PCB layout software

Karl ALEXANDRE alexandr at irit.fr
Tue Jan 12 11:48:18 CET 1999

> It takes a hell lot of time to set up the system.  You have to define
> object bodys, schematic views, simulation code, pinouts and a footprint
> for EVERY single type of component you use.  Most probably you have to

	95% of the component I use are in the packages.

> define a lot of resistor and capacitor types because of varying wire
> length (instead using wire bridges you often use resistors with long
> wires to get over some pcb trakcks, whenever possible etc.).

	One good thing with eagle is when you capture a schematic, you can
	tell the size of a component (for passive ones). Later, when you	
	route your board, you can change the body of anything very simply.
	If you your resistor was to short, just change the distance between
	pads with another footprint...
> Most software packages I know have lots of 74LSXXX in their librarys,
> and maybe a 741, but most of our analog stuff is not there.

	See above. Sure if you want an AD538 you have to create it yourself...

> I estimated that setting up such a system with all the components you will ever use will take the time of 3-4 complete modules alltogether.
> I think that this is much to much for diy (but ok for professional use).

	Sure, the first time you use a software, it takes 2 hours to board
	a blinking led :) But after...

	In 3 hours, with orcad, i didn't manage that.... I'm not intelligent :)	

> > So Jorgen has some reason for hand layout.

	Sure, for simple analog modules, you can... But i also make some
	stuff on double sided eurocards... I used to hand-wire some module, but
	it isn't reliable, at least durable...
	We have all habits which are difficult to change :)

	Don't start a "my method is the best" thread...



	PS: speaking of th AD538, did anybody checked this "Analog
computational unit" at
	analog device. It's a chip which compute 
	Vout = Va * ( (Vb/Vc) ^^ m)
	Analog device gives free samples of this thing, i have two and will
test them soon...

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