USA Capacitors values

[jophus]

Hi all,

I'm resident in the UK, but just started to get some components together for a tubescreamer from the fantastic tonepad- then I found this;

    * mF: Milli-Farad, 1x10-3 Farad (1,000th of a Farad) - uncommon
    * uF: Micro-Farad, 1x10-6 Farad (1,000,000th of a Farad)
    * mF: Micro-Farad, a very, very old term, still sometimes used in the US (True!) - Causes much confusion.
    * ufd: Micro-Farad, another very old term, still used in the US
    * mfd (or MFD): Yet another antiquated term - US again!
    * nF: Nano-Farad, 1x10-9 Farad (1,000,000,000th of a Farad) - Common everywhere except the US
    * pF: Pico-Farad, 1x10-12 Farad (1,000,000,000,000th of a Farad)
    * mmF: Micro-Micro-Farad, another extremely old term, also still used sometimes in the US

http://sound.westhost.com/beginners.htm

So does that mean the uk components  I have sourced are the wrong ones for the project? How common are these USA discrepancies?

Help much appreciated ;-)

[slacker]

Not sure what you mean, if you've bought caps that have the same uF value as the tonepad layout then you've got the right things. If you're buying stuff from Smallbear then he uses mf to mean uF.

[mdh]

And in fact a lot of folks use mF when they're specifying microfarad values.  Basically no one really expresses capacitance in millifarads, even when it would be appropriate (e.g., 1000 uF electrolytics, which could equally be called 1 millifarad electrolytics).  In any case, the huge difference in physical size between capacitors that differ by three orders of magnitude is so great that you'd be extremely unlikely to inadvertantly use millifarad caps when you mean to use microfarad caps.  Especially if you're talking about film caps, if the cap is smaller than your pcb, it's definitely not in the millifarad range.

Take home message: you're almost certainly fine!

[jophus]

Cool- that's fine then, cheers for the help guys