part values

[sinbad]

I have seen a few schematics that state resistor values as eg. 2K7 and caps 100nf. I have been used to seeing 2.7K and 100ufd or 100uuf(100pf). Is this some European standard? Anyone??
Sinbad

[clipclop]

Sinbad,
I beleive its an international standard of marking .
the reson for putting the k between the No's is the dot is not allways clear on skematics but with the k placed in the middle it is easily identified .
nannofarads have allways been about, they have just started useing them (last 30yrs) instead of decimal places or ooo's.
eg:- 0.001uF = 1n = 1,000pF
0.01uF = 10n = 10,000pF
0.047uF= 47n = 47,000pF
usein nanno farad values is much simpler and less confuseing
Stewart

[slipstick]

It's like so many things. America tends to use its own standard and the rest of the world agrees on an international standard.

BTW I've never in 40+ years of electronics seen a picofarad written as "uuF". I guess you live and learn.

Steve

[hwhall]

uuF was a common notation up thru probably the 1950s.
--Wayne

[JMP_blackfoot]

It's all part of the international standard which defines multiples and sub-multiples in powers of 3 :

M = mega = 10^6
k = kilo = 10^3

m = milli = 10^-3
µ = micro = 10^-6
n = nano = 10^-9
p = pico = 10^-12

[vintage1]

Yes. Its a standard that came in in the 70's I think. Mainly from Europe

It helps when drafting, because a decimal pont can get smudged out very easily.
so 4.7 might look like 47, and copy draughstmen were sloppy beasts. These days with CAD its less of an issue than it was then.


The idea was that the numbers would never have leading decimal points, or too many trailing zeros, or commas or points in them.

So you can get from 1R0 (1 ohm) to 999M (999Mohm) without using more than 4 charcters, none of them ',' or '.'

It gets a little messy when e.g. you want 0R12 for 120 milliohms.

and I have never seen millifarads use as in e.g 4m7 instead of 4700uF.

And its seldo used for coils either.

The R range is
R = one ohm
K = 1000 ohm
M = 1000000 ohms.

p = picofarad - one million millionth of a Farad
n = nanofarad one thousand millionth of a farad
u = one millionth of a farad.
Presumpably it's
m = one thousandth of a farad, but it looks awfully like an 'n'
F for a Farad itself. Unheard of in my day, but achieveable now.

I suppose one uses :

p for a pico Henry
n for a nano Henry
u for a micro Hhenry
m for a milli Henry
H for a Henry.

But mostly people still seem to wroite 470mH , 1.5uH etc...


Reminds me of the sliding scale used to define Feminine pulchritude, with a milliHelen being the sort of face capable of launching just ONE ship... :D