[hpsdr] Teamspeak - 21 June 19:30

Thu Jun 26 01:22:28 PDT 2008

Dear Eric, Joe et All,

Luckily I'm not a big soccer fan, otherwise I would be in a very bad
mood ;-)  The Netherlands lost their match against the Russians. Why or
how, I'm not goint to speculate about it, many other people already do.

Last weekend I was away with the Scouting. With a group of about 175
Scouts we paid a visit at the open day of the Royal Dutch Airforce in
Leeuwarden (the north of the Netherlands). My activities with Scouting
usually consume (a lot of) time of the weekend. Therefore it is
difficult for me to attend Teamspeak sessions. So if I'm not responding
very quickly to my E-mails, or I'm not at the Teamspeak session, its not
beacuse I'm not interested. But, I'm probably away with Scouting...
somewhere without internet-access...
However, coming weekend I hope I will be able to attend the Teamspeak
World-session. The time 19:30 (or 20:00) UTC is fine for me.
This week I will install the Teamspeak software on my PC!

At the moment,  I have been listening to the recordings of both
Teamspeak sessions. Based on the remarks which have been made there I
would like to write down the following comments:

* My intention is to build regulators from discrete components. The
reason for this is that they can provide better results with respect to
stability, power supply line noise rejection and they allow better
adjustment compared to integrated regulators. At this moment I'm doing a
number of simulations to see whether this advantage is really
significant. Personally I think that, even for Tiny Demeter, we should
stick to the "HP" of the HPSDR-project.

* In Teamspeak a comment was made about the series/pass transistors:
These transistors are the actual power regulating transistors. For those
who know the trick for current-boosting a LM7805 (and the like) this is
not the kind of series/pass transistor I have in mind! Power boosting a
regulator in such a way yields very poor performance.
The linear circuit needs a transistor for the high-currents. By using a
discrete regulator, more of these transistors can be put in parallel. By
doing this the power capability of the power supply increases, which
adds some flexibilty to the design. My idea is to reserve some space on
the circuitboard for adding extra transistors. E.g. for people who need
5V @ 2.5A instead of the rated 5V @ 1.5A.

* For those who fear a very complicated design: I have another
integrated regulator in mind which could be used, the LT3080. This
regulator can be put in parallel, thus adding the flexibillity in power
handling.  But, as mentioned before, I want to have a look first at the
performance of discrete regulators.

* Someone mentioned the crow-bars during the Teamspeak world-session. A
crow-bar is most effective at the power rail which it should protect.
This means that the crow bars will be added at the +12, +5 and -12V
supply lines. If, for whatever reason, a regulator breaks down, or due
to a short with another powerline, the voltage gets too high, the
crow-bar will short the power lines. This makes the voltage on the power
line zero, and will protect the expensive electronics (Ozy, Mercury,
Penny etc.) Adding a crow-bar at the input of Tiny Demeter is possible
but makes less sense (allthough I can think of some situations where it
would make sense....) A crow-bar doesn't have to be that difficult, it
consists of a TL431 (voltage reference) and a thyristor (or its
transistor equivalent, using 2 transistors). A crow-bar gives a lot
protection for very little money. At work we have been using these
circuits a lot, and they saved us a lot of time (and smoke ;-) ).

That's all folks, hope to get back to you soon!

73 Jeroen PE1RGE

Eric Ellison schreef:
> ***** High Performance Software Defined Radio Discussion List *****
>
> Hi Joe/Jeroen/All!
>
> Quite a match. Netherlands just scored in the final minutes to tie it. Still
> Watching here! Fantastic Match!
>
> First Saturday EU Teamspeak session took place at 19:30, however, with the
> EU football championships on, I can understand why more were not there. Tiny
> Demeter was the discussion. Let's produce one!!!
>
> Audio is posted at:
>
> http://www.hamsdr.com/personaldirectory.aspx?id=833
>
> Soapbox Here:
>
> [13:29:21] *chan* Henry, The Netherlands: Sorry folks, 
> I am away and unfortunately cannot attend the FIRST European Teamspeak.
> As Joe - AB1DO correctly mentioned on the Reflector, 
> The Netherlands are playing against Russia in the 2008 European Soccer
> Championship.
> But anyway, congratulations with the first European Teamspeak!!
>
> [15:06:06] Scotty - WA2DFI joined channel
> [15:18:16] Al - N0TVJ joined channel
> [15:48:22] *chan* Al - N0TVJ: link to PS Tester 
>
> http://www.officedepot.com/a/products/525005/ATX12V-Power-Supply-Tester/
>
> C U all next Saturday 19:30 unless some would vote for a different time!
>
> Back to the match!
>
> Eric - AA4SW
>
>
> Joe Said:
>
> Hope Jeroen is not a soccer fan, because if I'm not mistaken 19:30 UTC is 
> 21:30 local time in NL and Netherlands plays Russia in the quarter finals of
>
> the Euro2008 championship starting 20:45. (on the other hand, 21:30 is when 
> half time should start, so that gives him 15 minutes on the net, right 
> Jeroen? ;-)
>
>  
>
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>   

-- 
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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