Capacitor values

[eljib]

Can someone explain the relation between uf, pf, mf, K and anything else I might encounter while exploring the world of capacitors?

I could probably make sense of a conversion table, but can't seem to find one.

[johan]

"Capacitors are devices that usually have very small values. A one farad capacitor is seldom ever used in commercial electronics (however I understand that they are sometimes used when a lot of stored up energy is needed for an instant). Usually, your run of the mill capacitor will have a value of 1 thousandth of a farad to 1 trillionth of a farad. This is the other end of the scale compared with kilo, mega, and giga. Now we'll learn about micro and pico.

If you had a capacitor which had a value of 500,000 microfarads, how many farads would that be? Since it takes one million microfarads to equal one farad...

1,000,000 uF = 1 F || 500,000 uF = 0.5 F

What if we had a capacitor with a value of 1,000,000 picofarads? Pico is a very, very small number, so to have 1 million pico farads is saying that the value is just very small instead of very, very small. One picofarad is one trillionth of a farad. One picofarad is also one millionth of a microfarad. So it takes one million picofarads (pF) to equal one microfarad (uF)...

1,000,000 pF = 1 uF

By the way, just so you get a grasp of just how small a picofarad really is, remember, it would take one trillion (i.e. one million-million) picofarads (pF) to equal one farad (F), or...

1,000,000,000,000 pF = 1 F"

[Mini-Strat_Maine]

Johan, you are an artist! I almost hate to post this link, but it is the "quick and dirty" method I use for those times when an article says "pico" and the Mouser catalog only says "micro."
www.onlineconversion.com/electric_capacitance.htm

Great graph and explanation, though.

--
Doug C.

[UnklMickey]

yeah! things that are visual are always worth having around. long-term they help you better understand and remember how things fit together.


Nice work.
Thanks Johan.

[pollyshero]

Min-Strat, you are a godsend! I've been looking for a calculator like that since forever. Now I don't have to think so hard!

Bless you.

[Mini-Strat_Maine]

pollyshero said:

Min-Strat, you are a godsend! I've been looking for a calculator like that since forever. Now I don't have to think so hard!

Bless you.

Why, thank you, sir. {blush} I do try to be helpful as well as decorative. And some days, thinking is vastly overrated. ;D
Another calculator I've used is at www.electronics2000.co.uk/calc/convcap.htm

And finally, for those who haven't already discovered Wolf's parallel resistor/series capacitor calculator, here's another of my favorites: www.1728.com/resistrs.htm

I have a pocket-sized scientific calculator that will do all that 1-divided-by stuff, but it's way easier to just punch it into the Web page. (Although if you're working in the megohm realm, you may end up figuring out what all the "1.2345e5" jazz is in the result. )

[eljib]

Wow, Thanks everyone. Especially you, Johan. Explanation was crystal clear and I was able to find the exact parts that I needed. I really appreciate the help.

-Aaron

btw: I finally realized that mF was being used as uF in the catalogue i was looking at. But then I looked at Johan's table again and wondered what they use to designate a milli-Farad. Shouldn't it be mF?

[Mini-Strat_Maine]

eljib said:

btw: I finally realized that mF was being used as uF in the catalogue i was looking at. But then I looked at Johan's table again and wondered what they use to designate a milli-Farad. Shouldn't it be mF?

Probably so, but maybe anything with millifarads is so rare, they don't bother with it. Millivolts and microvolts, mv and uv (actually µv), don't seem to get used so interchangeably.

[UnklMickey]

ministratmaine said:

...but maybe anything with millifarads is so rare, they don't bother with it. Millivolts and microvolts, mv and uv (actually µv), don't seem to get used so interchangeably.

That was absolutely my intitial thought on that Doug!

but wait,

2200µF - 6800µF - 33,000µF,
i've used them all before.
and thats the same as:
2.2 (mili)F - 6.8 (mili)F - 33 (mili)F !

BTW: case is important.
M=Mega
m=mili

you were SO CLOSE with your thought,

"...but maybe anything with millifarads is so rare,"

even though the statement IS false.

{slick willie mode} "...that all depends on what the definition of is, is..."




hey, how did you make the mu?


unk

[Mini-Strat_Maine]

unklmickey said:

hey, how did you make the mu?

I knew that had a name, but that stuff is all Greek to me. ;D
I 'magine other Inquiring Minds Wanna Know, so: hold down your Alt key and type 0181 on the number pad. When you release the Alt key, the character should appear. (In Arial and Times New Roman, anyway.)

(___)
0 0
|
o "Mµµµµ."

[UnklMickey]

first he makes a mu, then he makes a Mooooooooooooooo.

our friend Doug has all sorts of tricks up his sleeve.




so did you get what i was saying about your statement being wrong Doug? or was i being too suBtle?


there's an interesting story about the reason why "m" was used for micro in capacitors, but i'm not certain of the accuracy.

[Mini-Strat_Maine]

unklmickey said:

so did you get what i was saying about your statement being wrong Doug? or was i being too suBtle?

I get whatcha mean now. What (I think) I meant was, we don't often see values written in millifarads, including in the catalogs. I went through almost the entire cap section of my Mouser catalog, and other than some aluminum electrolytics that are in Farads, pretty much everything was micro-, with some pico- and some nano- mixed in. (I keep typing "nono," but I kinda want to throw in "Nanoo, nanoo!")
But I did find one type that were 22, 50, 60, and 100 mF, so you're right.
"All generalizations are dangerous, even this one." -- Alexandre Dumas
"All generalizations are false, including this one." -- Mark Twain
"Uh huh." -- John Mellencamp

[UnklMickey]

eljib,

i hope you'll forgive us for horsing around on the tail end of your thread.

ministratmaine said:

unklmickey said:

so did you get what i was saying about your statement being wrong Doug? or was i being too suBtle?

I get whatcha mean now. What (I think) I meant was, we don't often see values written in millifarads, including in the catalogs. I went through almost the entire cap section of my Mouser catalog, and other than some aluminum electrolytics that are in Farads, pretty much everything was micro-, with some pico- and some nano- mixed in. (I keep typing "nono," but I kinda want to throw in "Nanoo, nanoo!")
But I did find one type that were 22, 50, 60, and 100 mF, so you're right.
"All generalizations are dangerous, even this one." -- Alexandre Dumas
"All generalizations are false, including this one." -- Mark Twain
"Uh huh." -- John Mellencamp

yes that is allmostly TRUE! that would be one way to make it correct. i would suspect that those mF values are really uF. it truly is impossible to be certain.

but what the "Master of Allusions" was going for there was the IS part of:
"...but maybe anything with miliFarads is so rare,"

making it:
"...but maybe anything with miliFarads was so rare,"



that tells you why it wasn't corrected back when.

but not how the use of mf (or mfd) interchangably for uF got started.

also "back in the day" mmfd was used for micro-micro-Farad (picoFarad)

see what you can find on this, and later i'll tell you what i have heard.

they probably won't be the same, and i have no real way of knowing what the truth is, or what is just rumor.

[wolf]

Not to be a "show off", but I decided to add a metric prefix converter to my website at this link:
www.1728.com/convprfx.htm

[eljib]

unklmickey said:

eljib,

i hope you'll forgive us for horsing around on the tail end of your thread.

I don't care...I got what I needed.

Plus this is the most replies so far to one of my threads!!! I'm glad I finally brought up something that people want to talk about.

[Mini-Strat_Maine]

wolf said:

Not to be a "show off", but I decided to add a metric prefix converter to my website at this link:http://www.1728.com/convprfx.htm

Cool! It's got some that we don't see that often (probably a Good Thing™), like "femto."
I was told or had read somewhere that a femtosecond was the smallest measurable unit of time, but it looks like they've come up with smaller ones: whatis.techtarget.com/definition/0,,sid9_gci212105,00.html

"A femtosecond is that interval from when the light turns green, to when the guy behind you starts honking his horn." ;D



Yeah, I know: . I was just leaving.

[UnklMickey]

ministratmaine said:

wolf said:

..."A femtosecond is that interval from when the light turns green, to when the guy behind you starts honking his horn." ;D...

i've been to Boston before, and had taxi drivers behind me.

i used to have a whole: what's the definition of nanosecond...national bureau of strandards,...light turning green... well you obviously know the rest.

told that one many times on the north shore, wonder if it migrated it's way up to you, or if it's one of those multiple source type things.



unk