transformerless power supply

TransformerLess Power Supply 12V 100mA

This is a transformerless power supply for low current applications. C1 is the X rated AC capacitor that reduces high volt AC. D1-D4 rectifies AC to DC and C2 removes ripples. R1 is the bleeder to remove stored current in AC when power is off. R2 limits inrush current. A Zener can be used in the output to get regulated DC.

Caution! Circuit is lethal since it carries high volt AC. Do not touch or test when connected to Mains. Enclose in a shock proof case.

Transformerless Power Supply Circuit Schematic

transformerless power supply


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  • alphonsetodd232gmail-com

    An excellent post on this topic! Quite comprehensive, accurate and readily understandable. Best of all I’ve seen on the internet…

  • dingski

    hello sir, can I please have a simple to convert my 60V ebike to have a 12v output at least 100mA, I want to use LED lights.. Thanks a lot

  • Subramanya

    how to make a circuit for 16v dc power supply with 1.25amps for any medical equipment

  • Haile

    How much is the measured voltage across each component?

  • raman kumar

    Sir plz send project of Transformer of dual power supply less then 12 volt

  • Saulmtz99

    I have an issue with heat. I am using US power 120vac 60hz, The R3:100ohm 1 watt resistor and the 5w zener diode is getting very hot. Cant touch!!! How can i fix this heat issue.

    The components im using are:
    c1: 2.2uF film capasitor 250v
    r1: 1w resistor
    r3: 100ohm 1 w resistor
    c2: 1000uf 50v capasitor
    zd: 24v 5w zener diode
    zd: a full wave bridge rectifier kbp202g
    r4: 2.2k resistor for the led’s

    i need a 24v output with as much current as possible to power up a sensor.

  • Dip

    Dear Mohankumar sir,
    i searched here and there but i did not find proper working principle of capacitive transformerless power ckt…
    so sir i want to know—

    i) what is the function of C1 (225K) & how is value of C1 determined?

    ii)what is funtion of R2(100 ohm)? (volt. drop or Current limiting)

    iii)the Apparent (VA) & Active power (Watt) of this ckt?

  • Damian S.

    Sir, greeting!
    Thanks for all your replies so far.
    Sir can you give me a formula for calculating the voltage output of this Circuit with the capacitor voltage and resistor ratings as the parameters.
    Thanks a lot in advance.

  • Walter

    I need help… I want to buil a power supply, and I want to use SCR to protect my circuit.. I want 3-5v of output voltage.. thanks

  • K B D Prasadrao

    I am a non technical man I started my hobby with this artical I did many projects sucessifully and still doing thank u very much

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