transformerless power supply circuit

Transformerless Power Supply 30V 1A

This transformerless power supply circuit is designed for medium current applications. During the negative half period, the capacitor C5 is charged to peak voltage network.

Transformerless Power Supply Circuit Schematic

transformerless power supply circuit diagram

The positive half wave will open the thyristor and the electric charge accumulated in C5 will be transferred in C4. The transport of electric charge through the thyristor begins when the voltage on C4 drop below a specified level of voltage (set by zener D4).
Thus the output voltage does not depend too much on the voltage variations or the output load.

The thyristor control signal is obtained as follows: main sinusoidal voltage is applied through capacitor C1 to D4 zener diodes that limit the voltage to 30 Vpp. Thyristor will trigger on the first front of the limited voltage that is applied through C2 – R2.

Do not touch any electrical parts of this transformerless power supply.

Semiconductors equivalent

  • BY127 = BY133
  • BA100 = BA127, BAY18, BAV18, 1N4148
  • BZY85C15 = ZF15, ZD015, 4V15
  • T6N600 = TH3V600T


Join the conversation!

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  • sylver

    Kindly assist with a diagram for 240acv to 48dcv rectifier.
    Awaiting your response

  • richard

    Please what simulating software did you ues…. case am using multisim and some of the components are not in there….. please help me out.

  • P.Prasana

    Pl give the detail for thyristor T6N600 the pin 123 which is in and out and gate thankyou,
    mail id

  • mouli

    i’ve try this 5ohm resistor burns, what is watt rating of all the resistors? and i put quater watt resistors.

  • owec

    Please, I am building a transformerless power supply, but am having a challenge. Immediately after rectifier and filter circuit, the moment I connect the regulator circuit or even ordinary divider circuit (at least to reduce the voltage level to a considerable level), the voltage will go flat to the point that it’s no longer enough to power the regulator. Please what do I do? I have tried using LM317 regulator and LM723 regulator at different times but none of them seems to be working. The target is to design power supply that will be able to power at least 10 LED lamps which I believe 5V 1.5A regulator will do

  • johnyarc216

    Hi all.
    I have complete the circuit with some changes because i couldnt find some components.
    BY127 –>1N4007
    BA100 –>1N4148
    T6N600 –> TIC126M
    Then i gave power to the ciruit… the output voltage was 5,2v
    and i don’t know how many ampere. After a few minutes C2 exploded why? Could anyone tell me… If the output voltage is logical after replacements or not. And with what capacity i should replace the C1.
    Thank you!

    • Chris Hpk

      This circuit may be designed for 220vac and make sure that C1 is bi polar cap (e.g. mylar); suggest increasing the v spec to 250v

  • Ifreke

    Hi P.Marian, please how can i modify this circuit to have a dual output supply(ie. 30v, and -30v) thanks.

  • jani

    Anybody work on the above circuit? Is it deliver 1A or not?
    please give answer because of i worked on this circuit but i did n’t get 1A.

    • Lu

      if it delivers 1A, pig flies.

    • jam56shikamaru

      I haven’t worked for it yet, but it is clear that you can only get a 1A output current when your load has an empedance of 30 ohms. Try to verify it. The 1A here is maybe just the rated maximum output current. But, a thing to remember is that trying to get current above it may affect the the output voltage stability.

  • Johnny

    But according to DMOHANKUMAR comment post that transformerless power supply ..does nt deliver high current,up to 1amp….transformer is necessary ..plz better understanding i am co nfuse..

    • jam56shikamaru

      I think, you maybe just misunderstood that post. What he really want to say maybe, is that using a transformerless power supply designed to deliver higher currents(1A or more) comes with many disadvantages. This could be the “danger(since not isolated)”, “impracticality(you’ll have to use higher farad of capacitors and higher watttage of resistors, then costs are affected)” and the output package would surely be bulky. Transformerless power supply mostly are design to power a microcontroller and other lower power IC’s. But the thing here is that if you really need to have a transformerless power supply with an output current 1A or above, then you’ll have to go through those disadvantages… Hope it could help.