Regulated power supply (darlington power) for LM317 10A 1.2..37V

kozak84 212957 121
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  • About Author
    Level 12  
    kozak84 wrote 56 posts with rating 44. Been with us since 2003 year.
  • #2
    Level 15  
    And what happens with this system in the event of a short circuit?
    Is it not necessary to call the PP Stasis?
    Although I like it myself.
  • #3
    Level 12  
    As you can see, I used a few additional LEDs on the LM317, that's probably enough. There is no output fuse in the diagram.
  • #4
    Level 16  
    How big a heat sink for it do you envision. :!: :!:
  • #5
    Level 22  
    You can use LM317 and add a high power transistor to it and you will have 10A.
  • #6
    Level 36  
    What is this output coil or something else that is shown in this diagram as a spiral?
    For this system, you need a veeeeery large heat sink, if someone would like to take 10A current from it. Especially at low voltages.
    :arrow: electronics321
    This power supply is built just like that.
  • #7
    Level 12  
    Maybe a little criticism

    26AC to 36.77VDC "NO LOAD"
    35V 2A - higher current will cause "feeds"
    and losses
    at 1.2 10 And you can forget because (greatly simplifying:
    With a consumption of 10 A, the peak-to-peak voltage is 11 V, which gives the average voltage behind the filter about 31 V
    31-1.2 * 10 is about 300 W
    The BD911 transistor dissipates a maximum power of 90 W
    A colleague forgot to mention that his transistor is cooled with liquid nitrogen (I already see how my friend checked, for example, 10V 10A)
    on this transistor, the optimal 10 A will be pulled at a voltage of about 25 and higher V
    One could give the tesla kd503 more power reserve
    A power supply with such a range of output voltages is best designed with impulse, there are ready applications.
  • #8
    Level 16  

    Ideal power supply for charging the Shuttle's batteries :D

    And seriously - in fact, at the smallest range and at high current, the power losses will be huge. As for the correct operation of the short-circuit protection - I am not sure.
    Power supplies of such power are currently made in the impulse technique - fear to think what transformer would be needed at such high currents.

    In the application note lm317 you can find a power supply circuit with an operational amplifier - I made it once, it works so far, quite smooth regulation of the output current - I recommend it at the beginning.

  • #9
    Level 12  
    My power supply cools the radiator with the fan + driver for it.
    The output coil is wound on the ring core with 1mm wire.
    The maximum voltage in this version of the LM317 is probably 37V if I want to
    have more, but it's already on a different version of this stabilizer and transistor.
    With this power supply, I have a 150W transformer.
    You can also make a similar power supply only with the voltage "-" using any power transistor PNP and LM337.
  • #10
    Level 32  
    I think 2N5302 or 2N5686 would be a little better. Although 3 x 2N3055 would be enough. A piece of heat sink is necessary.
  • #11
    Andrzej Maciejewski
    Level 20  
    The diagram shows that the stabilization of the output voltage when changing the load current from e.g. 1A to 5A is poor.
    (The voltage is stabilized on the base of the BD911 and not at the output).
  • #12
    Level 12  
    The transistor in this power supply acts as an element increasing the current efficiency. The output voltage is the same as that supplied to the base by the LM317.
  • #13
    Level 14  
    Andrzej is right. The voltage stabilization in this system will be lower than that of the LM317 alone. Unfortunately, transistors are not "perfect" elements. As the base current increases, the base-emitter voltage drops increase, while with the increase in temperature, the voltage drop at this junction decreases. These are the two factors that most affect the output voltage of this system. Therefore, the feedback for the voltage stabilization circuit should also include power transistors, i.e. it should be taken from the circuit's output.
    I don't know what to do, it's better to look at pdf lm317. There are diagrams of systems increasing the efficiency of the current without deteriorating the voltage stabilization.
  • #14
    Level 32  
    Uwy will be lower but this is compensated by the considerable simplicity of the layout.
    I think that "at the beginning" (talking about the less experienced) is enough.
  • #15
    Level 16  
    Honestly speaking, I do not recommend this system for little experienced (high currents, high temperatures). As the zipp says - in the application note there are other ways to implement the power supply on the lm317.

  • #16
    Level 32  
    This is what my first regulated power supply looks like, working until today but as a battery charger; P
    Unfortunately, this solution has a significant temperature drift, no protection, and low efficiency.
    But at the beginning, if you want to reduce the Uz and do it, for example, on 3xKD 502, it will pass in the crowd - it all depends on the requirements that are set for this system.
    Yours sincerely and kindly ...
  • #17
    Level 22  
    The first devices will not always be refined, we forgot something, we didn't know something.
  • #18
    Andrzej Maciejewski
    Level 20  
    I deleted the answer because I realized that a friend of zipp had "protected" me.
  • #19
    Level 23  
    I used to make a similar power supply, but instead of one I used two transformers (to power 12V / 60W halogen bulbs). To reduce the power loss on the transistor, I used a switch that connected the transformer outputs in parallel at voltages below 12V, thanks to which you can pull up to 10A, and at higher voltages, the transformer outputs are connected in series, which allows you to download up to 5A at 24V.
  • #20
    Level 12  
    WELCOME :)
    do you know any link with nice power supplies ...
    I need it to have stabilized 30V for power amplification
    I have a transformer that gives me 37.7V
    I also wanted to connect the led to 3.5 V so that when it is on, it should shine
    I do not know how to do this
    with three legs ... what is this system ??
  • #21
    Level 32  
    I used to use a power transistor from the MJ series in a similar system
    and coupling on optoizolacji and voltage out, unfortunately, the temperature drift did his job, of course, a lot of luck, i.e. 0.47kW and a serious bridge with capacity also over 90,000 micro. Unfortunately, I damaged connecting the battery: x
    I would like to go back to the construction of a similar power supply, but unfortunately I did not find a satisfactory diagram based on the available elements.
  • #22
    VIP Meritorious for electroda.pl
    I used to do such a power supply, there were three 15-amp transistors connected in parallel to the lm317 :) , I powered this quite a large DC pump
  • #23
    Level 13  
    I have a slightly off-topic question, what voltage can this L7815C-V stabilizer withstand? if I give him a single 19V and some heat sink it will burn or not? :D
  • #24
    Level 23  
    Withstands up to 35V input. But wouldn't it be better to look at the documentation for this system, e.g. on elenot?
  • #25
    Level 11  
    Something I am not convinced that this power supply will give 10 A with only one power transistor. I used 4 in parallel and gives only 5A in the entire range and during long-term operation, the 10cm x 17cm radiator is heated to a temperature of 45-50C. I doubt whether this power supply worked even 2 seconds or 5 minutes during an accidental short circuit when downloading 10A at 10V
  • #26
    Level 11  
    It can be converted so that its parameters are equal
    10A 1.2 ... 24V and that it works without problems.

    PS What is this brush in this diagram? :-)
  • #27
    Level 10  
    @ zenon05 it can be changed so that it works without a problem

    and after reading these spirals, I advise you to take a look at the symbols' appearance, then there will be no doubts.

    I must also join the discussion and criticize this solution. I do not advise anyone to do such a construction because it is just a waste of time and money, it has terribly poor parameters, as my colleagues have already mentioned. I will mention that a few years ago, when I was attending a technical school, I came up with the idea of such a power supply and unfortunately I had to deal with all the problems myself.

    That this power supply cannot cope with 10A, it is already known that the stabilization is wrong and with an increase in the current consumption, the output voltage will gradually decrease and with a consumption of about 10A it will be about 0.6-0.7V and this is a large value, practically not up to party.

    This type of power supply can be made, but instead of the NPN transistor, insert PNP, preferably several connected in parallel, and of course, do not forget about the emitter resistors. If someone does not know what it is about, have a look at the LM317 catalog note.

    Apart from that, another remark regarding the range 1.2 to 37V, as someone mentioned above, there will be huge losses of energy emitted on the heat sink, it can be partially prevented by using transformer with split winding and switching by means of a relay, i.e. for low voltage, let's say the power supply will be 15V and for higher 30V (or e.g. 12 and 24). It should also be remembered that if the transformer has 24V, the maximum voltage from the power supply at 10A will never be so high. with good voltage parameters, it will be possible to get about 19 20 V max.

    As for security in this type of power supply, they should be used absolutely. in the catalog note there is an application with overcurrent protection, but remember that the solution also has disadvantages, because in the event of a short circuit, the system does not allow the current value to be exceeded, but the output voltage drops practically to zero, i.e. the power dissipated on the transistors is terribly high and they can be damaged .
    You can use a system that tests the output voltage and when it drops below the set value (e.g. in the event of a short circuit), it will disconnect the stabilizer.

    As soon as someone is very persuaded that he wants a regulated power supply and with a large current, I recommend converting ATX power supply from a computer.
    With a minor modification, consisting in disconnecting the voltage protections and inserting regulations for the 12V range, you can get adjustments from about 7 to 25 and a large current resulting from the power of the power supply.

  • #28
    Level 24  
    interesting idea with this "test" of the voltage at the output ... hmmm ... But how will this system start?
  • #29
    Level 17  
    I know you will find my question strange, but in different places I saw different marking of the LM317 terminals, what is real or 1-IN; 2-Reg; 3-OUT (according to the scheme) or 1-Reg; 2-OUT; 3-IN. Thanks for the help.