PCB track layout to schematic conversion

[N Cook]

Capturing the track layout on polyester pcb - I've just tried holding
white card laid 45 degrees to the component side and illuminating the card
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
for first stage schematicing.
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
http://home.graffiti.net/diverse:graffiti.net/pcb1.jpg
http://home.graffiti.net/diverse:graffiti.net/pcb1.jpg
http://home.graffiti.net/diverse:graffiti.net/pcb1.jpg

 

[N Cook]

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
http://home.graffiti.net/diverse:graffiti.net/pcb1.jpg
http://home.graffiti.net/diverse:graffiti.net/pcb2.jpg
http://home.graffiti.net/diverse:graffiti.net/pcb3.jpg

 

[Dave Plowman (News)]

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
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

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.

 

[N Cook]

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.

--
*Don't use no double negatives *

Dave Plowman [email protected] London SW
To e-mail, change noise into sound.

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

 

[Dave Plowman (News)]

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

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.

 

[N Cook]

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.

--
*Why is 'abbreviation' such a long word?

Dave Plowman [email protected] London SW
To e-mail, change noise into sound.

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.

 

[Eeyore]

Is there a general guidance for human only layout to schematic conversion
anywhere out there?

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

 

[Dave Plowman (News)]

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.

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.

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

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.