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0-70V power supply,2A variable using LM723 and 2N3055

When you want to adjust the dc power supply circuit voltage up to about 70V. This is 0-70V power supply circuit,2A variable using LM723 and 2N3055.

But the “Cheap adjustable 0-30V 2A Laboratory DC Power Supply” project can fine maximum voltage is 30 volt only.

We need to add more 40V. You do not look difficult. We can adapt very easily, with the addition of just two devices only, and change in the value of equipment a little more.

How to modified this circuit.
When we consider from the original circuit. We can modify this circuit with cutting at point A and B apart.

-Then connect the resistor RX that value of 2K into both point A and B.
-and at point B to connect the zener diode ZD1 value of 18V 0.5W to the ground.
As new circuit modified, In the image below.


Must to change some parts.
We need to change some devices to appropriateness up such as the electrolytic capacitor will must to change to can be durable voltage higher than the original circuit, Which details are as follows.
1. To change the transformer voltage is 50V CT 50V at 3A full current
2. To change the capacitor C1 is 1000uF 80V.
3. To capacitor C3 is 100uF 100V.
How to build.
In the original PCB, we have provided the location, to install these already the more equipment electronics so Just place the equipment correctly and check that successfully is available.

If you want to have 0-50V DC adjustable power supply, be able to see in Power supply regulator 0-50V 2A by IC LM723 + Transistor

Buy components in this projects HERE!

This Post Has 19 Comments

  1. I t seems fine but, as I proceed to 5A greetings Daniel

  2. This ‘modification’ is exactly the same as under link >Power supply regulator 0-50V 2A by IC LM723 + Transistor<. In my opinion only one difference we have here is in values of resistors and diffrent conections of Q3 (vs TR3 in power supply 0-50V, but we have current control there också ;)).

  3. wonderful lesson.want more simplified diagrams

  4. hi, if my transformer output is 50v AC and 1Amp, what will be my final output?

    1. Start from simple formulas – do it yourself and you will develop your hobby skills and learn.

  5. If you put a iA rated transformer on this circuit your transformer will die!!!

  6. I ment….If you put a 1A rated transformer to this circuit your transformer will die.

  7. sorry to say this sir iam not satisfied ur web site
    sir i need input 0-100v ac to ajustable converter output dc curret 80v
    plzzzz sir give me this cercute and there componet list

    ur gd wshr

  8. Sirn ,
    what are to be modified in the circuit if i want an adj current limit setting from 0 t0 5 amps.
    Can we convert it into a dual power supply.

    Regards V.Sambath kumar

  9. Hello,
    I need a variable volts AND amps regulated power supply capable of handling 62 volts. Current output 5 amps. This circuit looks easy enough for this (me) novice to build. It will also have to operate on 120 V AC input.

    The variable current is probably wishful thinking. If it is not possible 5 amps will work just fine.

    I am probably asking for too much but a circuit board design and detailed parts list would be GREAT.

    I would be more than willing to pay somebody for help here.

    Thank you,

    Bill the “[email protected]

    I’m hoping this circuit can be modified for my use.

  10. Pretty! This was a rreally wonderful article. Thank you for supplying this information.

  11. Hi!
    Do you have sample circuit diagram for 70v to line level signal out converter? thank you

  12. Hi!
    Do you have sample simple circuit diagram for 70v to low signal output or line level output? its like a converter thank you?

  13. Hi,

    The project is quite interesting. Can you clarify whether 2N3055 Transistor be cascaded to increase the current limit to 10 Amps and additional circuitry to vary the current along with voltage.


  14. Hi!
    Nơw, i want DC power abjust 0V – 120V/1A. Pls, tell me about schematic. I use Lm723. With above schematic, when Voltage input is >85V, it is not abjusted and output = max voltage.
    Thank you so much!

  15. I am seeking a supply of a DC regulator module that will accept an unstable DC voltage of between 48 VDC and 64VDC at 1.8 amps and output a regulated 52 VDC. The 52 is not critical as it could be as high as 55. The source PSU is rated at 52VDC at 1.85 amps but it wanders as high as 64 and causes fires in the circuit it is powering. I am interested in either a fully complete and tested module, in case or out of case, or a p.c.b plus circuit diagram and BOM, or just a circuit diagram and BOM.

  16. Olá, poderia me mandar o pcb deste circuito com as modificações para 70v?


  18. Isn*t 0–70V too much for a 2N3055-transistor?
    A device with Uceo 100V is probably better.?

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