Hello Again,
Am 2008-02-28 19:43:01, schrieb Henrique de Moraes Holschuh:
> *If* every ATX12V PSU out there implements these requirements properly, all
> I can say is that they are NOT good enough. OTOH, if the bog-standard
> ATX12V PSU you get from China and Taiwan are not following all the
> requirements properly, then maybe they are good enough.
I have tested last weekend some of the Step-Down-Converter chips (I
have ordered several Evaluation Boards) and was realy surprised about
the quality of the Maxim and National Regulators...
They are all without any exception better as all of my 78 AC-PSUs (200W
to 900W) I have here and tested under a REAL environement...
So, if I have found a Reseller for InfraRed soldering Equipment, I will
order free samples :-) of the chips and build my first 24V-DC-PSU.
> DC inputs are always MUCH better since they have a lot less high-frequency
> noise than the AC power grid. So you have to filter out less noise in the
> first place. That's why people like -48VDC and -24VDC power supplies so
> much in anything but the consumer marketplace.
The4 waving is much more less then at the AC-PSUs (the ATX12V spec is
talking about 60-120mV) I have always (all Voltages) less then 30mV.
> BTW: if this is the kind of stuff you are going to leave in the field inside
> an airtight box, did you remember to add some EMP shielding and surge
> protection? Otherwise, the first time you get an electrical storm dropping
> a lightning bolt near your box, the entire thing will fry.
I will use the normal ATX-PSU case and a special Mini-ATX-PSU for 1U
racks, but for this I have not found a specification about the size.
> > I am simulation some PIGs on my programmable Load... :-)
>
> Make these PIGs switch on-and-off at high frequencies, with some minor
> filtering to simulate the motherboard VR, and you will have the load a
> modern CPU does :p
:-)
Currently I have my Opteron 140 running on a test installation...
Compiling a Kernel (3.3V line is increasing the consumation drasticly),
then do a "startx" to see what happen if my Matrox G450 Dual-Head must
work a little bit...
> My laptop actually *sings* in high frequencies because some of the crap in
> the mainboard is not phisically stabilized enough and ressonates due to the
> high-frequency load changes :P It is not induced noise in the speakers, the
> components actually make noise because they are vibrating at high
> frequencies(!). You can imagine the load profile that causes such a thing.
> Must have a RMS power factor close to zero...
>
> I will get a glue pistol one of these days and cover the damn chips and
> capacitors with it to see if that dampens the noise enough to not bother me.
> Drat :-)
I have had the same problem with ma IBM TP570...
....and solved it with a glue pistole too!
> The links point you to online up-to-date ATX PSU specs.
I will look @it
> Well, the open hardware crowd could help you, I think.
> http://en.wikipedia.org/wiki/Open_source_hardware#External_links has links
> to many open hardware sites.
This is very interesting for me...
> If you don't use the standard connectors, you can have different power
> requirements for them (just use high-quality connectors made for power
> transfer when dealing with power transfer, and made for signal transfer when
> dealing with signal transfer).
I use only the standard connectors from the AC-PSUs
> Otherwise, use the rates specified in the spec. They ask for a 18A type
> <whatever> connector even when you won't make more than 5A available there,
> because a conector of that type with less than 18A must be made of shinny
> crap instead of real metal :)
ACK
> You can get high quality stuff from China, but it is not easy. Just get
Right, and since I am on <http://www.globalsources.com/>, I get
updated newsletters but if you want too buy there, the minimum
quantity will be 1000 pieces.
> them from Europe or the USA because they either make it well, or do the
> quality checks on the chinese stuff.
I have found some European manufactureres but it does not help, if a
420Watt 24V-DC-PSU cost 200 Euro...
> The possibilities are endless ;-)
I have already heavy Equipment and if peoples visit me, they are
thinking, I am making a Science-Fiction Film @home...
Most peoples have never seen such professional equipment and of course
you should never tell them how much it cost... they will never believe
it (my experience; Most I have bought on real or internet auctions, so
the Insurance price would be arround 200.000 Euro where I have payed
only 30.000 Euro)
> I'd kinda expect to find ready-made DC-DC PSUs that do it for the telecomm
> market, but they won't be cheap at all.
Not more neccesary, since currently I am using a "National" Step-Down
Regulator which make 25A on 12V and it works heavyly stable...
The Evaluation Board cost only 36 US$ and then I have buyed in germany
some new parts (17 Euro) to increase the Output-Voltage from 5V to 12V.
> A proper UPS needs a bit more. If it is a DC UPS, it is easier (no need for
Right, but since I have 20 Sonnenschein G120 (12V/120Ah) Batteries,
which mean 24V with 1200Ah and they are charged from a Solar-Charger
and a "Windmotor 1803 Furlmatic" they must not be whatched.
> IGBT rectifiers and inverters), but you still need to at least have a good
> battery charge gauging system, and battery charging circuitry. Even for
> lead-acid this is not trivial (if you want anything that will make the
> battery last for five years instead of junking them within one year, that
> is).
I am measuring only the INPUT voltage and the consumation and then from
all other voltages the (V and A), and then I transfer the data over I²C
to my currently used DS80C411 (also Evaluation Board)...
I get nice statistics...
But I should heavyly improve my "ncurses" spagetti code. :-)
> If you make it an UPS based on Li-ION batteries, look for the SBS
> specification in google. It will help you a *lot* to get SBS ICs to make
> the entire charger, battery pack, and battery-capable VR.
Yeah, I have found some interesting informations about Li+ and 4-Cell
charger from "Maxim/Dallas" (up to 4A) but not realy something about
HEAVY chargers which can support a 14.8V Li+ accu with 20A or more on
a running system like an On-Line UPS...
Oh, I have already tried out my Multi-Cemistry Charger (also Evaluation
Board) to charger NiCd, NiMH and Li+ accus with it... Then I have put
an Alkaline on it and the charger has shutdown immediatly...
This is real Maxim Quality I like
(the MAX232 in 1983 was the first chip I have bought from them)
Thanks, Greetings and nice Day
Michelle Konzack
Systemadministrator
24V Electronic Engineer
Tamay Dogan Network
Debian GNU/Linux Consultant
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