Fractional Module Rack Case (FracRak)

The FracRak case holds up to ten 1.5" wide by 5.25" high modules in a
standard 19" wide, 3U high rack space.  The case shown houses modules
up to 7" deep. The case consists of 4 pieces: Mounting Rails, End
Pieces, Rack Ears and Covers. The Rack Ears are anodize flat black and
the rest of the pieces are natural finish.

The Rack Ears and Module Panels are standard 1/8" thick aluminum.
Module panels are black anodized and available in widths that are 
multiples of 1.5". Structural pieces are .050 aluminum. Cover plates are .040 aluminum.

files:

fracrwhl.gif - FracRak case and example panel components.
Shows how the pieces go together with 4-40 Machine screws and nuts and
#4 self-tap screws.  Also shows a sample system with more or less
random controls and connectors, just to give an idea of how much fits
on the panel sizes. I've tried a few case designs and this one is
strong, versatile, and good looking while still being inexpensiive to
fabricate because of symmetrical, identical pieces.  It conserves
materials and ships easily and inexpensively also.


fracrmod.gif - Typical double wide module
Circuit boards mount to the panels with "L" brackets (the technical
term is "PAiA mounted").  This module is a sketch of a vacuum tube
based mixer for single ended or balanced line inputs to 1/4" balanced
or unbalanced output.  It includes a phantom power mic pre as well.
The soft tube technology, pre/post tube mixing and symmetry panel
controls produce a flexible processor that provides a complete palette
of vacuum tube coloring for any audio source. In a synth, it's the
ideal element for a final output driver.


fracrdwg.zip - C sized dimensioned drawing of the pieces.
This unzips to an HPGL file named <fracrak.hpg>. Some viewers may
expect .plt or .hpl extensions. This drawing is readable down to a 
tabloid sized page.


fracrak.txt - This file

Excerpted from AH Mailing list post 3/21/95:

... I would propose distributing bulk power with a commonly 
available connector such as the molex connectors that are used 
for disk drives in PCs, they certainly are common enough and 
consequently inexpensive for a from-scratch builder as well as 
a manufacturer. 

Bulk power in this case would be bipolar unregulated 18V with 
local regulation at the module down to +/-15V, +5V, or whatever. 
Bear in mind that some modules (a mixer, for example) will probably 
not need *regulated* power at all. I've become a big believer in 
separate signal and power grounds back to an internal star point 
in equipment and consequently would recommend that the 4 pins of the 
power connector be:

 1) +Vunreg
 2) -Vunreg
 3) Power ground
 4) signal ground. 

For sure the kind of power distribution found in the 4700 and 2700 
synths will never do - I cringe to think that I once did stuff 
like that.

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Here are some prices:

FracRac Case (includes hardware,
7" deep end pieces, mounting rails
and anodized Rack ears).....................  US$16.25

Top/Bottom covers............................ US$ 3.65 / pair

Blank (except for mounting holes) black anodized panels

single wide blank panel (1.5 X 5.25)......... US$ 3.00
double   "    "     "   (3 X 5.25)........... US$ 3.50
triple   "    "     "   (4.5 X 5.25)......... US$ 4.00
four     "    "     "   (6 X 5.25)........... US$ 4.50


For further information, contact:

PAiA Electronics, Inc.
3200 Teakwood Ln.
Edmond, OK 73013
phn 405-340-6300
fax 405-340-6478
email paia@aol.com

Aloha - John Simonton