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You are here: Home / Power Supply Circuits / Transformerless Power Supply / 4 Simple Transformerless Power Supply Circuits Explained

4 Simple Transformerless Power Supply Circuits Explained

Last Updated on September 14, 2020 by Swagatam 222 Comments

In this post we discuss 4 easy to build, compact simple transformerless power supply circuits. All the circuits presented here are built using capacitive reactance theory for stepping down the input AC mains voltage. All the designs presented here work independently without any transformer, or no transformer.

The Transformerless Power Supply Concept

As the name defines, a transformerless power supply circuit provides a low DC from the mains high voltage AC, without using any form of transformer or inductor.

It works by using a high voltage capacitor to drop the mains AC current to the required lower level which may be suitable for the connected electronic circuit or load.

The voltage specification of this capacitor is selected such that it's RMS peak voltage rating is much higher than the peak of the AC mains voltage in order to ensure safe functioning of the capacitor. An example capacitor which is normally used transformerless power supply circuits is shown below:

105/400V capacitor 1uF 400V capacitor for transformerless power supply

This capacitor is applied in series with one of the mains inputs, preferably the phase line of the AC.

When the mains AC enters this capacitor, depending on the value of the capacitor, the reactance of the capacitor comes into action and restricts the mains AC current from exceeding the given level, as specified by the value of the capacitor.

However, although the current is restricted the voltage isn't, therefore if you measure the rectified output of a transformerless power supply you will find the voltage to be equal to the peak value of the mains AC, that's around 310V, and this could be alarming for any new hobbyist.

But since the current may be sufficiently dropped level by the capacitor, this high peak voltage could be easily tackled and stabilized by using a zener diode at the output of the bridge rectifier.

The zener diode wattage must be appropriately selected according to the permissible current level from the capacitor.

CAUTION:Please read the caution warning message at the end of the post

Advantages of using a Transformerless Power Supply Circuit

The idea is cheap yet very effective for applications that require low power for their operations.

Using a transformer in DC power supplies is probably quite common and we have heard a lot regarding it.

However one downside of using a transformer is that you cannot make the unit compact.

Even if the current requirement for your circuit application is low, you have to include a heavy and bulky transformer making things really cumbersome and messy.

The transformerless power supply circuit described here, very efficiently replaces a usual transformer for applications which require current below 100 mA.

Here a high voltage metalized capacitor is used at the input for the required stepping down of the mains power and the preceding circuit is nothing but just simple bridge configurations for converting the stepped down AC voltage to DC.

The circuit shown in the diagram above is a classic design may be used as a 12 volts DC power supply source for most electronic circuits.

However having discussed the advantages of the above design, it will be worth focusing on a few serious drawback this concept may include.

Disadvantages of a Transformerless Power Supply Circuit

First, the circuit is unable to produce high current outputs, but that won’t make an issue for most of the applications.

Another drawback that certainly needs some consideration is that the concept does not isolate the circuit from dangerous AC mains potentials.

This drawback can have serious impacts for designs which have terminated outputs or metal cabinets, but won’t matter for units which have everything covered up in a non-conducting housing.

Therefore, new hobbyists must work with this circuit very carefully to avoid any electrical casualty. The last but not the least, the above circuit allows voltage surges to enter through it, which may cause serious damage to the powered circuit and to the supply circuitry itself.

However in the proposed simple transformerless power supply circuit design this drawback has been reasonably tackled by introducing different types of stabilizing stages after the bridge rectifier.

This capacitor grounds instantaneous high voltage surges, thus efficiently safeguarding the associated electronics with it.

How the Circuit Works

The working of this transformless power supply can be understood with the following points:

  1. When mains AC mains input is switched ON, capacitor C1 blocks the entry of the mains current and restricts it to a lower level as determined by the reactance value of C1. Here it may be roughly assumed to be around 50mA.
  2. However, the voltage is not restricted, and therefore the full 220V or whatever may be at the input is allowed to reach the subsequent bridge rectifier stage.
  3. The bridge rectifier rectifies this 220V C to a higher 310V DC, due to the RMS to peak conversion of the AC waveform.
  4. This 310V DC is instantly reduced to a low level DC by the next zener diode stage, which shunts it to the zener value. If a 12V zener is used, this will become 12V and so on.
  5. C2 finally filters the 12V DC with ripples, into a relatively clean 12V DC.

1) Basic Transformerless Design

Simple Transformerless Power Supply Circuit

Let's try to understand the function of each of the parts used in the above circuit, in greater details:

  1. The Capacitor C1 becomes the most important part of the circuit since it is the one that reduces the high current from the 220 V or 120 V mains to the desired lower level, to suit the output DC load. As a rule of thumb every single single microFarad from this capacitor will provide around 50 mA current to the output load. This means, a 2uF will provide 100 mA and so on. If you wish to learn the calculations more precisely you can refer to this article.
  2. The resistor R1 is used for providing a discharge path for the high voltage capacitor C1 whenever the circuit is unplugged from the mains input. Because, C1 has the ability to store the 220 V mains potential in it when it is detached from the mains, and could risk a high voltage shock to whoever touches the plug pins. R1 quickly discharges the C1 preventing any such mishap.
  3. Diodes D1---D4 work like a bridge rectifier for converting the low current AC from the C1 capacitor into a low current DC. The capacitor C1 restricts the current to 50 mA but does not restrict the voltage. This implies that the DC at the the output of the bridge rectifier is the peak value of the 220 V AC. This can be calculated as: 220 x 1.41 = 310 V DC approximately. So we have 310 V, 50 mA at the output of the bridge.
  4. However, the 310V DC may be too high for any low voltage device except a relay. Therefore, an appropriately rated zener diode is used for shunting the 310V Dc into the desired lower value, such as 12 V, 5 V, 24 V etc, depending on the load specs.
  5. Resistor R2 is used as a current limiting resistor. You may feel, when C1 is already there for limiting the current why do we need the R2. It is because, during the instantaneous power switch ON periods, meaning when the input AC is first applied to the circuit, the capacitor C1 simply acts like a short circuit for a few milliseconds. These few initial milliseconds of the switch ON period, allows the full AC 220 V high current to enter the circuit, which may be enough to destroy the vulnerable DC load at the output. In order to prevent this we introduce R2. However, the better option could be to use an NTC in place of R2.
  6. The C2 is the filter capacitor, which smoothens the 100 Hz ripples from the rectified bridge to a cleaner DC. Although a high voltage 10uF 250V capacitor is shown in the diagram, you can simply replace it with a 220uF/50V due to the presence of the zener diode.

PCB Layout for the above explained simple transformerless power supply is shown in the following image. Please note that I have included a space for an MOV also in the PCB, at the mains input side.

transformerless power supply PCB layout

Example Circuit for LED Decoration Light Application

The following transformerless or capacitive power supply circuit could be used as an LED lamp circuit for illuminating minor LED circuits safely, such as small LED bulbs or LED string lights.

The idea was requested by Mr. Jayesh:

Requirement Specifications

The string is made up of about 65 to 68  LED of 3 Volt  in series approximately at a distance of let us say 2 feet ,,, such 6 strings are roped together to make one string so the bulb placement comes out to be at  4 inches in final rope . so over all  390 - 408    LED bulbs in final rope.
So please suggest  me best possible driver circuit to operate
1) one string of 65-68 string.
or
2) complete rope of 6 strings together.
we have another rope of  3 strings.The string is made up of about 65 to 68  LED of 3 Volt  in series approximately at a distance of let us say 2 feet , such 3 strings are roped together to make one string so the bulb placement comes out to be at  4 inches in final rope . so over all  195 - 204    LED bulbs in final rope.
So please suggest  me best possible driver circuit to operate
1) one string of 65-68 string.
or
2) complete rope of 3 strings together.
Please suggest the best robust circuit with surge protector and advice any additional things to be connected to protect the circuits.
and please see that circuit diagrams are with values required for the same as we are not at all technical person in this field.

Circuit Design

The driver circuit shown below is suitable for driving any LED bulb string having less than 100 LEDs (for 220V input), each LED rated at 20mA, 3.3V 5mm LEDs:

capacitive transformerless power supply for LEd strip lights

Here the input capacitor 0.33uF/400V decides the amount of current supplied to the LED string. In this example it will be around 17mA which is just about right for the selected LED string.

If a single driver is used for more number of similar 60/70 LED strings in parallel, then simply the mentioned capacitor value could be proportionately increased for maintaining optimal illumination on the LEDs.

Therefore for 2 strings in parallel, the required value would be 0.68uF/400V, for 3 strings you could replace it with a 1uF/400V. Similarly for 4 strings this would need to be upgraded to 1.33uF/400V, and so on.

Important: Although I have not shown a limiting resistor in the design, it would be a good idea to include a 33 Ohm 2 watt resistor in series with each LED string for added safety. This could be inserted anywhere in series with the individual strings.

WARNING: ALL THE CIRCUITS MENTIONED IN THIS ARTICLE ARE NOT ISOLATED FROM MAINS AC, THEREFORE ALL THE SECTIONS IN THE CIRCUIT ARE EXTREMELY DANGEROUS TO TOUCH WHEN CONNECTED TO MAINS AC........

2) Upgrading to Voltage Stabilized Transformerless Power Supply

Now let's see how an ordinary capacitive power supply may be transformed into a surge free voltage stabilized or variable voltage transformerless power supply applicable for almost all standard electronic loads and circuits. The idea was requested by Mr. Chandan Maity.

Technical Specifications

If you remember, I communicated you sometime before with comments at your blog.

The Transformerless circuits are really good and I tested couple of those and running 20W, 30W LED.Now, I am trying to add some  controller, FAN and LED all together , hence, I need a dual supply.

The rough specification is:

Current rating 300 mAP1= 3.3-5V 300mA ( for controller etc)P2=  12-40V (or higher range), 300mA (for LED)
I thought to use your 2nd circuit as mentionedhttps://homemade-circuits.com/2012/08/high-current-transformerless-power.html

But, I am not able to freeze the way how to get 3.3V without using extra capacitor. 1. Can, a second circuit may be placed from the output of first one? 2. Or, a second TRIAC, bridge to be placed in parallel with first one, after capacitor to get 3.3-5V

I shall be glad if you kindly help.

Thanks,

The Design

The function of  the various components used across the various stages of the above shown voltage controlled circuit may be understood from the following points:

The mains voltage is rectified by the four 1N4007 diodes and filtered by the 10uF/400V capacitor.

The output across the 10uF/400V now reaches around 310V which is the peak rectified voltage achieved from the mains.

The voltage divider network configured at the base of the TIP122 makes sure that this voltage is reduced to the expected level or as required across the power supply output.

You can also use MJE13005 in place of TIP122 for better safety.

If a 12V is required the 10K pot may be set to achieve this across the emitter/ground of the TIP122.

The 220uF/50V capacitor ensures that during switch ON the base is rendered a momentary zero voltage in order to keep it switched OFF and safe from the initial surge in-rush.

The inductor further ensures that during the switch ON period the coil offers a high resistance and stops any inrush current to get inside the circuit, preventing a possible damage to the circuit.

For achieving a 5V or any other attached stepped down voltage, a voltage regulator such as the shown 7805 IC may be used for achieving the same.

Circuit Diagram

voltage stabilized transformerless power supply circuit

Using MOSFET Control

The above circuit using emitter follower can be further enhanced by applying a MOSFET source follower power supply, along with a supplemental current control stage using BC547 transistor.

The complete circuit diagram can be seen below:

Capacitive and MOSFET controlled transformerless power supply circuit

Video Proof of Surge Protection

3) Zero Crossing Transformerless Power Supply Circuit

The third interesting explains the importance of a zero crossing detection in capacitive transformerless power supplies in order to make it completely safe from the mains switch ON inrush surge currents. The idea was proposed by Mr. Francis.

Technical Specifications

I have been reading about the transformer less power supply articles on your site with great interest and if I am understanding correctly the main problem is the possible in-rush current in the circuit upon switching-on, and this is caused because switching-on does not always occur when the cycle is at zero volts (zero crossing).

I am a novice in electronics and my knowledge and practical experience are very limited, but if the problem can be solved if zero crossing is implemented why not use a zero crossing component to control it such as an Optotriac with zero crossing.

The input side of the Optotriac is low power therefore a low power resistor can be used to lower the mains voltage for Optotiac operation. Therefore no capacitor is used at the Optotriac’s input. The capacitor is connected on the output side which will be switched on by the TRIAC which turns on at zero crossing.

If this is applicable it will also solve high current requirement problems, since the Optotriac in turn can operate another higher current and/or voltage TRIAC without any difficulty. The DC circuit connected to the capacitor should no longer have the in-rush current problem.

It would be nice to know your practical opinion and thank you for reading my mail.

Regards,
Francis

The Design

As rightly pointed out in the above suggestion, an AC input without a zero crossing control can be a major cause of a surge current inrush in capacitive transformerless power supplies.

zero crossing controlled transformerless power supply circuit

Today with the advent of sophisticated triac driver opto-isolators, switching an AC mains with zero crossing control is no longer a complex affair, and can be simply implemented using these units.

About MOCxxxx Opto-couplers

The MOC series triac drivers come in the form of optocouplers and are specialists in this regard and can be used with any triac for controlling AC mains through a zero crossing detection and control.

The MOC series triac drivers include MOC3041, MOC3042, MOC3043 etc all these are almost identical with their performance characteristics with only minor differences with their voltage spces, and any of these can be used for the proposed surge control application in capacitive power supplies.

The zero crossing detection and execution are all internally processed in these opto driver units and one has to only configure the power triac with it for witnessing the intended zero crossing controlled firing of the integrated triac circuit.

Before investigating the surge free triac transformerless power supply circuit using a zero crossing control concept let's first understand briefly regarding what's a zero crossing and its involved features.

What is Zero Crossing in AC Mains

We know that an AC mains potential is composed of voltage cycles which rise and fall with changing polarity from zero to maximum and vice versa across the given scale. For example in our 220V mains AC, the voltage switches from 0 to +310V peak) and back to zero, then forwarding downwards from 0 to -310V, and back to zero, this goes on continuously 50 times per second constituting a 50 Hz AC cycle.

When the mains voltage is near its instantaneous peak of the cycle, that is near 220V (for a 220V) mains input, it's in the strongest zone in terms of voltage and current, and if a capacitive power supply happens to be switched ON during this instant, the entire 220V can be expected to break through the power supply and the associated vulnerable DC load. The result could be what we normally witness in such power supply units.... that is instant burning of the connected load.

The above consequence may be commonly seen only in capacitive transformerless power supplies because, capacitors have the characteristics of behaving like a short for a fraction of a second when subjected to a supply voltage, after which it gets charged and adjusts to its correct specified output level

Coming back to the mains zero crossing issue, in a converse situation while the mains is nearing or crossing the zero line of its phase cycle, it can be considered to be in its weakest zone in terms of current and voltage, and any gadget switched ON at this instant can be expected to be entirely safe and free from a surge inrush.

Therefore if a capacitive power supply is switched ON in situations when the AC input is passing through its phase zero, we can expect the output from the power supply to be safe and void of a surge current.

How it Works

The circuit shown above utilizes a triac optoisolator driver MOC3041, and is configured in such a way that whenever power is switched ON, it fires and initiates the connected triac only during the first zero crossing of the AC phase, and then keeps the AC switched ON normally for rest of the period until power is switched OFF and switched ON again.

Referring to the figure we can see how the tiny 6-pin MOC 3041 IC is connected with a triac for executing the procedures.

The input to the triac is applied through a high voltage, current limiting capacitor 105/400V, the load can be seen attached to the other end of the supply via a bridge rectifier configuration for achieving a pure DC to the intended load which could an LED.

How Surge Current is Controlled

Whenever power is switched ON, initially the triac stays switched OFF (due to an absence of the gate drive) and so does the load connected to the bridge network.

A feed voltage derived from the output of the 105/400V capacitor reaches the internal IR LED through the pin1/2 of the opto IC. This input is monitored and processed internally with reference to the LED IR light response.... and as soon the fed AC cycle is detected reaching the zero crossing point, an internal switch instantly toggles and fires the triac and keeps the system switched ON for the rest of the period until the unit is switched OFF and ON yet again.

With the above set up, whenever power is switched ON, the MOC opto isolator triac makes sure that the triac is initiated only during that period when the AC mains is crossing the zero line of its phase, which in turn keeps the load perfectly safe and free from the dangerous surge in rush.

Improving the above Design

A comprehensive capacitive power supply circuit having a zero crossing detector, a surge suppressor and voltage regulator is discussed here, the idea was was submitted by Mr. Chamy

Designing an Improved Capacitive Power Supply Circuit with Zero Crossing Detection

Hello Swagatam.

This is my zero crossing, surge protected capacitive power supply design with voltage stabilizer,i will try to list all of my doubts.
(I know this will be expensive for the capacitors,but this is only for testing purposes)

1-I'm not sure if the BT136 haves to be changed for a BTA06 for accommodating more current.

2-The Q1 (TIP31C) can handle only 100V Max. Maybe it should be changed for a 200V 2-3A transistor?,like the 2SC4381.

3-R6 (200R 5W),I know this resistor is pretty small and its my
fault,i actually wanted to put a 1k resistor.But with an 200R 5W
resistor it would work?

4-Some resistors have been changed following your recommendations to make it 110V capable.Maybe the 10K one needs to be smaller?

If you know how to make it work correctly,i will be very happy to correct it.If it works i can make a PCB for it and you could publish it in your page (For free of course).

Thank you for taking the time and viewing my full of faults circuit.

Have a nice day.

Chamy

Assessing the The Design

Hello Chamy,

your circuit looks OK to me. Here are the answers to your questions:

1) yes BT136 should be replaced with a higher rated triac.
2)TIP31 should be replaced with a Darlington transistor such as TIP142 etc otherwise it might not work properly.
3) when a Darlington is used the base resistor could be high in value, may be a 1K/2 watt resistor would be quite OK.
However the design by itself looks like an overkill, a much simpler version can be seen below https://homemade-circuits.com/2016/07/scr-shunt-for-protecting-capacitive-led.html
Regards

Swagatam

Reference:

Zero Crossing Circuit

4) Switching Transformerless Power Supply using IC 555

This 4rth simple yet smart solution is implemented here using IC 555 in its monostable mode to control in rush surge in a  transfomerless power supply via a zero crossing switching circuit concept, wherein the input power from the mains is allowed to enter the circuit only during the zero crossings of the AC signal, thereby eliminating the possibility of surge inrushes. The idea was suggested by one of the avid readers of this blog.

Technical Specifications

Would a zero cross transformerless circuit work to prevent the initial inrush current by not allowing turn on until the 0 point in the 60/50 hertz cycle?

Many solid state relays which are cheap, less then INR 10.00 and have this ability built in them.

Also I would like to drive 20watt leds with this design but am unsure how much current or how hot capacitors will get I suppose it depends on how the leds are wired series or parallel, but lets say the capacitor is sized for 5 amps or 125uf will the capacitor heat up and blow???

How does one read capacitor specs to determine how much energy they can dissipate.

The above request prompted me to look for a related design incorporating a IC 555 based zero crossing switching concept, and came across the following excellent transformerless power supply circuit which could be used for  convincingly eliminating all possible chances of surge inrush.

What's a Zero Crossing Switching:

It's important to learn this concept first before investigating the proposed surge free transformerless circuit.

We all know how a sine wave of an AC mains signal looks like. We know that this sine signal starts from a zero potential mark, and exponentially or gradually rises to the peak voltage (220 or 120) point, and from there exponentially reverts to the zero potential mark.

After this positive cycle, the waveform dips and repeats the above cycle but in the negative direction until it comes back yet again to the zero mark.

The above operation happens about 50 to 60 times per second depending upon the mains utility specs.
Since this waveform is what enters the circuit, any point in the waveform other than the zero, presents a potential danger of a switch ON surge due to the involved high current in the waveform.

However the above situation can be avoided if the load confronts the switch ON during the zero crossing, after which the rise being exponential doesn't pose any threat to the load.

This is exactly what we have tried to implement in the proposed circuit.

Circuit Operation

Referring to the circuit diagram below, the 4 1N4007 diodes form standard bridge rectifiers configuration, the cathode junction produces a 100Hz ripple across the line.
The above 100Hz frequency is dropped using a potential divider (47k/20K) and applied to the positive rail of the IC555. Across this line the potential is appropriately regulated and filtered using D1 and C1.

The above potential is also applied to the base Q1 via the 100k resistor.

The IC 555 is configured as an monostable MV which means its output will go high every time its pin#2 is grounded.

For the periods during which the AC mains is above (+)0.6V, Q1 stays switched OFF, but as soon as the AC waveform touches the zero mark, that is reaches below the (+)0.6 V, Q1 switches ON grounding pin#2 of the IC and rendering a positive output of the IC pin#3.

The output of the IC switches ON the SCR and the load and keeps it switched ON until the MMV timing elapses, to begin a new cycle.

The ON time of the monostable can be set by varying the 1M preset.

Greater ON time ensures more current to the load, making it brighter if it's an LED, and vice versa.

The switch ON conditions of this IC 555 based transformerless power supply circuit is thus restricted only when the AC is near zero, which in turn ensures no surge voltage each time the load or the circuit is switched ON.

Circuit Diagram

Transformerless Power Supply using IC 555

For LED Driver Application

If you are looking for a transformerless power supply for LED driver application at commercial level, then probably you can try the concepts explained here.




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About Swagatam

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials.
If you have any circuit related query, you may interact through comments, I'll be most happy to help!

You'll also like:

  • 1.  3 Solid-State Single IC 220V Adjustable Power Supply Circuits
  • 2.  1.5V Power Supply Circuit for Wall Clock
  • 3.  Transformerless Relay Driver Stage
  • 4.  High Current Transformerless Power Supply Circuit
  • 5.  How to Calculate Transformerless Power Supplies
  • 6.  0-300V Adjustable MOSFET Transformerless Power Supply Circuit

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  1. Search Related Posts for Commenting

  2. Maulyani says

    Dear Sir,
    I am still newbie in this world of electronics even though I have studied it for 1 semester at university 40 years ago. I tried the circuit based on the first example of your diagram using a diode bridge ic and a 5 volt zener diode. It works for 0.5 watt LEDs, also for 1 watt. when I enlarge C1 to 1.5 uf, resistor R2 geting hot (about 50 degrees Celsius) even though I replace the resistor with 2 watts. Is there any other way than to replace the resistor with a larger wattage?
    Thank you and best regards

    Reply
    • Swagatam says

      Dear Maulyani, The R2 will become warm since it has to handle a significant range of current at 310V. The only way to correct is by adding 3 or 4 resistors in series to make an equivalent 50 Ohm, or use an NTC thermistor rated at 30 ohm 1 amp. Any of these options should solve the issue.

      Reply
      • Maulyani says

        Thank you for your attention and suggestion
        Best regards

        Reply
  3. Joseph80 says

    Good day Swagatam,
    I really appreciate all your teachings. Please, I am building a meter using Arduino and I need to power design with AC power. Which of the transformerless can I use to power my circuit because I want it to be compact.

    Reply
    • Swagatam says

      Thanks Joseph, Arduino designs being sensitive electronics must never be used with non-isolated transformerless power supplies, so none of the above should be tried, you should go for a good quality SMPS instead

      Reply
  4. Dang Dinh Ngoc says

    Hi Swagatam,
    I am still newbie in this world but after quite some readings, can I ask you a question on combining buck converter with this step down Transformerless circuitry and to have the board safe to user. My simple idea below:
    1. Applying a phase cut trigger: to cut the waveform when it come to 5V. This will need Zero crossing detector things like moc3021 and a microchip to handle this for controlling a waveform cut for the AC input)
    2. Apply bridge rectifier and other things after that to improve the stability of voltage and current.
    Can you please review this idea with thanks.
    Dang Dinh Ngoc
    NCP785A

    Reply
    • Swagatam says

      Hi Dang, you can try the following design:
      5V pwm zero crossing AC to DC circuit
      You can adjust the 5V zener value appropriately to get any other zero crossing based output voltage

      Reply
  5. Dolon says

    Hello Sir,
    Thank you so much! I spent 2 days looking for information on a PIR sensor circuit that 24 V DC and other DC voltages but no coils to step down the 220V mains power.
    Dolon

    Reply
    • Swagatam says

      Thanks Dolon, but I think you have posted your comment under the wrong article, since the above article is about tansformerless PS

      Reply
  6. Engr Daniel says

    Is there any possibility of designing a 50v 20amp from a capacitive transformer less power supply? If yes pls give a little hint on how to go about it..

    Reply
    • Swagatam says

      No, it is not possible since the capacitor would be huge and the surge current would be unstoppable.

      Reply
  7. Mike Millan says

    Hi dear Swagatam
    Thank you so much for your very useful and informative essay regarding Power supplies.
    would you please answer my questions 😕
    1. Is it possible to increase the power of Zener Diods by simply paralleling them? for instance to get one watt power by paralleling two 0.5 watt of those?
    2. what about increasing Zener Diods’ voltage? for example: to join two pcs. 9.1 and 3.1 volts in series to get a 12 volts Zener diod?
    Thank you again
    Bye

    Reply
    • Swagatam says

      You are welcome Mike!
      You can put zeners in parallel by adding a small value resistor in series with each of the zeners.
      Zeners can be added in series for increasing the total voltage

      Reply
  8. Kavindu gayan says

    Hello sir.
    I created your surge protrcted mosfet circuit, but IRF740 is getting too hot quickly.
    Will it be a problem. Will it blow up , i need to keep leds at least 8 hours a day.
    i tested it by turning on it for 5 mins. And i cant even touch it.

    Reply
    • Swagatam says

      Hello Kavindu, the heat will depend on the difference between the input and output voltages. As the difference increase so will the heat. You will have to connect a large heatsink on the MOSFET to control the heat, otherwise it may get damaged over time.

      By the way what is the current output of your load

      Reply
  9. Robert Simpson says

    Hi.

    Great web site.
    I need a TPS with about 3Amps in the USA so it looks like a TPS with aprox 70uF will do. Question is, could it be done with smaller (a) Caps like in parallel (b) No X1-2 Caps or low voltage 16-25v.

    Kind regards

    Reply
    • Swagatam says

      Hi, thanks, No it cannot be done with smaller low voltage capacitors, since it is capacitor value that decides the current output, larger the value, larger the current and vice versa. Voltage decides its tolerance threshold to the input supply

      Reply
  10. Miracle says

    Good day sir!
    I just decided to make one, unfortunately the voltage I’m getting from the zener diode always drops till the it gets shorted. Where could the fault be from? I’ve used different zener diodes and I’m still getting shorted zener diode at the end. Why?

    Reply
    • Swagatam says

      Miracle, did you put the series resistor with the input capacitor, without the resistor the zener will keep burning. Alternatively you can try a 5 watt zener diode.

      Reply
      • Miracle says

        Thanks for reply.
        Don’t think so. Let me try out. I’ll give you some feedback

        Reply
  11. Kumble says

    Hi,
    I am fascinated with many of your circuits. I am hobbyist and hasn’t studied engineering.

    I tried the transformerless power Supply design.
    All works Ok. But, when I test the output with voltmeter (selecting AC option) it shows approximately double of DC voltage. For e.g. if DC is 5V then voltmeter in AC tab will show 10V.

    If I attach -ve of voltmeter to +ve of output and +ve of voltmeter to +-ve of output.. then it shows correct (-)5v DC … And (0) AC.

    Can u help me resolve this AC element yo be zero. ?

    Reply
    • Swagatam says

      Hi, if you have used a 5V zener then the voltmeter must show a 5 V on the display, any other reading would indicate a malfunctioning meter. The best way to verify is to use an analogue voltmeter (needle type) which will help to read the parameters without confusions.

      Reply
      • Kumble says

        I will try that. But problem don’t appear to be in voltmeter … Because .. while I reverse the probes ..It shows exactly (-)5V Dc and 0V AC

        Reply
  12. Mauro says

    Hi
    In the case of a power supply for a few milliamps and using a limiting resistor of appropriate value in series with the capacitor, in order to limit the peak current to 1 ampere (max surge current of moc), could we eliminate the triac using only the moc? Thank you

    Reply
    • Swagatam says

      Hi, yes that’s possible.

      Reply
  13. vikas karad says

    using transformerless power supply my rtc get reset unfortunately. i have used MCP7940 RTC

    Reply
    • Swagatam says

      please use SMPS then.

      Reply
  14. Sriram says

    Hi, Could you please tell me the wattage rating for resistors 360, 39 and 330 ohms which are used in MOC3041?
    And How to calculate the Rin for MOC3041 ? Because am not able to understand from the datasheet.

    Reply
    • Swagatam says

      Hi, all resistors are 1/4 watt 5%, the Rin can be calculated using standard LED formula:

      Rin = Supply input – LED fwd voltage / LED current

      wattage = Supply input – LED fwd voltage x LED current

      Reply
  15. Mah says

    Hello again,
    I have a general question about Mosfets;
    can we use couple of mosfets with same voltage rating and different current(mean Vds, Ids, Vgs) paralell together in a circuit?

    Reply
    • Swagatam says

      Yes you can do that!

      Reply
  16. Mah says

    Thanks

    Is it possible to use mosfet type power supply to run a high amp consumer, like 5Amp, 12Vdc motor? If so what changes have to be made?

    Reply
    • Swagatam says

      It is possible but if the input/output difference is large, then the Mosfet will become very hot and waste a lot of power.

      Reply
  17. Mah says

    Hello Swag,
    I made the first circuit and uses 7812 regulator but the zener(15v, 1w) and regulator got broke both. I know that the transformer is the ideal appraoch but i need a 12vdc transformerless power supply. Is there any reliable circuit for 12vdc? Something which does not affect the rest of circuit in the case of failure?

    Reply
    • Swagatam says

      Hello Mah, the MOSFET version is the most reliable and is safe from switch ON surges.

      Reply
  18. Asif says

    Dear Swagatam, nice ideas and circuits you have given here, ut I want to share my thoughts and want your opinion too… introducing optoisolator or 555 IC will also increase the complexity or atleast the circuit will need more space… then why shouldn’t I use the transformer which eliminates all issues and also provides isolation from mains…

    Reply
    • Swagatam says

      Hello Asif, iron core transformer is the best option if weight and space are not a matter of concern to the user.

      Reply
  19. Mah says

    Hello again Swagatam,
    Is it possible to use the first circuit as 12vdc source to feed 555 ic in PWM controller?
    I dont want to use a 12v transformer for the application.
    If you have any suggestion, kindly refer it to me.

    Thanks

    Reply
    • Swagatam says

      Hi Mah,

      yes you can if the deadly floating mains AC around the whole circuit is not a concern to you. For your application you can reduce the 105/400V to 474/400V.

      Reply
  20. Ben says

    Hi Swagatam! Thanks for your help on these circuits. But then I really need your help on this;
    Am building a large power supply to power up a large building based on batteries. The battery bank capacity can go as high as 110V/400AH and 48V/1000AH. Charging up these large battery bank is a bit of a problem, I have already built an automatic charger and battery to load control and am currently customizing an SMPS from one of the circuit you posted (0-100v 0-100A variable power supply) which I believed will work perfectly. But I need a transformerless 230Vac mains to dc supply for the SMPS. How can I calibrate this circuit to be able to obtain an adjustable 120V/100Amps? Suitable for the SMPS. I believe stacking up the capacitor to about 2200uf/400v can obtain up to 100A? If am right, pls I need your prescription. Thanks

    Reply
    • Swagatam says

      Hi Ben, yes that may be possible. You can try the idea with the “MOSFET control” design….but make sure the MOSFET is rated to handle a minimum of 150V at 200 amps

      Reply
  21. Tony Caley says

    Hi Swagatam,

    I would like to use your Simple Transformerless Power Supply to replace a (60HZ hum) switching power supply for a radio.

    Can you provide the component value changes that would must be made for optimum performance on 120V AC input and provide 6.0V DC at 0.5A output?

    Thanks

    Reply
    • Swagatam says

      Hi Tony, you can try the “MOSFET control” design, and eliminate the T2, R2 from the circuit.
      After adjusting 6V at the output through the given pot, glue the pot so that the 6 V does get disturbed in future.
      After this, connect a 6800uF/ 25V capacitor across this 6V output DC to ensure there’s no hum involved in the DC.

      Reply
      • Anthony Caley says

        Hi Swagatam,
        Thanks for your timely response. Should I also change D2 to a 6V Zener Diode?

        Reply
        • Swagatam says

          Hi Anthony, no need to change the zener value, it should be a 12 V zener only.

          Reply
  22. MiracleTech says

    Hi sir. Can I increase c1 to be able to charge 12v battery

    Reply
    • Swagatam says

      Miracle, a capacitive power supply cannot be used for charging a lead acid battery.

      Reply
      • Miracle tech says

        But, In Flashlights, they use it, so why not?

        Reply
        • Swagatam says

          for small batts it will work, not for bigger batteries

          Reply
  23. Chandra Shekhar Gupta says

    Please guide me for a transformerless supply 3.3V with zener diodes

    Reply
    • Swagatam says

      Please Use 3.3V 1 watt zener diode for Z1

      Reply
  24. Reafe Ajero says

    Hi sir , I want to make an Aquarium Led Light, is this applicable?

    Reply
    • Swagatam says

      Hi Reafe, you can use it if the LEDs are not in contact with the water in any manner, because the entire circuit is attached with the AC mains and is fully prone to electric shock…

      Reply
      • Reafe Ajero says

        How many LED maximum sir?

        Reply
      • Reafe Ajero says

        I want to try the #1 Basic Transformerless

        Reply
        • Swagatam says

          If you remove the zener then dividing the supply output from the diode with the LED forward voltage will give you the total number that can accommodate.

          For example if the DC is 310V and the LED forward voltage is 3.3V then 310 / 3.3 = 93 LEDs approximately in series.

          Reply
  25. Swagatam says

    Requires brain to understand 🙂 Borrow a little from somewhere then may be you’ll start understanding.

    Reply
  26. Kingsley says

    Hello dear swagatam!

    Please I am having this issues with transformerless power supply; “Each time I intend to use transformerless power supply to power microcontroller 8051, atmega328P and even a DC FAN of 12V, 1.4A, I notice that they never get powered even though the power supply has been tested to produce the required 12v or 5v dc as the case may be. If I read the output of the power supply after I have connected the load say 12v, 1.4A DC FAN, I noticed that the voltage dropped further to 2.4vdc which of course never powers the FAN.” So Please help me in this case. What might be the reason for the further voltage dropping? and how can I prevent it from happening. In the design, I used 105, 400V capacitor at the input stage to drop the current and 12V zener for output stabilization. just like the first circuit in this page.

    Reply
    • Swagatam says

      Hello Kingsley, the 105 capacitor will produce only 60mA so it cannot be used to handle 1 amp current load.

      By the way a capacitive power supply is never recommended for microcontrollers or any sensitive electronic circuit.

      Reply
      • Kingsley says

        OK, Thank You boss.

        Reply
        • Kingsley says

          Please I need your help sir.
          Is their any circuit you can recommend me to use in handling high voltage supply apart from stabilizer? The problem I am having is this, I designed an inverter that powers my clients house; but their mains voltage supply sometimes go very high up to 315VAC, and this usually burns the MOSFETs each time the inverter is in charging mode and the small changeover transformer (12V, 500mA) also gets burnt too. But when the voltage supply is normal between 220VAC to 240VAC, the inverter charges and the charger switches off when the batteries are fully charged.

          Therefore, I was trying to use the transformerless power supply system to correct the issue in such a way that i have written a program in C language that will read the AC voltage level from the mains supply and which will automatically turn off the inverter charger whenever the voltage supply goes up beyond 240VAC. I thought of using the transformerless counterpart since the changeover transformer also gets affected too. But now that you said that transformerless/capacitive power supply is not recommended for microcontrollers, what can i do to stop this regular damage of my MOSFET and changeover transformer?

          Please sir your help is highly recommended and a good circuit will be very, very appreciated.

          Thank you in anticipation of your positive response.

          Reply
          • Swagatam says

            Hi Kingsley,

            In that case you can apply the following capacitive power supply:

            https://www.homemade-circuits.com/wp-content/uploads/2019/05/100-watt-LED-bulb-improved-design-1.png

            But remember these are not isolated from mains so everything in the inverter will be at 220V mains potential, even the battery terminals.

            Reply
            • Kingsley says

              Sorry I observed a typographic error in the first statements. Please kindly used this one.

              Good morning dear Swagatam. I sincerely appreciate your swift response to my many questions; Thank You for being always available to help resolve my circuit difficulties.

              Now, looking at the circuit you suggested for me, the AC (Mains) supply terminated at the bridge rectifier as usual right? and If carefully handled, it will remain within there! The only point where the inverter circuit and battery get connected with the suggested circuit is their common ground (GND) i hope, right? But you also pointed out that “these are not isolated from mains so everything in the inverter will be at 220V mains potential, even the battery terminals” please kindly explain that part more so I can be cleared before trying to implement this circuit with the existing predicament.

              i also implore you sir to help me with a surge protector circuit up to 30A that can work as a high voltage monitor just like conventional surge protector in the market that trips off if mains supply voltage is too high; maybe that would be better alternative than the capacitive power supply since the capacitive counterpart may result in huge damage.

              Thank you sir as you respond to me, God bless you.

            • Swagatam says

              Hello Kingsley, yes due to the common ground the 220V from the capactive power supply can easily reach the battery terminals, there’s no way to prevent this.

              Another alternative can be to use two 12V/500mA 220V transformer and tie their 220V wires in series. This will ensure the transformers can withstand 700V peak inputs. The secondary sides could be configured with separate bridge rectifiers and filter capacitor. The output from the bridge can be connected in series to get the required safe DC.

              For the high voltage protector concept you an refer to this post:

              https://www.homemade-circuits.com/highly-accurate-mains-high-and-low/

            • Kingsley says

              Ok, Thank you for your answers. You are too much sir. I will try the double transformer counterpart.

              thanks a lot.

            • Swagatam says

              No problem!

  27. youngking says

    good day sir, thanks for the good work u’re doing for man kind. pls can u sugest the kind of transformerless variable power supply circuit i can use to set your circuit i just came across which is twin/split change over circuit because i can’t afford transformer type. thanks i will be walting for ur response.

    Reply
    • Swag says

      Hi Young king, what is the current requirement of the power supply? if it’s over 200mA I won’t recommend a capacitive power supply

      Reply
  28. Godson says

    Hello sir Swagatam,
    I needed a transformerless power supply that can conveniently be used to power an IC and you referred me to this article. Thank you very much sir.
    In my application, the circuit will be permanently connected to mains supply, so I need it to be very free from power surge so that the connected components will not damage during operation. What modifications do I need to make in order to achieve this?

    Reply
    • Swag says

      Hello Godson, you can use the recommended design as given in the above article, just make sure C1 is selected as per the circuit’s current rating, for example if the current consumption of the circuit is 20mA, you can use a 0.33uF for C1 and so on…

      Reply
  29. Swagatam says

    7812 will work!! since it's rated at 1 amp while the input current from the 105/400V is just 50mA…so even if it's 120V or 220V it will be forced to drop down to 12V ultimately….

    but again this may be applicable only for ordinary circuits never for charging cellphones…..

    Reply
  30. Swagatam says

    Charging a cellphone through a capacitive power supply is dangerous and is never recommended…I accidentally failed to notice that you are intending to use it for charging a cellphone…

    get an SMPS charger instead..

    Reply
  31. Kesava Raj says

    Instead of using zener we can use voltage regulator like LM7805 & 7812…

    Reply
    • Swagatam says

      ICs can be prone to surge currents, and can get damaged, zener diode is more appropriate

      Reply
  32. Kesava Raj says

    For example if i use more then 3uf to 5uf capacitor. Need to increase zener watts or 1 watts enough.

    Thank u sir…

    Reply
    • Swagatam says

      yes, then you will have to calculate and upgrade the zener power accordingly…yo can calculate the input current from the capacitor through the formulas as explained in the following article

      https://homemade-circuits.com/2015/01/calculating-capacitor-current-in.html

      Reply
  33. Kesava Raj says

    Hai sir…

    Small confusion sir…

    I try this circuit using 224 capacitor..and i not use zener and R2..
    The output coming 39 to 40v…

    My doubt is if i use 12v zener o/p will come 12v means.. remaining 28v what happen sir,,if zener will cause damage or nothing happen…

    For eg if o/p coming 150v means if we use 6v zener what happen .o/p will 6v or zener will damage sir…
    Is there any limitations voltage to use zener?…pls guide me sir..
    Without using R2 we can connect zener or not…R2 is used for voltage drop sir..

    Pls tell 224 capacitor current value..

    Reply
    • Swagatam says

      Hi Kesava,

      the excess volts will get shunted through the zener diode to ground.

      the zener voltage has no restrictions, you ca use any.

      you can use it without R2…. but R2 is recommended, and it can be lower than 50 ohms…

      however if the input capacitor value is above 1uF then higher than 1 watt zener might be required…

      Reply
  34. Indrawan says

    Dear Mr. Swagatam,
    i have a mosquito zapper with 4v lead-acid battery in it. the charger circuit is similar as above, with C1=474 (is it 470nF?), no R2,Z1,and C2.
    how to limit the charging voltage to say 4.5-4.6v to keep the battery in float charge range?
    thank you.

    Reply
    • Swagatam says

      Hi Indravan, you can do that by simply using a 4.6V zener diode for Z1, or alternatively replace Z1 with 8nos of 1N4007 diodes in series, with its cathode towards the ground line side.

      Reply
    • Indrawan says

      about the 8-series of 1N4007, does they put in paralel with the battery?
      so the anode of 1st-diode connected to batt(+) and the cathode of the last-diode connected to batt(-)?

      and does the capacitor C2 is needed for this case?

      Reply
    • Swagatam says

      yes that's correct, C2 is optional, but including C2 would allow more average current to the battery and therefore faster charging

      Reply
    • Indrawan says

      Dear Mr. Swagatam,
      i have put 8-series of 1N4007 in paralel with the battery, and my multimeter reads steady 5.29v at the battery terminals.
      would you please help me to understand about the calculation here? why it needs 8-series of diodes and why my multimeter reads 5.29v?

      please be patient with me sir, as i am completely newbie in electronics and still have my basic learning curve for it.

      Reply
    • Swagatam says

      Hi Indravan, due to its internal characteristics a diode would block around 0.6 to 0.7V and short-circuit the rest of the voltage when its conducting or in the forward biased condition… , which implies that 8 diodes would block 0.6 x 8 = 4.8V…therefore the output would show 4.8V.

      In your case it's showing 5.29V which looks quite high, to correct this you can try reducing a couple of diodes in the series and adjust the output to the preferred lower level.

      Reply
    • Indrawan says

      it got quite steady as i need with 6-series of diodes.
      thank you very much for your kind explanation Sir. 🙂

      Reply
    • Swagatam says

      you are welcome!!

      Reply
  35. Rajib says

    Dear brother I made this power supply for my LDR light circuit. I made a PCB for that circuit including this power supply and found around 12.5 VDC across the capacitor diode. But the problem is the 12V relay is vibrating and the glow of the light is very low. When the circuit is powered from a separate DC source across the zener diode the circuit works perfect; no vibration. Is there any modification is required to use this power supply? Please advise.

    Reply
    • Swagatam says

      Dear Rajib,

      you will need to connect another capacitor parallel to C2 with a value around 1000uF/50V, this will solve the issue

      Reply
    • Rajib says

      Dear brother, now its working perfectly. Can I remove capacitor C2 as 1000uF/50V has been added?

      Reply
    • Swagatam says

      Hi Rajib, C2 will help to safeguard switch ON surges better, if you want to remove it then make sure to connect an NTC thermistor at the input mains side of the power supply to prevent switch on surge into the connected circuit.

      Reply
  36. kirams says

    Swagatam, thank you for your kind responses since 2013 and probably earlier!! Hats off to your consistency. I read through all the responses written on this page.

    I came here to find if I can charge Li-Ion battery (The one in dead cell phone) using this circuit and you said it is not possible. But didn't get why it should not work. cell phone battery rating is 3.7v-4.2v. if we configure the circuit to give 5 to 6 v, 50mA would be more than sufficient for charging current, only thing is about auto cut-off. You had suggested cell phone charger circuit for Li-Ion batteries but should I directly connect the Li-Ion battery across 5V SMPS output. This is where I've stuck.

    Other interesting note I wanted to tell others is your circuit is used in most cheap chinese mosquito zapper bats. Since it is cheap, it does not have zener diode and instead of capacitor, they have connected battery to be charged. So, I was thinking if I could use Li-Ion battery instead of Lead acid battery that they have.

    Sorry, I've asked many questions and comments but please direct me to appropriate threads. and thanks for your help

    Reply
    • Swagatam says

      Thank you Kirams, I greatly appreciate your involvement with my site!

      Li-Ion cells are costly and highly efficient cells and that's why I don't recommend charging them with the above cheap transformerless type design, where even the mains is not isolated.

      It is ofcourse possible to use these power supplies for charging a Li-ion cell but is not advisable.

      Li-ion normally accept and work with high current, for quick charging, which the above design may be incapable of delivering therefore the overall feeling is that one should avoid using such crude and dangerous versions of power supplies rather use an SMPS or transformer based designs.

      Still if you plan to try it make sure you include the zener diode, otherwise it can become even more dangerous for the cell.

      Reply
  37. lima toshi says

    Thank you thank you Swagatam you are the greatest, I was like 50% sure about adding extra ppc but I guessed it right lol but its all because of you sir, I am learning a lot only after I found your great site, wish I had found it sooner but its never too late BTW I never thought I will learn so much in less time, and its all because of great and kind man like you who gives hope to new beginners like me, in what we just loves to spend time on whenever we get time. God bless you sir. Looking forward to learn as much as I can. Keep up the great work, appreciated.

    Reply
    • Swagatam says

      You are welcome Lima, keep posting your queries, your involvement will help others also to learn more… keep up the good work…

      Reply
    • lima toshi says

      OK, surely i will(: thank you so very much sir, i just love this site… keep up..

      Reply
  38. lima toshi says

    Ok, so I just have to add extra ppc to get the amperage needed, anyways thanks to you sir, I am learning a lot.

    Reply
    • Swagatam says

      yes that's right!!

      Reply
  39. lima toshi says

    OK what i have learned so far:lol…. if i connect two extra Z2 and Z3 in series and parallel, will i get 24Volt-@2amp. Thank you.

    Reply
    • Swagatam says

      you are partially correct, it will give you 24V, but not 2 amp current, because current level is determined by the input capacitor value…..you can read more on this here

      https://homemade-circuits.com/2015/01/calculating-capacitor-current-in.html

      Reply
  40. Norman Kelley says

    Thanks for the quick response! I will build the circuit as soon as the parts arrive. Have a nice day!

    Reply
    • Swagatam says

      OK thanks!

      Reply
  41. Norman Kelley says

    Hi, Swagatam,
    In the above simple transformerless power supply, the circuit shows a reduced DC voltage after the zener diode and a ground connection. What provides the ground. It is not connected to the neutral, so what do I ground the connection to? I'm using this with a 120vac supply and I am using a 6v zener diode. I have connected a 1n4007 across the cap and the resistor as you suggested, but I don't know how to ground the low voltage circuit. I am using the low voltage(6vdc) to power a white LED in a night light circuit. Help! Thanks!

    Reply
    • Swagatam says

      Hi Norman, you don't have to connect anything in the indicated area, the ground symbol emphasizes the negative line in all DC circuits….so here too the symbol just signifies the negative common line in the DC section…you can simply ignore this symbol if you wished to.

      Reply
  42. SUDIP BEPARY says

    i have a query about out put from this circuit that if there is variation on input voltage like 220 volt to 180 volt or below, will this circuit change the out put voltage ?

    Reply
    • Swagatam says

      NO, unless and until the input AC drops below the zener voltage value

      Reply
  43. Davis Kakumba says

    hi swagatam , i made the circuit and its working i used it to power my 12vdc 3w led bulb, now how can i modify it to be used on 240V AC instead of 220v AC

    Reply
    • Swagatam says

      Hi Davis, you can use the same circuit for 220V as well as 240V.

      3 watt LED will not work with this circuit.

      Reply
  44. Waqasafridi says

    Sir I want to make an rechargeable 12v emergency light with battery level indicator without transformer plz help me

    Reply
    • Swagatam says

      waqas, similar circuits are already present in this website please search it through the given search boxes…

      Reply
  45. Sonal Kumari says

    Sir ,thanks for your previous reply. Can you please recommend me any of your circuits without transformer suit able for the incubator circuit.

    Reply
    • Swagatam says

      Sonal, Would you be able to build an SMPS circuit? I don't think so.

      So it's better to buy a ready made 12V 1 amp SMPS adapter and use it for the purpose

      Reply
  46. Sonal Kumari says

    Sir can I use this circuit to power your egg incubator thermostat circuit.

    Reply
    • Swagatam says

      no you can't, either an SMPS adapter or a transformer based power supply can be used and is recommended.

      Reply
  47. mr. ravinder goyal says

    can i change the polarity of input(Line and N)?

    Reply
    • Swagatam says

      yes you can!

      Reply
  48. kamlesh_sexy says

    Hi friend,
    I see that in the above pic, you used 12v zener, so the output of this circuit is 12v.
    I did not get 12v 1w zener so I made little changes,
    Here is my alteration:
    I removed zener and placed with 7812 and replaced c2 with 10uf 16v..
    this is correct????

    Reply
    • Swagatam says

      Hi friend, yes that will do, but if due to surge current 7812 blows-of then it will be a bigger lose than a 12V zener….put an NTC at the input to solve this issue

      Reply
  49. beni says

    thanks,
    i adding a 1N4007 diode parallel with the zener, i use 12V 1 watt zener ,then i use 12V 5 watt zener
    the power is OK.OK.
    But while the no-load power(If any consumer is not connected to the circuit) Warm up zener diode.

    Reply
    • Swagatam says

      you can keep the circuit switched OFF when there's no load connected because anyway without a load it may not be a good idea to keep the circuit switched oN

      Reply
    • Arun Kumar says

      I want 12v/300ma transformer less power supply circuit diagram please send link sir

      Reply
    • Swagatam says

      https://homemade-circuits.com/2014/02/simple-1-watt-to-12-watt-smps-led.html

      Reply
  50. beni says

    Thank you Swagatam.
    i can not speak english fluently.
    i need a transformerless in this conditions:12V,180mA
    i use C1 = 2uF/400V , Z1=12V 5 watt zener
    output voltage =12.3v
    but,while the no-load power, Warm up zener diode.(why the zener diode Heated ! ?)
    and too: make two zener diodes in parallel each rated at 1 watt. but zener diode Heated !!!why ?
    plz help.thanks.

    Reply
    • Swagatam says

      beni, a 5 watt zener is not supposed to get warm, but if it is then you can try adding a 1N4007 diode parallel with the zener in the same polarity, and check the difference.

      Reply
  51. Tiago NET says

    R2 is NTC for inrush current or power resistor?

    Reply
    • Swagatam says

      R2 is an ordinary resistor but you can definitely replace it with a suitable NTC

      Reply
      • amor says

        Hi Sir,
        can i use a 10k NTC in place of R2?

        and a 474 630vac mylar in place of 105 400vac capacitor?

        im using it as a power supply for a 12v relay driver circuit to power a 12v dc motor, can i just also use the same power source for the 12v dc motor?

        thanks,
        amor

        Reply
        • Swag says

          Hi Amor, yes you can try the mentioned components, it should work. If it is a relay that you want to connect at the output, you can eliminate the 12V zener, or use a 24V zener instead. Because a relay is a relatively heavy load and will never burn from a 474 capacitor’s surge, therefore the zener diode can be eliminated or a some higher value can be used.

          Reply
          • amor says

            Thank you Sir,

            how about the 12vdc motor can i just tap it with the same power source? i mean one source to power both relay driver stage and a 12vdc motor load

            Reply
            • Swag says

              Amor, If the motor current is within 100mA or 200mA then it might be possible otherwise I won’t recommend using a capacitive power supply

          • amor says

            good day Sir,

            Without the 12v zener the output after the rectification will be 310vdc (as mentioned above) if i eliminate the 12v zener i think it is not safe for the relay driver stage to connect in the output Sir.

            another thing Sir a dc motor will be connected to the relay output which is also a 12vdc my question is can i just tap the common terminal of the relay in the above power supply?

            Reply
            • Swag says

              Amor, a transistor driver stage won’t be required here. You can connect the relay coil directly at the output of the transformerless power supply, that’s the zener diode would be necessary. If your motor is a low current motor then you can tap the power from the same source otherwise not.

  52. Tiago NET says

    i need a transformerless in this conditions: 6V at 120VAC and 12V at 220VAC! have you circuit for this ?

    Reply
    • Swagatam says

      just change the zener value accordingly in the above shown design…that's all is neeeded

      Reply
  53. Vicky Gowtham says

    hai friend…how can i do my project of mobile charge sharging transfromerless+

    Reply
    • Swagatam says

      Hi Vicky, have you previously built an SMPS circuit? if yes then you can try the following design for your requirement:

      https://homemade-circuits.com/2014/02/220v-smps-cell-phone-charger-circuit.html

      Reply
  54. M- Furqan says

    please sir tell me , i want 220v ac to 60v dc transformerless circuit without transistor

    Reply
    • Swagatam says

      you can use the above shown circuit and replace the zener with a 60V zener

      Reply
  55. Harvest Palm says

    Sir, I have made egg incubator timer that you have written on another article, and I want to ask that, can I use this transformerless to be power supply the egg incubator timer circuit that use two 4060 ics?

    Reply
    • Swagatam says

      Harvest, no it's not recommended and might not work….use a 12V ad to dc SMPS adapter or a transformer power supply

      Reply
  56. MALAY WANE says

    Sir i replaced 3 diodes but the problem remains same…every time the diode blows off.
    Can i attach any resistor or capacitor in series to diode,and hece collect 12v power.?

    Reply
    • Swagatam says

      the zener should be rated at 1 watt…connect a 1N4007 also in parallel to the zener to reduce the stress on the zener…the 1N4007 anode should be connected to the positive line

      Reply
    • MALAY WANE says

      I tried this too but it still not working sir.
      I am not getting the output.
      Instead of zener,can i use any other component?

      Reply
    • Swagatam says

      It means your capacitor is faulty…you can try 7812 IC

      Reply
  57. MALAY WANE says

    Hello sir,
    I had made this circuit and trying to get output
    But whenever i connect zener diode as shown,i gain the output of 1.5v while removing the zener i get 28v so can u plzz tell me where i am getting wrong?
    How could i get 12v 1a finally..?

    Reply
    • Swagatam says

      Hello Malay, It could be due to a faulty zener diode or may be you are connecting it with a wrong polarity…try replacing it with a new one.

      12a/1A from this power supply could be impractical and not recommended.

      Reply
  58. Unknown says

    hello sir
    i am tring to make supply from 220v ac to 72 v dc with 2ampere
    could u please help me in it

    Reply
    • Swagatam says

      sorry I do not have this circuit at the moment…

      Reply
    • Abu-Hafss says

      Hi

      You can try to find a center-tapped transformer having 220V input and output 36-0-36V rated 2A or 3A. Leave the center-tap and use the remaining two terminals of the transformer with suitable diodes (bridge rectifier) and 1000µ (or more)/100V capacitor to get 72VDC.

      Reply
  59. binu says

    Sir good work. But what is the use of r2 50ohm 1w resistor. Can I use 100ohm resistor instead of this. Plz replay me.

    Reply
    • Swagatam says

      Binu, it's for limiting current, you can use lower values than 50 ohms, higher values can cause increased heat for the resistor and lower current outputs

      Reply
  60. Swagatam says

    Arun, you'll need an auto-transformer for that

    you can wind 300 turns of magnet wire (25SWG) over an iron laminated core (transformer E core) and connect the ends to the 220V, the 110V may be collected from anywhere at the middle of the winding

    Reply
  61. Arun Das says

    sir can u help me to convert 230v ac to 110v ac …step down circuit

    Reply
  62. khant hnin says

    Please help me.Can I use 2uF/400V for C1?
    1uF/400V is not available near my area.

    Reply
    • Swagatam says

      2uF will cause more surge current to flow into the circuit….you may use it, but make sure to employ two zener diodes in parallel each rated at 1 watt

      Reply
  63. pakol27 says

    Can I use this circuit to power 12v computer Fan?

    Reply
    • Swagatam says

      yes, but at a slower speed…

      Reply
    • pakol27 says

      What should i do to maximize the speed of the fan?

      Reply
    • Swagatam says

      add anther capacitor parallel with C1

      Reply
    • pakol27 says

      Thank you Swagatam.. Can you give the modified circuit? Just to make sure that I make this right.

      Reply
    • Swagatam says

      My pleasure pakol, make C1 = 2uF/400V that's all, and preferably use a 12V 2 watt zener.

      Reply
  64. Saqib Mehmood says

    Plz just tell me how capacitor contribute in step down ac voltages and what value of capacitor we will choose for 220-6v and how???plzzzz

    Reply
    • Swagatam says

      capacitor steps down the current not the voltage…voltage is controlled by the zener diode

      Reply
  65. Sudhee Krishnan B says

    can i use regulator ics instead of zenar dode?
    what is the dc output after the rectifier, without using the zenar ( capacitor is not removed)

    Reply
    • Swagatam says

      yes regulator ICs can be used, without a zener it would be restricted to the capacitor's breakdown voltage rating…..but that would create a lot of stress of the capacitor

      Reply
  66. basit momin says

    For wat purpose the circuit can be used for……….

    Reply
    • Swagatam says

      for powering any DC circuit below 50ma

      Reply
  67. Ritwik Ghosh says

    can you please explain the function of R1 and C1 ?
    i mean why they are in parallel ?

    Reply
    • Swagatam says

      R1 makes sure that C1 gets discharged immediately while someone unplugs the unit from the mains socket, thus cancelling any chance of an electric shock to the user from C1 discharge

      Reply
  68. Nirvikal Lal says

    I want to convert 230 or 220 vac to 5 or 6v dc without transformer so pls help me it's urgent i need for a project

    Reply
    • Swagatam says

      you can try the circuit discussed in the above article….use a 5V zener at Z1, and 0.33uF/400V for C1

      Reply
  69. Kusal Wijesingha says

    there isn`t 50 ohm/1w resisiton to find then what can i use to that?

    Reply
    • Swagatam says

      the value is not critical, you can try other values such 33, 47 68, ohm etc.

      Reply
      • Reafe Ajero says

        why the 50ohm 1watt resistor is very hot?

        Reply
        • Swagatam says

          It is not a calculated value, it’s only to prevent surge current to the load. You can reduce it to 20 ohms and check the difference.

          Reply
  70. Abu-Hafss says

    Hi Swagtam

    Can this supply be used to power up the following project:

    https://homemade-circuits.com/2014/06/energy-saver-solder-iron-station-circuit.html

    I am bit concerned about the voltage surges.

    Reply
    • Swagatam says

      Hi Abu-Hafss,
      although I too don't recommend capacitive power supplies for operating sophisticated electronic circuits, the above circuit could become relatively safer if C1 is reduced to 0.47uF/400V….the zener diode is crucial here and should not be removed from the circuit.

      Reply
  71. Raja Banerjee says

    Surprisingly in cheap led bulbs available in the market, they use 474K /250V main cap and no filter cap.and they are doing good… Now how these bulbs servibe in the 240 V mains?? thanks

    Reply
    • Swagatam says

      Yes it's possible, I'll try to address it soon in my blog

      Reply
  72. Deepam Paul says

    Hello Sir;
    I want to try this circuit for Making LED series for Diwali. I try to test this circuit using Circuit design PCB software but in this software there is no 250v electrolytic capacitor so i use 200v electrolytic capacitor so it give me a voltage of approximately 13V but i am satisfy with output current . My Doubt is if i use 250v electrolytic capacitor then it will give the 12v output voltage or less than 12 . And how much watt is R1.
    Please tell me some PCB design software which use AC power supply component and can run stimulation test.

    Reply
    • Swagatam says

      Hello Deepam,

      200V capacitor will also do, this voltage is not relevant to the the output voltage of the circuit, the zener diode is responsible for it.

      Don't use simulators, they are very unreliable and mostly give misleading results.

      Reply
    • Swagatam says

      R1 will be always 1/4 watt

      Reply
  73. BlogSerba says

    Have u made it?
    my friend said we can't put resistor facing 220 volt AC

    Reply
    • Swagatam says

      a resistor can be inserted anywhere in a circuit for suppressing surge, the position is never critical.

      Reply
  74. ravindra metri says

    Sir. Plz give ac oprated mobile battery li – ion batt circuit

    Reply
  75. ravindra metri says

    Above circuit can i use in your Li-ion Emergency Light Circuit with Over charge and Low Battery Cut off Features circut. Instead off cellphone charger circuit

    Reply
    • Swagatam says

      No, it won't charge Li-ion batt

      Reply
  76. Fazal Ellahi says

    oh thanks a lot dear

    Reply
  77. Pete Skinner says

    I did try a .47uf with no luck but will try with a .68.uf. Thx for quick response! Great name by the way Swag.

    Reply
    • Swagatam says

      sure Pete! thanks, my pleasure:)

      Reply
  78. Pete Skinner says

    They also have model TM-619-1(120vac) and TM-6331(120/220vac). When I plug in the 619-2(220vac) to 120vac the timer portion will work but the power supply is suppose to convert to 24vdc to run a relay which it is not doing. I have 2 brand new and neither will switch relay running at 120vac.

    Reply
    • Swagatam says

      you ca try increasing the value of the 0.33uF cap by putting another 0.33uF parallel to it or by replacing it with a 0.68uF/250V cap.

      Reply
  79. Pete Skinner says

    have two TM-619-2 timers that work on 220v.Would like to run a 120v. Uses transformerless cap power supply. Components are .33uf cap with 1M ohm resister in parallel as well as 180 ohm resistors in series on both sides of 220v input. Bridge rectifier follows. Can you help?

    Reply
    • Swagatam says

      you can use the same circuit with 120V also, the output result from transformerless supply would be the same as for 220V.

      Reply
  80. Jagdeep Singh says

    Sir
    I made this circuit but sum time after r2 is burn
    Help me

    Reply
    • Swagatam says

      Jagdish, use 474/400V in place of 105/400V

      Reply
  81. jason bobis says

    Hello Swagatam Majumdar.. How can I make the output of this power supply be 12V 1A?

    Reply
    • Swagatam says

      hello Jason, getting current above 100mA is not recommended for capacitive power supplies…because it could dangerous for the connected load under those specs.

      Reply
  82. Swagatam says

    Hi Fazal, yes you can use a 5V zener to get a 5V output from this circuit.

    Reply
  83. Fazal Ellahi says

    hi dear SWAGATAM
    if i need only 5v from this circuit then can i use 5v zener diode in it
    help me to produce 5v

    Reply
  84. Niel Kristopher Vargas says

    Do you have a 12V 1A transformerless? Or 2A

    Reply
    • Swagatam says

      presently i don't have it.

      Reply
  85. Swagatam says

    50mA

    Reply
  86. Niel Kristopher Vargas says

    How much AMPERE is this 12V transformerless,?

    Reply
  87. Shriram S says

    Sir i want to replace a 12-0-12 transformer in one of my projects with this transformerless power supply you have mentioned here. I want your help in implementing it, would you please guide me on how to do it, whether i can use the same circuit mentioned above or any changes are required.
    Thanks in advance

    Reply
    • Swagatam says

      Hi Shriram, what is the current requirement of your circuit? If it's above 100mA then capacitive power supplies as described above should not be used

      Reply
  88. josef says

    Hii…

    what will be the voltage across the output terminals for this circuit, given that the Zener diode is not used for regulation?

    Also, does the AC capacitor(PPC) act as the series reactance as opposed to the Series resistance(Rs) in a standard Zener Voltage regulator circuit?

    Reply
    • Swagatam says

      The voltage will be always equal to the input mains peak, for 220V AC it would be 330V DC.

      In presence of load, whether a zener or any other load, the reactance behaves like a resistance and restricts current as per the load.

      Reply
  89. Justin Adie says

    yes. however that is not practical when the power supply and device are in their container and freely movable by the consumer from socket to socket.

    it is not, of course, reasonable to require a user to have a phase tester and insert it into a socket to test (and in fact for security reasons it is not quite that simple either).

    i guess by not answering the question about fusing you are indicating either that it is not safe to use this circuit when there is no visual way to determine phase or you do not have an opinion on whether it is good practice (and effective) to fuse both poles.

    as always, thanks for your time.

    Reply
    • David Barner says

      Justin, since this circuit utilizes a full wave bridge rectifier (the 4 diodes in a circle) input polarity is not an issue. All Swagatam was saying is that if you wanted to add a fuse for additional protection, then polarity would be important.

      Reply
    • Swagatam says

      Thanks for your understanding David, yes a fuse is not essential for the above circuit since it has a DC output, but for other appliances a fuse must be added to the LIVE line so that in case it blows of no Phase current stays floating within the house electrical.

      Reply
  90. Justin Adie says

    and therein lies the problem! In my country (France) there is _no_ way to determine visually which line is the phase and which the neutral. the plugs and sockets are not physically polarised.

    so what is the recommendation? to fuse both lines?

    Reply
    • Swagatam says

      You can simply identify them by using a line tester device, the touching the tester to the relevant lines will provide an illuminated neon indication for the phase line and no illumination for the neutral.

      Reply
  91. Justin Adie says

    so it doesn't matter that the filtering circuit is on the neutral (tied to ground) rather than the phase?

    is that true even for electrical systems that do not tie neutral to ground?

    and does that also mean that it makes sense to put fuses at both terminals of this kind of AC circuit?

    Reply
    • Swagatam says

      It doesn't matter to the circuit operation, but certainly matters to living beings in terms of getting or avoiding a lethal shock.

      Therefore when it comes to adding a fuse, it must be always added to the phase line, never to the neutral.

      Reply
  92. Justin Adie says

    Hello

    is input polarity important in this design? e.g. in many european countries there is no wiring standard to dictate which wire/pole is the phase and which is the neutral. and even if there were, the plugs can just be reversed.

    and if input polarity is not important could you give a brief explanation why?

    many thanks
    Justin Adie

    Reply
    • Swagatam says

      For mains AC inputs the polarity is never critical because of its alernating nature which oscillates from positive to negative at the specified frequency, in your area and India it's 50Hz (50 cycles per second), therefore the polarity is undefined and becomes immaterial.

      Reply
    • kirams says

      I don't quite agree completely with this comment. There may not be a difference in the operation of the circuit but if Ground is connected to LIVE/PHASE instead of NEUTRAL, inner circuit becomes vulnerable for electric shock and there is no way to prevent this 🙁

      Reply
    • Swagatam says

      The ground connection is a different issue, we are not considering ground here, we are only discussing how the phase/neutral may be used for a given AC load.

      The polarity consideration is not critical when the output is DC, just as in the above explained transformerless power supply, but is definitely crucial if an AC appliance is used such as fridge, geyser etc, and also in plug sockets, where the phase must always come through the switch in the socket…

      Reply
  93. Swagatam says

    No, it isn't.

    Reply
  94. Abu-Hafss says

    Hi Swagatam

    Is it possible to have current in between 100mA and 200mA?

    Reply
    • Swagatam says

      Hi Abu-Hafss,

      It is possible, provided the load voltage is rated at the input mains level, otherwise most of the current would drop producing no significant enhancement in current.

      Reply
  95. Swagatam says

    you can use a 5.1V zener in place of the shown zener, 0.22uF will not work because it won't be able to support the relay.

    Reply


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