Transformerless Power Supply

One of the major problems that is to be solved in an electronic circuit design is the production of low voltage DC power supply from AC to power the circuit. The conventional method is the use of a step-down transformer to reduce the 230 V AC to a desired level of low voltage AC. The most suitable and low cost method is the use of a Voltage Dropping Capacitor in series with the phase line.

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19 thoughts on “Transformerless Power Supply

  1. Ramesh, Madurai. 18 Feb 2012 / 2:12 pm

    Can I use the condenser (2.5uf) which is being used in the FAN for this purpose?

    • D.Mohankumar 18 Feb 2012 / 5:32 pm

      Dear Ramesh
      The FAN capacitor is not suitable. See the circuit published to day in this link If you want more, current use two more capacitors parallel to C1 and C2.

      • Ramesh, Madurai. 18 Feb 2012 / 9:50 pm

        Thank You for your kind reply, Sir.

  2. Campbell Rasmond 5 Feb 2012 / 12:13 pm

    Great post. I very much enjoyed it! Exactly what I was looking for. Keep up the great work!

  3. acai berry 23 Jan 2012 / 2:44 pm

    Hey nice site, simply looking round some blogs, appears a fairly good platform you are using. I’m presently using Drupal for a few of my sites but seeking to change one of them over to a look very much like yours as a test site.

  4. Anubhav Goel 16 Jan 2012 / 7:11 pm

    Mohan Ji,

    Thanks for this great information.
    I am thinking of replacing smps supply with capacitive supply as my current requirement is low (~150ma),however, the question of long term reliability has been nagging me.
    Could you share your experience and advice on reliability & approximate life with 24×7 on state with an mcu consuming the output ?

    I did test my circuit after putting in the capacitive supply, but observed that if any load is switched on from the mains (seperate from this supply output/load) , even then, the spikes are passed into the capacitive supply, even the MOV across the line is unable to stop this.

    Please advise.


  5. dg4666 13 Nov 2011 / 1:43 am

    please give output voltage and current without load for following x rated capacitor

  6. Ayaz 28 Oct 2011 / 4:26 pm

    Hello sir !
    i am a student of electronic engineering and currently working on final year project.
    i need your help sir.i want to know that using this transformerless power supply can i get “250 to 300 mamp” at output…
    waiting for your reply sir..thanks

    • D.Mohankumar 29 Oct 2011 / 1:42 am

      Hello Ayaz
      Use Three 1 uF capacitor in parallel connection. As a rule each 1 uF can give 75-100 mA current. See the 12 volt Capacitor power supply

      • Ayaz 29 Oct 2011 / 4:00 pm

        thanks for your assistance sir…but i am yet to achieve i am using dropping capacitor of 5.1uf….i need 5volt and 250mA at output.i have selected the correct zener for 5volts but couldn’t get required current….

      • D.Mohankumar 31 Oct 2011 / 1:58 am

        Hello Ayaz The output voltage from the AC capacitor depends on many factors, mainly the input AC voltage. It should be around 220-250 volts. If the voltage is below this, a corresponding reduction in the output voltage appears. D.Mohankumar

      • Ayaz 30 Oct 2011 / 9:00 pm

        hello sir
        your valuable advise gave me the correct concept..
        thanks a lot…
        GOD bless U !

      • D.Mohankumar 31 Oct 2011 / 1:16 am

        Thanks for the feedback D.Mohankumar

  7. acvsdc 27 Oct 2011 / 6:50 am

    thanks sir,
    i dont know the voltage of x rated these capacitor
    please publish on your website

    • D.Mohankumar 27 Oct 2011 / 3:36 pm

      The X rated AC capacitors are available in 250 V, 400 V, 600 V etc irrespective of its capacitance. It is better to choose 400 V or 600 V

  8. VGC 18 Oct 2011 / 3:22 pm

    A big hello, this information is of the largest and most important thing I’ve seen so far, because in other blogs give you a little information diagrams and the operation of the circuit, and here is detailed, it seemed to me something very , very special, many thanks
    God bless you
    From Monterrey Mex.

    • D.Mohankumar 18 Oct 2011 / 3:41 pm

      Thanks for your valuable feedback and comments. Keep in touch. Thanks a lot.

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