times smaller than a
> millifarad (one thousandth of a farad). In other words 1x10^12 pf = 1x10^6
> uf = 1000 mfd = 1 farad.
> The basic unit of capacitance is the farad, a very large amount.
> Capacitance is determined by the amount of static charge it can hold per
> unit of electromotive force. One farad is equal to a coulomb per volt
> (F=C/V).
> Paul Maurer
> maur...@pgh.net
L. West
Great. Now... How'd you do that?
Did you use the <Alt> <3-digit number> combo?
L. West
L...@engr.uark.edu
.................