Six. The circuitry is pretty simple. All the fast stuff is on layer 1,
and the miscellaneous signals are on 6. Ground is 2. The other layers
are all power pours.
Three of us worked on the pcb layout. I did the fast stuff... still
tweaking it in fact. My cad guy did the basic board setup and the
pours (he's great at pours) and will do the formal release and
gerbers. One of my engineers designed and layed out the power supplies
on the right. Another one of my guys worked out the optical receiver
stuff.
My production manager is also a great mechanical designer. We looked
around for standard boxes, but nothing was right, so he designed this
to be custom fabbed from sheet metal. It will be cheaper than a
standard enclosure, which seems silly. The pic is from SolidWorks.
The front and back will have polycarb label/overlays. Nowadays they're
digital printed in unlimited colors (not screened) and laser cut (not
steel rule die) so we can go crazy on graphics.
The next spin, once we get this to work, will dump the switches and
trimpots for a uP with dacs, and add time trims per output.
The goofy looking run upper-left is an impedance test trace. I'll TDR
it on a bare board to see how things came out. The two square SMA's
are for experimenting with plane impedances and noise, just for fun.
John