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  • 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

    attentionThe author D Mohankumar is not an active member anymore. Please take into consideration that the presented information might not be correct.
    
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    218 Responses to "TransformerLess Power Supply 12V 100mA"

    1. Pls. provide me the circuit for charging the 2.4 V rechargeable battery using resistor & capacitor, but without transformer.current is 50MA.

    2. good day!!! can u help me with a transformerless power supply with a 6v output at 500mA….plz…thanx

      • D Mohankumar D.MOHAN KUMAR says: on January 18, 2010 at 2:28 pm

        It is difficult to get higher current from a transformer less power supply. Even with a 225K capacitor, maximum output current will be 100 mA. To get high current, transformer is necessary. Transformerless power supply is used to power low current circuits drawing less than 30 mA current

      • ..good day sir!, what happen if values of the components will be changed? Say from 225K 400V to 225K 630V and 100R 1W to 100R 5W?

        ..THANK YOU VERY MUCH!

      • khurram says: on June 5, 2012 at 12:38 am

        Sir it this above transformer less power supply is accurate because i want to make a device or we say product

      • D Mohankumar D.MOHAN KUMAR says: on January 18, 2010 at 2:32 pm

        The same circuit can be used for recharging 2.4 volt battery. Reduce the value of C1 to 105K and fix a 3 volt zener across the output with cathode towards positive

      • Wouldn’t it be possible to increase the output current by exchanging r2 for a smaller value resistor and parallel circuits of capacitors?

      • Sir, is this circuit will produce heat??

        is it applicable for industrial application??

        if any drawback in this circuit pls advice.

    3. what is the best amount of voltage and current supply of a passive infrared circuit usig M7615 as passive infrared controller??can u also email me the circuit of a suitable transformerless power supply…if u also have any circuit for a passive infrared sensor, can u also email me…..pls. reply ASAP..thanx a lot..

    4. D Mohankumar D.MOHAN KUMAR says: on January 18, 2010 at 2:35 pm

      It is necessary to know the power rating of the M7615. It is better to use a step down transformer because Mains spikes may give false triggering in sensor circuits

    5. Krishna says: on March 3, 2010 at 4:28 am

      Thanks for the information, its nice…

      i want to modify the same circuit for the output of 12V and 2 amps…

      can you please tell us the required changes in the circuit…

    6. D Mohankumar D.Mohankumar says: on March 3, 2010 at 11:48 am

      It is difficult to get high current from capacitor based power supply. It can give maximum 100 mA with a high value capacitor like 225K.These designs are used for low current applications.Maximum 50 volt can be obtained. For high current, transformer is necessary

      • D.Mohankomar,
        gud day!!!
        do i need to change the value if use the 110vac as an input instead of 220vac … pls advice
        regrds,
        czar

      • jayakrishnan says: on December 28, 2011 at 12:22 pm

        Hello,

        I need to construct a circuit which will operate a 12V or 48V DC relay from 230v AC mains.That is the relay should be closed when AC mains in present ans it should be open when Mains in not present.
        How to make such a circuit without using transformers? I have required number of 48v and 12v DC relays. Please help

      • I need to construct a fan circuit which will operate a 12V or 48V DC relay from 230v AC mains.That is the relay should be closed when AC mains in present ans it should be open when Mains in not present.
        How to make such a circuit without using transformers? I have required number of 48v and 12v DC relays. Please help

      • Hi,
        It is possible to get more than 50V of current from this circuit with some modifications. I have extracted upto 180V to work for around 40-50 LED’s and it runs quite well.

      • chandran says: on August 18, 2013 at 5:29 pm

        Plz inform by wiring diagram&.transformerless one only
        parts of a charger of out put 6Volts 500mA dc with 11ovolts Ac&230v acin

      • (1)Plz send me circuit diagram with parts7value of a transformerless Charger of 6Volts 500mA

        (2)Plz also send me the circuit diagram of a common table Raleigh Fan with parts&its value of 3 speed working on 230Volts Ac.50Hz with Induction motor &capacitor&3 way speedcontrol etc by reply g mailof mine ,thanks chandran 20-11-2013

    7. D Mohankumar D.Mohankumar says: on March 4, 2010 at 4:31 pm

      You need not change the values.Try with 110 v input. If the output voltage is low use 0.1 UF capacitor in the place of 225k

    8. Kimseng says: on April 14, 2010 at 4:26 pm

      Dear D.Mohan Kumar,

      Can you tell me? if I want to change the outut voltage from 12V to 5V? And after changing what is the maximum output current of the circuit?

    9. D Mohankumar D.Mohankumar says: on April 15, 2010 at 4:15 am

      The current from the power supply depends on the Capacitor C1. 225K can give around 100 mA in ideal conditions.You can reduce the output voltage to 5 volts by adding a 5 volt Zener across the output.In this case, output current will not be reduced much

      • Sir, for 5v supply i have to replace 12v Zenar diode by 5v zenar diode right…

      • sir.. i need to 220v AC to 48v DC Supply with transformer-less circuit.. can you guide me to get the circuit. or can we use this same and modify some component.if it is possible then please instruct me sir.

        waiting with anticipating.

    10. hi…..im fr indonesia….i love most ur design i hope you have another one that easy to DIY for beginer…
      Back to topic …so….about the voltage that out from this design depend to ZD value…..?

    11. D Mohankumar D.Mohankumar says: on April 23, 2010 at 1:43 pm

      The output voltage and current depends on the value of dropping capacitor C1. With a 225K capacitor around 12 volt and 100 mA will be available.This can be regulated from 3 volt to 10 volts using Zener

      • TAPAN BANERJEE says: on April 1, 2012 at 5:42 pm

        Sir,
        I have made a remote controlled regulator for celling fan, but the problem is the power supply is made by a stepdown 9-0-9v, 250ma transformer because there is a zero crossing detection. I want a transformerless power supply of 9-0-9v with zero crossing detection can you help me with a circuit that can meet my requirement. If yes, then pl.send the circuit at my email address.

    12. Hi guys thanks for giving this project on a transformerless power supply. I want to know the calculations involved in tin design of this project and to know if it worked because i want to construct it. Thanks

      • The project work…i have realized withe 2 electrolitic capacitors anti serial – ++ – of 4,7uF 450v with a final diode zener 12V 5W and give me 140mA.

    13. Hi thanks for giving out this project. I want to know the calculations involved in the design and also if it worked. Thanks

    14. Sorry, but 225k is a capacitor of 2,2uF or 0,22uF?
      Thanks.

      • D Mohankumar D.Mohankumar says: on May 9, 2010 at 7:22 pm

        225K capacitor is 2.2 uF.It is X rated Metallized Polyester Film capacitor 400 V AC.

      • nil agrawal says: on December 3, 2013 at 6:17 pm

        dear

        pl give brief detail of x rated ac capctior . why we choose Ac intsted of dc? & why Metalised Polyster type Not polypropelne type?

    15. @ Tami

      The project work…i have realized withe 2 electrolitic capacitors anti serial – ++ – of 4,7uF 450v with a final diode zener 12V 5W and give me 140mA but the capacitors are very hot..it’s best to put Metallized Polyester Film capacitor 400 V AC.

    16. Thanks pls i want to know if the heat generated can make the capacitors go bad in a short time and can a transformerless power supply circuit of 12v and 100mA power a battery charging circuit of 12V 1mA. Thanks

      • D Mohankumar D.Mohankumar says: on May 17, 2010 at 7:36 am

        Capacitor will not generate much heat.It will not be destroyed due to heat problems.Dielectric of the capacitor will be destroyed only if the line voltage goes above the rated voltage of the capacitor.It is better to avoid capacitor power supply for battery charging, if the battery is kept open.Generally these forms of power supply are not recommended to use in circuits that require human contact .If you want to charge a battery that is kept in an enclosure, use a series resistor at the output to get desired current. Use ohms law for the current.

      • Sir
        i need 6v dc supply
        can u tell me how could i get 6v dc from above circuit i.e. Transformerless Power supply

      • D Mohankumar D.Mohankumar says: on May 31, 2010 at 10:28 am

        Connect a 6.1 volt Zener across the output

      • nil agrawal says: on December 12, 2013 at 6:05 pm

        DEAR SIR

        how can i check capacitor specified voltage shows on body.& leakage of it.

        i want to check electrolytic capacitor & multilayer ceramic capacitor voltage rating & leakage of it.

    17. Thanks for your support. The battery charging circuit in question can be used to charge a 6watt or 12watt battery. The input voltage ranges from 9V To 40V and the current is 1A. Thanks for your contribution

    18. I have a pumpmotor 240VAC / 50W that is controlled by a mecanical thermostat switch. I would like to indicate that it is running with a simple LED in serial with the pump somehow. The problem is that i only have very limited physical access only to the switch that controlls the 240VAC for the pumpmotor. How can i sifon off 5V/20mA for the led with som simple componets that will not significantly affect the pumpmotors capacity? I tried connectin a cheap battery eliminator 240VAC/5VAC but that made the pump slow. Im looking for a super simple solution and i dont want to use a battery that recuires changing.
      I am wondering if perhapps a simple ferite ring with a few loops (<5) and a small resistor on the secondary side could be used as a transformer. How would one go about calcuating the number of loops to get 5 v/ 20mA. Would this affect the pumpmotor. Will I perhapps need an extra sparc protection on there realay since I have a serial tranformer. I have electronic schooling but it was to decades ago.

    19. D Mohankumar D.Mohankumar says: on June 1, 2010 at 4:33 am

      The most simple solution to light an LED is to connect a 47k 1 watt resistor in series with the LED . This should be connected across the phase and neutral after the pump switch.The brightness of the LED will be low since it is lighting only in the positive half cycle of AC.

    20. Thank you for your quick and wize reply. Im sure it would work if i had access to the neutral cable after the pump. 240V/47K equals 5,1mA thru the LED. But would it not be to much voltage for a “simple led” to handle?
      I was schooled 20 year ago and have not practised electronics since. Back then the diodes we used “handled” quite low voltages i think it was 0,7V – 12V. Does modern day LED’s handle 240 V or how would the voltage be over/on the LED. Im a bit afraid it might blow up violently taking out an eye and a few brain cells
      (murphys law :-) ).

      Sadly I do not have access to the neutral wire after the pump. I want to put the indication diode at the switch (in serial somehow). Im sorry for the unclear problem description. What i would like, if it possible, is some simple cirquit thingie in serial with the switch. That would not affect the pump noticeably.

      If i parallel connect three 10 ohm resistors i would get a 0,03 ohm resistor. 10+10+10/10*10*10=0,03 ohm.
      In serial with the switch that would make 240VAC*0,03 Ohm=7,2V over the resistor(s). If i then also put a (diode and a 360ohm(7,2V/20mA) in serial) in paralell over with the 0,03 ohms. What would i get? What kind of Watt tolerance resistors would i need for this? I cant realy figure out the watt here and i dont want redhot resistors just to lite the LED. Would this be safe?

      Here is a link to the boyler thermostat i want to put the indicator led in serial with. It’s basicaly a normal cirquit switch. http://www.ra.danfoss.com/TechnicalInfo/Literature/Manuals/04/ICPDP10F102.pdf

      With grattitude
      Nick

      • Nick,

        You can loop your hot wire going to the pump through a CT (current transformer), the turns ration determines the current in CT winding, for example if your pump current is 1Amp then 100turns will induce 10mA in the CT coil, you can use this to light up a LED.
        You can try a small ferrite core and wind the magnet wire onto this.

        John.

    21. D Mohankumar D.Mohankumar says: on June 2, 2010 at 2:12 pm

      Do not think too much theory. Just connect the LED with a 47 K or 56 K resistor( 1/2 watt) .LED will glow with half brilliance. But you have to connect it between the phase and neutral lines.

    22. how can i calculate thecharge rate of a battery and to know the charge rate of my circuit. also the calculation to know the capacitor to use in rectification

    23. nouman nayyer says: on July 25, 2010 at 9:06 am

      dear sir
      sir i made it but with correct component but after few minutes the 100uf-25v capacitor overheated and destroyed and the voltage was also 33 volts dc…..
      plz help me regarding this
      thank u

    24. The problem is with the capacitor C2. Use 100 UF 100 Volts capacitor and check output voltage. If required use a 12 volt zener across the output

    25. sir i have a small problem that i need a circuit without transformer which provides 12v 1 ampere current can u please give me suggestion

    26. D Mohankumar D.Mohankumar says: on July 27, 2010 at 4:26 pm

      Transformerless power supply can give only 500mA or less current.If you want 1A,use a transformer

      • sir you are saying that transformerless power supply can only give 500mA,then how the cahrger of a mobile phone is giving 895mA??
        i checked that on NOKIA charger..its rated as 875mA output.kindly elaborate the reason
        thanks

      • That is because that uses smps high frequency switching which is very difficult to design and make.

      • phone charger is not include as a transformerless charger..it is a SWITCHING MODE POWER SUPPLY..it used a small trnsformer that trigger by a mosfet…try to searched in google and learned abt SWITCHING MODE POWER SUPPLY…it gives more power output than a conventional charger..

      • Transformerless power supply can give only 500mA or less current.If you want 1A,use a transformer

      • Hi,
        It would be great if I am able to draw 350mA current from the same circuit to run a 1w (3.5v 350mA) High power LED. In a previous post I have mentioned that I can make 40-50 LED circuit with LED’s rating 3.5v 20mA. But I would like to ask, what would happen if I connect 2 or 3 225K caps in this circuit, with a changed C2 value and lower voltage Zener, cant it give me my required output (Capacitance increases when connected in parallel).

    27. japanjot singh suri says: on September 1, 2010 at 9:58 pm

      hello sir, i am doing electronics engg,your post seems to be very usefull to me and my frnds, sir as we work on simple projects, we require batteries,and the main problem is bulky transformers in the project, sir we require 6v 350 to 500 ma dc supply from 230v w/o transformer to charge 4v 1amp battery, and we also require 8v 500 ma supply to charge 6v 4.5 ah battery.

      acording to your circuit i judged dat we could do dat using zeners of our required voltage, but how to calculate and adjust the output current which we would get

      would be glad if u would help us
      thank you :-)

    28. Is there a way that we could increase the Amp supplied by this Circuit,Cause i’m trying to develop a LED tube Light which Req 12 V n 1 AMP,Thnks

    29. Dear sir, is this power supply enough to activated the panic alarm circuit?

    30. D Mohankumar D.Mohankumar says: on November 9, 2010 at 1:18 pm

      Dear Vincent

      Th Capacitor power supply can be used for any circuit that requires less than 100 ma current including the Panic alarm circuit. But relay will not work satisfactorily in capacitor power supply since it requires more current. If you use Capacitor power supply, take all precautions mentioned in the article. The power supply section should be isolated from the circuit. Do not touch or trouble shoot the circuit while it is connected to mains. It can give a fatal shock.

    31. @D.Mohankumar

      sir you are saying that transformerless power supply can only give 500mA,then how the cahrger of a mobile phone is giving 895mA??
      i checked that on NOKIA charger..its rated as 875mA output.kindly elaborate the reason
      thanks

      • D Mohankumar D.Mohankumar says: on November 29, 2010 at 3:48 am

        Dear Khayyam

        Mobile charger uses SMPS power supply which can give up to 1Amps current.There are components to give high current.In simple transformerless power supply, the current depends on the value of the capacitor.That is around 100 mA / 1uF.

      • Sir, I am trying to do a mobile charger ckt. kindly tell me if I can check this ckt using a common board, or will I need a PCB to test this ckt.
        I want to know if the high voltage, high frequency input will short the board pins..

    32. Hello Mr Mohankumar thanks for this circuit, I am planning to use this circuit in one of my patented eco switches, but the design company inform me that it is only able to deliver 40mA.I need a circuit that can deliver over 60mA.Please confirm that this circuit can definately deliver 100mA.My email address is prad123rita@yahoo.co.uk kindly advise.Matter urgent.pradeep

    33. sir i wantcircuit of Transformerless power supply only230v to 12v 500mA /200mA

    34. sir we want circuit of 220v to 12vdc 200mA detail please

    35. hi sir, I am also an electronics engineering student . we are going to build a transformerless power supply 24V / 3A and no using of IC . can you please give me the circuit? thanks in advanced .

    36. sir thanks for poer supply but i want 1qu. iwant circuit of 12v 12amp transformerless shock proof

    37. sir,

      The circuit is designed for 12v 100mA. Will you help me sir as to what component should i replace/adjust to have a 12v 500mA.

      Thank you so much in advance.

      • The out put voltage from the Transformer power supply depends on the value of the AC capacitor used. As a rule 80-100 mA current will be available per 1 uF. If you want 500 mA, you have to use Five 1 uF AC capacitors in Parallel. But the output current depends on the input AC also. Accurate output cannot be expected and high current devices cannot be connected to this power supply. This type of power supply is used only in low current applications requiring less than 100 mA current.

    38. jhun s. viloria says: on April 24, 2011 at 6:43 pm

      Dear Sir,
      I just want to ask you about my problem,i want to buy a transformer with 2 separate secondary outputs,1 is for 50v another 1 is for 25v,the case is..im trying to fix a bose amplifier board,there are 2 separate supplies,the first supply is having a 25v capacitor and another 1 is 50v…i want to make sure from you what is the correct specs of the transformer im going to buy,im not sure whether the output should be at least 20v for the 25v capacitor and at least 40v for the 50v capacitor.
      Please guide me.
      Thank you very much in advance.

    39. Abhishek kumar says: on April 27, 2011 at 11:04 am

      Hey everyone,
      I want to design a transformerless power supply, whose output must be 5V,200mA.
      Please guide me how yo do…….

    40. patrick vaz says: on May 4, 2011 at 8:58 am

      Hi,

      If i need 12v & 20mA, instead of 100mA what changes in the components i need to do,

      thanks in advance

      • This transformer less power supply is already giving an output of 12V, so you can use it, actually you can use any 12V power supply that can output a current higher than 20mA because the device you use will consume as much power as needed.

    41. sir i tried the power supply for another circuit but the R2 is burned off, i used 100R 1 watts .and another problem is the R3 is also becoming hotter.kindly reply sir.

    42. sir i tried the power supply but the R2 is burned off, i used 100R 1 watts .and another problem is the R3 is also becoming hotter.kindly reply sir.

      • depend on ur load…more load current getting more hotter til burned it…try to put higher resistor up to 1k wattage of 3watts…for better performance

    43. ThanhHoangDang says: on July 23, 2011 at 7:46 am

      Hi sir,I’m doing this circut,everything ‘s ok but why is the R3=220(Ohm) too hot,I’m worrying it’ll be destroy.I don’t know what’s wrong with it.pls send to some solution to do it better soon,thanks sir so much for this!

    44. Dear Sir.
      Thanks a lot. I use this circuit to charge my LED lamp battery and working good.

      Regards
      karsang dorji
      Bhuatn

    45. @abhin raj
      @ThanhHoangDang
      maximum current in the circuit is 100ma(0.1A)
      now apply Ohms Law , power is equal to current squared into resistance
      P=I^2R
      for R2 we get 0.1^2X100= 1 watt
      Use twice this value
      So we need to use a 2 watt resistor for R2
      Similarly for R3 we get 0.1^2X220=2.2 watts
      Use twice this value which comes to 5 watts
      So we need to use a 5 watt resistor for R3
      hope it will keep the circuit cool
      regards

    46. Bhanu Reddy says: on August 3, 2011 at 7:24 am

      I would like to stepdown the voltage from 3 phase system..i dont have the neutral..is there a way with out using transformer to step down (12 v 50ma)voltage from 220v 3 phase 3 wire system..

    47. sir,i wud like to make a restless(always working) led flasher circuit which works on 6v,is it possible to connect this circuit to power flasher always from 230v ac supply?plz reply

    48. plz sir , i tried the transformer less power supply shown in this site , but using 5.1 v zener , in case of open circuit output is 5v but when loading, output becomes 1 volt , so how to fix this problem or how to design suitable trans.less power supply to feed 20 leds parallel together with output 5v sharp.

    49. P.Jagannathan, says: on August 9, 2011 at 2:36 pm

      Thank you for the interesting circuit idea, can u please suggest alteration so that I can get 12V 210mA to light my LED which can give me 3W light

    50. Can i use SMPS for audio amplifiers

    51. Rajubhai Maru says: on August 12, 2011 at 2:50 pm

      Dear Sir, D.Mohankumar

      Sir i priped this circuit but R3(220R)is Very hot after 3 to 5 minitus & R2 also so whot can i do sir

      sir please replay me……

      Thanks

    52. on the 100R1W and 200R1W resistor, can you please tell me what does R mean? thank you! :)

    53. I want to replace the 9V battery with transformer less power supply. Please suggest. With Advance Thanks
      Kannan

    54. sir i need transformerless (-35 to +35)volt dual power supply circuit diagram with 5amps current

    55. Sir,
      How to design a dual 8V,100mA power supply? which regulator IC can we use?

    56. Plz also give me circuit diagram.

    57. Doctor What says: on September 23, 2011 at 2:06 am

      Hey, love the circuitry, but how could i set it to 5V and 150mA?

    58. Rohan Valvekar says: on September 24, 2011 at 9:50 am

      How to make 1amp 12v power supply ? or which capacitor to use to make the same circuit 1 amp output

    59. Sir kindly take us to next level and with a bit complex circuitory tell us to get increased current

    60. Thanks for this circuit it work i have been built for auto emergency light

      i want to build simplified 12v, 5v power supply from main smps transformer that i get it from broken PC Power Supply Unit, can u give me the schematic?

      for your respone thanks before.
      i has been search for half year

    61. asad ullah jan says: on September 30, 2011 at 6:48 pm

      my dear sir,
      i want to know about transformerless power supply,
      how can we built power supply from 220ac to 6vdc with the transformerless or capicito resister method,
      if u do, i will be very thankfull of you.

    62. How this capacitor C1 reduces high volt AC to low volt AC. pls elaborate the principle behind this

    63. Dear mohan kumar sir,i seen your designed circuit, all are working fine but i need a transformer less power supply from the two different kind of Phase supplies, with the current of 100mA and the input supply is 210v – 450v / phase, out should be 5v / 100mA .

    64. Dear sir, Can you please let me know how to give DC power transformerless supply of 12V to IR LEDs (60+60). And also please provide me the link of the same circuit diagram. Any reply shall be highly appreciated. With Regards!

      • C.Mitra Chinmoy Mitra says: on December 14, 2012 at 4:21 pm

        Hello Virender, the problem is that people like you want a quick and magical solution for your problems, without providing sufficient and clear information about the problem. To get a free answer to your problem, the least you can do is sit down at your computer and spend at least 10 minutes to write the details about the project. What does (60+60) mean? Is it 60 led’s in series in one group connected to another 60 led’s in series? Or is it 120 led’s in series? Or is it all 60 led’s in parallel connected in series to another 60 led’s in parallel?

    65. pls try to clear the value of the resistor labeled 100R…is it 100R or 100K? try to be consistent in your posting..otherwise shits are the result….

    66. i have 6v AC and 100ma input current. i want to charge cell phone or any device. i put the circuit through rectifer 1n5408 and for ripple i used 1000uf to remove ripple but i am getting 1ma current after it. i put it through voltage regulator and i am getting 5v dc voltage but i am getting enough current to charge device…any suggestion how can i improve

    67. jayakrishnan says: on November 26, 2011 at 8:33 am

      How to drive a 12V DC relay using this circuit?

    68. waseem ahmad says: on November 30, 2011 at 4:23 pm

      Most respected sir,
      please send me 12 volts 55 watt transformer less power supply circuit urgently
      Please guide me how yo do……

    69. Samiuddhin says: on December 2, 2011 at 7:15 am

      Sir. I made this circuit, but after few mins resistor R3 and R4 get overheated and burn out.
      The No load voltage is 90V before the zener. So, pls help to get the output 12V 100mA.

      • try to change higher resistor and its wattage…check also ur zener diode maybe got defective after resistor burned out…
        mke sure c1 wrking properly

    70. it is very efficient methode.but it i used only for small outputs.

    71. VERY GOOD

    72. osama bin laden says: on December 25, 2011 at 8:20 pm

      I have an idea

    73. i want a charge 6v 4.5 ah battery in a emergengy lamp so i need a transformerless power suplly to that so plz help me to do this circuit sir

    74. i want a charge 6v 4.5 ah battery in a emergengy lamp so i need a transformerless power suplly to that so plz help me to do this circuit sir my mail adress rockzs1419@gmail.com and same adress for facebook and ph.no 9247200307

    75. can you display the 900MHz oscillator circuit diagrm please..

    76. good day sir, I’ve tried the experiment but it’s giving me some problems. the resistor r2 is getting burnt.pls what can i do? thanks

    77. Hello sir,
      Actually we are using same circuit for toggling relay nd it’s working fine for normal ac supply nd for UPS…but when we provide ac supply through invertor it doesn’t work..the voltage across zener drops to 7.7V from 13.30V when ac input is through invertor.
      In our case C1 is 1uf 250v,R1=1Mohm c2=22uf 25V ,we haven’t used R3 & R2,Zener same 15V…
      what is use of R3 nd R2??
      please can anyone suggest solution as early as possible??

    78. Hello sir,
      Actually we are using same circuit for toggling relay nd it’s working fine for normal ac supply nd for UPS…but when we provide ac supply through invertor it doesn’t work..the voltage across zener drops to 7.7V from 13.30V when ac input is through invertor.
      In our case C1 is 1uf 250v,R1=1Mohm c2=22uf 25V ,we haven’t used R3 & R2,Zener same 15V…
      what is use of R3 nd R2??
      please can anyone suggest solution as early as possible??

      • Cheap invertors don’t produce pure sine wave. Since the impedance of C1 is a function of pure sine wave, with a distorted or modified sine wave, the voltage and phase angle may both fluctuate abruptly and may stay at 0V for some time before changing its polarity, the behaviour of C1 is unpredictable and normally won’t work correctly with this kind of circuit.

        R2 is a inrush current-limiting resistor. The circuit works the same without it. For consumer applications, this is one of the feature to compile with UL specifications.

        R3 is to limit the current flowing through the zener diode. The zener diode is rated at 15V/1W. Mathematically, it can handle a current of 66mA. As the circuit can only supply roughly 140mA, if the current drawn by the relay is more than (140-66)mA = 74mA, the inclusion of R3 can be ignored. However, you have to make sure the relay (the load) has been connected to the circuit before AC power is supplied to the circuit. Otherwise, the full amount of current (140mA) available from the circuit will pass through the zener diode that would be damaged gradually.

    79. sir i want to charge 4v 0.4ah battery plz help me says: on January 10, 2012 at 1:06 pm

      helpful

    80. hello sir……
      I want simple circuit for lighting 20 led (ac to dc transformer-less circuit )without using transformer
      please help me…

    81. Mosses .A says: on January 12, 2012 at 12:17 pm

      dear sir,
      Good evening
      i need a detail about electronic mosquito repellent and circuit.
      pls do me favour sir
      thank you

    82. hello sir
      am trying to detect AC 230V using optocoupler
      please give me any circuit idea

      and in circuit shown top above
      give me formula how to calculate R1, R1, C1

    83. Hi Mohan

      Can you recheck the Xc = 225k value ?

      Xc= Vrms/Irms

      if Xc= 225k then Irms = 230V/225k = 0.001 A = 1mA

      C = 1/2*pi*f*Xc = 1/2*3.14*50*225k = 14nF

      Let me know

    84. Dear Mohan,

      225K refer to 2.2uF (the 5 is number of zeros in pF so 2200000pF=2.2uF)
      in calculation:
      Xc=1/2*pi*f*c=1/2*3.14*50*2.2u=1447 Ohm
      I=V/Xc=230/1447=0.159A

      • hello Eli T,

        by using 2.2uf can i get perfect circuit for to deliver 150ma .

        whats the output voltage of that.

    85. On DC side, if touched, do we get shock?

    86. Gostei muito dessa fonte. Legal cara (a brazilian)

    87. sir, individual needs/comments are knowledgeable.
      sir i have a spot billing printer(electricity bill printer) having 12 volt 1 amp baterry charger having surge protection. But these chargers are not lasting. Now i am using 12v, 400ma adapter for charging purpose. It serve the purpose but it takes 8hrs to get full charge.
      Can i have your support to built a charger of the same capacity.Or circuit diagrame.

      Thaking you

      sherab gyamtsho
      Corporate employee
      Trongsa Bhutan

    88. md gaffar beag says: on February 24, 2012 at 5:09 pm

      sir i have a 9V transformer i want a dc voltage of 2 volt 1.5A……can you pls help me regarding this..

    89. Duc.Chu says: on March 4, 2012 at 5:48 pm

      Dear sir ,
      I read your article for transformerless on the internet. It was very interesting, I was trying to understand it. I think it is a reduce the voltage circuit with impedance of the capacitor but I can not calculate its parameters (voltage, current). It’s better if you kindly me the formula.
      Thanks and regards.

    90. http://www.electronicsforu.com/electronicsforu/circuitarchives/view_article.asp?sno=148&article_type=1&title=Muscular%20Stimulator&id=429…..
      In this can i use the concept for 220v-12v concept sir…
      Please Reply me as soon as possible sir..

    91. hi
      plz give a transformer circle for convertur 220 to 12 voltage thank very much

    92. Amer Rehman says: on March 13, 2012 at 1:56 pm

      What are the benefits of using transformerless power supply, to reduce cost?

    93. i need explanation of circuit..as early as pssble..pls..thnx..

    94. i need explanation of circuit,,pls rpl as fst as pssbl..hv v appld both ac & dc voltg 2 the circuit,,as shwn in the fig.

    95. Mr. Mohan Kumar
      I need a circuit which will replace the 9V battery. Is this circuit will help in that. Please …

    96. ritesh kumar says: on March 19, 2012 at 10:39 am

      i need circuit diagram description for power supply without transformer 12v,10mA

      • i need circuit diagram description for power supply without transformer 12v,100mA ( is R2=100 OHM,or 100k),(r3=220 ohm ,or 220K)

    97. Sir, how i calculate the output voltage? is the value of x rated capacitor depends on output voltage?

    98. plz sir!!!! give me the ckt of 230v AC to 9v DC without using transformer……. plzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz

    99. can u plz provide me wth the design of the power supply wth the rating of 12 V DC and 10 mA current. Thanking you

    100. Anil HRD says: on April 11, 2012 at 3:27 pm

      in the given ckt resistor 220r 1w is getting very very hot …. it will not work for long time and output supply also high .. around 16-17 VDC

    101. Parmjeet Singh Parmjeet Singh says: on April 12, 2012 at 11:23 am

      sir,i need transformerless power supply circuit for 30 yellow coloured leds(5mm),can u send me circuit.

    102. vineesh says: on June 21, 2012 at 1:44 pm

      vineesh says: June 21, 2012 at 1:43 pm 0 0
      i am an electronics enggr. just gone thru this ckt. this ckt wont last for long. the resistors ob both ac side and dc side will heat like anything. even you use 5w resistor also same effect can observe.zener also will heat like anything even use high watts zeners. if use less value caps say 0.2uf, then this ckt is very fine,but only 20ma current can deliver

    103. chandu says: on July 7, 2012 at 7:23 pm

      I agree with Vineesh. This circuit is crap. All the resistors R1, R2 and R3 will heated up and burn off within 5 minutes. This circuit would have tested before publishing.

    104. sushant patil says: on July 10, 2012 at 12:40 pm

      i have to know that ow transformer couple amplifier work as voltage follower ….. and gie me the aaplication of charge couple amplifier.. reply soon i am waiting for your reply

    105. the capacitor c1 used in the circuit 2.2 mfd(225k)which is difficult to find in my nearby local market…
      my question is that can i use the ceiling fan capacitor(2.5mfd,440v) in place of c1..
      ceiling fan capacitor is available everywhere..

    106. Can u just least all AC capacitor and give me their maximum voltage and current,,,,

    107. Can u just least all AC capacitor and give me their maximum voltage and current, plz

    108. scabbasrh says: on August 20, 2012 at 5:56 pm

      Hello sir
      I am Beginner .
      so i confused whats the red led

    109. cellphone battery packs require 3.7vdc and 180ma=to=200ma current for charging.. can hi use this transformerless%power%supply as a mobile phone charger to replenishes$the cellphone -batt!”within two or three hour..as matter of fact$will current of 100ma is sufficient for charging cellphone…plz can u just help me and tell the real fact of this….thanks

    110. [Colin mitchell] help me ooooooooooo@0ooooooooo???????????treasure

    111. @d. mohan kumar sir can u tell me what value of dropping capacitor and c2 have to be selected in order to get 5v dc supply with 20ma current… her im giving input from supply mains 230v ac power supply(50hz)

    112. sama nkenyi ramson says: on August 29, 2012 at 5:56 pm

      hello sir.i was very satisfy with this circuit design.thanks

    113. sir.!!!! can u give me layout for transformerless ac to dc for fabricate it on pcb…….

    114. Dear sir,

      i want ask you, that output is in DC??? ant can direct connect with LED??
      can i add the LED (10 LED or above)??

    115. Sir,
      i want to make a supply for ATmega32 MCU. I need 5v input voltage which i will get using zener diode. Or using 7805 IC. But is this ckt can realy replace Step Down transformer to such a great extent that i can use it in place of that? I also want to know can i solder this ckt on a PCB? (I think it will burn…).so better to ask first….THANKS in advance and waiting for an early reply….thanks a lot

      • Jim Keith Jim Keith says: on October 10, 2012 at 10:12 pm

        This type of power source is not recommended for human interface type of equipment due to shock hazard.

        Recommended is a wall wart (outlet mounted) power adapter containing isolation /voltage matching transformer–there are 5V regulated versions available, or you can add a 7805 regulator to a 9 or 12VDC version.

    116. @jim – thanks your valueable reply…

    117. Can someone pls help me a circuit diagram of a battery charger that can charge 3 24 volts battery at once and maximum 6 24 volts. Having regulator to select if to charge 3 or 4 or 5 at once

    118. hello sir, the above circuit diagram exactly output 4.9v , so what i replaced or change the circuit diagram please send my email address.

    119. sir, i have one battery 3.7v dc 1020ma i am increase the voltage 4.9v dc so what are the elements using the increasing the voltage plz reply me.

    120. In all probability, this is an untested & dangerous circuit. In a transformerless capacitive power supply, the output current (not voltage) is limited by the primary component-the series capacitor. As per the diagram, how it produces +12V output with a 15V zener diode? Here,I observed a chance of C2 failure (because of the “strange” R3-ZD combination, too!

      Interested readers can refer this document from Microchip http://ww1.microchip.com/downloads/en/appnotes/00954A.pdf

      • C.Mitra C.Mitra says: on July 22, 2013 at 4:59 pm

        Dear Mr.Hareendran, your comment here is quite right to some extent, and also wrong. Let me explain…

        1. As you have said, this circuit is dangerous, but to an experienced hobbyst it is as safe as safe can be! Beginners should make this under the guidance of experienced and knowledgeable experts. The completed circuit should be enclosed in a pastic container.

        2. Untested, maybe. Since the components used seem to be a bit unrealistic in value. The series capacitor is too large (2.2uF), since it has to be a polyester or paper type, rated at atleast 1000V AC.

        3. A few simple ohms law calculations shows the following facts:-
        a) The total shorted current capacity of this circuit is about 130 mA, since the capacitive reactance of a 2.2 uF condenser is 1.44 kohm at 50Hz.
        b) A zener diode of 15V across the output (with only a 220ohm dropping resistor) is absurd, since it will draw a heavy current and heat up the 220 ohm and 100 ohm resistors. Zener diodes used as shunt regulator, as in this circuit, can only provide small currents. A zener diode can not regulate a load current of 100 mA.

        3. You are right that a 12V output is not possible with a 15V zener. Yet, there can be an explanation for that too…that 15V zener may be just sitting there doing nothing, since the default output voltage itself may be 12V. So the zener is not conducting at all, and (maybe) sitting there as a safety device to limit the output voltage to 15V in case the source votage goes beyond 15V DC.

        4. This type of circuit is very common and is widely used in all chinese made rechargeable torches, lanterns, decorative lightings etc. C2 failure in these gadgets is very common where they have used ordinary polyester capacitors rated at 100V to 250V. Capacitors rated at 600-1000V never fail.

        Finally, the truth of the circuit can only be ascertained after actually assembling it and trying out. I will try to do that in the future and post the results.

      • John Lam says: on August 25, 2014 at 7:59 am

        Mr. T.K.Hareendran,

        You are right about the R3+ZD combination. It is weird.

        R3 is normally required in a transformer power supply to limit the current passing through the zener diode. In this circuit, the maximum current supplied is limited to roughly 150mA that always exists and cannot be changed. The R3 here is in fact redundant. It can be taken away. If included, power rating should be at least 5W.

        Even with the redundant R3 included in the circuit, C2 is fine.

        Potential difference across R3 = IR = (220 * 0.150)V = 33V

        Potential difference across ZD = 15V

        So Potential difference across C2 = R3 + ZD = 48V

        The schematic suggests 470uF, 100V is absoutely fine.

        Other than that, power rating for R2 is too low, should be at least 3W.

      • Mr. T.K.Hareendran,

        I take time reading the Microchip AN954A note that you mentioned. There are at least two major errors in the paper.

        The first one is the equation for calculating total impedance of RC circuit in series. In its Equation 4, Example 1 and 2, instead of using Pythagorean Theorem for vector quantities, it use regular addition to calculate total impedance of RC.

        Another major error is the formula for calculating Iin or maximum current the circuit can supply. Microchip use Vrms to calculate Iin, and the result is the Irms the circuit can supply. This is a big mistake.

        When a zener diode is connected after the current-limiting capacitor, the output voltage turns from sinusoidal to DC, so average voltage instead of RMS voltage must be used in the calculation of current (average current). That means, instead of using the factor SQRT(2) / 2 as in Microchip equations for RMS calculation, the factor 2 / pi for AVERAGE must be used. In short, Microchip inflates Iin by 10% (difference between 0.7071 and 0.6366).

        Microchip AN954 is an informative note. Just be sure you know where it put down wrong information.

    121. duho9057 says: on June 15, 2013 at 1:12 pm

      Chân thành cám ơn trang web đã có nhiều mạch điện thiết thực hữu ích.

    122. h.i.singh says: on July 9, 2013 at 12:22 am

      good site for begineers.

    123. Hi
      I need to 24V,4A power supply circuit,
      can you help me?

      • C.Mitra C.Mitra says: on July 22, 2013 at 5:06 pm

        Dear Mary, I can help you if you provide a little more data about your requirement.
        1. Firstly, do you need a switched mode supply or ordinary transformer type supply?
        2. Do you want a regulated power supply?
        3. What is the purpose or use of the power supply? Is it audio related for powering audio amplifiers, or is it for charging lead acid batteries, or some other purpose. The use will decide the design, since the ripple content and filtration is dependant on this.

    124. i want to convert 230v supply into 5v without transformer circuit i.e. by using only resistor and capacitor circuit

      • It can be achieved but the voltage will not be stabilized, and the output voltage will decrease as the current consumption will increase. So you can make a circuit that outputs 12V for example then use a 7805 voltage regulator if you need a fixed voltage.

    125. ashwini says: on August 9, 2013 at 7:25 am

      can give me any resistor,capacitor circuit idea so that
      it can be used for long time without heat dissipation

    126. ashwini says: on August 9, 2013 at 7:30 am

      as you shown ckt diagram,it taking big capacitor.i want
      to make small and handy circuit

    127. sir can you please explain me how to convert 230v/5A 0r 3A/50Hz to 5v DC of 20 mA….Sir please brief me operation.

    128. sir , can plz tell, how to know how much current my circuit needs..

    129. Dear Sir,

      I need 22v 1A transformerless power supply

    130. Hello sir,
      I read all of the above ,but cannot understand that how to calculate or find out the different output voltage(s)to the circuit with or with out load from different x-rated capasitors of different values(uF) using on 230v AC main line in india?
      please give the calculation as I am very confused to
      select the proper x-rated capasitor for my home application?

      wating for your reply eagarly.Thanks in advance.
      MK.

    131. Anoop K Anand Anoop K Anand says: on October 16, 2013 at 10:41 am

      Sir…
      Can i connect a 7812 IC voltage reg. instead of Zener diode..?

    132. Digil David says: on October 16, 2013 at 8:10 pm

      Sir, what will be the output voltage of 225k capacitor series with a volt meter

    133. We design this circuit but it’s provide heat very strongly. We changed the 220ohm resister 1W to 10w its heating was reduced but it’s still produce heat in the long run. Can you give us a diagram that heat less.

    134. Any one please let give the either ic no or circuit diagram, which convert high volt dc to low volt dc

      ex: 30v dc to 9v dc

    135. MUHAMMAD ZAIN UL ABIDIN says: on November 23, 2013 at 6:49 am

      sir i want to make transformerless power supply with 100 watt at the output plz suggest the values of capacitors.

    136. nil agrawal says: on December 3, 2013 at 6:41 pm

      it help so many persons to change their know how

    137. I want to know the safety of the transformerless circuit.
      thanks

    138. For safety, the low side must tie to the power distribution neutral line, all electrical outlets used must be polarized correctly and the distribution system must be connected and grounded properly. For me, this is a little too much to depend upon.

      Frankly, I’m surprised that we do not hear horror stories associated with this type of power supply. I take this back, because the old series string electron tube radio sets used this trick back in the 1950′s — and I received nasty shocks from them. Subsequently, they added a ‘protection’ circuit that isolated the chassis from the power supply via a parallel RC arrangement that limited ground fault current to an uncomfortable 5mA. (got them through UL approvals anyway)…

      I, for one, do not recommend it and suggest that experimenters use wall wart power supplies instead of this potentially dangerous power source. Over the course of time I have collected a box of them and it is rare that one does not fit the reguirements. Check out this post:
      http://www.electroschematics.com/6938/of-wall-warts-wall-transformers/

      • Good day Mr Keith,

        I hope you are well.

        Just a question with regards to the Transformer-less schematic. Will it be OK to replace the recommended 2.2uf/400v AC cap, with a 4.7uf/275V hight quality AC capacitor for an increase mA output?

        Secondly, I should amend the values if R1, R2,R3.

        Thanks & Regards

    139. In this circuit how can vary output voltage and Current? What component determine o/p voltage and current?

    140. hi sir..
      can i use this ps for driving knight rider circuit using 555 and 4017,what will happen if i replace lower wattage zener

    141. D.M.Gharat says: on April 13, 2014 at 5:44 pm

      pl. provide me the 230ac to 48 vdc transformerless circuit

    142. pankaj says: on May 24, 2014 at 2:57 pm

      Sir,

      I am lookinh for circuit which can give 3 phase to 12volt DC.
      Please help.

      Pankaj

    143. C 530J 400V how much current and voltage? thx.

    144. karthik says: on July 22, 2014 at 8:14 pm

      the 220ohm, 100ohm 1w resistor produces heat so much. what to do that

    145. karthik says: on July 23, 2014 at 2:43 pm

      i get the output 12v and current 100mA. but the circuit was heat up within 20sec. especially the 220ohm resistor was overheat.
      what to do?
      please give me the solution

      • If the load is always connected to the circuit and will draw roughly 100mA, get rid of the 220 ohm resistor.

        For R2, either use a 2W or higher resistor or get rid of it as well.

    146. I requir 48v dc convert to12v dc 1amp if regulator available pl give no or circuit digram..pl.

    147. i have tried this schematic on a breadboard and it doesn’t seem to work the 100ohm 1 watt resistor over heats a lot can u plz help me to get this to work the output voltage i keep getting is like 0.03v and even 1.5v

      thank you

    148. hi!
      a made a regulated power supply with transformer on it. i needed it to make my wiper motor work. but the odd thing is, it works for dc and stepper motors but not on the wiper motor.
      i used a 220v ac to 12v dc (3 amps). i was wondering current must also be taken into consideration?
      here are my components:
      * 2200 uF capacitor -1
      * 1n5400 diode – 4
      * 10k resistor – 1
      * 7812 and 7805 regulator
      here’s my schematics:

    149. what transformer-less power supply can i use to run a wiper motor?
      by the way, i will be using an l293d to control my wiper motor.

      • John Lam says: on August 25, 2014 at 4:36 am

        A wiper motor will usually consume a few amperes of current that varies dependent on speed. Transformerless power supply are for gadgets that consume fixed and small current from a few mA to a few tenths mA. In short, that’s not going to operate a wiper motor.

      • here’s a motor circuit that i’ve made. i’ve already tested it. the wiper motor is working but it’s rotation was so slow. it’s not the output that i need.

        what do you suggest?

      • L239D can only safely provide current up to 600mA. I am afraid the motors you use are rated way higher than that, possibly rated at 12V 1.5A or even higher. Touch the surface of L239D when the motor is running, you will feel the chip is very hot and may automatically shut down after a while.

        If you have an DC ammeter that’s capable of measuring current of a few amperes, try to connect the motor directly to 12V DC and measure the current drawn. If necessary, replace the L239D with one that can at least supply the current measured.

      • The four relays sound redundant. They don’t seem to do any job at all in your circuit.

        One possibility is that you actually want to use the L239D to control the relays that in term determine the +- or -+ power connections to the motor (control direction of rotation).

        If this is the case, you have to connect the common pins of both RL1 and RL2 relays to each of the motor terminals, 12V+ to both NO (Normally Open) pins of both relays, 12V- to both NC (Normally Closed) pins of both relays, OUT1 to one terminal of RL1 relay coil, OUT2 to one terminal of RL2 relay coil. Of course, connect the other pins of both relay coils to GND of L239D. Then by changing the two switches connected to IN1 and IN2, you are able to fully control the top motor (clockwise, anti-clockwise or OFF). Do the same for the other half to control the second motor.

        By doing so, you are running the motors directly from 12V power supply. The motors will run at full speed if the power supply is rated at a higher current rating than the motor. The L239D is used to control only the four relays that probably only consume around 10mA from OUT1-4.

      • Digil David says: on September 16, 2014 at 8:37 am

        Hi,
        Its no need for l293d, l293d only deliver max:600mA. Also the another problem in power supply is you use 3Aps supply but 7812 can deliver max:1Aps. So my suggestion is connect motor to common point of rellay and another one end to be GND and other to 12V and then switched on relays logically u can rotate motor to both side.(no need of regulator or put 3Amps regulator,or put a transistor accross regulator to bypass exceed current)

    150. The circuit diagram shows the output at 100mA but in some comments it is mentioned that without a transformer a current of 20mA is the best one can get. Does this circuit guarantee a 100mA supply?

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