have private email now

[Kimmo Koli]

On Wed, 18 Feb 1998, Tony Allgood wrote:
> 
> I think that mistakes can get hidden in a fantastically presented CAD
> schematic. For some reason, I can spot mistakes easier in a hand drawn
> circuit. This may be purely in the mind, but it also seems to apply in
> the written word. Word processed texts may look nice but they can be
> full of rubbish. Its almost as if the presentation is more important
> than the content.... Oh, by the way has anyone seen Titanic yet?????
> 
Well, I haven't seen fantastical CAD schematics yet. More like the CAD/CAE
vendors compete in making as ugly and as nonstandard schematic symbols as
possible. And there are standards for drawing schematics but still I
haven't seen any ISO-standard symbols in any of the many PC and UNIX
CAD-tools I've used, unless I haven't drawn them there myself.

In all conference and journal papers I've written I've NEVER used
CAD-tool schematics (oops! exept my first one back in -91). Their quality
just is not good enough at least when you need to scale them into a 
5cm x 4cm space. A simple vector drawing program like Idraw in UNIX is
better suited for presentations.

The other thing is that when you use CAD-tools you first draw the
schematic and then simulate it to make sure that the circuit operation
even vaguely resembles what you want and finally your PCB can be at least
verified against the schematic if not even generated based on it.

Unfortunately simulator models for discrete transistor, opamps etc. don't
come even close to the accuracy of the models used in IC design (which I
do for living) so simulating discrete circuits is no alternative to
breadboarding. But for example comparing different temperature
compensation principles without a circuit simulator would be very hard
indeed, although in spice all devices have the same temperature !

But let's go back to synth-DIY issues again,
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
   Kimmo Koli                         Helsinki University of Technology 
   kimmo at ecdl.hut.fi                  Electronic Circuit Design Laboratory
   http://www.ecdl.hut.fi/~kimmo      P.O.Box 3000
   Tel:  +358 9 451 2273              FIN-02015 HUT
   Fax:  +358 9 451 2269              Finland 
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=