No announcement yet.

I need fast help...please

  • Filter
  • Time
  • Show
Clear All
new posts

  • I need fast help...please

    Hi, I have a project with an epiaboard, but i donīt know how to power the board with a car batterie..i have a 60W konverter with dc12V should i connect it to the batterie to have a constant voltage of 12V and 5A?

    how do you make it?

    the project havee to be ready in two weeks..

    thanks and sorry for my bad english..

    bye Beetle

  • #2
    Have a search, there's plenty in the same boat - in fact I posted a suggestion yesterday.

    The 12V output by all accounts is unregulated. The other components can take >12v input with no apparent side effects.

    I'm going to regulate the 12v line out of the PSU just for safety using an LM2587 in a flyback configuration - see national semiconductor for the datasheet.

    You might also want to consider a tanking circuit, but TBH with the flyback then this becomes unnecessary.

    Please someone correct me if I'm wrong, but this is what I've found so far from searching/asking. I assume your converter is the one from a Cubid case.



    • #3
      Your in the right forum, read or search the privious posts, there are about a dozen different ways to do it.

      You can buy a special power supply that accepts 12v in, build your own, or use a regular power supply and an invertor.


      • #4
        sorry chiark, my english isnīt perfect and i donīt understand some pieces of your thread..can you maybe write it a little bit easier for me?? :-)


        I have already searched, but its not easy to understand all..there are some words i donīt know and so i thought i make a new thread, maybe i will understand a little bit more...


        • #5
          I tried to sum it up in my post.

          You can use an invertor and a regular Pc supply as one solution

          The opus power supply is a 12v in expensive solution

          There is the mini-box and a morex and another 12v in supply

          There are homebrew like the sproggy or others based on switching regulator chips.

          What is your price range and skillset and what is available in your country will help you to decide.


          • #6
            it shoulb be really cheap and i sould be able to built it by myself....


            • #7
              I'll have a go - but rather than guess what you already have, could you tell us the make of your current power supply?



              • #8
                sorry, but i can you only give some pictures..i donīt know the make..I hope you know this supply



                • #9
                  Well, it isn't a PW60, and it isn't the Morex PSU from a cubid case, so I don't know - hopefully someone will recognise it and tell you what you need. Sorry


                  • #10
                    ..i only know, that i have to go in with 12V , carbatterie has 12V 45Ah..maybe i should try it with a 12V 5A regulator...mybe it works..but when someone has other ideas, pleas say it..


                    • #11
                      Do have a search and you'll find lots.

                      A regulator has a voltage drop across it of around 1.3V, so when your engine is off the PSU will receive 10.7V, even if you use a low drop out regulator.

                      Flyback regulators take 8-16v input and produce 12V, but will not handle that much current - at least the LM2588 won't.

                      I would put a flyback regulator on the 12v output of your PSU.


                      • #12
                        sorry, but why on the output of my psu?my psu needs 12V isnīt really a PSU..only an inverter, which invert 12V 5A input to 12,5,3.3V (atx or itx) output..
                        and i have to give to the psu 12V 5A input, but i donīt know how to get it from the battery constant..



                        • #13
                          No, an inverter converts DC to AC. What you have is a genuine PSU that takes +12V in and regulates down to +5V and +3.3V, and probably just tries to condition the +12V output but does not regulate it.

                          Why do you need 5A at 12V?

                          You're not going to find a cheap solution to provide a regulated 12V 5A from 8-16V input, the best that you can get cheaply would be a 2A regulated output, which is fine because all you really need to do is regulate the +12V output from the PSU, not the +12V input to the PSU. The PSU can likely handle 8-16V for the 5V and 3.3V, so there is no sense in regulating it beforehand, and this way 12V 2A is usually enough to drive whatever you need.
                          IN DEVELOPMENT -- '96 Mustang, lilliput with PII/450 laptop, custom DC-DC power supply, 60GB; Garmin GPS; 802.11g; compact keyboard, small graphical LCDs, OBDII.


                          • #14
                            Now i understand...I have to try it, but i donīt know if it wold work. I thought, the best solution would be, when i am going to regulate the 13 Volt from the battery to 12V 5A, cause the PSU has 60watts--> 60watts/12Volts=5A....
                            But i try it and i thank you for your help...


                            • #15
                              regulating like that works when your car engine is on and the alternator is generating power. The typical voltage of the car supply with be 14V.

                              Step down regulators have an inherent voltage drop in them of around 1-2V.

                              If you regulate your power supply then your 12V line will go to 10V (or something like that) when you turn your engine off.

                              If you regulate the 12V output after your PSU (on the ATX lead and on the drive connectors) using a flyback regulator (8-16V input, 12V output LM2588) then you're getting the best of all worlds.

                              Unfortunately, there's no way of using a flyback regulator in front of the PSU as the national semiconductor stuff will only produce around 1.2A at 12V.

                              Ich habe so viel Deutsch vergessen - als ich 16 war koentte ich gut Deutsch sprechen, aber jetz... "wie schade!".