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  • 3.3 Volts

    I'm in the process of building my own PSU based on the one used in the InMotion project, as the IC are avalible for free, from Maxim.

    However I require a 3.3v supply with a bit of current, so a simple voltage regulator is out of the question (Images of smoke, spring to mind!).

    So I was thinking about using a MAX788 chip to creat 3.3 volts for me. InMotion are using the same series of chip for there 5v supply.

    One small problem is that the only circuit I can find is for the 5v chip. Has any one used these chips before, and if so you know if the circuit is the same as the 5v one?

    Or does anyone know of any otherways to create 3.3v for little or know money. I've order a couple of chips so I'll have a play with them, but as I don't know their internal workings (& because PSU lectures where dead boring at Uni!) I'm reluctant to experiment too much. Although I'll let you know if I get it right.

    Sightly side tracking, a possible solution to the problem of laptop PSU having -7v ground, would be to connect the sound card to the head unit/amp(s) via a low pass filter (LPF) set at about 1hz. This would remove the DC offset, but not effect the sound quality.

    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 :)

  • #2
    Hi Rob,

    I think the 3.3V is connected exactly the same as the 5V from maxim, tjek sproggies PSU
    ..
    uhm what's this InMotion project? where can I find it?

    cheers!
    If at first you don't succeed.........
    destroy all evidence you tried

    for info on t6369c LCD or Presslab's powersupply check:
    http://www.namms.tk <=updated!!

    Comment


    • #3
      Cheers, the answer is always out there it's just a case of finding it.

      InMotion was one of the original in Car MP3 players, and is probably one of the better know ones. Although someone will probably correct me on this.

      web page

      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 :)

      Comment


      • #4
        Let me be the first to correct you on this. THE problem with almost all DC-DC PSU's is the 12V a lot of the home made PSU's rely on the 7812 or MC78T12. Problem with these is that they need 14,4V input for an output of 12V, so your carputer wont work when the engine is not running, or your dynamo (is this english?) is not at its best.

        BTW if your not too much in a hurry, wait for me to build the DC-DC forward converter described as presslab describes it. I'm gonna give this a try, and in the process I will be writing a complete guide with pics etc. I originally planned it for this weekend, but it was way too hot to be soldering and stuff..

        [ 08-26-2001: Message edited by: marsjell ]
        If at first you don't succeed.........
        destroy all evidence you tried

        for info on t6369c LCD or Presslab's powersupply check:
        http://www.namms.tk <=updated!!

        Comment


        • #5
          marsjell get up ur fat *** and do it...you know how long we ALL have being dying to get our hands on the how-to-do it..... BTW, did you get it working???? Was it REALLY easy to do??? Can i get all the parts i need local (ie radio shack)????

          Ps. joking about the fat ***...
          abcd-1
          Author of CobraI,II,III and now CobraIV.
          You can contact me on AOL instant messenger....nick is cenwesi or cenwesi3

          Comment


          • #6
            Hey rob i have one PSU for sale which has 3.3vdc / 5amps along with 5vdc 10amp and 12vdc 2.68amps also -12vdc and -5vdc

            Its all ready to use for USD100 with shipping.

            If requird let me know

            Mastero

            Comment


            • #7
              Mastero let me ask you this...

              What are you using (Which IC/Regulator and what Transformer if any) for the +12v section of your PSU?
              Fosgate

              System Comp V3 - In progress.
              Low power MB with C7 CPU, DC-DC PSU, car ECU link, USB TV, GPS, 7" TFT, Wireless, Voice.

              Comment


              • #8
                Few points

                1) I want to avoid buying stuff as it cost money which I don'y have.

                2) My Dell motherboard has a very weird PSU, A cross between AT & ATX, a bit weird to say the least.

                3) I have no plans on running it with the engine off, my car battery can barely start the car let alone run electronis stuff!

                4) The suppley for the 5v & 3.3v switch mode power supplies is comming direct from the cars wiring loom.

                5)The 12volts is provided buy an L7812 as I don't require that much power.

                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 :)

                Comment

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