Re: gEDA-user: Resistor valuesâ

[Vanessa Ezekowitz <vanessaezekowitz@xxxxxxxxx>]

On Fri, 24 Dec 2010 12:15:17 -0500
John Doty <jpd@xxxxxxxxx> wrote:

> > Yes, a default 
> > library can only be a starting point and cannot fit 
> > everybody's needs. But does the starting point really
> > have to be so poor that it fits virtually nobody's needs
> 
> Well, I was using the valueless passive symbols quite a bit yesterday. But
> I guess I'm "virtually nobody".

By "virtually nobody" I am sure he means "an extremely small number", and if you are referring to just yourself (rather than a team, perhaps), then his statement is still accurate.    There are more of us that would appreciate such defaults than those who would not.

Resistors are just one of many component types out there have a value, no matter what type of package they come in - with rare exceptions, every single one of them you pick up will have numbers or color bands indicating that value, we all know that.  That value might be zero ohms, but it is still a *value*.

The same goes for every last capacitor, inductor, etc., though I think you'd be hard-pressed to find any that have a value of zero.  

Anyway, I suggest the following:

* If the part in question can usually be described by a single value, for the purposes of the signal flow in the schematic that is, then give it a default of "value=0".

* If it is a discrete part that is specified entirely by its part number rather than a measurement, like a diode or a transistor, then pick a reasonable default; "value=1N914" or "value=2N2222".

* If the part is something like a logic IC, use the standard name of the part in the fastest commonly available series for that particular gate; "value=74F74" or "value=74HCT245".

* If none of these fits, then leave the "value=" attribute off entirely, since the user would have no choice but to get creative anyway.

The point here is that every one of the component types in question has a value, therefore the "value=" field will end up being utilized by nearly everyone who instantiates the symbol for that component.  Otherwise, schematics with a lot of such symbols become nearly impossible to read, let alone debug.

-- 
"There are some things in life worth obsessing over.  Most
things aren't, and when you learn that, life improves."
http://starbase.globalpc.net/~ezekowitz
Vanessa Ezekowitz <vanessaezekowitz@xxxxxxxxx>


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