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Thread: GW-DEC-1: A New Quad Height DEC Prototyping Board

  1. #1
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    Default GW-DEC-1: A New Quad Height DEC Prototyping Board

    RetroHacker_ and conmega were trying to figure out how to replace some missing boards in RetroHacker_'s VT05 and decided they would just make them by hand on protoboard. Unfortunately, Sark didn't like the available protoboard layouts, and so conmega and I worked on laying out a new pad-per-hole board. To maximize flexibility, since we don't know how many people will want, it's designed so it can be sheared in half to make two dual height cards. Here's the prototype, with two DEC-style handles riveted on:



    There's no hard gold plating on this one, just HASL, since it's a prototype to check sizes and fitment. Figured we ought to nail that down before ordering 50 - 100, with the expense of a large board *and* hard gold plating!

    Installed in my PDP-11/10:



    Backplane fitment in the 11/10:



    Fitment in an older style DEC backplane block:



    Silkscreen markings on front:



    The connections are labeled both front and back, front in silkscreen and back in copper/solder mask relief. I haven't run numbers on a production quantity with hard gold plating, but I expect the final version to cost $30-40 USD, which is a lot cheaper than currently available prototype boards, new-made or vintage. I'll be opening a preorder for these in the near future, and we'll be making them available at VCF Midwest!

  2. #2
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    Very nice! It would be helpful to have the bottom array of holes (labeled with bus signals) arranged in a 2x18 lineup with .1 pin spacing so a male header could be installed for easy logic analyser connection. Regardless, save one for me at VCF-MW.

    Thanks!

  3. #3

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    Will the fingers be properly beveled?

  4. #4
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    Will the fingers be beveled? Really helps on insertion!

  5. #5

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    Nice, but make the traces between the connector contact fingers an the pads fatter, there is no meaning to make them thin.

  6. #6

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    Quote Originally Posted by glitch View Post
    RetroHacker_ and conmega were trying to figure out how to replace some missing boards in RetroHacker_'s VT05 and decided they would just make them by hand on protoboard
    Making a proto board is nice. But if you are making these boards for the VT05, why don't you just draw the boards you need?
    That is probably the same amount of work, less error prone than making it on a proto board and much easier to debug.
    Especially after a few years when an error occurs in a board. And it might help others in the future if they are missing a board...

    But a nice very proto board! I like the blue color and white handles.

    Regards, Roland
    WTB: Case for Altair 8800 ...... Rolands Github projects

  7. #7
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    Quote Originally Posted by pbirkel@gmail.com View Post
    Will the fingers be beveled? Really helps on insertion!
    Yes! The edges had to be dressed down with a file since this one was a prototype run, but I typically spec a 45 degree chamfer for production boards. I think conmega found the DEC-specified chamfer angle, we'll be using that if I'm remembering correctly.

    Quote Originally Posted by anders_bzn View Post
    Nice, but make the traces between the connector contact fingers an the pads fatter, there is no meaning to make them thin.
    We probably will, I went with 0.016" for the prototype to visually check clearances.

    Quote Originally Posted by Roland Huisman View Post
    Making a proto board is nice. But if you are making these boards for the VT05, why don't you just draw the boards you need?
    There's significant expense in doing a run of, say, five of a board with actual hard gold plating. RetroHacker_ wants to build them up by hand, it's not that he can't use EDA tools, it's that he likes doing point to point projects Having a general purpose board helps more people, IMO. And, laying out new ones would take a lot more time!

  8. #8
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    Where did you source the DEC style handles for the board?

    How did you rivet the handles to the board?

  9. #9
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    Quote Originally Posted by legalize View Post
    Where did you source the DEC style handles for the board?
    They're still available from various suppliers. The ones pictured were removed from scrapped CNC boards, though.

    Quote Originally Posted by legalize View Post
    How did you rivet the handles to the board?
    I have the tool for riveting them on with tubular rivets:

    http://www.glitchwrks.com/2017/04/25...ng-dec-handles

    I also now have the larger production tool, which is foot-operated.

  10. #10
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    Nice job Glitch.

    My son has done a 3D printable model for the DEC handles. He has 'tweaked' the holes to suit Vince's PDP-8 flip-chip PCBs for the straight-8 (someday I will build it...).

    I did find the supplier of the handles, but the colours are somewhat limited. 3D printing them gives a much larger range of colours.

    Willing to share if anyone requires it.

    Dave

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