[sdiy] First the Queen, now Harry...

[Robert Kent]

On Tue, 22 Oct 2002, Peter Snow wrote:
> ...One that facinated me was a circuit containing a couple of chips
> with no markings on them at all.  Turns out that Mark had etched the
> PCB as a mirror image of what it should have been. Instead of trashing
> it, he simply bent the legs of the ICs upwards and soldered in the
> chips up-side-down.

  That happened to me recently. I redesigned Ken Stone's drum
simulator circuit to use LM324s, and tried out a new toner transfer
process that doesn't need a mirror image when I etched the board.
Of course I had mirrored the image out of habit, and spent about
30 sec. examining the board in total disgust before realizing
that the LM324 is perfectly symmetrical from end to end. I then
populated the board as usual (with pin headers on the solder side
to retain the original pinout) and of course it worked perfectly.

  Now I'm faced with a puzzling psychological quandary: if the
board is functionally identical in mirror image, why did I choose
to lay it out one way and not the other?

-- 
--Robert Kent
  hanuman at ccsi.com