+4V5 __ -4V5 Notation

This is gonna sound really simple but what is the notation of 4V5? I know it has to supply voltages

Can some one supply me with the "magic decoder ring?" ie what does the "V" between the 4 and 5? Is it a decimal point or notation for "4 to 5" volts?

thanks for your tolerance :)

hoke

Is it a decimal point

I have seen it used this way.

Would you direct us to the example you are talking about?

It's used in quite a few areas. The unit of measure replaces the decimal point. You can also express resistance as say 4k7 (ie 4.7 kilohms) or 3M9 (3.9 Megohms)

thanks muchly

It seems to have become a common practice when photocopiers started being commonplace. If you make a photocopy of schematic in a book say... (especially in the 1980's), the first thing to lose in the details is the tiny little decimal points. Using a "unit": value (like K for ohms and V for volt) where the decimal place would go leaves no doubt about a decimal point being there. This now holds true for really crappy JPG compression of bitmap schematics... so the practice stayed in use.

Once you know the secret... it makes a lot of sense.

Common uses are 3V3, 1R8 (1.8 ohms), 3k9 (3.9k ohms), 2n2 (2.2nF), etc. Never seen it used for current, ie never seen 3m3 for 3.3mA or 10A5 for 10.5A. Can't recall it being used for frequencies either. inductors maybe.

thanks to all, now I have a new wrinkle in the gray mater

Apart from making things clearer it also saves on one character of text. 3.5v takes 4 characters and the decimal point may be overlooked 3v5 uses only 3 characters and there is no decimal point to overlook.

It might also be that there are some big dog CAE packages for IC layout and such that do not allow decimal points in node names, so designers just cater to that.

thanks Jack and Keith – good points
hoke

This was the standard there are more than 50 years.

Today 4V5 notation is prohibited. It should never be used in schemes to internationnal standards.

But between what is mandatory and what is still practiced ................ However it is best not to use this banned standards

68tjs: This was the standard there are more than 50 years.

Today 4V5 notation is prohibited. It should never be used in schemes to internationnal standards.

But between what is mandatory and what is still practiced ................ However it is best not to use this banned standards

What was the standard and what do you mean by "prohibited" What should be used to what "international standard" in what circumstances What do you mean by "banned" Don't get me wrong - i'm not bitching - just asking for clarification of the points you are making

Is this another example of some big brother beuracrat trying to tell the rest of the world what to do? If it is banned under what jurisdiction is is banned? And what are the penalties for those that transgress the ban? Don't be silly.

grumpy_mike: "cures diction" is banned. You need to use "jurisdiction." I assume that was an autocorrect error?

Yes auto correction plus the fact that on this new forum there is a five seconds delay or longer between me typing anything and seeing it appeare on the screen.

Grumpy_Mike: Yes auto correction plus the fact that on this new forum there is a five seconds delay or longer between me typing anything and seeing it appeare on the screen.

Ain't life grand?

I see -lots- of terrible usage of incorrect capitalization (m for M, K for k, etc), incorrect units (A where it should be Ah), but most of all I see horrible schematic diagrams. Sadly, I see terrible practices being taught in books.