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  • Need more 5v....

    With my new setup, I am going to have to power:

    * Slimline DVD (+5v, right?)
    * USB 4-Port Hub (+5v)
    * USB IDE Adapter (+5v, or does it power off USB bus?)

    Plus the stuff in my PC already.

    Assuming my PC's PSU's 5v rail is maxed just for powering my motherboard and laptop Hard Disk, I need more 5v I think.. How do I go about doing this? I'm scared to put too much draw on my 55w DC-DC PSU (Morex Cubid 2799 Case/PSU)..

    Any ideas?

    Can I pull it directly off of my ITPS (12v output) and use some kind of circuitry to drop it down to 5v??

    Or will the 55w DC-DC be enough? After all, I won't be using my DVD player and USB Touchscreen (uses USB hub) at the same time very often..

    Thanks!

  • #2
    dude thats why you just use an inverter
    Carputer: 2.8Ghz P4, 512 RAM, 120gb HDD, WIFI, TV tuner, CDRW/DVDROM, Slot load DVD in front.
    Screen: Lilliput 7" touchscreen (Custom made Carbon Fiber Screen Enclosure)
    S2000 Carputer

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    • #3
      Get a second dc-dc power supply?
      EPoX mATX SocketA w/onboard Geforce4MX / 512MB PC2700 / AthlonXP 1600
      Lilliput / DVDrom / Opus 150W / WD 3.5" 160GB / SB Audigy NX
      XP home / Road Runner / iGuidance 4.0

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      • #4
        No inverter, thanks..

        Hmmm, 2nd DC-DC, I hadn't actually thought about that.. interesting...

        Do you think this is too much load for my current DC-DC, then?

        Comment


        • #5
          I have the same devices as you... but I'm running a laptop in my truck...
          and I had to make my own 5 volt dc-dc power supplies. The load on my one
          supply is a tad over .6 amps.. and thats powering a slotload dvd player... a
          usb2.0 hub which is then powering a dlink radio, usb2ide adapter, lilliput
          touchscreen, and deluo gps.

          That .6 amps comes out to about 3 Watts of power if my brain remembers right...
          as far as what ur pc is pulling.. I have no clue.. but adding up ur watts will tell u if
          your overloading your ps.
          CarPuter: Dell P3-500 Laptop; D-Link WiFi; Deluo GPS; D-Link Radio; iMac DVD w/ ide2usb
          Audio: Audigy 2 NX; Kicker KX700.5 amp; 20w center amp; Kicker L7 10" Sub
          Display: Lilliput 7" TouchScreen
          CarPuter Install

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          • #6
            might want to pickup a keypower dc-dc atx supply instead.

            Comment


            • #7
              add up the "factory reccomended" amperages on the 5V devices to get an idea of how much you are using/need. I would just buy a cheap pw60 or something and hack it up. you could probably come up on one in the FS forum here.....

              i was wondering the same thing about circuitry though....ill bet someone here could tell us how to use voltage regulators to build a REALLY cheap 5v converter (for those of us with trunkmounted PCs and slimlines/hubs upfront, too)

              EDIT apparently im a slow typist - squid beat me too it. squid - how did you make your own? for those of us who are not already electonically inclined pelase

              Bgoodman: good call on the keypower....that arise you posted about works well too (i have one), and it is only $79!
              Cheap Laptop, great for Carputer!

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              • #8
                But how do I figure out what the power needed for each of these is?? It doesn't say it anywhere that I could find:

                * 7" StarVision Touchscreen - USB
                * 4-Port USB 2.0 Hub
                * Matsu****a SR-8185-C
                * GPS eventually
                * USB Thumb Drive eventually
                * USB Game Pad eventually
                * Via M10000 w/Audigy 2zs sound card

                I found:

                * 40GB Laptop HD needs 2.7 @ +5v

                Comment


                • #9
                  5 volt dc-dc schematic

                  Here it is..... I'm a Mechanical Engineer.. not Electrical... so I just stole
                  this from the typical applications sheet of the IC



                  The circuit is super stable... only downside is it creates a fair amount of
                  heat. I used 5 amp heatsinks on the IC's but still too hot to touch.
                  So I used thermal paste and bolted to an alum radioshack box also.
                  Still hot... but u can touch it. Just have to have them mounted with space
                  around them.

                  I got all the parts from Jameco

                  LM350T - IC (used in place of LM150) p/n: 23940
                  Heat Sink - p/n: 164734
                  Diode - p/n: 76961
                  240 Ohm Resistor - p/n: 30568
                  .1uF Cap - p/n: 33486
                  10uF Cap - p/n: 10882
                  1uF Cap - p/n: 154860
                  5k potentiometer - p/n: 95450

                  You use the pot to set the output voltage... I found that for 5.15 volts I
                  needed 750 Ohm resistor p/n: 31561, but I'd recommend getting the pot
                  also to test for your needs.

                  Total Price: $10.93 (but most parts are qty 10... except IC.. 1.75 each.. so
                  add 1.75 for every one after the initial money up to 10 ps)

                  My final results:




                  The second one I did was alot prettier... since I worked out all the bugs on
                  mounting the circuit inside the case. But I have no internal pics of 2nd one!
                  And these pics are before the mounds of hot-glue to support the board
                  Hope that helps some!

                  Squid
                  CarPuter: Dell P3-500 Laptop; D-Link WiFi; Deluo GPS; D-Link Radio; iMac DVD w/ ide2usb
                  Audio: Audigy 2 NX; Kicker KX700.5 amp; 20w center amp; Kicker L7 10" Sub
                  Display: Lilliput 7" TouchScreen
                  CarPuter Install

                  Comment


                  • #10
                    any USB device that does not need external power should be no more than .25 amps (could be .5, not sure). the hub/sound card should have the rating on them. if not, check their AC adaptors. whatever the amp limit is should be what you count for that.

                    so all we have left is the hub, assuming its externally powered, the DVD drive (should be on it), the M10000, and the audigy. check via's site/epia's site or manual about the mobo, and check the power adptors rating for the audigy.


                    EDIT: our posts keep crossing on the internet - damn you're fast squid, how much were all the parts? you said it puts out .6 amps.....my slim dvd drive is rated @ 1.8 amps.....is that WAY overrated, or did i mis-understand what you were saying?

                    .....maybe i could build two of them ....
                    Cheap Laptop, great for Carputer!

                    Comment


                    • #11
                      Oh.. sorry about that.. yea.. when the cd/dvd spools up.. it pulls 1.3 amps.. sometimes 1.5... but we're talking split second...
                      maybe .5 to 3/4 of a second... at normal spinning speed it was only .3 amps
                      if I remember correctly.. maybe lower.

                      These circuits are good for about 2 amps... so I figured with the .6 of the hub and
                      all the other parts mentioned earlier... it was fine....

                      And I built another for the audigy 2 nx in the back.. it pulls .83 amps constantly when
                      on.. no variation.

                      ps... I added price to above post.. sorry
                      CarPuter: Dell P3-500 Laptop; D-Link WiFi; Deluo GPS; D-Link Radio; iMac DVD w/ ide2usb
                      Audio: Audigy 2 NX; Kicker KX700.5 amp; 20w center amp; Kicker L7 10" Sub
                      Display: Lilliput 7" TouchScreen
                      CarPuter Install

                      Comment


                      • #12
                        SAWEEET!!! Next project

                        so for every extra IC i get i can make another board - ie after the first one it is $1.75 a piece to make these bad boys?


                        awesome

                        1 question - im not too good at schemo's yet, are the red and black wires the 12V in and the 2 black wires the 5v out?
                        Cheap Laptop, great for Carputer!

                        Comment


                        • #13
                          I updated the schematic with the +12 and +5....
                          Yes on my build... the heavier wires are the ones to the car.. the smaller black
                          wires is the audigy plug i just hacked off

                          As far as the price.. yea... most of the small parts are 10 or more pieces...
                          Can't recall right now.. buy IC is 1 per as are the heatsinks I think....
                          So yea.. for a few bucks you can build one after the initial parts buy.

                          Get a small prototyping breadboard.... I always prove all my circuits out before I
                          waste time soldering...
                          CarPuter: Dell P3-500 Laptop; D-Link WiFi; Deluo GPS; D-Link Radio; iMac DVD w/ ide2usb
                          Audio: Audigy 2 NX; Kicker KX700.5 amp; 20w center amp; Kicker L7 10" Sub
                          Display: Lilliput 7" TouchScreen
                          CarPuter Install

                          Comment


                          • #14
                            but soldering is so fun


                            thanks so much for the advice - squid, you're the man!
                            Cheap Laptop, great for Carputer!

                            Comment


                            • #15
                              Originally posted by darkhalo
                              dude thats why you just use an inverter
                              AMEN BRUTHA!!!!
                              Aura MR62 (F and R)
                              My Current MP3s
                              IamDefiler.com

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