[hpsdr] Tiny Demeter

Wed Jun 4 16:46:16 PDT 2008

Jeroen

Great! Scotty and I had a really FUN time discussing this. What Scotty was
planning made a LOT of sense, and probably could be very 'quiet' and
powerful enough to handle a lot, and plug into the Atlas connector directly.

You are right! Although it is NOT meant to circumvent this list, and is
almost ALWAYS recorded, Teamspeak can LEAP things forward by 'rapid'
collaboration. There is MOST definitely a problem with Timezones. TAPR,
AMSAT, Digital Voice, Astronomy, and other core groups and others use the
resource productively and Collaborate all the time. The good thing is that
you DID listen to the audio and posted comments back to the list, so others,
if they are interested, can go back and listen.

Actually Phil, Bill, and other HPSDR project leaders, are there virtually
every week on Sat 01:00 UCT, since the beginning over 3 years ago. It is
probably the best place to get updates on almost every active HPSDR project!
And make contributions. I think the 15 to 25 diehards who come every week or
couple of weeks, are attracted, now, by being able to interact or even
listen to the fantastic HPSDR discussions between Phil  and Bill. Phil is a
fantastic designer and even more fantastic educator! He DOES slow down for
'turtles' like me, and patiently answers even the most elementary of
questions!

I would be glad to sponsor a more "EU friendly" time to discuss HPSDR
projects on Saturday (Early Daytime Eastern Daylight time) if anyone is
interested. If we do this It would probably be best to favor all US
timezones and no later than early evening EU on Saturday. I'm open to
suggestion, and will try to be there.

As a side note, although I am not quite ready to moderate discussion, I am
planning to get the Pandora project going again. Ben - KD5BYB for very
understandable personal reasons has communicated that he has had to back
down as active project leader. This IS open to new project leadership. I
feel the project is/was quite 'mature' in concepts. There might be someone
else to take over the project leadership. I will 'stand-in' until someone
would like to claim project leadership. I talked with Bob - N5BRG at Dayton
who has SolidWorks designs for the project which he was working with Ben as
it stands. We are having a few problems publishing the files.

HPSDR is Fertile!! You fantastic contributors are 'cultivating' it for a
fantastic yield! (I'm a farmer at heart!)

Thanks
Eric - AA4SW

-----Original Message-----
From: hpsdr-bounces at lists.hpsdr.org [mailto:hpsdr-bounces at lists.hpsdr.org]
On Behalf Of Jeroen Bastemeijer
Sent: Wednesday, June 04, 2008 4:47 PM
To: hpsdr at lists.hpsdr.org
Subject: [hpsdr] Tiny Demeter

***** High Performance Software Defined Radio Discussion List *****

Dear All,

I was delighted to hear the name "Demeter" again in the Teamspeak 
sessions! About a year ago I started a design for the HPSDR power 
supply. At that time a lot of things were not clear. E.g. how much power 
is needed, which voltages are really needed to run the HPSDR system.

Due to a lack of time the project moved to the background, however, it 
never "left" my mind. Continuously I have been searching for 
information, talking to people, reading publications. Now I finished a 
number of projects, both work-related and private, I can afford to spend 
more time on the Demeter project! Because the HPSDR system is getting 
more mature, it is getting more clear what the demands are for the power 
supply for the HPSDR.

During the past months, I found out that a switcher can be succesfully 
used when carefully designed. Furthermore, a good linear regulator can 
be constructed far better from discrete component (compared to an 
integrated IC-regulator). Another pro, a discrete regulator will give 
more flexibility in terms op maximum current (e.g. by adding extra 
regulating transistors).

In the last Teamspeak-session there was some discussion about a small 
"experimenters" power supply, to be used in the meantime until Demeter 
becomes available. I would be very happy if I could offer my help in 
designing a "Tiny Demeter" (and maybe try some simple concepts?!). 
However, I found, by listening to the teamspeak sessions, that talking 
to each other gives better results than sending numerous E-mails. Due to 
my location (the Netherlands) and time-zone it is difficult to attend 
the Team-speak sessions. Maybe someone on the list is willing to bring 
in the Tiny Demeter and Demeter in the discussion to find out what the 
requirements and wishes are for these units.

As far as I can see the 3.3Volt regulator is not necessary, as each 
board is creating its own 3.3 and 1.8Volts from the 5 Volts. Maybe, this 
could be a discussion in the coming Teamspeak session. Another thing 
which should be defined are the current-requirements for each supply 
voltage.... I'm very curious if we are able to give a sensible answer to 
this question at this moment. ;-)  For the power requirements we should 
disregard any "big" RF power amp, as this probably get its own regulator.

Looking forward to reactions from the list! Hope to get the (Tiny?) 
Demeter project really going now!

For now, 73 Jeroen PE1RGE

-- 
Ing. Jeroen Bastemeijer

Delft University of Technology
Department of Electrical Engineering
Electronic Instrumentation Laboratory
Mekelweg 4, Room 13.090
2628 CD Delft
The Netherlands

Phone: +31.15.27.86542
Fax: +31.15.27.85755
E-mail: J.Bastemeijer at TUDelft.nl
GPS: Lat N52.00002 Lon E4.37157 Alt 46.2m

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