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Transformerless Switch Mode Power Supply Circuit

By on July 4, 2011

This website was recommended by Beh about "Transformerless Switch Mode Power Supply Circuit".  If this circuit/IC can be further improve then in the future we may not need transformer to get the secondary output voltages. Manufacturers could save the cost of not using the transformer and electronic components. The troubleshooting could be much easier too. Please click on the above photo for more information:

transformerless switch mode power supply



  1. bijoy

    July 13, 2011 at 11:51 pm

    thank you

    bijoy India kerala(gods own country)

  2. mohamamad jusuf

    July 16, 2011 at 9:32 am

    Thank you your diagram that I will to make this circuit....

  3. Amir Mukhtar

    July 20, 2011 at 4:12 am

    Transformerless power supply diagram is useful but please express some more information about to increase power output and voltages upto 36 volts and 1500 mili Amperes.
    iam very thanksful to you in this regards.

    A student
    Amir Mukhtar

  4. admin

    July 20, 2011 at 7:25 am

    HI Amir,

    It all depends on the ability of the IC and the circuit. If the manufacturer produce many different type of similar ICs as above i don't see why your request cannot be done.


  5. Sagar

    August 28, 2011 at 1:25 am

    My smps is not working how to check it, solution to repair it

  6. admin

    August 29, 2011 at 9:14 pm

    Hi Sagar,

    May i know what are the components you have checked? Did you get any supply voltage to the power ic?


    • werdan

      December 28, 2016 at 10:00 am

      Good day! puzzled regarding p/b led TV, it was a/c input with rectifier bridge but output reads 1000 volts with a capacitor 450v/68mf, is it normal, what was the causes of getting more than capacitor rating?

      • Jestine Yong

        December 28, 2016 at 3:24 pm

        Hi Werden,

        If more than a 1000 volt, the cap already blown. How do you test the cap?


  7. ali

    September 8, 2011 at 1:57 pm

    really it was to hard for me to get your website
    cause i have alot of questions first of all let me itroduce
    my self.iam ali from yemen ihope u heard about it
    and working as a photocopiers pls accept me as a begainner

  8. admin

    September 8, 2011 at 9:15 pm

    HI Ali,

    You are welcome to this blog.


  9. M Shahbaz khan

    November 17, 2011 at 12:23 pm

    I need the chooper circuit diagram of the fixed 24 volt and 6 Amp circuit.
    If any one can designe the required circuit so contact with me.
    Circuite detail is as below.
    chooper circuit diagram
    Input voltage 210 to 240 volt AC
    Constant 24 Volts DC 6 Amp

    M Shahbaz Khan

  10. admin

    November 18, 2011 at 5:01 am

    Hi Shahbaz,

    Sorry i do not such diagram.


  11. Leo

    November 24, 2011 at 3:15 pm

    Transformerless PSU is good for some systems. Those systems that the user cannot touch the conductors...

    This type of PSU, as you can see in the schematic, isn't isolated from the high voltage mains. If ever the user touches any conductor while his/her body is in contact with the ground(earth), the user has a very high tendency to be electrocuted.

    The transformer on PSU's doesn't only serve to step up/down the voltage, but serves as isolation as well.

  12. admin

    November 28, 2011 at 5:23 am

    Hi Leo,

    You are right and thanks for the comment!


  13. Mamade Ibrahim Joomun

    March 22, 2012 at 11:29 am

    Hi Jestine,

    I would like to know if you have a circuit diagram for:

    Input voltage 50 to 440 volt AC
    Constant 5 or 12 Volts DC 100mA.


    M I Joomun

    • Jestine Yong

      March 22, 2012 at 8:56 pm

      Hi Mamade,

      Sorry I do not keep circuit diagram.


  14. GIrma Assefa

    July 14, 2012 at 8:34 am

    Hi jestine i  am  from addis ababa Ethiopia .
    I am reading ur news letter & bouneses it is very important to me & i use it as manual thanks to u especially about LCD repairing & power supply throubleshooting  i thanks u from my heart .mr.jestine  in my country there no on line bussines opportunity  that is why things littele dificult to buy ur books & diffrent  testers.I trying via USA to communicate u and send money to u well send me the thinks which i need.
    Thanks Jestine keep intouch  Girma Assefa
    Electrical & hardware Engineer

    • Jestine Yong

      July 14, 2012 at 9:43 pm

      Hi Girma,

      You are welcome and in fact you can use money gram services to send me money to buy my products.


  15. Rahul

    October 7, 2012 at 1:13 am

    Sir Please Tell me about efficiency of the above main circuit.
    & please describe the efficiency calculation & also the power factor & ripples calculation... Thanks.

    • Jestine Yong

      October 8, 2012 at 11:05 pm

      Hi Rahul,

      I suggest that you email the owner in the link below for more information:


  16. dbgrg

    December 18, 2012 at 1:57 am

    hi justine Young, 
    I want to construct 12 volt power supply with auto cutoff.but how to start.please help me

    • Jestine Yong

      December 18, 2012 at 6:42 am

      Hi Dbgrg,

      Sorry I'm not into electronics design thus I can't give any advice on this.


  17. raymundo saura

    October 19, 2013 at 5:10 pm

    Great info thanks and GOD bless

  18. Gurpreet

    July 31, 2015 at 3:04 pm

    Hello Mr. Yong

    Thanks for sharing information with us.


    • Jestine Yong

      July 31, 2015 at 9:34 pm

      HI Gurpreet,

      You are welcome.



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