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Re: [Xylo-SDR] Some design thoughts requested


I would tend to vote for regulated +/-12V,+5V to keep most of the heat
out of the box.  Local regulation using 78L09/79L09 can be used where
required to produce cleaner local supplies.

If you are looking for a commercially made three output power supply,
it will have regulated outputs - to get unregulated supplies, we would
be building them ourselves (I would anyway to save the $100, but
others may desire the choice of buying premade).  Buying a premade,
UL approved supply avoids a lot of legal responsibility in case
something goes wrong.

John  KK6IL


At 07:59 PM 1/5/2006, Eric Ellison wrote:

Cecil - Phil

Comments noted, leaving MB open for extension good idea. My pref in that
case, is 3 vertical connectors for daughtercards on each MB 1 connector
horizontal for additional MB's.

Power schema noted, end runs noted, caps noted, Powerpoles noted. Can we get
away with +/- 12 instead of 15, much more choice for 12 than 15.

Eric


-----Original Message-----
From: xylo-sdr-bounces@lists.ae5k.us [mailto:xylo-sdr-bounces@lists.ae5k.us]
On Behalf Of KD5NWA
Sent: Thursday, January 05, 2006 10:41 PM
To: Xylo-SDR Discussion
Subject: 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 ... "

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