Homebrew PCBs

On Thu, 06 Jan 2011 00:42:16 -0000, you wrote:

>Your idea is interesting.
>I use to service gestetner products in my hay-days. They had a machine which used a 24 inch long rotating aluminum drum. A paper copy on the left side was read by a photomultiplier/microscope assembly and the signal was used to drive a high freq power osc. This signal went to a tiny stylus (think it was tungsten) in contact with a stencil. The sparks burned holes through the stencil to make an image silkscreen for a duplicator ( a thingy with 2 4inch rollers that squeezed ink through the stencil and onto the paper)for the youngsters. Sparks (high frequency only) actually do a nice job but 
>the mechanics to do this on a flat pwb I think isn't worth the effort considering the cheap imaging devices that can be hacked to do the same.  
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Back in the '60s there was a similar device (made by Fairchild) that mounted 
a photograph  on one end and a plastic sheet on the other side with a hot needle
to make plates for newspaper photographs on ink-based printing presses. They
still had Linotype machines and lead type for text.

There was another takeoff on the same idea for proto pc boards. A 1:1 board drawing
on one side and a flex pcb on the other. The traces were cut by something like
a dremel tool using a little disk/burr. The flex board was then glued to a thicker piece
of fiberglass. Needless to say you didn't run traces between dip socket pins 8-)

Keith Bowers WB4LSJ- Thomasville, NC