Resizing Schematics for printing PCB?s?

Hi Guys,

I?m really keen to make a pair of the ?What Compressors? to pair up with my
Peter C Green?s. Peter has the PCB layout up on his site here: http://1176neve.tripod.com/id5.html

If I download those .gifs and open them up in Photoshop they are HUGE 106cm
x 66cm at 72dpi. I need to obviously resize these and print them out...

What is the best way to do this? I am a web designer by trade so am pretty
proficient in Photoshop. My though process is to open the file, convert mode
to RGB from Indexed Colour, then resize as as a resolution of 300dpi to the
allotted size.

Peter shared I need to resize to get the IC pins to be 2.5mm apart and the
row of pins to be 7.5mm. The closest I can get is 2.46mm between pins
(resizing the image to 152mm x 98mm at 300dpi), but even with constrained
proportions on the space I then get between the row of pins is 8.8mm?

What am I doing wrong? Please help, this is the first time I am trying to
etch my own boards. Has anyone else built this comp from Peter?s PCB layout?
Maybe you have it in a PDF at the right printable size?

Thanks in advance.

Cheers

Matt

What about resizing to e.g. 297DPI in stead?

Or use something like ACDsee to print it out to a specified size?

But yes, generally .PDF is the best format for schematics.

Hi Jacob,

Thanks for the info, out of interest why 297pdi? Peter gave me the dimensions
of the board, I don't have them on hand, but I remember when I did this in
Photoshop the pin spacing was nowhere where it should be. Anyone have any
luck with doing this? I guess as long at the pin spacing is right
everything else should fall into place. I don?t see the board size mentioned
on Peters site.

Thanks

Matt

I wouldn't trust photoshop for absolute precision - it's not vector based after all. The 297dpi is a guesstimate to get your pin spacing up to the correct 2.54mm

Jakob E.

Thanks Jakob,

I imported the .gif into Freehand I resized the pic to the size of the board, which I got from from Peter,
which is 121mm x 78mm, guess you can't trust Photoshop to do the job. Things seem to check out when printed, but I'd love a second opinion.

If anyone has the time and wouldn't mind would you confirm my figures and check if you resize the gif
below to the sizes above you get a pin spacing of 2.5mm between adjacent IC pins and 7.5mm
on a row of the IC pins. Thanks again



Cheers

Matt

hey glad it all worked out for your.

I would have probably done a few things different/extra.

first I would not have converted to RGB but...
Black and white
(color images will give you a lot of unwanted artifacts (moire) and be hard to select and delete the unwanted areas)
then:
photo shop allows selection by; color,hue, highlights and shadows.
select>highlights>delete
this will give you absolutely zero coloration on you unprinted areas.
you will need to adjust the tolerance of this tool/method and try a few times for best result
.eg. a zero tolerance might give you a jag look arouned the edges
a tolerance of 11 or 22 would be a good place to start.

ABOUT SCALING:
If possible,
Create a canvas the size of your PCB dimensions
pshop allows canvas size shoices of: inches,pixels,points,picas and cm.
All in all:
I believe if you start with the exact canvas size you can't go wrong.
Copy original image>create canvas>Paste to new canvas>scale to new/current canvas size...done.
ALSO: It may have been helpful for you to use the "layers" of photoshop.
layers appear clear
using pshops rulers you could put a couple of reference points
or a grid the desired spacing...
using a grid/ref point approach you could:
have two seperate clear layers with the two grids
you can turn grids(layers on or off as desired)
So..
use your reference points or grid ( BTW making a grid from scratch is a pain ...try to scan one or find a file in a word processing program or something)
then resize and move to match desired grid points or refence mark on your clear layers. (make your PCB scan the bottom layer and the grids/ref points floating above)

Also:you culd print your best effort ...measure...and create canvas sizes increasing or decreasing the width unit it matched then...
do the same with this legth.....
kind of a hunt and peck method if everything else seems to confusing.

hope this was helpful
Toobie Snack