Homebrew PCBs

to continue on this thread.  I've found that if I lay out my board 
and then look at how the traces run, I can make a few tweaks and 
significantly reduce routing complexity.  For example, I put an LCD 
display header on a board I'm doing now.  after first routing, I 
noticed that a couple of the traces were going all over the place.  I 
went back and switched 2 of the control lines going imto the micro-
controller and rerouted.  wow, what a difference, the traces were 
direct and I was able to get rid of 8 vias (4 top side wires).  Its 
still 2 sided but, my design is now much more manufacturable in my 
little "pcb factory".

Another thing is that routers are pretty dumb.  at least the Eagle 
one is.  I'll often route, rip-up, hand route a couple of problem 
traces and then reroute to a much better result.  It also pays to 
understand the router cost tables and what each cost item means.  
I've gotten comfortable at getting eagle to route the way I want but 
it still makes some stupid choices and winds up putting waaaay too 
many traces on the component side even with top layer at max cost 
(for through hole stuff).

This brings up the thought of having a set of home brew design rules 
(and an HB-DRC lol).  I have my own informal set in my head but would 
love to hear what others use. 

--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
<stefan_trethan@g...> wrote:
> I noticed on the end of the mail that it went off topic,
> even off topic of the already a bit off topic discussion.
> If you still want to read it go on...
> 
> 
> 
> >
> >    Check this case in unnecessary design:
> >
> > http://www.rigelcorp.com/r535j.htm
> > http://www.rigelcorp.com/__doc/8051/R535JASSM.pdf
> >
> 
> 
> Especially for a prototype / evaluation board 2 layer is a great 
advantage.
> you can follow the tracs and you also can make changes as needed.
> i would like to see how you make changes in a 4 layer board.
> 
> 
> You can take apart whatever consumer equipment you like, 2 layer 
boards are
> still very popular, as are 1 layer boards.
> 
> I do not know how this will develop, the demanding boards have more 
layers 
> now,
> but also the things get more and more integrated.
> If you look how many layers they use for IC internal 
interconnection (14 
> or so??)
> you can maybe guess how the boards will develop. On the other hand, 
as the 
> integrated
> circuits get more and more functionality, requiring nearly no 
external 
> components
> the external circuit should get simpler, allowing less layers there.
> 
> The requirements are so different - some things need to be as small 
as 
> possible, some
> as cheap as possible, some both, some high quality, some easy to 
> manufacture.
> the demands are very different, and i think the solutions to meet 
them 
> will be as different
> in the future.
> 
> Development is not stopping now, that is the only thing you can be 
sure of.
> 
> I think the trend will be towards integration, but the human is not 
built
> to interface silicone chips, it needs to use the fingers to operate 
the 
> stuff
> and needs audio and video feedback. this human interface is (in 
this way) 
> impossible
> to integrate into anything (on chip buttons and such ;-).
> maybe the soultion to that is that the human carrys a
> "Human interface device" with him all time, and the machines we 
build have 
> no direct
> interface at all, and communicate wireless with the HID of the 
individual.
> 
> This has certain advantages, but also a lot of disadvantages.
> I'm known around here for my skills with electrics/electronics so 
if there 
> is some problem
> people call me to help them. I regualrly come somewhere only to 
discover 
> there is no fault, but it
> is just a user "inability". some equipment is simply too 
complicated for 
> some people, especially
> elderly people with disabilities like bad sight and such. If the TV 
or sat 
> receiver is operated through
> a complicated menu and they simply can't remember how this works, 
or if 
> the buttons on the remote are simply
> to small to read the lable (this happens) then i really question 
the 
> purpose.
> I mean, back a few years each tv had a row of buttons, and that's 
it. just 
> press and look.
> 
> Now, if you follow the thought of the "universal human interface" 
this 
> could lead to two consequences:
> a) everything gets far too complicated for some. this limits the 
market - 
> BAD.
> b) you can program it, also in a "simple" mode. so that the stuff 
works 
> with maybe limited functionality,
> but WORKS. you could design human interfaces even for people with 
severe 
> disabilities if you like.
> 
> 
> Sure, the society changes, gets used to the technology, learns to 
keep up 
> with it, but everyone?
> and with each and every machine?
> It happens not seldom that one of my professors, on a technical
> university, (teaching electrotechnics or much more advanced stuff) 
can not 
> manage to make the laptop
> computer operate with the video beamer and switch all things on. 
Not that 
> he is too stupid for it, of course
> not, if he has some time and reads the manual it would work easily, 
but 
> there and then there
> is no manual, and no time to read it. He wants nothing else than a 
big 
> green ON button and a big red OFF button.
> he has no interest in all else of the functionality.
> 
> On the other hand, if you know what you do exactly, and the machine 
tells 
> you "you can't do that now"
> you are also upset (like formatting your system partition on the 
PC).
> 
> I could go on and on, but i think everyone who kept up reading so 
far got 
> my point.
> 
> There will still be much development going on, no doubt, faster, 
cheaper, 
> more functionality.
> But we also need to keep in mind that the limited human needs to 
operate 
> and use the stuff. Not the designer,
> which knows every function and error, the simple consumer who wants 
not to 
> waste much time with the manual.
> 
> 
> 
> THE END ;-)
> 
> Didn't read it after writing, there may be much errors.. you can 
keep them 
> i have plenty.
> look forward to discussion and possible solutions.
> 
> ST