Hi Dave
i'm a bit embarrassed to say so, but i was worried about the 4x6
real estate limit..... but not having the cajones to try it myself, i
held my all too eager tongue. All i can do is say thanks for being the
'first pioneer out of the wagon' on this shenanigan.
Clearly (thanks to your efforts, Dave) the integrated 16-ch
approach is not a trivial enterprise and it will require the talents
of folks experienced with high-density digital and analog layouts to
make it robust and allow for assembly by human-sized fingers.
i did a tentative layout based on my default platform, which is
plate-thru-hole perf protoboard (i got a pile of surplus ones with PCI
fingers on one side) they're about 4x8.... i gave up when i was up to
3 boards!
For my part i'm willing to accept that this may be too expensive
and finicky to do -right- on an amateur basis.
My perf design inclines me to believe that a modular approach has
merit. (that German fellow took the modular/backplane approach on a
different PIC platform) but that paradigm has it's own set of problems:
-coordinating consensus for a spec, again
-a robust reliable interconnection scheme
Perhaps we should just try for a good frame-out of the BasicAtom28
on a 'motherboard' and leave the ADC/DAC daughterboards to the
resources and imaginations of the 'private sector'
No matter how we slice it though, much gratitude is due to you for
determining how deep this quicksand is!
patiently circling (like any good buzzard)
;'>
-doc
--- In
ComputerVoltageSources@yahoogroups.com, "djbrow54" <davebr@...>
wrote:
>
> It is 4x6 so it is too big for this service. It needs to be even
> larger. I couldn't fit the MIDI components, I have 1/8 watt
> resistors UNDER the AtomPro28 part in the interior of the socket, my
> I2C protection changes use 1/8 watt resistors, and there is no room
> for the 8 input filter capacitors so those are piggybacked on the
> feedback resistors. I also believe the SMT DACs should be changed
> to SMT/DIP combination and there is no way to do this in an overlay
> so that is a couple of additional components. I would guess you'd
> want to add 1 - 2" in each direction to spread things out a bit so
> I'd start with a board size of 5 x 7 to 6 x 8.
>
> I paid $120 for two quicks with no solder mask. I know the price
> for solder mask has the $233 setup charge plus the charge per board.
>
> As to the runs, I'll have to look but I think they are 10 mil runs
> with 12 mil clearance and no solder mask. For reference, that is
> half the spacing of the SMT pads. I'll try and upload some 1:1
> photos of the clearance this weekend.
>
> I'm also not happy with the ground planes. They aren't connected
> the way they should be and I can't get the software to do what I
> want. The board needs to be redone.
>
> Dave
>
> --- In ComputerVoltageSources@yahoogroups.com, "Larry T."
> <larry@> wrote:
> >
> > Dave, and others that may be interested. ExpressPCB offers
> ProtoPro
> > service. This is 4 boards for $179.00, which includes solder mask
> and
> > silk screening. That works out to about $45 per board. Size is 21
> > square inches per board max.
> >
> > Dave, just how hard was your current board to work on? How big is
> it?
> > In your opinion, could some that does everything from MOTM to CGS
> > boards be able to build it in it's current configuration?
> >
> > Larry T.
> >
> >
> >
> > --- In ComputerVoltageSources@yahoogroups.com, "djbrow54" <davebr@>
> > wrote:
> > >
> > > The issue is ExpressPCB is very expensive for solder mask in
> small
> > > quantities. The setup fee is $233 so you have to order a lot of
> > > boards to cover this cost. The board needs to be larger so this
> cost
> > > would increase. Someone with PCB layout software needs to
> layout the
> > > board in a larger size with standard PCB output files. This
> larger
> > > size would also allow DIP versions of the DACs to be added so
> SMT
> > > could be avoided. My layout could be used as a starting base.
> I know
> > > there are people on this list that have PCB layout skills,
> software
> > > and experience.
> > >
> > > This project will only move forward if others volunteer. I've
> > > contributed all I can.
> > >
> > > Dave
> > >
> > > --- In ComputerVoltageSources@yahoogroups.com, "Larry T."
> <larry@>
> > > wrote:
> > > > Don't get me wrong. I know that this is a volunteer effort.
> > >
> >
>