Simple transformerless power supply circuit

I often make the small projects. They require the small power supply.  But I cannot find the small transformers. The normal transformer is big and heavy, not suitable for my project.

But I  look around my home in a small appliance in China. They use the transformerless power supply circuit.

They use a capacitor instead of a transformer. Thus, power supplies are smaller and lighter.

Today, I collect these transformerless power supply circuit.  So you can select as you want.

Hopefully, it will be useful to you. There are three circuits, as follows.

SEE  Below!

Do not touch any part of these circuits. Because you may be hit by electric shocks. Though it makes low voltage. We cannot touch it all.  Because it does not use the isolated transformer.

Frist. 9V DC Power Supply circuit, no transformer

This is  9V DC power supply no transformer, It is an easy circuit and small size.

The output voltage is the same as the voltage drop across the Zener diode-ZD1. The Output Current is about 100mA (min).


9VDC  Power Supply circuit diagram, no transformer

You may know the reason that makes power supply is large-sized.  Because of a transformer. How to do if not use it. We use a capacitor instead of a transformer.

In the 9V, DC Power Supply circuit, no transformer. First, the capacitor 0.33uF and R1 makes a low AC voltage. The F1 protects output overload. R2 is the limited current resistor.

The Zener diode keeps the output voltage to be stable 9V DC Regulator. This circuit cannot power the output with high current.

Second: No transformer DC power supply circuit

How does it work? Both C1 and R1 reduces AC Current Source to rectifies to DC pulse voltage with bridge diodes. Which D1 through D4 convert AC to DC.

circuit diagram of DC-power-supply-not-use-transformer

Then, the C2 filtering capacitor smooths to the stable DC voltage. The output voltage is regulated to maintain a constant DC voltage with the Zener diode, ZD1-9V.

Last, the C3-capacitor filter the output voltage to be more smooth.

Three, 6V Negative Voltage Regulator without transformer

This is the mini power supply circuit out of 6V, in negative voltage. Also, it does not use the transformer like the above circuits.

It can give the output current at less than 100mA. It uses the Zener diode to provide a constant output voltage, 6V. There is a transistor to increase the current up.

It has still overcurrent protection or Shot Circuit Protection with Transistor as well.

5V Transformerless supply

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very useful ckts.


require over load protection ckts.. plz help.

Bob Bozanic

These circuits on this page are VERY dangerous to work with because of mains voltage present. You have not posted warnings to that effect to potential builders. A lot more information must be included for ALL components used in these and circuits alike. For the people begining in electronics, these circuits can be a DEATH TRAP. I would also sugest that you get someone to proof read, before you publish material on this WEB site.


“DC Regulator supply 15V non transformer”

Stop! Attention! To the diagram is drawn ground!!! Probably not (??!) – regards Piotr [ google translation ]


Thank so much for all comment.
All circuits I see in the Electronic product made in China that low price but low quality.
I sorry if you make not works.

I think its is simple ideal for beginner.
Thank you @Bob Bozanic for the Good advice.
and…sorry for my English is poor.


The Circuit you are posted is dangerous
it work but it can kill the use
please take warning to beginer
yes China product is not care about security
and you will follow?


All the circuit so dangerous, no safety for human


helpful innovations for the
new generation

Bob Bozanic

I would like to add more to my first comment. After reading great many posts by readers and would be constructors, especially the questions on various subjects and your answers to those, I believe that the greatest DANGER is to those people who DO NOT KNOW THE OHMS LAW, that is, the relationship between the current (A), voltage(V) and resistance(R). That is where a mistakes are made and with these circuits presented here, it is only a metter of time. Consider this, at 220-240 Volts AC, one will get killed if ONLY 80 milliAmps flows through your body!? Do not… Read more »


Please Be Careful!! If You Are Uncertain Of Your abilities Don’t Even Get close To Building these Transformless circuits,,I touched 120 volts as a wee lad and am VERY HAPPY to survive this scary experience,,OUCH!!! Please listen to BOB’s advice,,He sounds like he’s been around the block a couple times when it comes to safety in Electronics,,Thanks BOB…I couldn’t have said it BETTER!!!


your ckts are helpfull….but your explanations are not detailed..and your english command is a little bit poor.

Thanks for your feedback. I try to rewrite this post to improve English.


Just don’t build ANY of these circuits EVER. They’re all stupidly dangerous for even the most experienced electrical engineer (knowing electronics does NOT make you immune to electric shock-induced cardiac arrest). Transformers are not that expensive and many of the components used in these diagrams (like a 470uF cap over rectified mains) are MUCH larger than a good trannie


how can we know the value of reduced ac voltage through capacitor


pls help me to build a transformer-less power supply output with 45V 0.27A


can you tell me the voltage rating of the capacitors in first circuit.


can you tell the voltage ratings of the capacitors in the first circuit


Circuits 3 and 4 cannot possibly work with just D1. The other half cycle needs to be bypassed or C1 will just charges up to 350V DC within a few miliseconds, then everything will stop working.


The schematic layout of (1) Power Supply 9VDC no transformer. I live in USA using input of 120 Vac. Do I need to changed any other electronic components after this changed of 220 to 120 Vac? Does it provide very smooth ripples or no ripples of 9Vdc?

al mtdrs

How about, if we need 13.8 V DC 60 A with the PS tranformatorless


may i know the voltage rating of the .33uf capacitor???


whats is the role of transister here used in 15 v transformerless dc supply if any one have idea plzzz answer that…thank u

Bob Bozanic

Once again, it is very obvious by reading these questions that some of you are not taking notice! There is an AC theory that governs and explains all relationships in these and similar circuits. If you value your life, do not do it till you learn what I am talking about. For starters, ANY component used in an AC circuit must have a working voltage of twice the supply voltage. For an example, no capacitor should have less the 400V WV!if a supply is 220-240V. In countries with 110-120V domestic supplies the capacitors must have at least 250V WV. The… Read more »


very good for normal cct

Billy Marrowbone Bow Bowling

I want to know if I can get some info on how to build a for my 75A 16.8V power supply I am trying to build! Would think there would be more info out there on this subject or you could buy a plug and play to your advantage kit! Thanks

Billy Marrowbone Bow Bowling

I want to know if I can get some info on how to build a voltage regulator for my 75A 16.8V power supply I am trying to build! Would think there would be more info out there on this subject or you could buy a plug and play kit! This is going to be a HF amplifier power supply and I was also wondering your thoughts about Unregulated? Thanks


Good evening, I have need to AC 220 to DC 220 Voltage Converter Circuit digram 5 amper thank you


I need to create AC 230V to 3.3V DC. And I need about max 150mA. Is it possible to that in this way, without transformer?
Maybe to gain the output with a transistor also?


chayapon’s circuits are all practical and functional. If your power supply has a transformer that is connected to mains then you can kill yourself with it by doing stupid things. chayapons’s circuits are just as safe as a transformer power supply. Just because they run off the mains does not mean that they harbour mysterious leathal properties ! One must understand what one is doing when working with any electronics circuits. If you cannot properly understand these things then you should sell every electrical device that you own, (flashlights too)then buy a horse and move to the backcountry of Usaria.… Read more »


Reading your comments makes me wonder about your name Anynominus. Perhaps a better name would be Moron !


pleas post correct and safty circute otherwise


Billy Marrowbone Bow Bowling: I have 30 years experience designing and building power supplies. That is not an easy thing to build. It will have to be a switching power supply which is even more difficult to design and make. The layout is also critical. I am sure you can find some circuits on the web. If not then email me and tell me what you have done to date and I will try and guide you along. 16.8Vx75Amps = 1260Watts. The power supply will be perhaps 85% efficient which brings the wall output to 1575 Watts, which is almost… Read more »


I don’t want to be awkward but I’ve been looking into the design of transformer-less power supplies for a while now and great care has to be taken to ensure their reliable and safe use. The use of good mathematics and circuit analysis cannot be overlooked. Also consider that the type of capacitors used should be suited to mains operation and not _JUST_ the voltage either. What about when the dielectric develops a fault. X Rated caps maybe.

I’m still not ready to switch on my first transformer-less PSU without a chicken stick and safety goggles.

John Lam

Stop accusing the poster who have done nothing wrong. Instead, start providing some valuable inputs to the circuits. The purpose of the post is to provide four transformerless power supply circuits and start the discussion. Instead of discussing how and why the circuits work, some readers focus on the dangerous side of the circuits that involve AC. Even if you try to build a traditional DC power supply with transformer, the input is still high voltage AC, 110-220V. No matter what, caution needed to be taken in both scenarios. By the way, China-made products are not as bad as some… Read more »

Peter Tyrrell

These circuits seem safe to use. Each has current limit protection that will blow the fuse that protects the circuit. One can use an online calculator ( for example) to figure out what the capacitve reactance of the “main” capacitor is and from that what the maximum current can normally flow through the circuit. For example, The second circuits main capacitor is CI. C1 limits current by its reactance at mains frequence (60Hz). Therefore in this circuit, it will have a reactance of 2652.6 ohms. This will limit current to 82ma. If this capacitor breaks down, the 250ohm resistor limits… Read more »

stay alive. Carefull




Yes, these non-isolated drivers are used in China and outside China, provided that even when the casing breaks, the unaware user can never touch the life-wires. Thats the law/CE mark/TUV/DEKRA etc etc.



Can you tell me Transformerless 9v power supply what should i use capacitor volt only you have mention farad?
Eg : 0.33farad/…V?,470farad/…v?

Bob Bozanic

Dear Mr Tyrell, I can not agree with your very first sentence, I’m afraid. You have looked at circuit number two, calculated reactance of C1 and found the current to be to be around 80mAmps! And if you measure the resistance of your body (easily done) you will find that 80mA is just enough to kill you! Ask you Medical Practitioner, if you do not believe me. You can not be serious saying these circuits are safe to use. No bloody way. Take a look again at the circuit number four as a prime example. Or just for the hell… Read more »


Is this circuit is good for lead acid battery charging.

Thanks for your feedback.


will this 9v circuit surely work as it should ?? and I also want to know what is this f1 and In4007 x 4 0ls help me by replying thankz in advance 🙂


I made that 9v circuit but the current im getting is not stable pls help


when I made that 9v circuit im only getting 0.70v pls help me pls pls

m.anwar ziai

i need circuit diagram of voltage stabilizer which produce from input 110 volts ac – up to 230 volts ac output stable 220 volts ac. thanks,


how to find capacitor value in this circuit???


I want to make 0V TO 24 Volts DC supply without transformer..and I want to use LED indication on 6V, 9, 12V , 15V 18V,24 Volts






who ever is thinking about safety , that means you knows the circuit well, then suggest safety in the circuit. he has started the work, lets finished by putting safety.




first one circuit is using by a brand company in their 0.5W night lamp led bulb. what you will say about this.

give constructive comment


John Lam

Hi ujjval,

I think you have connected the zener diode in the reverse direction that becomes forward biased and gives you only 0.7V.

On the zener didoe, there is normally a black ring marked on one side that is the cathode. Connect this side to the positive side in parallel with the 470uF electrolytic capacitor. That means the ring side of zener to positive terminal of capacitor, and the no-ring side of zener to the negative terminal of the capacitor. You will then get an output voltage of 9V.

John Lam

Some readers want more details on this kind of circuits. Where is my other comment that was sent a few hours before the reply to ujjval?

Richard Meckstroth

Would it be possible to make a high current (15 amp), 55 VDC output battery charger using 110 VAC input without a transformer? Maybe with just one large amp diode that delivers just the positive 55 volt pulse from the 110 VAC current? Would that work?

Meak Phalla

Dear sir/madam! I’m Phalla Meak, an Electronics Engineerings student of the 4th Year at Preah Kossomak Poly-technical Institute( PPI) in Cambodia. Now, I’d like to have/know on the schematic/diagram circuit of regulator/auto-voltage (input: 100V t o 270V, output: 35V) used without transformers. So, excuse-me, if you don’t mind, could you help to send/show me this schematic/diagram circuit I requested, please? And if I’d like to reduce/drop the output voltage (from 35V to 30V, 25V, 10V, …etc to 0V) to any Electronics devices (such as: mobile-phone charger, radios, etc.), how must/should I use any devices+their values(i.e. variable resistors, etc) to reduce/drop… Read more »


Hi, Phalla Meak
Thanks for your feedback.
I am sorry now any circuits as you need.

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