Announcement

Collapse
No announcement yet.

12v Regulator Schematic (15A)

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • 12v Regulator Schematic (15A)

    Well I dont know much about electronics so I asked a friend of mine to make me a 12v regulator. Please do not ask me about it since I have no idea about those kind of things. However, I wasn't able to find a decent schematic of a 12v regulator so here it is. The Voltage on the car must be over 12.8 to supply a regulated 12V but the nice thing is that it is 15A and with a fuse can be lowered to 5A. He said that the components are cheap and not hard to find. He uses a so called "zener" which I havent got any idea what it is!

    I am interested in your comments since you know more about this stuff. I know this isnt the BEST regulator available but it is a simple solution that I wanted to find and never did. Hope that it will be usefull to you all.

    Thanx
    Attached Files
    Time displayed in a different way!

    http://www.lares.dti.ne.jp/%7Eyugo/s.../03/index.html
    http://www.humanclock.com/

    FREE 3D Glasses: http://www.rainbowsymphony.com/freestuff.html

  • #2
    unfortunitly a car's input would be anywhere from 8-16v but those are extremes

    Comment


    • #3
      Yes I know........well at least in my 18year old car the input never drops lower than 10 except when I turn the ignition on. Moreover, once the engine is running it never drops lower than 13.4. Extreems are extreems though. Like when thunder hits your car! Thats also extreem
      Time displayed in a different way!

      http://www.lares.dti.ne.jp/%7Eyugo/s.../03/index.html
      http://www.humanclock.com/

      FREE 3D Glasses: http://www.rainbowsymphony.com/freestuff.html

      Comment


      • #4
        Yup thats fine, as you said keep the voltage higher than 12V.

        The 12.7V zener diode is there to regulate the voltage across the base of the transistor at 12.7V. You will have a 0.7V drop on the emitter, so your final output is 12V.

        You cant just buy a 12.7V zener diode, as they normally come as 11,12,13V...etc. Quick solution is to use a 12V zener and stick in another diode such as the 1N4148 this will drop the voltage by other 0.7V so your total = 12.7V You can use 13V but you end up with 12.3V on your final output.

        The capacitors are just there to smooth out noise/spikes/dips and whatever. A small smoothing capacitor is typically required across the zener diode though.

        For 15A rating the transitor dont have enough current gain, you will need to add a small NPN transistor connected as darlington paired with the 2N3005.

        LOL what did you want to know anyway

        Comment


        • #5
          Thanx for that! Nice to know that I am in the right direction!
          Time displayed in a different way!

          http://www.lares.dti.ne.jp/%7Eyugo/s.../03/index.html
          http://www.humanclock.com/

          FREE 3D Glasses: http://www.rainbowsymphony.com/freestuff.html

          Comment


          • #6
            EDIT :

            opss no..not exactly fine, ask your friend to test it out anyway


            You might find that useful :

            http://www.the-cool-book-shop.com/fr...nics_guide.pdf

            Comment


            • #7
              Now this is the updated schematic with the 12V zener.
              Attached Files
              Time displayed in a different way!

              http://www.lares.dti.ne.jp/%7Eyugo/s.../03/index.html
              http://www.humanclock.com/

              FREE 3D Glasses: http://www.rainbowsymphony.com/freestuff.html

              Comment


              • #8
                I think you reversed the new diode you added.

                --Tom
                ME-6000, Lilliput 7" vga + touch, generic GPS, RedHat 9, custom mapping software.

                Comment


                • #9
                  Nah, it's the right way around. You want the forward voltage drop across the diode to add to the zener voltage.


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

                  Comment


                  • #10
                    I am still stuck on the part about thunder hitting your car...
                    current projects

                    Comment


                    • #11
                      why not use an IC for this? only needs 1 component?
                      www.digital-car.co.uk - The UK CarPC Forum

                      Comment


                      • #12
                        why not use an IC for this? only needs 1 component?

                        Because a standard 7812 regulator need > 13.7V or so. Zener diode/transistor only need > 12.7V.

                        There are low voltage drop regulators around though

                        Comment


                        • #13
                          Welll I finaly tested it out. Works fine. Well actually both versions work. Because I couldnt find a 12.7 zener, I used a 13V one(with the first schematic) and my Voltage is now 12.3 which is just fine even with my C134 case that has a 5% tolerance.
                          Time displayed in a different way!

                          http://www.lares.dti.ne.jp/%7Eyugo/s.../03/index.html
                          http://www.humanclock.com/

                          FREE 3D Glasses: http://www.rainbowsymphony.com/freestuff.html

                          Comment


                          • #14
                            Thats cool

                            Have you tested it with full load? Check how much the voltage will drop by.

                            Comment


                            • #15
                              Well at first it did drop to 7V when I connected the carputer. That was because the 2N3055 had a low hFE (which sometimes happens). I did overcome this by changing the 1KΩ resistor with a 220Ω one. You can go as low as 120Ω. Another way it to change the 2N3055 with one that has a higher hFE. Works both ways
                              Time displayed in a different way!

                              http://www.lares.dti.ne.jp/%7Eyugo/s.../03/index.html
                              http://www.humanclock.com/

                              FREE 3D Glasses: http://www.rainbowsymphony.com/freestuff.html

                              Comment

                              Working...
                              X