Without knowing more about the application I am not sure if I have any recommendations. What kind of availability is required (is it going to be on 24/7). What is the expected size and nature of the data being stored, what is the expected network load, what are the usage patterns, and so on.
For a lower power draw, you could use an ARM or something like a Soekris and a laptop SATA drive (or SSD). Most of the off the shelf solutions assume a number of large spinning pieces of metal. On Fri, Jul 22, 2011 at 9:03 PM, <[email protected]> wrote: > > The wikipedia artical actually states that many switching power supplies can > be plugged directly into a DC power source. This happens because the > rectifiers turn the AC into DC as the first stage and after that it is all DC > anyways. > > So the thing is in this mode one would need likely more than 100V DC _or_ the > power draw would have to be less than 1/2 of what the supply is rated for > _or_ one would have to modify it and double the capacity of the input side by > putting two (2) rectifiers in parallel. > > The problem with 24V is that its so low the amperage the thing will try to > draw will overload it (unless the draw is very low). > > > > I think in general none of these ideas are practical - I'd just go get an > inverter and swap the 24V DC back into AC. Talk to Staples. Any cast out > UPS does this. The APC model I have here is 24V internal (I think) and its > rated for 450 watts. > > NOTE. > > Every UPS I have seen is terribly underpowered on the battery side. Even a > deep cycle battery cannot handle more than a few deep discharge cycles or it > will die! > > There are things like battery desulphonators which are little circuits > designed to counter the effects of deep discharge and they are reported to > bring back dead car batteries as well. I've looked at building some and > would be interested to work with a small team because why should each of us > re-invent the wheel. > > --------------- > > The problem however is that other than in very specialised applications, a > battery power source is just not suitable. > > I'd like to know more about the application. > > > > > On Fri, Jul 22, 2011 at 08:01:09PM -0600, [email protected] wrote: >> Yes >> >> Excellent. >> >> This is exactly the stuff he is looking for. Then he pulls the 120/240v >> switching power supply and installs DC-DC. THe likely won't fit in his case. >> >> Next if he has maybe of the external enclosues which come with a wall wart >> then he is more than 1/2 way there. He needs to match the power output of >> the wall wart and that should be going into some sort of DC-DC regulator to >> power his equipment. >> >> I would think its right off the shelf because many need mobile offices which >> need to run in cars and campers. >> >> Any of the big RV stores should be able to help. A couple years ago I spoke >> with Novak RV and they said they have solutions. But I think they might be >> running inverters - which in this case likely make no sense. >> >> Still the way the DC-DC transformer might work would be just a switching >> power supply to chop the incomming DC current same as the AC power supplies >> chop the incomming AC current. Then at very high frequencies its easy to >> get the right voltage and smooth it back out. >> >> http://www.hardwaresecrets.com/article/327 >> >> >> http://en.wikipedia.org/wiki/Switched-mode_power_supply >> >> >> Note his 24V power is "nominal" 24V. It can be anything from 0-24V if the >> battry is undervolt (going flat because he is discharging it to run his >> gadgets) to a normal 26.4 volts to over 28 volts if there is a charger on it. >> >> So his power supply must clean this up. >> >> He should make sure he has the MOV's in the circuit as well but I'm not sure >> about them in a DC application. He can still get spikes! >> >> >> On Fri, Jul 22, 2011 at 03:07:52PM -0600, Hendrik Schaink wrote: >> > Do you mean DC-DC type pwer supplies? Take a look here: >> > >> > http://www.mini-box.com/DC-DC >> > >> > Hendrik >> > >> > > I am in the market for a harddisk storage device of some sort (like >> > > Drobo Qnap FreeNAS) >> > > that takes 24V dc in (max) no 110V available. >> > > >> > > Has to have 500GB or 1TB storage and an ethernet connection so I can >> > > give it an IP address. >> > > (Pref linux based) >> > > >> > > Like a freeNAS type of thing ... >> > > >> > > I could take probably one of those mini-itx ones and shove 2 disks in it >> > > and install freeNAS... >> > > >> > > But wonder if something exists off-hte-shelve ... >> > > >> > >> > >> > _______________________________________________ >> > clug-talk mailing list >> > [email protected] >> > http://clug.ca/mailman/listinfo/clug-talk_clug.ca >> > Mailing List Guidelines (http://clug.ca/ml_guidelines.php) >> > **Please remove these lines when replying >> >> _______________________________________________ >> clug-talk mailing list >> [email protected] >> http://clug.ca/mailman/listinfo/clug-talk_clug.ca >> Mailing List Guidelines (http://clug.ca/ml_guidelines.php) >> **Please remove these lines when replying > > _______________________________________________ > clug-talk mailing list > [email protected] > http://clug.ca/mailman/listinfo/clug-talk_clug.ca > Mailing List Guidelines (http://clug.ca/ml_guidelines.php) > **Please remove these lines when replying > _______________________________________________ clug-talk mailing list [email protected] http://clug.ca/mailman/listinfo/clug-talk_clug.ca Mailing List Guidelines (http://clug.ca/ml_guidelines.php) **Please remove these lines when replying
