Author Topic: Millifarad VS Microfarad abbreviation  (Read 13801 times)

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Offline Kiriakos-GR

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Millifarad VS Microfarad abbreviation
« on: July 01, 2011, 01:29:50 pm »
Ok it took me some time to realize that  1mF = 1000uF  :)  ( an dusting the theory)

But from the other side,  what is commonly used or called as correct so to describe one capacitor
like  20.000 uF  Or 20mF ?
What do you use mostly in your village ?    :D

 

Offline Ronnie

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Re: Millifarad VS Microfarad abbreviation
« Reply #1 on: July 01, 2011, 01:47:44 pm »
I use the Greek small letter mu (µ can be inserted using Microsoft Symbol) to specify micro (10^-6) and m for milli (10^-3). I've noticed most used the small letter u instead of µ for micro to save time   ???
 

Offline Frangible

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Re: Millifarad VS Microfarad abbreviation
« Reply #2 on: July 01, 2011, 01:48:09 pm »
As far as I can tell, mF may be proper terminology for a millifarad, but no-one I know uses it for that.  Since standard US keyboards do not include the Greek alphabet, most people use mF to mean microfarad.  I use uF, since the "u" looks like ? with the descender cut off.  Anything between 1 and 999 millifarads seems to be referred to in thousands of microfarads.  e.g. 20,000 ?F vs. 20 mF

Also, I think it's kind of a hold over from the days when capacitors were known as condensers, and 1mF always meant 1 microfarad.  nanofarads where in fractional form (e.g. 0.001 mF) and picofarads were termed micro-microfarads (mmF). 

Edit: Even this editor changed the mu I inserted into a question mark.
 

Offline Neganur

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Re: Millifarad VS Microfarad abbreviation
« Reply #3 on: July 01, 2011, 01:53:20 pm »
I do not remember ever having seen mili Farad labelled on those beefy PSU capacitors.
It's always uF right up to Gold Capacitors from Panasonic which start with 0.047 F.
 

Offline MrPlacid

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Re: Millifarad VS Microfarad abbreviation
« Reply #4 on: July 01, 2011, 01:55:14 pm »
I use mF=MF=uF.

Milli gets F****

example:
20miliFarad=.02F
 

Offline CodeDog

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Re: Millifarad VS Microfarad abbreviation
« Reply #5 on: July 01, 2011, 04:51:51 pm »
Although millifarads and mF are technically correct to express one thousandth of a farad,
I've never seen them used in practice.

Of interest to me is when to capitalise (or not) the first letter of the unit.
e.g 3.3 V, but 3 volts
I think when you use the symbolic abbreviation it is usually upper case (V, A, mA, uF,...)
but when you spell it out you use lower case (volts, amps, ...) even though it stems from someone's surname. Go figure.

And on the subject of multipliers and dividers in prefix, it's always handy
to express time in apparent useless denominations ...

e.g. a weekend be referred to as ~170 kiloseconds,
or a year might be 32 megaseconds
a coupe of minutes could be 1.5 microdays

endless fun for confounding nontechnical management
 

Offline ejeffrey

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Re: Millifarad VS Microfarad abbreviation
« Reply #6 on: July 01, 2011, 05:41:23 pm »
In the US, neither millifarad nor nanofarad are traditionally used.  It is picofarads up until around 0.1 uF, then microfarads up to 100,000 uF or so, then farads.  mF/MF/MFD used to be used as abbreviations for microfarad even on component labels, but now the proper mu is used on capacitor labels and most people write mu if it is handy and uF otherwise.  Still, even as of a few years ago I think when you ordered capacitors from digikey they came in a baggie with a label that read "10,000 MFD".  I don't know if this has changed.

nanofarads are becoming more commonly used mostly due to the internet I think, but millifarads are still rarely used.  I certainly always avoid them simply because of the possible confusion due to the possible confusion between milli and micro.
 

Offline RayJones

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Re: Millifarad VS Microfarad abbreviation
« Reply #7 on: July 01, 2011, 06:41:19 pm »
Oucha Wa Wa.

Using m for micro is oh so wrong.

If I were to state a time delay is 10ms and then add a disclaimer stating "m = micro" I'd hung drawn and quartered.
Even though u is not a proper replacement for "mu" (the Greek letter) it is certainly unambiguous and far more palatable.
The SI units exist and have done so for many years now.

As for capacitors, yes nobody ever really refers to millifarad, 47,000uF is quite common which would be 47mF.

Likewise some people have an aversion to using nF.
I actually like nanofarad as it avoids using decimal points. Each to their own on that front I suppose. The nF range though is smack bang in the middle of "usual values" so it makes sense in that regard, much like how the common resistor values use ohms, kiloohms, megaohms (and milliohms!) - each a x1000 step.
 

Offline ejeffrey

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Re: Millifarad VS Microfarad abbreviation
« Reply #8 on: July 01, 2011, 07:16:49 pm »
I think the aversion to nanofarad comes from "back in the day" when tubes were the main active component and most electronics were for radio.  At RF frequencies, and when compared with the high impedances and high voltages of vacuum tubes, picofarad capacitors are the more useful range.

At least MFD is clearly a non-SI abbreviation, and if anything the capital M would be mega.  10 megafarad capacitors are somewhat less common :)
 

Offline RayJones

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Re: Millifarad VS Microfarad abbreviation
« Reply #9 on: July 01, 2011, 08:06:12 pm »
LOL, memories of when I was taught that the Farad is such a large unit that we'd never see Farad capacitors in a small form factor.

One presumes they have reached the physical size limit for supercaps, but who knows what may lie about the corner. We'd then be throwing away batteries and using the Megafarad caps :-)
 

Offline baljemmett

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Re: Millifarad VS Microfarad abbreviation
« Reply #10 on: July 01, 2011, 09:44:16 pm »
And on the subject of multipliers and dividers in prefix, it's always handy
to express time in apparent useless denominations ...

e.g. a weekend be referred to as ~170 kiloseconds,

I was trying to fix a problem I had on an OpenVMS installation the other day when I stumbled across a parameter with the unit 'uFortnight'.  The documentation included a note advising that "the implementation uses the second as an approximation to the listed unit"; little bit of fun from the guys at DEC back in the day, I guess!
 

Offline Hero999

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Re: Millifarad VS Microfarad abbreviation
« Reply #11 on: July 02, 2011, 02:27:01 am »
Yes, m was used for microfarads in old publications but it's dying out. Because of this, people avoid using mF, capacitances less than or equal to 99,999uF are normally specified in uF and capacitances equal to or over 0.1F are normally specified in Farads.

like  20.000 uF  Or 20mF ?
Here in the UK 20.000uF is 20uF, 20,000uF is 20mF we use . for decimal points and , as a separator for large numbers. Some European countries do it the the other way round for some reason.
 

Offline Kiriakos-GR

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Re: Millifarad VS Microfarad abbreviation
« Reply #12 on: July 02, 2011, 06:41:44 am »
Some European countries do it the the other way round for some reason.

I am lucky that I drive a motorcycle and the handle bar is at the middle.
All the planet drives at the right side and UK drives by the opposite way, for some reason.

If I was driving a car in UK, I would had two problems,
wrong driving direction, and the steering wheel would be in the passengers seat.    :)
 

Offline Zad

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Re: Millifarad VS Microfarad abbreviation
« Reply #13 on: July 02, 2011, 02:25:46 pm »
Japan, Australia, New Zealand and a few others also drive on the left. Driving / riding on the left leaves your right hand (most peoples dominant hand) available, ostensibly to use your lance, but also to greet the oncoming person and shake hands etc.

The short reason why the rest of the world drives on the right is because we drive on the left. Napoleon decreed that because the British drove their carriages and rode their horses on the left, then France should be different. He the proceeded to invade most of Europe and imposed that method.

Using m for micro has been quite common on capacitor markings for many years. Confusing? Maybe, but if you can't tell the difference between a 20 microFarad and a 20 milliFarad capacitor from looking at it, then you shouldn't be doing the job. I can't remember a time here in the UK when nanoFarads weren't used.

Offline EEVblog

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Re: Millifarad VS Microfarad abbreviation
« Reply #14 on: July 02, 2011, 03:17:04 pm »
Oucha Wa Wa.

Using m for micro is oh so wrong.

Technically it may be, but it is extremely common, especially on older gear.
Until maybe the late 70's early 80's there were traditionally only two units in common usage, micro farads (pronounced "mike") and pico farads (pronounced "puff").

Dave.
 

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Re: Millifarad VS Microfarad abbreviation
« Reply #15 on: July 02, 2011, 03:27:53 pm »
I am lucky that I drive a motorcycle and the handle bar is at the middle.

Curious! Traditionally, and certainly on almost every motorcycle I've ever come across, the handlebars have always been at the front.  ;D
 

Uncle Vernon

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Re: Millifarad VS Microfarad abbreviation
« Reply #16 on: July 02, 2011, 03:38:13 pm »
Japan, Australia, New Zealand and a few others also drive on the left.

But now that we are multicultural it is quite normal to see folks drive on the middle of the road while they adjust to the  cultural changes. Prior to the introduction of random breath testing drivers on the footpath or in the gutter was also a common sight.  :D

Samoa changed their road rules and the side of the road they drove on overnigh to take advantage of cheap imported 2nd hand cars. http://www.abc.net.au/news/stories/2009/09/08/2679412.htm  A change to LHD back her in Australia would be wonderful with so many available US muscle cars and a strong $ exchange rate.
 

Online Simon

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Re: Millifarad VS Microfarad abbreviation
« Reply #17 on: July 02, 2011, 05:18:53 pm »
The SI system exists for a reason. Multipliers are D (deca X 10) H ( x 100 I forget but something like hetto - I did my SI's in Italian) K for kilo x1000
M for mega x 1'000'000, G for giga x 1'000'000'000, and T for tera x 1'000'000'000'000. Note ALL capitals as they are multipliers.

The dividers (or whatever they are called - again did it all in Italian so not sure) are:
d fr deci 1/10, c for centi 1/100 m for milli 1/1000, u (the greek one) for micro 1/1'000'000, n for nano 1/1'000'000'000 and p for pico 1/1'000'000'000'000. All of these are SMALL letters so as to not cause confusion with the multipliers where the "m" has two meanings.

The unit of measure is always expressed in a capital letter too, although units that have more than one letter usually only have the first letter as a capital like in Hz.

There is also and amstrong which I think is used in chemistry mainly and may not fall into the SI units and is either 10 millions or ten billionths, I'm not sure as i never needed it. The symbol is a capital "A"
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Offline ejeffrey

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Re: Millifarad VS Microfarad abbreviation
« Reply #18 on: July 02, 2011, 07:00:05 pm »
There is also and amstrong which I think is used in chemistry mainly and may not fall into the SI units and is either 10 millions or ten billionths, I'm not sure as i never needed it. The symbol is a capital "A"

The angstrom (Å) is not a prefix, but a now obsolete independent unit of distance.  Originally in the metric system, the meter was defined as the length of a physical object.  However, spectroscopy and X-ray diffraction and crystallography were able to measure distances relative to the wavelength of light much more accurately than they could be related to the physical object used for measuring large distances.  Thus, the angstrom was designated a unit of distance based on the wavelength of light approximately equal to 10^-10 meters.  When the meter was redefined spectroscopically, the separate unit became unnecessary.  Chemists and crystallographers continue to use the angstrom as 0.1 nm, although the rest of optical physics has switched to nanometers / microns, the standard SI units.

Quote
The unit of measure is always expressed in a capital letter too, although units that have more than one letter usually only have the first letter as a capital like in Hz.

Only units of measure named after a person are capitalized when used in the short form.  Meter, gram, and second  are always lowercase (m, g, s).  When written out in full form, units are capitalized as common nouns: only capitalized at the beginning of a sentence in English.  This distinguishes them from the proper name from which they are derived (which are always capitalized).
« Last Edit: July 02, 2011, 07:04:43 pm by ejeffrey »
 

Offline Bored@Work

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Re: Millifarad VS Microfarad abbreviation
« Reply #19 on: July 02, 2011, 07:31:59 pm »
Maybe, but if you can't tell the difference between a 20 microFarad and a 20 milliFarad capacitor from looking at it, then you shouldn't be doing the job.

That is not the point. Units are a means of communication. Getting them right means you get part of your communication right. Units are not the place for becoming creative and not a way to express your individualism.

One such communication might be a specification. When someone works with a specification he often doesn't have the physical components in his hands. And yes, there are people handling specifications in a production process and ordering process who can't determine from a schematic if it should be milli or micro, assuming they have the schematic at all.

Using m for micro is just sloppiness. No mu on your keyboard? Cry me a river. You did use m for micro in the good old days? Guess what? The good old days are gone.

Getting your units meticulously right is basic engineering craftsmanship.  In the good old days you maybe had to talk to a few engineers in your lab only. And you all talked the same lab slang "We use a 47 babule with a 12 nocker for the hufnduff". These days are gone. Today you have to communicate with people all over the world to get something produced. And you often communicate indirectly, i.e. you don't talk to them on the phone or via e-mail. You just talk to them via your specification.

When something goes wrong you want at least have made sure that it isn't your fault. One way is to get your units meticulously right.
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Offline RayJones

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Re: Millifarad VS Microfarad abbreviation
« Reply #20 on: July 02, 2011, 07:37:29 pm »
Couldn't agree more BoredAtWork.

The 70's and 80's were at least 3 decades ago.
Knock knock, it is 2011 people  :o
 

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Re: Millifarad VS Microfarad abbreviation
« Reply #21 on: July 02, 2011, 09:14:43 pm »
There is also and amstrong which I think is used in chemistry mainly and may not fall into the SI units and is either 10 millions or ten billionths, I'm not sure as i never needed it. The symbol is a capital "A"

The angstrom (Å) is not a prefix, but a now obsolete independent unit of distance.  Originally in the metric system, the meter was defined as the length of a physical object.  However, spectroscopy and X-ray diffraction and crystallography were able to measure distances relative to the wavelength of light much more accurately than they could be related to the physical object used for measuring large distances.  Thus, the angstrom was designated a unit of distance based on the wavelength of light approximately equal to 10^-10 meters.  When the meter was redefined spectroscopically, the separate unit became unnecessary.  Chemists and crystallographers continue to use the angstrom as 0.1 nm, although the rest of optical physics has switched to nanometers / microns, the standard SI units.

Quote
The unit of measure is always expressed in a capital letter too, although units that have more than one letter usually only have the first letter as a capital like in Hz.

Only units of measure named after a person are capitalized when used in the short form.  Meter, gram, and second  are always lowercase (m, g, s).  When written out in full form, units are capitalized as common nouns: only capitalized at the beginning of a sentence in English.  This distinguishes them from the proper name from which they are derived (which are always capitalized).

i stand corrected
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Offline Wartex

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Re: Millifarad VS Microfarad abbreviation
« Reply #22 on: July 04, 2011, 06:52:58 am »
Yes, m was used for microfarads in old publications but it's dying out. Because of this, people avoid using mF, capacitances less than or equal to 99,999uF are normally specified in uF and capacitances equal to or over 0.1F are normally specified in Farads.

like  20.000 uF  Or 20mF ?
Here in the UK 20.000uF is 20uF, 20,000uF is 20mF we use . for decimal points and , as a separator for large numbers. Some European countries do it the the other way round for some reason.

http://en.wikipedia.org/wiki/File:DecimalSeparator.svg

If by "some" you mean MOST of the world, then yes, you are right.
 

Offline Hero999

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Re: Millifarad VS Microfarad abbreviation
« Reply #23 on: July 04, 2011, 07:26:08 am »
If by "some" you mean MOST of the world, then yes, you are right.
No, most of the world use . as a separator, the combined populations of China, Canada and the USA, exceed that of the whole of continental Europe, Russia and South America.
 

Offline RayJones

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Re: Millifarad VS Microfarad abbreviation
« Reply #24 on: July 04, 2011, 07:47:46 am »
LOL, the irony of all this is that if people used all the SI prefixes consistently we would not need the ambiguous decimal points.
Simply shove the appropriate prefix as required to keep the value between 1 and 1000.
 


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