0-30V Laboratory Power Supply

Arief Laksono   theripper555_96@ymail.com     


This project is based on the 0-30 VDC Stabilized Power Supply with Current Control 0.002-3 A and a new PCB layout is introduced here. It’s a stabilized power supply with variable output voltage in the range 0-30Vdc (33Vdc peak) – and variable current 3A and is ideal for your laboratory power supply.


Schematic and PCB are designed in Eagle software and the source files are available on the links at the bottom of the page. The PCB design has connectors for 2N3055 transistor, input and output voltage. Also on-board potentiometers are added.









60 Response on “0-30V Laboratory Power Supply

      1. sir the dimensions shown are incorrect eg: 3300uf capacitor position is marked as c2 actually it is c1.could you provide correct layout?

  1. Excellent webpage with very good photos and design too.
    Does this modified circuit is working?? Still no part’s list
    how can get it ??? anyone ??

    1. A B C D E F G H I
      id value quantit package componen
      y ts
      1 1N5402 4 DO201-15 D1 D2 D3 D4
      2 1N4148 2 DO35-10 D5 D6 3 2 2K 1W 1 P061315 R1
      4 82Ohm 1 2047 R2
      5 47碌F5 2 TT2D4 C1 C3
      6 3300碌 1 EB20D C2
      7 220Ohm 1 2047 R3
      8 5V6 2 DO34Z7 D7 D8
      9 BC54854 1 TO92-EBC Q1
      10 2N2219 1 TO5 Q2
      11 BC557* 1 TO92-EBC Q3
      12 CURRENT 1 LED3MM LED1
      13 3K9Ohm 1 2047 R4
      14 2K2Ohm 2 2047 R5 R16
      15 10KOhm 5 2047 R6 R7 R12 R14 R22
      16 TL081 3 DIL08 IC1 IC2 IC3
      17 330pF 1 C025-024 C4
      Ceramic X044
      18 10K 2 3RP1610N R8 R9
      19 33Ohm 1 2047 R10
      20 2N3055 1 TO3A Q4
      21 4 7KOhm 1 2047 R11
      22 56KOhm 2 2047 R13 R24
      23 27KOhm 2 2047 R15 R17
      24 100 nF 1 C050-025 C5
      Polyest X075
      25 1N4148 2 DO35-7 D9 D10 26 1KOhm 2 02072V R18 R19
      27 100 pF 2 C050-024 C6 C8
      Ceramic X044
      28 100K 1 CA6V CALIBRAT
      29 270KOhm 1 2047 R21
      30 200 nF 1 C075-032 C7
      Polyest X103
      31 1 5KOhm 1 2047 R23
      32 10碌F5 1 E5-4 C9
      33 0.47Ohm 1 VTA54 R25
      34 1N4001 1 DO35-7 D11 35 DC 1 1X02 JP2
      36 2N3055 1 1X03 JP3
      37 AC 1 22-23-20 X1
      INPUT 21

  2. Hi there!
    Is it possible to use 12VAC as input voltage as well or do I have to change all the values of the components?

    Best regards!

  3. 1. You can buy a chinese kit which is exact copy of this project on ebay !
    2. One reader warned about exceeding the AMR of the TL081 op-amps and suggested regulating the positive voltage for them to 29V. This will limit the output voltage to 29 – 2*Vbe. To overcome this one can use a LT1007 from Linear Technology (AMR=44V V- to V+ ) for the last op-amp and feed it from the unregulated positive rail.However the output zeroing arrangement will be different.

  4. It will be simpler if you use ic 723. It has a 7.2 volts reference voltage. You can connect any npn transistor and 2N3055 power trasistor. Only precaution is that adujust base resistor to keep transistor in linear region i.e. do not allow them to go in to saturation. Ihad made 100s of them in 1972 i.esome 45 years ago. You canalso do the same thing with 7805 3A voltage regulator whose common pin is connected to output of op amp. The op will be a voltage follower mode. The input is given by a simple potentiometer.

  5. I found it

    R1 = 2,2 KOhm 1W
    R2 = 82 Ohm 1/4W
    R3 = 220 Ohm 1/4W
    R4 = 4,7 KOhm 1/4W
    R5, R6, R13, R20, R21 = 10 KOhm 1/4W
    R7 = 0,47 Ohm 5W
    R8, R11 = 27 KOhm 1/4W
    R9, R19 = 2,2 KOhm 1/4W
    R10 = 270 KOhm 1/4W
    R12, R18 = 56KOhm 1/4W
    R14 = 1,5 KOhm 1/4W
    R15, R16 = 1 KOhm 1/4W
    R17 = 33 Ohm 1/4W
    R22 = 3,9 KOhm 1/4W
    RV1 = 100K trimmer
    P1, P2 = 10KOhm linear pontesiometer
    C1 = 3300 uF/50V electrolytic
    C2, C3 = 47uF/50V electrolytic
    C4 = 100nF polyester
    C5 = 200nF polyester
    C6 = 100pF ceramic
    C7 = 10uF/50V electrolytic
    C8 = 330pF ceramic
    C9 = 100pF ceramic
    D1, D2, D3, D4 = 1N5402,3,4 diode 2A – RAX GI837U
    D5, D6 = 1N4148
    D7, D8 = 5,6V Zener
    D9, D10 = 1N4148
    D11 = 1N4001 diode 1A
    Q1 = BC548, NPN transistor or BC547
    Q2 = 2N2219 NPN transistor
    Q3 = BC557, PNP transistor or BC327
    Q4 = 2N3055 NPN power transistor
    U1, U2, U3 = TL081, operational amplifier
    D12 = LED diode

    1. Excellent webpage with very good photos and design too.
      Does this modified circuit is working?? Still no part’s list
      how can get it ??? anyone ??

  6. I built it
    I use AC 24v transformer and i can measure voltage on filter cap 33v dc , all TL081 very very hot
    TL081 using maximum 30v
    somethings wrong

  7. final situation
    parts are correct
    but still does not work 🙂

    Part Value

    C1 47µF/50v
    C2 3300µF/50v
    C3 47µF/50v
    C4 330pF Ceramic
    C5 100 nF Polyester
    C6 100 pF Ceramic
    C7 200 nF Polyester
    C8 100 pF Ceramic
    C9 10µF/50v
    Calibrate 100K Trimmer
    D1 1N5402
    D2 1N5402
    D3 1N5402
    D4 1N5402
    D5 1N4148
    D6 1N4148
    D7 5V6 Zener Diode
    D8 5V6 Zener Diode
    D9 1N4148
    D10 1N4148
    D11 1N4001
    IC1 TL081P
    IC2 TL081P
    IC3 TL081P
    JP3 2N3055 Extensionare
    Q1 BC548/547
    Q2 2N2219
    Q3 BC557
    Q4 2N3055
    R1 2,2K 1W
    R2 82Ohm ¼W
    R3 220Ohm ¼W
    R4 3K9Ohm ¼W
    R5 2K2Ohm ¼W
    R6 10KOhm ¼W
    R7 10KOhm ¼W
    R8 10K Potentiometer
    R9 10K Potentiometer
    R10 33Ohm ¼W
    R11 4,7KOhm ¼W
    R12 10KOhm ¼W
    R13 56KOhm ¼W
    R14 10KOhm ¼W
    R15 27KOhm ¼W
    R16 2K2Ohm ¼W
    R17 27KOhm ¼W
    R18 1KOhm ¼W
    R19 1KOhm ¼W
    R21 270KOhm ¼W
    R22 10KOhm ¼W
    R23 1,5KOhm ¼W
    R24 56KOhm ¼W
    R25 0.47Ohm 5W

    1. The only thing I know is that the C1 is 3300uF it is the filter capacitor . With this error I suspect that other components can also be wrong. Owner of this project, please help us !!!!

      1. It is a filter capacitor, I used 6800uF instead, higher value caps helps eliminate ripple provided with correct voltage rating , don’t hesitate to play a little bit upgrading the value of this cap, since we never knew the output quality of the transformer used, one could find a very unpleasant step-downed output due to electrical disturbance, that is, some sufficient filtering procedure needed to eliminate the ripple

  8. Has anyone found an alternative to the TL082 as 33.9 volts is a little close to the chips max supply for comfort… not to mention some manufacturers quote a max supply of 30 volts (+/- 15)…

    1. This is a new copy of the original unreliable project. It has the parts list all messed up and it has a new pcb with some high current traces too thin. Many of its parts are overloaded. If a 24VAC transformer is used and it produces 25V when this project has no load then the TL081 opamps have a total supply of 39.6V (positive 34V plus negative 5.6V) but 36V is their maximum allowed voltage. I could not find what is the transformer in this copy but it was 24CAC/3A in the original which has a voltage too low for this circuit to produce 30V at 3A and this little transformer will be overloaded since it must pass 35.3V x 3A= 105.9VA instead of 24V x 3A= 72VA which is too low.
      There are long threads in the forum where we fixed its errors by using 44V opamps, a newer more powerful driver transistor, additional output transistors each with current-sharing emitter resistors, many larger resistors for them to survive the heat, a much larger main filter capacitor and a higher voltage and higher current transformer. A few pcb designs have been made. The improved version works very well and is reliable.

  9. id value quantity package components
    1 1N5402 4 DO201-15 D1,D2,D3,D4
    2 1N4148 2 DO35-10 D5,D6
    3 2,2K 1W 1 P061315 R1
    4 82Ohm 录W 1 02047 R2
    5 47碌F50v 2 TT2D4 C1,C3
    6 3300碌F50v 1 EB20D C2
    7 220Ohm 录W 1 02047 R3
    8 5V6 2 DO34Z7 D7,D8
    9 BC548547 1 TO92-EBC Q1
    10 2N2219 1 TO5 Q2
    11 BC557* 1 TO92-EBC Q3
    13 3K9Ohm 录W 1 02047 R4
    14 2K2Ohm 录W 2 02047 R5,R16
    15 10KOhm 录W 5 02047 R6,R7,R12,R14,R22
    16 TL081 3 DIL08 IC1,IC2,IC3
    17 330pF Ceramic 1 C025-024X044 C4
    18 10K 2 3RP1610N R8,R9
    19 33Ohm 录W 1 02047 R10
    20 2N3055 1 TO3A Q4
    21 4,7KOhm 录W 1 02047 R11
    22 56KOhm 录W 2 02047 R13,R24
    23 27KOhm 录W 2 02047 R15,R17
    24 100 nF Polyester 1 C050-025X075 C5
    25 1N4148 2 DO35-7 D9,D10
    26 1KOhm 录W 2 02072V R18,R19
    27 100 pF Ceramic 2 C050-024X044 C6,C8
    28 100K 1 CA6V CALIBRATE
    29 270KOhm 录W 1 02047 R21
    30 200 nF Polyester 1 C075-032X103 C7
    31 1,5KOhm 录W 1 02047 R23
    32 10碌F50v 1 E5-4 C9
    33 0.47Ohm 5W 1 VTA54 R25
    34 1N4001 1 DO35-7 D11
    35 DC OUTPUT 1 1X02 JP2
    36 2N3055 Extensionare 1 1X03 JP3
    37 AC INPUT 1 22-23-2021 X1

  10. Caution! This PCB is poorly designed. Look at the scheme for R25-shunt resistance. On the left side is bonded directly to the rectifier bridge, on the right to the output terminal of 0V. This connection can be loaded with a maximum output current of 3A. Now find this connection on the PCB and look at how thin it is and how it runs. Connection is done very wrong. Use ticker wire and connect it to bottom pin of R25, other end of wire connect to output pin 0V_GND. Second tick wire connect on Emitter of 2N3055 and other end on positive output pin. This is it, hope it help’s to someone. Use tick wires also from AC input to bridge (D1-D4).

  11. I don’t trust this power supply and the circuit i have build ed this power supply 2 x in the past and what i have found was that the Voltage adjustment worked fine adjusting from 0V – 30V but when you use the Current limiter over 2 amps it blows the output transistor 2N3055 every single time and yes before somebody asks I did use a very big heat sink to no avail so i would rather the say the amps rating for this power supply is 2 Amps and not 3 Amps as Stated

  12. I do not know why the unreliable original project was replaced by this copy that has the same problems and added more problems instead of using the version that we fixed in the forum.

  13. What is the link to the forum where this power supply’s where fixed as there seems to be so many forums about this project it’s not even funny maybe Electronics Lab is jus continuelly putting up this faulty power supply just to generate traffic thru their webpage to keep some paying advertisers happy please supplycthe correct midified circuit as well as the correct modified pcb and the correct transformer specs and part specs if you are unable to do so please remove this stupid aeticle of a power supply which doesent work as promised at stip fooling people in wasting their money and time in this not well thought thru project. I wasted a lit of money time and effort building this fake and error ridden circuit i would have been better off buying a power supply in a shop

  14. Yet another observation :). Look on ground pin 4 of IC”.Why it is connected to right side of R25 (shent)? There is happening a voltage drop of output current. That voltage drop is info for calculating and comparing of that current and not for powering off IC2. So, R11,R12,4-IC2,R9,C5,R17 and C7 should be connected to real ground coming from C2 (left side R25). BTW R21 and upper trimmer has no point here. I didnt build any of this PS. If I will, I will buy one from Banggood and rearrange it. Actually that PS is that bad, it is just old design and fully good for home lab.

        1. Will this circuit work as i am seeing many negative comments for the loaded pcb design and components…actualy i bought the components and is in dilemma to proceed or not…

  15. This is a good instruction. I am just a newbie, and i want to build this project. I just want to use it as my own (not hard use). So will it work perfectly? I just use it for my lab

  16. Hello, Thanks by your work. May I use other type of AOs like LM358?, I have some of them and I like to use them in a power source like this.

    1. LM358 have maximum input voltage 32V, in this power supply you need to use an OPAMP with at least 40-42V maximum voltage.

  17. hi sir. i have 2 Q
    1(Important)-how can i upgrade it to 0-30V 0-5A ?
    i used a 5A Transforme but the current is limited on 3A and i can not use more than 3A ?
    2(Non-Important)- how can i add FINE Volume side of this 2 volumes?

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