[Cryptech Tech] Updated novena noise board

[Fredrik Thulin]

Hi all

Since we're not going to have Alpha boards by the summer (this year), we've 
said we would produce some more noise boards for Novenas to get in the hands 
of testers and early adopters.

I've been updating the schematics and am ready to order a couple of test PCBs 
to verify the layout, but thought I would ask Pavel, Jacob and any other PCB 
designers on the list for feedback (any lurking circuit designers are welcome 
to give feedback too) and constructive criticism. Attaching PDFs and Eagle CAD 
files.

Noteworthy changes since rev02:

  - Made separate ground plane for analog circuit to try and keep ground 
    signal noise away from noise generator. Please comment especially on this
    as it is a first for me. Too many/few vias for the shielding cabinet? Also 
    want mechanical stability from them since I've ripped a shielding cabinet 
    from the FR4 once. Good sized connection between AGND and GND?

  - Added some rudimentary filters to the 5.0V input and DC/DC converter 
    output. Filters made from oscilloscope observations and SPICE simulations,
    plus basic bread board testing. This seems to clean up the power lines 
    quite a bit, but maybe an 12V LDO should be added too.

  - Changed to a 1-gate Schmitt trigger, and removed the bus transceiver.

/Fredrik

PS. I might be slow on answering e-mail for a couple of days. AFK.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: rev03_brd.pdf
Type: application/pdf
Size: 60607 bytes
Desc: not available
URL: <https://lists.cryptech.is/archives/tech/attachments/20150513/66b56238/attachment-0002.pdf>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: rev03_eagle.zip
Type: application/zip
Size: 125641 bytes
Desc: not available
URL: <https://lists.cryptech.is/archives/tech/attachments/20150513/66b56238/attachment-0001.zip>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: rev03_sch.pdf
Type: application/pdf
Size: 41341 bytes
Desc: not available
URL: <https://lists.cryptech.is/archives/tech/attachments/20150513/66b56238/attachment-0003.pdf>