Schematics & standards

The jumping over loop is much easier to read on a messed up copy than trying to determine if it is a dot or just a smudge. Using 5K6 for markings also makes it earier to read.

On 6/20/2010 7:09 PM sparky spake thus:

Well, then let me ask you the same question I'm asking others here: if that's so, then why don't we use that system (8K2, etc.) for other values like voltages, currents, etc? Aren't they also likely to be hard to read on a "messed-up copy"? Why not be consistent?

Am 21.06.2010 04:19, schrieb David Nebenzahl:

...

The range of commonly used resistors starts at about 0R1 and ends at 1M. Capacitors from a few 12pF to some 1000uF. Voltages and currents in common devices do hardly exceed 2V to 400V (uC incl. SPS on mains) resp.

When you find fuse marked 630A in a cell-phone, you do directly know, that it is 630mA.

Falk

But surely, it is you who misses the point. Considering that 30 or 40 years ago, just about all semiconductor houses were American, then is it not likely that it was an American company that came up with the system of marking zener diodes? And why would you imagine it was done ? Why to avoid any ambiguity caused by poorly printed decimal points, of course ...

I suppose you're also one of those Luddites who likes to see all of the capacitor values in decimals of a microfarad as well, or have you caught up to nF ?

I'm all for not changing systems that are tried and tested just for the sake of it, but I'm just as happy to embrace change where it has a positive benefit. And there is one here. All I can say is that if you have never seen a poorly reproduced schematic where the component identifiers and values are hard to read, then either you are not professionally involved in service work, or you are lying to keep pressing your point.

Arfa

It's not 'mandated'. Nobody has forced their will on anybody. It's nothing to do with committees, European based or otherwise. I know we have some pretty dumb laws and such forced on us by the Euromachine, but it hasn't reached the point yet where they are dictating how we draw schematics. It's just a system that someone somewhere - probably a Japanese or Korean manufacturer, has come up with because they feel that it removes any possibility of ambiguity on a component value. It's a bit like putting traffic light turn filter arrows on junctions. For sure, you could argue that it's not strictly necessary in order to be able to successfully negotiate the junction. You can do that on a green light alone. But putting a filter arrow there, removes any ambiguity from when it's safe to go, particularly for less experienced drivers, or those not absolutely familiar with a junction.

And as to voltages, some schematics do now use the system for showing voltages that are in decimal parts. "3V3" is commonly found on schematics. It's also common now to find the same system in use for capacitors, so 4n7 for instance or 2u2. Whether you like the system or not, it seems to be getting used more and more, so I think it's a case of learn it and accept it. It's really no more difficult than any system currently in use, just different, and it *can* under some circumstances, be an improvement.

Arfa

no, it's you that doesn't get it.

you mean like a 1N5351?

So when is the last time you got confused over "missing" periods again?

seriously.

the short answer is they don't know, and like being slaves to stupid committees.

On Sat, 19 Jun 2010 10:10:10 +0100, "Arfa Daily" put finger to keyboard and composed:

Those blocky symbols are an IEC standard. I find them utterly unreadable.

- Franc Zabkar