power supply

Discussion in 'General Electronics Chat' started by dio123, Sep 18, 2013.

  1. dio123

    Thread Starter New Member

    Feb 12, 2010
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    I want to remake my power supply, improve the voltage adjust, and put current adjustment. Besides going for voltmeter and ammeter digital occupying less space than analog.
    The features for my new power supply, are very simple. The source 0-15V 2A, stabilized, with adjustable current and voltage.
    Will be to work with atmegas, build circuits in beardboard, basic things for beginners.

    vi alguns esquemas pela net, mas depois algumas opiniões que tem erros.
    However I would like to know some circuit that recommend me to use.


    I thank you
     
  2. crutschow

    Expert

    Mar 14, 2008
    12,974
    3,220
    If you want suggestions how how to remake your power supply then you need to post a schematic of it.
     
  3. dio123

    Thread Starter New Member

    Feb 12, 2010
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  4. bountyhunter

    Well-Known Member

    Sep 7, 2009
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    It sounds like you want a lab supply. They are not trivial to build. The typical LM317 circuits are pretty junky. They can not adjust to zero volts and they can not regulate current. You really need a lab supply where you can adjust either voltage and current. I happen to have designed a good one, you will not like how much circuitry it takes to build a decent lab supply. I recommend you buy one.

    http://www.ebay.com/itm/15V-2A-Digi...741?pt=LH_DefaultDomain_0&hash=item1c35fdd095


    http://www.ebay.com/itm/MASTECH-Swi...915?pt=LH_DefaultDomain_0&hash=item35c55d68cb
     
    Last edited: Sep 18, 2013
  5. #12

    Expert

    Nov 30, 2010
    16,247
    6,744
    I recommend you change some resistor values.
     
  6. dio123

    Thread Starter New Member

    Feb 12, 2010
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    In America are very cheap sources of power.
    In Portugal these power supplys are very expensive almost $ 100.
    However this is lab power supply that need. I had seen a circuit, but the transformer needed negative voltage, and my transformer does not have.

    I had seen this circuit at google, but did not know how it worked, spent.
    Now we know it's yours, I'll try to do.

    I have a doubt in your circuit.
    Since it does not need two outputs, the circuit is in the medium is necessary, the source or work without it. ?
     
  7. ScottWang

    Moderator

    Aug 23, 2012
    4,850
    767
    I was used the bjts and pot to adjust the current, and used LM317 and LM337 to be the power regulators.

    I'm not translate the article to english, so you can see them translated from google, the important thing is the circuits diagram.

    Adjustable Voltage and Current Power Supply - 1~29V/0~1.5A.
     
  8. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
    507
    I don't understand your question, but the circuit I posted definitely works: it is the lab supply I use on my bench. It does not need a negative voltage supply to allow the output to go down to zero Volts because of the type of design it is.
     
  9. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    Bountyhunter,
    I believe that our O.P. is trying to say that they only need one output; so could they simply eliminate the circuitry for B OUT and the items in the middle?
     
  10. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
    507
    Yes, the B output can be omitted. Also, the auto parallel mode between the two sides.
     
  11. Jibby

    New Member

    Sep 12, 2013
    15
    1
    Use LM 317 3 in parallel by a special circuit .317 is meant for 1 A only.
     
  12. dio123

    Thread Starter New Member

    Feb 12, 2010
    6
    0
    I apologize for the delay.

    see circuit. http://cl.ly/image/3V1c2S3N3q0x

    My question is if the source works well only with the green circuit, or also I have to build the red part of the circuit?
     
  13. ScottWang

    Moderator

    Aug 23, 2012
    4,850
    767
    The red part has a temperature detection and overheating auto shutdown function, if you didn't used that function then the power will lose protection, it's not good for you.
     
  14. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
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    The over temp protection is not necessary as long as your heatsink is large enough that you KNOW the pass transistors will never overheat. That circuit was included in my design because it is a dual output (3A) design and if both outputs are shorted at 3A, the heatsink is not enough. I didn't want to use a huge heavy heatsink so I included over temp protection.

    The auto parallel function is only for connecting the outputs in parallel. Not required for only a single output design.
     
  15. dio123

    Thread Starter New Member

    Feb 12, 2010
    6
    0
    Good night,
    I have finished making the schematic, but I'm having trouble organizing the components so as to have to do less bridges possible.

    bountyhunter - not by chance have any pictures of your circuit so I have more or less an idea of how to arrange the components on the board.

    thank you
     
  16. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
    507
    sorry. The circuit was not built on a PC board. Since it was a one off only for my bench, I built it on vector board and hard wired it by hand.

    I did create a cut down simplified schematic to show a more generic version of only one channel without the protection circuits.
     
  17. dio123

    Thread Starter New Member

    Feb 12, 2010
    6
    0
    Good morning,
    I apologize for the delay, but time and money has been little, and things are being done slowly.
    I concluded that I will make the full power source, the two outputs are always useful.

    Have made ​​a part of the source and it works great, has everything you need in one source.

    The power supply has 3 simple buttons.
    If you connect the 3 buttons, the 2 outputs are the same voltage 0-16V, and the amperage is 0-5 A?

    When you have finished the source I send you the eagle files of the entire project.
     
  18. russ_hensel

    Well-Known Member

    Jan 11, 2009
    818
    47
    If it is a transformer it has negative voltage 1/2 the time. It may not be center tapped.

    A center tap transformer is nice for full wave rectifier for both polarities relative to ground. If not center tapped use 1/2 wave rectification.

    1/2 wave tends to double current load on diode and ripple voltage. Filtering should be able to take care of that.

    If you are building a bench supply you should be able to figure out the details mentioned above, at least with a little help from the web.
     
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