I would add a few fine points to this point to point layout discussion
using PCB software.
From what I see, the most important thing is size your components
first. Measure the size of the resistors, caps, etc, then either find,
in the parts database, or make yourself, with the component editor,
the parts to correct size. I also use Eagle lite, and if you go to
their website, you'll find quite a few parts libraries you can
download. A few of those contain tube with correct pinouts as well.
Then do the layout of the circuit just like you are making a circuit
board. Using a laminator or iron, print the top component layout, and
the bottom wiring diagram onto an unclad fiberglass board (I recommend
.125 thick). With this method, it's not so picky that things are
perfect, so label backing paper and a hot iron would likely work just
fine.
Then using the component layout, drill the board for turrets or
eyelets. Attach these, then install components, and point to point
wire the board using the bottom side black traces as a wiring diagram.
With point to point, one thing you are allowed to do is cross wires.
You can also do this by using a two layer design, and using top and
bottom wiring for crossed wires.
The problem with Eagle lite is the board size limit. I work around
this in some cases by doing subassemblies, which can then be
conveniently all "printed" onto on big board using the toner transfer
technique. Of course a better solution is to use another program cheap
layout that doesn't limit board size. The two I have used are Protel
(free DOS version) , and Ivex Winboard.
http://www.nteinc.com/cad/prodwb.htmlThe cheap version of the Ivex Winboard program is 39. and limits you
not to board size, but to 200 pins.
This technique is also perfect for large component layouts like power
supplies with big electrolytic caps and board mounted transformers. I
like things to be sturdy, and don't feel good about using 1 oz. copper
pads to hold a multi-pound transformer in place. Copper eyelets on a
1/8" board is fine, though. Just some thoughts.
Bob
--- In Homebrew_PCBs@yahoogroups.com, "dl5012" <dl5012@...> wrote:
>
> Hi Dave,
>
> Yes, I'm using PCB layout software to plan boards that I wire by
> hand.
>
> There are several techniques to facilitate layout. The first is to
> draw a "pretty" schematic. If you minimize wire crossings and
> routing lengths; it's easier to translate that into good layout. If
> you size the components on the schematic to reflect their relative
> sizes, that helps too (i.e. if you're using a transistor in TO-3,
> draw it larger than one in TO-92).
>
> I only started making boards again last year. Before that, I used
> PCB layout software to help me do point-to-point wiring. Minimizing
> wire crossings will address the rats nest issue you mentioned. Not
> to mention that it makes reworking the board easier.
>
> Doing the layout gives you the documentation you'll need anyway
> (component diagram, schematic diagram, wire routing). I also size
> the traces depending on current requirements and having that
> documented makes assembly go faster.
>
> If you're working on amplifiers, minimizing wire crossings also
> helps you avoid unintentional feedback; which can turn amplifiers
> into oscillators...
>
> Regards,
> Dennis
>
> --- In Homebrew_PCBs@yahoogroups.com, David Frascone <dave@>
> wrote:
> >
> > I meant for the point-to-point wiring technique? Do you use
> layout
> > software for that?
> >
> > -Dave
> >
> > dl5012 wrote:
> > > Hi Dave,
> > >
> > > It boils down to component placement to minimize wire lengths
> and
> > > crossings. I used to do it on paper; now I use PCB layout
> software.
> > >
> > > For simple circuits, I just do the layout and routing manually.
> For
> > > more complex circuits, I might draw a schematic so the program
> can
> > > make routing easier and check connectivity.
> > >
> > > In general, I don't use autorouting.
> > >
> > > I use Eagle Lite. It's free, but can only autoroute small boards.
> > >
> > > Regards,
> > > Dennis
>