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Create a PCB from an image

Discussion in 'Electronic Basics' started by logjam, Dec 30, 2005.

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  1. logjam

    logjam Guest

    I have scans of an unpopulated PC circuit board that I would like to
    reproduce using a company that requires Gerber files.

    I'm trying to duplicate a S-100 bus card from an Altair 8800 and I want
    to preserve the layout for historical accuracy. Is there any "Good"
    way to do this? Is there low quantity PCB company out there with an
    input file acceptance other than Gerber that would be helpful to me?

    I would also like to preserve the font of text items like the logo.

    Any suggestions on what I should do would be great.

    Thanks,
    Grant
     
  2. Pooh Bear

    Pooh Bear Guest

    Is the 'scan' a 'picture' of the pcb ? If so it's only good for reference.
    To make a pcb you'll have to recreate the whole thing again from scratch.

    Other than Gerber, some outfits may accept certain cad files directly or
    you could of course do it the way it certainly was back then and do a tape
    up.

    Graham
     
  3. logjam

    logjam Guest

    The scan is a 300dpi "picture" of the board. With image processing
    tools I can get a view of JUST the traces...if that helps.

    Are you aware of any PCB programs that will allow you to overlay your
    work on top of a picture? That might help me out.

    This is a single layer PC board, so it is probably easier than some.
     
  4. jibberjabber

    jibberjabber Guest

    If it is to scale you can make one yourself pretty easily and fairly
    cheaply.

    Press-n-Peel Blue (http://www.techniks.com/) lets you print an image on a
    laser printer and iron it onto a blank PCB. I would first bring it into
    Photoshop to create a clean black and white (only) image. Don't forget to
    also "mirror" the image at this time if needed. Etch it with Ferric
    Chloride (from Radio Shack), drill with a Dremel using their cheap PCB bits.
    A "wash" with Liquid Tin (Allied Electronics) will protect the traces from
    corrosion and make it look much better. Use PnP again on the top (non
    copper) side for a silkscreen (it will be black). Do this before drilling
    otherwise you won't be able to iron the silk-screen image satisfactorily.
    Coat with Polyurethane or acrylic when done.

    jj
     
  5. Rich Grise

    Rich Grise Guest

    If you have a laser printer or a copier, there's a technique where you
    can take an image of the artwork, either print it on a laser or print
    it on a dot-matrix and copy it in a copier, and iron it on to the
    board and the toner becomes your resist.

    See if you can find a board house that will accept negatives, and
    print the artwork precisely 1.000:1.000 on transparency film, and
    have them do that.

    Single "layer"? Do you mean single "sided"? In S-100?? You just
    mean "not multilayer," right?

    Good Luck!
    Rich
     
  6. Jasen Betts

    Jasen Betts Guest

    If it's single sided can you etch from the image you have?
    (possibly enhance it a bit in a photo-editing tool like the Gimp
    (gimp.org) or photoshop se (Adobe.com) it's not like you need plated
    through holes, and there's no alignment issues...

    another option may be printing it out on transparency film (possibly
    enlarged a bit) and taping it to
    your monitor and then re-entering it into a PCB editor. :)

    It's computationally difficult to convert raster images to vector
    (outline) images, and even harder to convert them to stroked images.
    guess which you have and which gerber files are.

    Bye.
    Jasen
     
  7. logjam

    logjam Guest

    Thanks for the suggestions on home grown PCBs. I have done that
    before, but Its not "easy" enough for what I want. I need to be able
    to easily make these without effort, and the S100 bus card is by far
    the simplest. Others will be double sided.

    Yes, I meant single sided. :) I can get a copy of the BUS card posted
    here.

    I have used a PCB program called WinQCad, Protel, CircuitMaker, etc.
    Correl draw can trace an image into an HPGL. Is there any chance that
    I would find a DXF or HPGL to gerber converter?

    Thanks,
    Grant
     
  8. Pooh Bear

    Pooh Bear Guest

    The 'language' of gerbers is something special. The idea of gerber
    conversion from a jpg ( or anything else ) is a non-starter. You need a
    program that is designed to output gerber data. Other than that the
    traditional film approach is the best idea.

    Graham
     
  9. logjam

    logjam Guest

    So its either film or start from scratch. Are there good DXF to gerber
    converters? I'm just trying to find an easy to overlay the new design
    over the old.

    Film and a drill pattern is what they used in the "old" days?
     
  10. Pooh Bear

    Pooh Bear Guest

    As I tried to explain there isn't a simple 'conversion'

    Gerber is based around commands that flash light onto a photosensitive
    film.
    http://en.wikipedia.org/wiki/Gerber_File
    Manual tape up. Followed by photographic reduction. Drilling for small
    quantities was manual.

    Graham
     
  11. logjam

    logjam Guest

    I found that ViewMate includes the ability to import a bitmap. Does
    anyone have this software who could try and see if they could draw on
    top of the bitmap? Basically tracing the traces in the image?

    The Free version of ViewMate does not allow importing bitmap images.
     
  12. Rich Grise

    Rich Grise Guest

    Yeah! When we were their age, we didn't even have computers! And we
    had to walk to school 40 miles through 8' of snow, uphill both ways,
    barefoot! ;-)

    Cheers!
    Rich
     
  13. Jasen Betts

    Jasen Betts Guest

    DXF is a vector format - it gives outlines of all the dark areas, AIUI
    gerber uses the centerline.

    I don't know that converting outlines to centrelines is any easier than
    converting bitmaps to centrelines.

    Bye.
    Jasen
     
  14. logjam

    logjam Guest

    I'm not that old. ;) I've found quite a few places on the net that do
    PCB scanning to gerber file conversion. If the price isn't too bad
    then I'll do that. I have to factor in my time involved. If it costs
    $200 to scan a PCB then I coudl work an hour over time for a week. ;)\

    http://www.westwindcad.com/
    http://www.etsind.com/pcbartwork.php
    http://www.mhtest.com/scanning.shtml
    http://www.scancad.com/ - software/hardware manufacture
    http://www.sxlist.com/techref/app/format_conversion.htm - This web page
    has instructions for a BMP to gerber conversion, much more work than
    mailing the boards to be scanned. ;)
    http://www.artnet-tech.com/scan.htm
    http://shaaiscanner.com/ - these guys don't have the best grammer on
    their site...could be scary to send them an origional card!

    I guess the next step is to ask around on usenet who has used one of
    these services, what it cost, and how happy they were with the results.
    I'm set on making the process automated, that is e-mail a file and get
    a board, because otherwise the "project" becomes making boards. ;)

    Any ideas on good groups to ask?

    Thanks,

    Grant
     
  15. Rich Webb

    Rich Webb Guest

    Corel Trace (and, I'm sure, other similar apps) can do a trace "by
    centerline." Tried it out just for grins with a Postscript created by
    pcb (from the gEDA family) that I converted to a black'n'white bitmap
    by importing it into Corel Draw.

    The centerline trace actually looks pretty reasonable when the results
    of the bitmap -> vector are brought back into Corel and the line widths
    adjusted appropriately.

    Corel can save the result as a .dxf file and there are some dxf to
    Gerber translators out there (according to Google; haven't tried any).
    So it's possible in principle to go from a bitmap to a Gerber via a few
    intermediate steps.

    I'd be concerned about all the misalignments along the way, though.

    The OP's best bet is still probably to load up a board layout package
    and create "real" Gerbers. Having a working original board to duplicate
    should make it go quickly.
     
  16. Jasen Betts

    Jasen Betts Guest

    hmm, it was about 15 years ago that I last played with corel trace,
    if a grid was set at 0.1" would that help?
    yeah, probably more time has been spent talking about it.
     
  17. Rich Webb

    Rich Webb Guest

    I'd forgotten that I had it. ;-) IIRC, it's now a standard part of the
    "Corel Draw" set.
    Probably not. Many types of individual components are 100 mil pitch but
    may well be placed onto a finer grid. Traces almost certainly weren't on
    a 100 mil grid even back in the day.

    Try printing the result of (bitmap -> centerline trace -> Corel vector
    -> dxf -> Gerber) on a transparency and overlaying it onto the original.
    If it looks like it's good enough then it might really be so.
    The gEDA suite is free and works pretty well (at least under Linux; I
    haven't tried it on Windows). If you're ever planning on making
    additional boards, you'll need it (or something like it) anyway.
    Recreating a "known" board is a good first project.
     
  18. logjam

    logjam Guest

    These are the boards I will be copying. I plan on desoldering all the
    components, getting the board art duplicated, and then reassembling
    them.

    http://media.diywelder.com/images4/060101-cpu.jpg

    http://media.diywelder.com/images4/060101-1K_static.jpg

    In the spirit of getting as much data as possible I will be digitally
    x-raying the cards too. The x-rays should make debugging easier since
    you can easily see which traces go where via the vias. ;)

    Here is a quick and dirty shot of a 68000 chip. The ram chips are in
    the top and the PROM are visible in the lower left:
    http://media.diywelder.com/images3/090605-512kProcessor.jpg

    Here is the RAM section:
    http://media.diywelder.com/images3/090605-512kRAM.jpg

    For the altair boards they will have no components installed for the
    x-ray and I will have adjusted the levels of the picture to provide
    less contrast than the above pictures.
     
  19. Rich Webb

    Rich Webb Guest

    Looks like fun! Good luck -- and also check the 'net for assorted
    schematics. A quick check shows that you might be able to find some
    out there.
     
  20. logjam

    logjam Guest

    A nice thing about the Altair I found is that it came with a complete
    set of documentation. I bought it from the 2nd owner, and he has had
    it in the basement since 1981 when he got it.
     
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