I bought an old pair of speakers which had a problem with the tweeters in one of them.  First port of call was to check the crossover circuit, and sure enough one of the electrolytic capacitors looked like it had given up the ghost.  Not surprising really considering they’re about 30 years old!

Simple solution, overnight some new ones from rs-online.  But wait, what is this.  The capacitors have a value with a comma instead of a full stop.  What is this magic, and what does it mean?  It turns our that despite the world’s knowledge available over the internet, Google simply wasn’t helping with this one.

I tried the local amateur repeater, which is frequented by a whole bunch of electronics whizzes, again no dice.  No-one had any idea.

Anyway, after extensive research I finally concluded that a comma is simply the European way of writing a decimal place.  So just in case others may be wondering:

2,2μF = 2.2μF  i.e. the full stop and comma are interchangeable.

Out of interest, one source suggested that as a full stop is easily erased or obscured, the comma’s larger “footprint” better withstands the rigours of time.  A little dubious if you ask me.  I would imagine that any capacitor that’s getting constantly rubbed or bumped so as to erase its printing will soon give up the ghost anyway.