On Wed, Jun 25, 2008 at 10:56:20AM -0400, M. Adam Davis wrote:

> Regarding printing resistor values with less cryptic numbers:
>  * There's simply not enough room to make it legible.
>  * You need more digits to specify your system (6834 vs 9.76M, and
> unless you give the decimal a full digit's worth of space it's hard to
> identify)
>  * Your example of 10e9 is great - but if you're always going to have
> the e, then why not simply remove it and mark the capacitor 109?
>  * Further, what is the base unit, and how do you specify values
> smaller than the base unit without adding more characters?

There is also the problem of realizing in what format the markings are
presented; there are many cases where constraints demand that one
compress the data to a few characters, and it isn't trivial to
tell in what way it was done.

In my recent project I guess I was distracted when I assembled the basic
PIC circuitry, and was perfectly content to use a cap marked 221K for
decoupling the PIC internal USB power supply, probably thinking something
like 22*10^1 kilo-pico-Farad=0.22uF should be alright.

The PIC worked fine, but for two weeks my USB bus would go haywire at
random - attaching a scope probe, touching the table, soldering a
different board, almost anything would make the computer spew a ton of
EMI warnings and require reloading or reattaching all the devices.

Only after replacing all the mains cables in the room, and going over all
the parts on the board (by then a shroud of wire wrap mashes, solder
puddles and secondary boards) I worked my way to the center and found my
stupid mistake - in the context of capacitors a K postfix is a
designation of precision, not a value modifier, and my cap was a
thousand times smaller than I thought.

At least with color bands you know what they're supposed to mean. There
is also an old capacitor color band code, but these usually look
different.

As an aside, I think you'd be hard pressed to come with methods which
are completely non-discriminatory (except by using UV and IR LEDS,
perhaps). Specifically Roman numerals will discriminate against users of
Arabic/Jewish/other systems, and that's a way you really don't want to
go ;-).

Cheers,
Yair.
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