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Low-Cost, Complete ECB Enclosure Design [message #7778] Wed, 10 June 2020 11:30 Go to next message
farmerpotato is currently offline  farmerpotato
Messages: 3
Registered: May 2020
Junior Member
Hello all,

This is my first post. I'm very interested in learning from this community, and I hope to contribute back.

I am constructing a ECB computer around the TMS99105. It will be backwards compatible with the Geneve 9640 and TI-99/4A, and share a good deal with an MSX2, like the V9958 and OPL3. All the cards will be available separately as open-source. Hopefully they can work with other CPUs, and I can use existing ECB cards like the V3 Disk IO.

This post is about the low-cost enclosure I am designing for it. Where low-cost is around $150.

I would appreciate feedback on the ideas I have so far. Especially on how to get the cost down.

I am using the 8-slot ECB backplane from jcoffman,

The backplane is mounted on some flat rails I saw at Electronics Goldmine.

The $7 rails were ideal, at 17" long, 0.4" wide with 0.2" spaced 4-40 holes. Obviously I will cut them to length. I have not found any other source for this! Extruded aluminum Eurocard rails are way too expensive! (The rails were $3 on sale.Wink

The box will be a standard Hammond enclosure like the 1458VD5B, 8x8x5", or the 10" wide 1458VG5B. It is a very nice Altair blue!

The rails fit into the back panel holes, horizontally side-to-side. But vertically, one rail is off by 1/2 a hole or 0.1". Argh! I don't know what kind of bracket would fix that, but maybe it's enough to use a cotter pin or bend a nylon standoff?

The card guides will be common $1 PCI guides from Bivar, though the snap-in pegs are a big too large.

What I have assembled now:

/forum/index.php?t=getfile&id=1804&private=0
(Card guides were from a junker PXIe chassis--those cost $5 each, so I will use the boring $0.80 kind.Wink
(second backplane is just a stand-in for a card)

I may just use acrylic sheet, laser-cut with precise holes, to hold the card guides, supported with metal.

Cost for the enclosure is about $50, so that leaves a budget of $50 for all the other parts.

In the 8x8" enclosure, there is just enough room for power and fans. Power will be a $35 pico-PSU. For cooling, some <10mm fans underneath, or a blower on one side vent. (are there squirrel cage blowers that can reverse-suck air into the blower?Wink

Here's how low-cost is working out so far:

$ 20 Backplane, 8-slot
$ 50 Enclosure, Hammond 1458 series, 8x8x5" or 10x8x5"
$ 13 Card Guides
$ 25 PicoPSU
$ 21 Steel rails ($9 on sale)
$ 10 Acrylic, laser-cut (by me)
$ 10 Fans
$ 10 Misc hardware (screws, brackets, Mate-n-Lock, etc)
====
$159

Additional labor will be milling the front aluminum faceplate, to expose front panels, and holes in the back faceplate.

There could be an option to use a common PC tower as the case, mATX or Mini-ITX. Maybe the cage could mount in one. I didn't get far on that; how would the PCI brackets work?

I hope to offer this as a kit.

I will post more as the computer is built - PCBs are in the mail.

-Erik
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[Updated on: Thu, 11 June 2020 10:48]

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Re: Low-Cost, Complete ECB Enclosure Design [message #7779 is a reply to message #7778] Wed, 10 June 2020 11:32 Go to previous messageGo to next message
farmerpotato is currently offline  farmerpotato
Messages: 3
Registered: May 2020
Junior Member
Links

Steel Rails
https://www.goldmine-elec-products.com/prodinfo.asp?number=G 22303

Hammond 1458 Enclosure
http://www.hammondmfg.com/dwg15.htm

Card Guides
https://www.mouser.com/ProductDetail/Bivar/DC-600?qs=6qR8IwH vvocIcVWUVycZOQ%3D%3D


What I have assembled now:

/forum/index.php?t=getfile&id=1804&private=0

Re: Low-Cost, Complete ECB Enclosure Design [message #10622 is a reply to message #7778] Fri, 23 February 2024 12:12 Go to previous messageGo to next message
rcini is currently offline  rcini
Messages: 64
Registered: October 2015
Location: Long Island, NY
Member
Just to bump this a bit, has anyone developed a 3D-printable card cage for the 8-slot backplane? I'm kind of thinking plastic rails that either have integrated grooves for the boards or holes where you can snap-in the card guides quoted above from Mouser, with plastic brackets to keep the "top" and "bottom" together. I have a printer but zero experience with designing in 3D, so just curious. I could sketch something out on paper if the group thinks it worthwhile.

I have a wood box kind of thing I built, but it's not perfect, and I'm getting tired of it.

Thanks!

Rich


Rich Cini
Re: Low-Cost, Complete ECB Enclosure Design [message #10637 is a reply to message #10622] Sun, 17 March 2024 16:14 Go to previous message
vk5hbl is currently offline  vk5hbl
Messages: 6
Registered: May 2020
Junior Member
Someone cant remember who designed a 3 card slot version.
I hacked it up a bit and lasercut a box to fit around it.
Not very pretty but it works. I would love a 8 slot version if you do design something
Im good with hardware (built my own lasercutter and 3d printers) but i suck at designing stuff.
Also no patience to learn new software Very Happy

/forum/index.php?t=getfile&id=3002&private=0
/forum/index.php?t=getfile&id=3003&private=0
/forum/index.php?t=getfile&id=3004&private=0
/forum/index.php?t=getfile&id=3005&private=0
/forum/index.php?t=getfile&id=3006&private=0

cheers
Darren
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