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Re: [Xylo-SDR] Some design thoughts requested

One of the nice things about the DIN connector is that it doesn't not require any routing of the board, by placing the pins in the right spots, the connector just plugs in. If you need it you connect a male to one motherboard a female to the other and plug them into each other to extend it to 8 slots, or 12 etc. On most projects four boards would be enough. On some small projects no motherboard or connectors would be needed just wire a ribbon cable to the holes for the connector.
If you place the power and grounds on the ends of the connectors then the traces can be quite heavy without interfering with other pins without having to go to four layer boards.
I agree with Phil, put the traces heavy enough for more power, heavy traces will help keep the power cleaner.
Voltage regulators on each card gives the cleanest power, makes the boards independent of motherboard, but cost a little more. For radio equipment where we want low noise and to minimize coupling between cards I would favor local regulators on each card as needed, let the bus carries raw unregulated power. 

+7-8Volts raw
+-15Volts raw ought to be enough, other voltages can be derived from those sources. Make provisions for de-coupling capacitors on the motherboard.
Powerpole connectors for the power into the motherboard, cheap, very reliable, can be stacked for multiple connections, can carry a lot of current. 


At 06:09 PM 1/5/2006, you wrote:

On 1/5/06, Eric Ellison <ecellison@comcast.net> wrote:
>
> Do we want the raw power sources/Regulators on the MB?
> If so what powers and current do we want? (+/- 12 +5? Etc)
> How many boards plug into the MB? (along extruded rails)
> What should be the spacing between those boards?
> What are the logical projects we should work on.
>
> I'll lead:
>
> Yes power should be on MB +/- 12V 500 ma + 5 V 1 A.

Maybe the currents should be a little higher on each supply since it
will come from an external supply and we are not doing the regulation
on the motherboard... we just need to make sure the traces are sized
right.  I think each DIN connector can handle up to an amp or so...

> 3 or 4 boards.

At least, maybe we can come up with a way to plug motherboards
together to extend it in groups of 4 or something?  Two right angle
DIN (plug & receptacle) connectors could handle that.

> .75 inch between boards.

Sounds ok.

> Projects:
>
> 1. FPGA board + HS USB
> 2. Super high accuracy Timebase/OSC source.
> 3. Audio processing board.
> 4. Software Defined Radio Board.

IO Interface... AD9954 board...  PLL board... etc... etc... LOL

73 de Phil N8VB
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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 ... "