reklipz:
OK, well, heres my “finished” board. Oh, just realized I have to add the USB power transistor, so, nearly finished.
Greetings Nate,
Your design looks very good! I’m new to the “display board”
project, are they related?
I don’t have your schematic, not sure if you’re willing to
share the EAGLE files, so what are you using for the
temp interface? (What is IC3?).
My suggestions are:
(1) Move C14 away from the hot AC side of the transformer,
perhaps you can fit it near the 16 pin connector?
(2) Route the low voltage side of OK1 away from the hot AC
side of the transformer. Perhaps you can run the pin2
trace under the trace to R4 to compact the design?
(3) Move R4 nearer to either the 16 pin connector or
the uC, to keep its pads away from the hot AC side of
the transformer.
(4) For peace of mind you should keep a 6mm (400mil)
guard band around all hot AC traces. This is a VDE
requirement, and a tough one at that. The process of
thinking about a 6mm creepage will get you a much
better hot AC intergrity even if you can’t do 6mm for
100% of the hot AC traces.
If you are familiar with the “Mark” command in EAGLE
use it to measure line-of-sight from pads and traces to
each other on the hot AC circuits.
(5) I don’t see any test points. When it comes to SMT
layouts I find that sprinkling a few pads on ground,
power rails, and at least one unused uC port (if available)
will allow a scope probe or DMM to be used later.
My preferred testpoint is a 100mil diameter pad with
40mil drill. It can be used as-is or fitted with a[Keystone THM test point.
(6) Your screw terminal blocks look familiar, but
I’m not sure of their size. Do you really want to run 13.5A
through these? I use two sizes, the['blue’ones have single
hole mounting and can take a 14 - 22AWG wire, I use
these up to five amps (they are UL approved for 15A).
For heavier loads I use the [‘Black’ ones rated to
10A but with two electrical lugs each.
Why not run heavy wiring in the project to the heaters,
Triac, and a chassis mounted fuse (15A)? Run a second
AC circuit after the 15A fuse to the PCB and use a smaller
fuse (5A or less)? This will give the required protection
and reduce the copper needed on the PCB.
Comments Welcome!](http://www.on-shore.com/catalog2/tpg7b.pdf)](http://www.on-shore.com/catalog2/tpg7.pdf)](http://www.keyelco.com/pdfs/M55p51.pdf)