ca063@unocss.UUCP (Thomas Davis) (11/17/88)
I've got a friend who wants to put a computer into his Van. Now, he
wants to run the system off the battery without going through an invertor,
since the invertor generates a lot of heat and very heavy current draw.
The system needs +5V @ 5amps, +12V @ 1amp, and -12V @ 100mAs. The +5
and +12 are no problem, it's the -12. Like, it's just not available
on a normal 12v car batttery system. So, any ideas? I have no desire
or time to sit down and design an +12V dc to -12V dc convertor. Is there
a commercial power supply available that can be feed +13.8 volts, (car
battery), with outputs close to those listed?
Any ideas?
--
Internet : ca063%unocss.unl.edu@RELAY.CS.NET | Thomas Davis
BitNet : conslt16@unoma1 | Consultant, Campus Computing
UUCP : uunet!btni!unocss!ca063 | U. of Neb. @ Omaha, NEmarkz@ssc.UUCP (Mark Zenier) (11/20/88)
In article <500@unocss.UUCP>, ca063@unocss.UUCP (Thomas Davis) writes: > > I've got a friend who wants to put a computer into his Van. Now, he > wants to run the system off the battery without going through an invertor, > since the invertor generates a lot of heat and very heavy current draw. > The system needs +5V @ 5amps, +12V @ 1amp, and -12V @ 100mAs. > ... Is there > a commercial power supply available that can be feed +13.8 volts, (car > battery), with outputs close to those listed? About 5 years ago, someone was selling a line of DC input switching power supplies. They were like the standard open frame power supplies but there were 3 families with inputs of 12, 24, or 48 volts, and within each family there were supplies with different power capacities. Does anyone (someone with an EEM) know which company this was? Mark Zenier uunet!nwnexus!pilchuck!ssc!markz markz@ssc.uucp uw-beaver!tikal!
sgt@dukeac.UUCP (Stephen G. Tell) (11/20/88)
In article <500@unocss.UUCP> ca063@unocss.UUCP (Thomas Davis) writes: > The system needs +5V @ 5amps, +12V @ 1amp, and -12V @ 100mAs. The +5 >and +12 are no problem, it's the -12. Like, it's just not available >on a normal 12v car batttery system. So, any ideas? I have no desire >or time to sit down and design an +12V dc to -12V dc convertor. Is there >a commercial power supply available that can be feed +13.8 volts, (car >battery), with outputs close to those listed? I have used some switching power supplies from Converter Concepts, Inc., and noticed that they have some that run on a DC input of 10-40 volts. (I used the models that ran on 100-380VDC or 90-265VAC, and liked them.) Their VT/VX-50 (50-watt) series has one that can take 10 to 40 volts DC input and produce that following outputs: +5 @ 1.2 to 6 amps +12 @ 0.05 to 1 amps -12 @ 0.05 to 1 amps as for input current; the requirements you specified of 5(5)+1(12)+.1(12) = 38.2 watts; call it 40. They specify efficiency of typicaly 70%, so input power is 57 watts, or just under 5 amps at 12 volts. The other 17 watts comes out as heat, which doesn't look too bad. I paid somthing like $160 for a single-output, 100 to 380V input one of these last year, so while they aren't cheap (and a multi-output is probably a bit more) that is probably less than a good inverter. I would caution against connecting too directly to the vehicle's battery (say using that 13.8 as the +12 supply directly.) The regulation won't be good enough, and automotive electrical systems have lots of noise of all kinds. A switching regulator of this sort will help insulate you from a lot of that. My only connection with these guys is as a satisfied customer: Converter Concepts Inc. Industrial Parkway, Pardeeville WI, 53954 800-253-5227 or 608-429-2144 -- Steve Tell: senior, Duke University school of Engineering (please hire me). Former Chief Engineer, Cable 13 / Duke Union Community Television. sgt@dukeac.ac.duke.edu; !mcnc!ecsgate!dukeac!sgt
sky@nscpdc.NSC.COM (Sky Archuleta) (11/23/88)
> I've got a friend who wants to put a computer into his Van. Now, he >wants to run the system off the battery without going through an invertor, >since the invertor generates a lot of heat and very heavy current draw. > The system needs +5V @ 5amps, +12V @ 1amp, and -12V @ 100mAs. The +5 >and +12 are no problem, it's the -12. Like, it's just not available >on a normal 12v car batttery system. So, any ideas? A quick look through my DC/DC converter goodie file I find several converters that will do the job. Since your friend will already be building some sort of box and/or board to house the +5V and +12V regulators, I assume a board or box mounted converter will be acceptable. The following is a list of Vendors, part numbers and phone numbers for devices that will meet the 100ma spec: VENDOR PHONE NO. PART NO. V in I out@12V --------------------------------------------------------------------- CALEX 415-932-3911 12S12.250 12 250 ma (PCB Mounted) COMPUTER 617-268-1170 H12S12/125W 12 125 ma PRODUCTS (PCB Mounted , 14.5VDC max input) INTEGRATED 206-882-3100 MDP121212DB 12 125 ma CIRCUITS or DIP121212DB 12 125 ma INCORPORATED (Different prices, Output cap required) INTERNATIONAL 617-782-3331 DRS1212 12 160 ma POWER DEVICES TOTAL POWER 617-453-7272 UM213 or UM214 12 125 ma INTL. INC. --------------------------------------------------------------------- Hope this helps! Sky Archuleta _ /| * I'm sorry, but * National Advanced Systems \'o_O * my karma just * Portland Development Center (^) AAAACKKK! * ran over your * UUCP: sky@nscpdc.nsc.com U THHHPPPT! * dogma! *