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Power Supply

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  • Power Supply

    I have almost everything I need to build my system. But I still have to make a decision on the power supply. From what I have heard, power inverters are to choose as the last option: problems with sound, DC to AC then AC to DC, space, ... I still haven't haven't found a DC-DC converter for ATX motherboards, even the pricey one from is only for AT boards. I have heard that I just need to add a 3.3V (I guess)on that, but I don't know anything about it.
    I have seen industrial power supplies with 8-16VDC on the net. Some people mentioned it on the board, but it looks like nobody use it. Here are some URLs. What are does? Would it be easy to install?

    What do you guys advice me to do (for my power supply)?


  • #2
    DC/DC is certainly only way to go.
    There is several comercial AT style 12VDC input power suplies available at reasonable price, as those you showed in your mail.
    ATX is not so easy case but you can find those also, example is
    Its 250W at $145.
    AT power suplies are about half price of that.


    • #3
      Even though my inverter was free( on loan from a friend ) it still gives off alot of noise, and its also inefficient. It creats a larger strain on the battery as well (so Im told) I would go with DC-DC


      • #4
        145$ ?!!!!
        well I don't think that I'll need more than 100W-120W...
        Is there anybody out there who could tell me how to modify an AT power supply to make it work with an ATX motheboard?
        Thanks Guys! It's great to be able to count on a community like this one :O).



        • #5
          Ok. I am very new to the electrical side of computers. I don't even know the difference between amps, volts and watts. What do I really need to operate a computer, a Sharp 6 inch display w/ backlight, and how would I hook it to the battery? I know an inverter is one option, so how many volts or watts or whatever does it need to be? If I don't go with the inverter, what specificly is my best bet? (Please be a simple as possible) Thanks alot in advance!


          • #6
            Bakassi -

            Can't help ya. Check Ebay for REALLY cheap inverters. I didnt even know certain inverters only work on certain types of motherboards. I thought that as long as it could cover the wattage it was good.

            CaptainBeast -

            An inverter is something that takes the small 12v produced by your cigarette lighter or other power source and turns it into a ****load of wattage so it can power yer 'puter. "simplicity"

            - JustAGuy


            • #7
              there might be a diagram on the net to convert the 12v to the different voltz that need the motherboard , if someone know one plz tell me , thankz


              • #8
                In response to sj saying that the DC-DC is the ONLY way to go:

                In the beginning, I thought "Yeah, DC-DC sounds the best way to go.. it'd be heaps efficient".. but now I'm a firm believer in DC-AC inverters.. they are cheap as ****, you don't have to mess with the computers power supply.. so if you wanna whack the computer out of the car and run it in the house or something you can.. and inverters are pretty efficient.. maybe you'll loose a little bit of power as heat.. but not much.. they are really quite good..


                • #9
                  I agree with inmytree...i'm running TWO inverters (hardwired) and I don't have any power problems. One is 140 watts and powers a VCR, the other is 300 Watts and powers the computer and a playstation. It's a lot more convenient to pull the box out and plug it in at my desk to mess around with the interface and playlists than using a DC DC power supply (although you could just buy a AC-DC convertor from Radio Shack)
                  pics of my install are at
                  for anyone interested (mp3car website soon)


                  • #10
                    I'm using an switch mode power supply chip from Maplins. It is a Maxim device that is capable of taking 12Volts input and supplying 5Volts output. It generates little heat, no noise and even has thermal overload protection, short-circuit protection, warm start etc..

                    I am building and designing the board myself. I also have a 12V supply from a TIP122 darlington pair and a diode. It only needs to supply 600milliamps.

                    The +5 volt line needs only 3.6 Amps and these include the HDD and my circuits for the LCD etc.

                    If you are not going to use the serial ports, then you don't need to worry about connecting the -5V and -12V lines which means less complexity.

                    Maxim chips are 7 quid so good price.

                    I will hopefully have details and a PCB if anyone is interested on my new website, when completed.


                    • #11
                      Using standard $60 DC/DC AT style power suply is my way to go. I have never need to run my car pc elsewhere, i just take my HD from car and plug it with same removable IDE bracket to my home pc ( to load new data etc ).
                      But yes, if you are running something else in car which requires AC then i understand or you have plenty of space.
                      And yes inverters are also cheaper way to go but not so much, i did not had power suply so ac/ac suply + inverter is not so much less than dc/dc @ $60.


                      • #12
                        It looks like you forgot that my problem is that I ave an ATX board :O). I am still looking for an affordable DC-DC converter.


                        • #13
                          Sorry, a DC-AC inverter won't work for me when my entire power supply can only be 2"x6" and 1/2" thick !

                          I have designed an ATX DC/DC switching power supply because of my space constraints and also because:

                          - DC/DC is cleaner: All subsystems in my DC/DC supply run above the range of human hearing: at least 100kHz, so 60Hz noise is not introduced into my audio system. Car audio equipment, unlike home stereo equipment, is not designed to deal with the 60Hz hum present in AC power lines. This is part of why people using inverters in their car have so many problems with hum and buzzing. Using an inverter is even worse since the output is a "psuedo-sine" wave with spurious frequencies and lots of noise.

                          - DC/DC is more efficient. With an inverter the draw is 5.5A from 12V, but with a DC/DC converter my calculations show it will be around 2 or 3A instead.

                          - DC/DC doesn't suffer from the voltage variance in a vehicle. I used to use an inverter, but the computer would reboot if I tried to start the car with it running. My DC-DC supply can operate from as little as 7V, so this won't be a problem anymore.

                          Since my DC/DC supply is ATX 2.0 compliant, it will handle auto shutdown and everything itself.

                          BTW: -12V is sometimes needed by (S)VGA video cards to generate video signals. Some video cards won't generate a signal without this -12V.

                          Also, I do not advise passing the 12V from the car to your motherboard and drives. The voltage from the car can vary from 8 to 16 volts DC and I have heard reports of people having their hard drives spin down when the engine is off.

                          Johnson Interface Solutions
                          Jason Johnson
                          Yorba Linda, California

                          MPC Phase IV - *** PENDING ***


                          • #14
                            Jason Im wonder if you could put a site or send information to how to build a power supply to an atx board , thank you.


                            • #15
                              Jason, I was going to purchase a DC-DC converter from Arise Industrial Power Supplies for about 80 bux. Do you think there will be problems going this way? Are you going to sell power supplies like you are talking about building? The power supply from Arise Industrial Power is only going to be an AT power supply, but I figured I'd just shut the power off in Windows (as I haven't had a problem with it yet).

                              sj - Where did you find the DC/DC power supplpy for 60 bux?