understanding capacitor values

[mtomlins]

So - here's a noob question for you:

I see in the parts listing for my pedal that there are some capacitors I need to get:
   3 - 0.047 uF
   1 - 0.1 uF
   1 - 100 uF

Then, when I go to order the parts I see things in pF, pf, mf, nf and uF...confused me quite a bit, but here's what I think I'm about to order:

3 - Capacitor Silver Mica 500V (47 pf.)
1 - Capacitor Silver Mica 500V (100 pf.)
1 - Capacitor, Electrolytic 16 V (100 mf.)

Are my conversion right - uF to pf. and uF to mf???

Thanks,

Mark

[R.G.]

No, not quite.

Scientific prefixes are :

milli - 1/1000 (one one-thousandth)
micro - 1/1,000,000 (one one-millionth)
nano - 1/1,000,000,000 (one one-thousandth of a millionth)
pico - 1/1,000,000,000,000 (one one-millionth of a millionth)

These are abbreviated (in the case of Farads, "F") mF (milliFarad, doesn't get much use), uF (micro-Farad from "mu" the Greek letter), nF (nano-farad) and pF( or sometimes just "p", pico farads).

So your caps are
0.047uF, which is equal to 47nF and 47,000pF; all the same value, expressed different ways.
0.1uF, equal to 100nF, or 100,000pF
100uF, equal to 100,000nF, or 0.1 millifarad.

They used to use mmf for "micro-micro-farad" instead of pico farad, but that's fallen into disuse.

[R.G.]

I thnk this is in the FAQ from the last time I wrote it up, too.

Good reading, that.

[Alex C]

EDIT: RG beat me to it and his answer is better than mine.

I think that on the "100mF" electro cap you listed, "mF" is being used to mean "microFarads," rather than "milliFarads."  I could be wrong though.  I think it depends on the supplier, but I can't recall seeing anything listed in milliFarad units; someone with more experience can probably provide a better answer than I.

[John Lyons]

Uf and Mf are the same (microfarads)

Most small pf value caps will be ceramic, silver mica or polysyrene. Silver mica is popular these days...

The 100uf is an electrolytic capacitor
The other two  caps (.o47 and .1) you mention can be polyester, film, etc. still uf though (microfarads)

Basically the caps 1 uf or larger will be electrolytic an under 1 uf will be film, poly, etc etc.
There are film caps in large values but these are pretty big and will not fit on a stompbox circuit board. The main reason for electrolytic is the small size.
Here's a nice capacitor chart to help you out. http://www.justradios.com/uFnFpF.html

John

[psiico]

You can use Google to do conversions.  Just type "47uf in pf" in the search field and it'll convert 47uf to pf, it works with all sorts of conversions.  You can do cm, inches, miles, km, litres, all sorts of stuff.

[markm]

Here's a nice capacitor chart to help you out. http://www.justradios.com/uFnFpF.html

John

You can use Google to do conversions.  Just type "47uf in pf" in the search field and it'll convert 47uf to pf, it works with all sorts of conversions.  You can do cm, inches, miles, km, litres, all sorts of stuff.

Cool!!

[psiico]

My bad, I forgot that you have to type the full term in Google.  uf won't work, use microfarads, so it'd be for example "47 microfarads in picofarads."

[mtomlins]

Thanks to all for the help and in depth answers.  I have collected a few key conversion charts for resistors and capacitors.

Now, I have to learn about transistors!

Thanks,

Mark

[blackbirdneo]

you could also download elcetronics assistant here: http://www.electronics2000.co.uk/ it automatically gives you the code of the capacitor ang the color combination of resistors

[John Lyons]

Here is another cap code chart. Single page even!
http://i2.tinypic.com/qn1t86.jpg

John