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Thread: 12v Regulator Schematic (15A)

  1. #31
    FLAC Mastero's Avatar
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    This is too big a risky design and definatley not very stable design... Not putting you guys down... but as wat i feel this design is as good as having a couple of linear regulators together like say LM1084-12.

    Good luck .... keep it up...

    Mastero

  2. #32
    Maximum Bitrate MaleBuffy's Avatar
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    Well at least it works.....and like I said in the first post, this isn't the best regulator available but at least it is one. Everybody talks about the best way of regulating 12V but have failed to provide a schematic with their solution. I think that it isnt enough information to just say it works another way etc.....that was my reason for my initial post. I wanted a schematic for a 12V regulator but could not find one. Eventualy I found one and posted it here for others to see.

    P.S. Me and my m8 are working on a better design as we speak. Well he is working....I am watching

  3. #33
    FLAC Mastero's Avatar
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    good luck guys

  4. #34
    Constant Bitrate
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    Here is my $0.02 worth...

    Be careful about the power dissipation across the 3055 as well.

    In your car, you aren't likely to actually encounter the 30v input I see on the schematic (at least not for anything other than real short spikes), and I haven't studied this enough to know if the transistor has enough gain and is driven hard enough for 15A of current under the conditions, but consider this: If the input is 30 volts and the output is at 12V with 15A of current, thats (30-12)*15 = 270 watts dissipated in the transistor. I don't think a 3055 can handle that unless you're planning to dunk it in liquid nitrogen or something! (I don't know if a 3055 can handle 270W under any conditions but I do know it would require some SERIOUS cooling measures to do it!) So, you might not want to have anything that looks like a claim it will work over that voltage range unless you want a power supply with a transistor that literally blows up or lights up like a lightbulb - at least momentarily. Its been too long since my circuit design days to remember if the transistor is likely to become an open or a short circuit in the process to say what collateral damage there might be. You don't want to go through the OPUS 90W supply scenario do you?

    If the input is 13.8V, thats 27 watts at 15A, which I think will still require a heatsink on the transistor. At 5A its a much more reasonable 9W, but you'd still want to check the specs to see what if any heat sink is required to make sure it is reliable.

    This is why linear power supplies are pretty rare these days except for low power or special cases. They waste too much energy in the form of heat and have bulky heat sinks, etc.

    You may plan to use one, but just in case, note that the fuse won't prevent problems upstream of it from frying the wiring to the supply so you'd probably want a fuse on the input as well.

  5. #35
    Maximum Bitrate MaleBuffy's Avatar
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    Good point. I actually have a heatsink on the transistor....which isn't on the schematic. My mistake. This design was made for 5A Max and I havent tested it with anything more than that!

  6. #36
    Newbie lhseong's Avatar
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    Quote Originally Posted by MatrixPC
    Okay I did a little simulation for this schema, this is the result.
    The output will be a little less than 12V if the input is less than 12V. The time the output is decrease is depend on load and how low is the input.
    what software you use? so interesting!

  7. #37
    Raw Wave Rob Withey's Avatar
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    Quote Originally Posted by lhseong
    what software you use? so interesting!
    Quote Originally Posted by MatrixPC
    If you guys wanna try it out, the software is Preteus 6 by Labcenter Electronics in UK. I am using the demo version so I can't save the design.

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

  8. #38
    Constant Bitrate
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    Quote Originally Posted by MaleBuffy
    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


    This is basic linear regulator,and you can never exceed the input voltage.In fact,the output will always be 0.7v less than the input voltage (it's also slightly depends on the zener diode).To get voltage higher than input,you need somehow to boost it to AC,then to DC (flyback design - for example).

    The guy with simulation - in your simulation you measure the output voltage with no load,that's why you get 12v at output.Put small resistor at the output,put current meter,and then check the voltage
    Enjoint life!

  9. #39
    Raw Wave
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    Dima I think they talked about that already

  10. #40
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    Exclamation about your new schematic

    Quote Originally Posted by MaleBuffy View Post
    Now this is the updated schematic with the 12V zener.
    Sir is your new schematic design work? im just worried about the the zener and the in4001 the silicon you added..
    pls inform me coz i need that design..

    by the way.. my ckt ive design i add up some SCK 2r55a (surge current killer), knb1560 in the input section..
    pls reply thanks

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