Re: gEDA-user: Embedded Power Pins

[Vanessa Dannenberg <vanessadannenberg@xxxxxxxxx>]

On Saturday 04 March 2006 15:29, Stuart Brorson wrote:

> > Em Sex 03 Mar 2006 21:32, John Luciani escreveu:

> > > The gschem logic symbols seem to have embedded Vcc and GND connections
> > > (at least the ones that I was looking at). Since I am working on a
> > > board that has 3.3V and 5V logic this is a problem.

A project I am planning requires three supplies.

One supply from the computer's main power supply "Standby" current to power 
some 7474's (after I step it down... acts as a simple collection of status 
bits) and one or two other parts.

The other two supplies come from the primary switched +5v and 12v rails, to 
power everything that should only be turned on when the rest of the computer 
is on, like the 12VDC->9VAC invertor, status LEDs, one or two pieces of 74xx 
logic, etc.

Obviously +12v isn't a big deal, but confusing or overwriting the 5v-switched 
and 5v-standby supplies would lead to unpleasant side effects like loss of 
settings, or wasted power, etc.  Nothing that would cause damage, just 
annoying.

Personally I think power pins should be made visible, but exactly how they're 
shown is a matter for debate I'm sure.  A separate slotted symbol might be a 
good idea, as long as it's clear which package each such symbol goes with.

-- 
"Sometimes paranoia can be helpful. Usually it
isn't, and when you learn that, life improves."
Vanessa Dannenberg