[hpsdr] Tiny Demeter

[Jeroen Bastemeijer]

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