Homebrew PCBs

>I'm convinced the photo i linked to wasn't shot at that angle by accident.
>The corner is obstructing view of the tube...
>
>But if one really wants to copy it in large-scale they will simply buy a 
>unit.

Yes and no. It works and I'm sure there are multiple ways to build a
good working unit.

>I wonder who has the patent.

Bungard, but since it dates back to the sixties I figure the patent
protection is meanwhile void. I'm however not experienced, that said I
don't know if a patent is protecting "forever" or if it's only
effective for some years.

Markus