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Re: Homemade PCBs!

Original poster: "Jim Lux" <jimlux-at-earthlink-dot-net> 

Might be OT, but here goes...
Gerber makes highly specialized photoplotters, used for all manner of
things, including exposing artwork for PCBs and for ICs (although probably
not much of the latter any more). They're quite similar to how
phototypesetters (used to) work.

The basic machine is fairly simple and is entirely done by optical means.
It has a rectangular aperture that you can control the height and width of,
so you build up your image by combining a series of rectangles, specified as
the position of the rectangle (x,y) and the height and width of the
rectangle.  There's also a series of apertures with funky shapes (i.e.
circles) that can be exposed onto the film. The machine has a wheel with
holes in it with the apertures that rotate into the optical path. The
rectangular apertures have actual blades that come in from the side.

So, a Gerber file consists of a series of numbers specifying:
the type of aperture (rectangular of arbitrary dimensions, or one of the
predetermined apertures)
the position of the aperture on the film
the dimensions of the aperture (h & w)

The whole process of exposing a film with a gerber machine is really, really
slow. (lots of mechanical operations)

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Tuesday, April 27, 2004 8:05 PM
Subject: Re: Homemade PCBs!

 > Original poster: Ed Phillips <evp-at-pacbell-dot-net>
 > "Original poster: "Jim Mitchell" <Electrontube-at-sbcglobal-dot-net>
 > Oh my.  Why doesn't anyone know what gerber files are?!  You can use
 > eagle
 > to do them,  or I can make them for you.
 > Regards - Jim Mitchell"
 > Know what Gerber plotters are and assumed they work from data files of
 > some sort, but that's as close as I've come; I'm a radar systems /
 > microwave guy who doesn't make circuit boards (about two generations too
 > early), and I don't know how the files are generated.  To continue my
 > ignorance, what is "eagle" and is it freeware or one of those expensive
 > CAD programs?  Thanks for the offer but I'd rather "do it myself".
 > Ed