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-   -   silver mica and pp caps (http://www.diyaudio.com/forums/parts/54119-silver-mica-pp-caps.html)

ronardi 24th March 2005 05:46 AM

silver mica and pp caps
 
Hello,

First, am I true that 0.1uf = 1000pf?

If space is allowed, would the silver mica caps be better than its pp cap counterpart of same value? or depends on manufacturer?

audiousername 24th March 2005 06:43 AM

No.

0.1F = 100nF = 100,000pF

Dr. Photon 24th March 2005 06:45 AM

no, 0.1 uF = 100 nF = 100,000 pF
1 nF = 1000 pF
1 uF = 1000 nF
1000 pF = 1nF = 0.001 uF

This is a common mistake if you are not very familiar with the metric prefixes. nanofarads (nF) are not very popular with American schematics. I personally think of almost everything (except for capacitoances under 1 nF/1000 pF, those I think of in terms of picofarads) as microfarads (uF), and convert nF to uF.

for example, I have some small ceramic disc capacirtors on my desk right now that are marked "4700" They are 4700 pF, or 4.7 nF, or 0.0047 uF.

when you do calculations, you typically need to use the value in terms of farads. in which case you need to convert based upon the prefix. You cna either divide by a large number (i.e. a million), or multiply by a small number. I have used both techniques, but typically use the multiply.

to convert uF to F, either divide the uF by 1,000,000 (1E6), or multiply it by 1E-6. If you use a TI graphing calculator (most other math tools should be similar), you can simple enter in the number of uF, and then enter "E-6" right after it.

use E-9 for nF and E-12 for picofarads. see how large a farad really is?

Just use the film capacitors. Silver Mica is only useful/practical for capacitances in the tens to hundreds of picofarads.

Mr Evil 24th March 2005 02:06 PM

It's easy to convert between them once you realize that they are all three orders of magnitude apart, e.g.

F = F * 10^0
mF = F * 10^-3
uF = F * 10^-6
nF = F * 10^-9
pF = F * 10^-12

Thus to convert from one to the next just move the decimal point three places to the left or right.

This is something that's worth learning because this three-order-of-magnitude gap is standard engineering notation that you will see everywhere to do with electronics, and indeed all forms of engineering.


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