Phil
Thanks! I'll take a look at this again. The only reason I did not proceed
along this track, is that "Hunt as I might" I could not find commercial
riser cards, and symstik had too few connections. Even If I did find a
riser
the spacing would be too close. The sockets are available, but we would
have
to design our own motherboard. I don't think is that farfetched an idea
since we could define the spacing and put the raw voltage regulators (5,
12,
and perhaps -12) on the motherboard.
I am sort of tired of sending out stuff without the forthought for
packaging. I think in this project it is especially important, since we
can
do A LOT of things with the PGA if we think about the project design from
the outside - in, and create something which can be an anything design
based
on the FPGA like a Scope card, a Spectrum analyzer card, a Radio etc!
I think that 184 pins should give us all we need even if we ground every
other pin for better noise immunity.
Comments?
Eric
-----Original Message-----
From: xylo-sdr-bounces@lists.ae5k.us
[mailto:xylo-sdr-bounces@lists.ae5k.us]
On Behalf Of Philip Covington
Sent: Tuesday, January 03, 2006 1:12 PM
To: Xylo-SDR Discussion
Subject: Re: [Xylo-SDR] Some design thoughts requested
Hello all,
I considered using DDR SIMM sockets for a project. You get 184
contacts and they give you a card width of 5.25". The height of the
card is not restricted (within reason).
http://www.molex.com/pdm_docs/sd/876362002_sd.pdf
It is kind of like the SIMMStick idea, but with more contacts (184 vs
30). 30 pin SIMM sockets are very hard to get these days and I see
that Molex has scheduled the 72 pin SIMM sockets for obsolescence.
The DDR DIMM sockets should be around for a while yet. They are
relatively cheap ($1.92 ea Digikey).
73 de Phil N8VB
On 1/2/06, Eric Ellison <ecellison@comcast.net> wrote:
Cecil
Yes, I'll go back and look at Eurocard standard. This looks great. GUD
HUNTING! Thanks for all the links. One way or tother I think we need a
buss
for our end product. Your point about size of the boards we might want to
manufacture is well taken. They should be able to go on a little more
than
a
postage stamp, and be VERY inexpensive to produce - external connectors
being the limiting size factor! One reason I was looking at Memory Chip
risers.
I moused around a little today, and really can't see where I can justify
Eagle Software in any serious production version. So I'll probably monkey
around with Kicad, which is a really nice GPL product. I mentioned
earlier
that there was some problem with the Drill files, which they have
corrected.
Only benefit of Eagle IS the plethora of template files available. I
don't
mind eating on my lunchtime and creating new parts! Good exercise and I
am
getting fatter! (No Testosterone!)
Sparkfun has a pretty good batch deal for prototype boards and also a lot
of
interesting new products. I like their little 3 buck power supplies. Also
have a some 28 pin SOIC to DIP experimenter stuff for about the same
price.
http://www.sparkfun.com/shop/index.php?shop=1&cart=525299&cat=1&PHPSESSID=ab
ce58b426cb8d0d0c3cf4b1495f0312
Other prototype boards can be had at:
http://protoboards.theshoppe.com/index.html
Will return!
Viva the Project
Eric
________________________________
From: xylo-sdr-bounces@lists.ae5k.us
[mailto:xylo-sdr-bounces@lists.ae5k.us]
On Behalf Of KD5NWA
Sent: Monday, January 02, 2006 2:06 PM
To: Xylo-SDR Discussion
Subject: Re: [Xylo-SDR] Some design thoughts requested
I'll second the DIN connectors,they are very reliable, and come in
different
sizes, single, and dual connector cards. I have used them in an
industrial
environment and they worked flawlessly for years. But I'll go one more
step
forward.
The Eurocard standard allows for mix of one 96 pin connector, two
connectors or even three connectors (not needed). Prototype boards are
cheap, most PCB houses have specials on Eurocard size boards. Card cages
are
available for low prices for the Eurocard format
Like Leon said the connectors are expensive but they are self aligning,
and
I've seen then for under $3 on the Internet.
Although the PCI is tempting and cheap for the backplane, it's a bus
that
is designed for digital logic, all pins are tied to the same pins in all
cards. Prototype cards tend to be large and expensive.
A brief blurb on Eurocards;
< http://www.yotor.org/wiki/en/eu/Eurocard.htm >
Cheap prototype boards are available for $10 or less, a very important
point, $50 to $60 for a PCI card is very expensive, maybe I'm too cheap,
but
the blank board should not cost more than the components.
< http://www.sbszoo.com/ve6sbs/sale/cct-brds.htm >
Here are some available at Mouse;
<
http://www.mouser.com/index.cfm?handler=data.getPcodes&pcode=BPS%2BPrototype
%2BBoards&pcodenumber=85400
>
Sample enclosure, can be home made from aluminum extrusions.
< http://www.busboard.net/bps-enc.htm >
At 03:34 AM 1/2/2006, Leon Heller wrote:
----- Original Message -----
From: Eric Ellison
To: 'Xylo-SDR Discussion'
Sent: Monday, January 02, 2006 5:17 AM
Subject: [Xylo-SDR] Some design thoughts requested
Folks
Even since the PIC 4550 days I have been thinking on how we might conduct
experiments as well as have a reasonable environment for adding on to
the
project. The obvious answer is a buss of some sort. I have looked at
everything from Simm riser boards to ISA buss stuff. PCI risers might be
the
way to go since they are inexpensive ($15) for 3 slot extenders. Also in
an
end product they fit into the L-brackets of a computer case, or 2U
mounts.
They have assigned power buss we can use, fairly inexpensive
prototyping
boards. ($50 - $60), are four layer and designed to minimize intra trace
noise. The buss wouldnt be used for PCI, however it would allow power,
(on
designated standards based lines), intra board connections, and FPGA,
I2C,signals etc.
PCI seems to be a little large for what we are proposing, and the
product
boards would cost more to produce, however, with an established buss we
could put a radio on one card, FPGA on another Audio on another etc.
$15 Board amongst others:
http://www.plinkusa.net/riser.htm
Am I off the wall here?
That's the sort of thing I was thinking of doing. I used to work for
Racal
and they used to build their military radios from separate screened
plug-in
modules on a backplane.
I favour DIN41612 connectors for this sort of thing. They are expensive,
but very reliable, and have pins on 0.1" centres. They can even
accomodate
co-axial connectors. They are more commonly used in Europe than the USA,
but
you can get them over there without any problems.
73, Leon
--
Leon Heller, G1HSM
leon.heller@bulldoghome.com
http://www.geocities.com/leon_heller
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Cecil Bayona
KD5NWA
www.qrpradio.com
"I fail to see why doing the same thing over and over and getting the
same
results every time is insanity: I've almost proved it isn't; only a few
more
tests now and I'm sure results will differ this time ... "
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