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  • My mini linear power supply..

    Okay, I had this GREAT idea.. right?? to put a linear DC-DC PS into an old HD case.. and use the case for a heatsink.. does anyone see any problems with this??? the case should provide enough of a heatsink to draw 3amps [email protected] and 1.5continuous @ 12volts.. right??? this should ha enough to power a mobo, with external cards (2 or so) and a harddrive...... This idea would provide easy mounting of the powersupply.. and prevent shorts of the PCB, as you probably wouldn't need one... anyway, post your feedback, positive and negitive.. thanx..
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  • #2
    Sounds like a good idea to me, but don't waste time with linear. A switching supply would be best, and the form factor of the HD would allow a small fan to draw air through the whole case...
    Player: Pentium 166MMX, Amptron 598LMR MB w/onboard Sound, Video, LAN, 10.2 Gig Fujitsu Laptop HD, Arise 865 DC-DC Converter, Lexan Case, Custom Software w/Voice Interface, MS Access Based Playlists
    Car: 1986 Mazda RX-7 Turbo (highly modded), 1978 RX-7 Beater (Dead, parting out), 2001 Honda Insight
    "If one more body-kitted, cut-spring-lowered, farty-exhausted Civic revs on me at an intersection, I swear I'm going to get out of my car and cram their ridiculous double-decker aluminium wing firmly up their rump."

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    • #3
      Well, I made one, using linear regulators, in a LAPTOP HD CASE!!! LOL!!!!!!!! works fine... only prob is that I was originally gunna use 2 5amp 5volt regulators, but using one generated ZERO noticible heat.. so, I am gunna rip out one of teh 5volt, and replace it with another 12volt low dropout (only rated @ 1amp) so as to have 2amps constant on teh 12volt, rather than 1amp, with I had and powered a HD, 48X cdrom, and a fan, and then something started smoking, lol... ahh, time for some pics I suppose, DODGY DIGITAL CAMERA!!!!!!! (not mine) (don't have one)



      The masking tape on teh PS is becaseu I nolonger had teh screws.. Also, I thought I would pointout that I have ZERO sucsess in teh past with using 1084 12volt regs to give me a regulated output, even with input of around 14volts... This is why I chose lower power regs which give a regulated output of 11.8 volts with as low as 12.2 input... and, as teh volatge drops, teh output is teh same is the input, but with the 1084 regs, I got a drop of around 1volt between out and in when a lower input was used.. so, with this setup I am using, when cranking, teh battery voltage drops to no less than 10.5volts... this is therefor what the 12volt rail then is, and this is actually still enough to SPIN UP a hd, not just keep it spinning.. so, andone in Australia want to buy a sproggy PS without half teh diodes (I was unable to source these, or afford them, after my money went missing in teh post... lol)
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      • #4
        Originally posted by THEMP3KID
        I have ZERO sucsess in teh past with using 1084 12volt regs to give me a regulated output, even with input of around 14volts
        Did you have a LF decoupling cap on the input & LF & HF decoupling caps on the output? These can make quite a bit of difference, especially the LF on the input.

        Rob
        And you say people actually pay money for M$ Windows?
        www.mp3mini.co.uk (Does what it says on the URL) www.openclassic.co.uk (The new car, with zero rust!) www.rob-web.co.uk (My other site)
        Total re-design underway: on the whole progress is very slow as the car is taking up too much time :)

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        • #5
          Do you have the part numbers of the regulators you used? Also, do you have a wiring diagram? Thanks, that is exactly what I am looking for, 5V 5A and 12V 1A...

          mike
          1999 voyager pontoon boat
          (soon to be computerized)

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          • #6
            Originally posted by Rob


            Did you have a LF decoupling cap on the input & LF & HF decoupling caps on the output? These can make quite a bit of difference, especially the LF on the input.

            Rob
            Ahh..... I forget now, lol..

            Well, the regulators I used were......
            Hasn't this all been covered before or something??? anyway.. thay were:

            5volts -
            LM1084-5

            12volts - LM2940C - 12

            Or something like that, not too sure on teh 12volt one, but teh specs are right... can't check part number on teh ic now, can't find the PS.
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            • #7
              Thanks..
              1999 voyager pontoon boat
              (soon to be computerized)

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              • #8
                Okay, I swapped one of the 5volt regulators for another 12volt regulator, but now I need 2 resistors to balance the output voltages... Will post results soon....
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                • #9
                  Have you run a PC for any length of time with this supply? What was the heat output? I would be concerned that the HD case will simply act like thermal storage, and keep heating up without any real transfer to the air. Might be a good idea to bolt on an old CPU heatsink to each side...That will give more surface area and help keep the temp down.
                  Player: Pentium 166MMX, Amptron 598LMR MB w/onboard Sound, Video, LAN, 10.2 Gig Fujitsu Laptop HD, Arise 865 DC-DC Converter, Lexan Case, Custom Software w/Voice Interface, MS Access Based Playlists
                  Car: 1986 Mazda RX-7 Turbo (highly modded), 1978 RX-7 Beater (Dead, parting out), 2001 Honda Insight
                  "If one more body-kitted, cut-spring-lowered, farty-exhausted Civic revs on me at an intersection, I swear I'm going to get out of my car and cram their ridiculous double-decker aluminium wing firmly up their rump."

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                  • #10
                    Well, I powered a HD a cdrom and a fan for about half an hour, and then something started smoking, this was before I had 2 12volt regulators.... The HD case was evenly warm, and I couldn't even tell which chip was creating the heat, so it must conduct heat well.. Some time soon I will try it with the computer.....
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                    • #11
                      Hang on a minute, you said that you had a single 5v regulator and that it generated "ZERO noticable heat". But you haven't powered up the computer with it yet? How much load were you putting on the 5v line when you said it generated "ZERO noticable heat". I'd expect it to produce about 47W of noticable heat when shoving out 5A and powered from a 14.4v running car battery.


                      Rob
                      Old Systems retired due to new car
                      New system at design/prototype stage on BeagleBoard.

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                      • #12
                        Yeah, but you will only be drawing 5amps for a few secs while spinning up, thats the problem. Before, you guys were working out how much heat it would generate if you drew the maximum, but that is never going to happen... When I said there was no noticble heat, it was with a destroyed HD connected that constantly spun up, and then down again every few seconds... so, the load would have been 1.5amp surge, 500ma continous, which isnt much, I know..... But, will try it with a greater load tomorrow...
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                        • #13
                          My smallish computer draws 3.8 A on the 5v line.
                          With a linear regulator that is 35w dissipation.

                          Basically you posted that there was no noticable heat without actually testing it, didn't you? :-)


                          Rob
                          Old Systems retired due to new car
                          New system at design/prototype stage on BeagleBoard.

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                          • #14
                            Nooooooo............
                            Well, what do you mean by testing???
                            I connected a large 6volt glode to the 5volt rail, and monitored the current, (about 3.5amps) but then as the filiment int eh globe heated up (this tok a matter of seconds) the current draw went up to about 4amps, adn something made a high pitched whistling noise, (I think it was the old computer power supply Iwas powering it from) So, I had to cut the tests short. . but, I think the efficience is over 80% that was found out by means of testing.. lol
                            I don't see why your system would draw so much.. Are we talking about the one pictured under your name??? How would that draw so much?? anyway My system is just a P200MMX with usb sound 6.4gig HD and an external graphics card... which, doesn'yt draw much.. so, I am happy.. :P
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                            • #15
                              I checked just the 5 volt draw from my sbc with p150 and it was somewhere around 3.6 amps, add in the hdd and usb stuff and it will be somewhere in the low 4 amp range... I dont know why these little boards draw so much current but they do...


                              Mike
                              1999 voyager pontoon boat
                              (soon to be computerized)

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