PCB track layout to schematic conversion

revised version Capturing the track layout on polyester pcb , I just tried holding white card laid 45 degrees to the component side and illuminating with a bright light, masking off around the board with opaque card. Photographing and then greyscaling and upping the contrast, loses the small component shadows. Giving a very usefull track layout with a bit of manual touching up for big component shadows etc . Other photos for resistor values and overall views plus manually recording overlay numbers that are hidden, transistor types, capacitor values etc

Now the fun bit, it would be nice to expose, onto rubber sheet, pcb etch fashion. Mark node numbers and stretch into straight lines the DC rails and one or more other major lines and then manually cut and bridge or whatever. Anyone know of a pc application that does this stretching of a digitised image under human control. cut-down example without any manual retouching of the photo stage

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

I use a flat bed scanner - with a black cloth over the top to keep out the light. By playing with the grey scale values you can usually separate the tracks from the rest. The component side can be flipped and overlaid. Beauty of the scanner is the size can be actual and repeatable.

I've previously tried that but I could not get separation as not enough contrast between laquer covered tracks and polyester.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

Right. If it's any help I use an Epson GT 9500 in 24 bbs colour. Can't really help with the software as it's RISC OS.

Is there a general guidance for human only layout to schematic conversion anywhere out there? I tend to start with DC rails but then what. I imagine the numbering sequence for Rs and Cs should give a broad area of where to plonk them in the final schematic but a thin infinitely extendable rubber matrix would be nice.

The other problems with using a scanner are possible scratching the document glass and the solder points end up white rather than black.

-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on

You do have some of the most curious ideas ?

Do you want to improve a layout ?

Creat a netlist and import it back into a pcb package. You'll have to draw the schematic manually though which will give you a netlist anyway.

Graham

I really don't know. It's one of these jobs I find enjoyable, but then with me it's mainly a hobby. What I do do is keep 'building blocks' of the common things like say an op amp component layout.

Generally the business side of PCBs don't contain anything which will scratch glass.

I only use the pic as a guide and retrace the tracks using a vector drawing prog. You need to have nice crisp artwork to start off the PCB producing process and a photo of the board complete with lacquer can't do this IMHO.

But I've not used any of the clever CAD progs that are around. It's quite possible some short circuit a lot of the donkey work.