[sdiy] PC board from artwork?

Fri Oct 21 05:51:18 CEST 2016

Hey you guys, leave Dave alone!  He's a maverick, and a diyer with best
selling designs by a major manufacturer, all while using a spreadsheet
program to design prototype PCBs!  I think he deserves Sunglasses and A
Snoop Dogg soundtrack :D

On Thu, Oct 20, 2016 at 10:19 PM, <rsdio at audiobanshee.com> wrote:

> I find it very therapeutic to work on a layout in Eagle. I can spend hours
> fine-tuning placement of parts and traces.
>
> The nice thing about using a tool is that you can then quickly check your
> design for the different specifications of various PCB fab houses. I might
> start by designing to OSHPark's Design Rules, which they provide in Eagle
> format for download, but then I'll switch to a custom Design Rule file that
> I've developed while working with Advanced Circuits (4PCB.com). Sometimes,
> changing the Design Rules will require more work on the layout, which is
> potentially another opportunity for therapy, depending upon how you look at
> it and whether there are any deadlines.
>
> Another nice thing about having a tool is that almost nothing is any
> harder than it really needs to be. That way, the effort is spent on the
> unique aspects of the project at hand, rather than spending time on the
> limitations of the tool.
>
> Brian
>
>
> On Oct 20, 2016, at 5:56 PM, David G Dixon <dixon at mail.ubc.ca> wrote:
> > Tom,
> >
> > The Excel thing was originally for laying out breadboards.  I hated
> "improvising breadboards at the workbench" and wanted a tool for laying
> them out.  After getting fed up with breadboards, I decided that I could
> also use it to lay out PCBs.  Since I make all my own PCBs in my laundry
> room basin, I had no need for anything more sophisticated.  Plus, I was
> able to do pretty decent layouts in fairly short order, and I found it
> somewhat therapeutic to do so, so that's why I never bothered to learn
> anything else.  However, lately I've been thinking that I really ought to
> join the 21st century with this stuff.  I'm taking a sabbatical from
> teaching in 2017, and will be devoting a lot of time to  synth-DIY
> activities (including finally learning how to program microcontrollers), so
> perhaps I'll learn a layout software.  (One thing, though, is that I hate
> soldering "professionally made" PCBs.  I much prefer soldering my own
> single-sided boards, even though they often require a fair
>   number of wire jumpers.)
> >
> > Cheers, Dave
> >
> > From: Tom Wiltshire [mailto:tom at electricdruid.net]
> >>
> >> David,
> >>
> >> It's truly remarkable that you put up with such a hideously involved
> method. I mean, I know how these things evolve, so I completely understand
> how you got there, but if you stand back and look at what you're doing,
> given the software that's available, it doesn't make any sense. At the
> time, you used the tool you had. Then you used the tool you'd used before,
> and developed it. Before you know it, you're doing full-scale layouts in a
> tool designed for something completely different, with none of the benefits
> of a tool designed for the job.
> >>
> >> Honestly, try one of the options that have been mentioned. I'd put in a
> shout in for RS' Designspark too, although maybe they don't have such a
> presence on your side of the pond. I don't use it (I'm on DipTrace which
> has already been mentioned, and which I'd also recommend) but I've heard
> lots of good things from people who do.
> >>
> >> Regards,
> >> Tom
> >>
> >>
> >> On 20 Oct 2016, at 04:40, David G Dixon <dixon at mail.ubc.ca> wrote:
> >>> Hi Quincas,
> >>>
> >>> I have made a bunch of little graphics in Excel, using just
> rectangles, lines of various colours, etc, which represent chips,
> resistors, caps, diodes, etc, with their leads and pins.  The first thing I
> do is set the grid to 16 x 16 pixels so that the spreadsheet cells are all
> little squares.  Each square represents 0.1".  Then I select "Snap to Grid"
> in the Drawing menu so that when I move the parts around they snap to the
> 0.1" grid.  Then I just do the layout by pure blunt force by carefully
> working through the schematic.
> >>>
> >>> The layouts are facilitated by sticking to a certain basic plan.  The
> power rails go down the middle of the board from left to right, and all the
> chips straddle these rails.  Hence, the first row of pads next to the rails
> accommodate the chip pins.  The next rows of pads are for things that
> connect between adjacent chip pins, like small stability caps in opamp
> feedback loops.  The next pads are for components connecting out from the
> chips, such as resistors and diodes.  These are all 0.4" long, and thereby
> straddle three potential rows of traces and/or pads.  I call this
> three-lane conduit the "boulevard" and it is through here that I route
> signals around the board.  Beyond that is a row of pads for the other end
> of all the resistors and diodes, and then a row of pads for off-board
> connectors, and finally a ground trace which typically encircles the entire
> board.  The boards are arranged symmetrically around the rails.  This means
> that all of my analog boards are either 2
>  .1" wide, or 4.0" wide for "double-wide" boards (which share a ground
> trace down the middle between the two halves).
> >>>
> >>> Once I've got the layout done, connecting all the parts with different
> coloured traces (lines with ball ends in Excel), and the layout is reviewed
> and error-free, then I copy this layout to make several different
> graphics.  One is "parts-only", one is "traces-only", and one is "pads
> only".  The "traces-only" graphic is made up of all the traces in the
> layout, and is made up of several layers of lines.  All traces are made up
> of three layers of lines, with ball ends of various sizes to make up pads,
> and smaller lines with small ball-ends on every line to give rounded
> corners.  Finally, all power and ground traces are copied and made wider
> than other traces.  These are all consolidated into a single graphic.  The
> "pads-only" graphic is made up of small circles combined with larger
> invisible squares to force them to align on the grid.  These small circles
> sit over the ball ends of the traces, and exist to provide small
> drill-guide holes for the pads for easy drilling.
> >>>
> >>> Finally, the pads and traces are turned black and combined to make the
> transfer graphic.  This is what is printed and transferred onto the PCB.
> Finally finally, the transfer graphic is covered with a semi-transparent
> white rectangle, and then the "parts-only" graphic is superimposed on this,
> and that makes the "build pic" which is actually what the completed board
> will look like.  I use this graphic when I'm stuffing the board.
> >>>
> >>> Sorry, that was long, and probably hard to follow.  I'll just email
> you an example so you can see for yourself.
> >>>
> >>> Dave
> >>>
> >>> From: Quincas Moreira [mailto:quincas at gmail.com]
> >>> David, could you describe how you lay out PCBs in Excel? very curious
> :)
> >>
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-- 
Quincas Moreira
Test Pilot at VBrazil Modular
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