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Re: gEDA-user: Embedded Power Pins



Stuart Brorson wrote:

> FWIW, I wrote a blurb about this question for the wiki a couple of
> weeks ago.  Here it is: 
> 
> http://geda.seul.org/dokuwiki/doku.php?id=geda:faq-gschem#what_should_i_do_about_power_pins_on_my_symbolsmake_them_visible_explicit_or_invisible_implicit

Well, I agree only half way with you.
It is true, that power pins in analog circuits should be visible on the
schematic. But having them on attached to the triangular shape is not
correct either. Imagine a quad opamp: If you use symbols with visible
power pins, you get eight visible power pins.

My preferred solution would be a special slot just for the power
connections. This is how we dealt with this issue in Protel99 and it has
its advantages for circuits that contain lots of opamps. The power
connections plus the necessary caps don't clutter the feedback loops. So
the circuit is easier to read. Still the power pins are explicitly drawn
and can be tied to some exotic net. I usually draw all the power symbols
with their caps in some quite corner of the paper.
The only drawback is that the supply caps are not in the neighborhood of
the corresponding triangular  shape. But with quadamps the triangular
shapes that belong to one component are scattered over the schematic anyway.

Nevertheless, I don't see how I could implement this technique with
gschem. There seems to be no way to let a gschem symbol contain slots
with different pinout. The same problem arises if a component has slots
that perform different functions. This is the case for some analog
multipliers that contain an additional opamp with no internal connection
to the multiplier. Did I miss something obvious?

---<(kaimartin)>---
-- 
Kai-Martin Knaak
kmk@xxxxxxxxxxxxxxx
Blog: http://lilalaser.dyndns.org/blog

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