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3 Best LED Bulb Circuits you can Make at Home

The post elaborately explains how to build a 3 simple LED bulb using many LEDs in series and powering them through a capacitive power supply circuit

UPDATE:

After doing a lot of research in the field of cheap LED bulbs, I could finally come up with a universal cheap yet reliable circuit that ensures a fail-proof safety to the LED series without involving costly SMPS topology. Here's the finalized design for you all:

Universal Design, Developed by Swagatam

You just have to adjust the pot to set the output according to the total forward drop of the LED series string.

Meaning, if the total voltage of the LED series is say 3.3V x 50nos = 165V, then adjust the pot to get this output level and then connect it with the LED string.



This will instantly illuminate the LEDs at full brightness and with complete over voltage and over current or surge inrush current protections.

R2 can be calculated using the formula: 0.6 / Max LED current Limit

Why use LEDs

  • LEDs are being Incorporated in vast magnitudes today for everything that may involve lights and illuminations.
  • White LEDs have especially become very popular due to their mini size, dramatic illuminating capabilities and high efficiency with power consumptions. In one of my earlier post I discussed how to make a super simple LED tube light circuit, here the concept is quite similar but the product is a bit different with its specs.
  • Here we are discussing the making of a simple LED bulb CIRCUIT DIAGRAM, By the word "bulb" we mean the shape of the unit and the fitting secs will be similar to that of an ordinary incandescent bulb, but actually the whole body of the "bulb" would involve discrete LEDs fitted in rows over a cylindrical housing.
  • The cylindrical housing ensures proper and equal distribution of the generated illumination across the entire 360 degrees so that the entire premise is equally illuminated. The image below explains how the LEDs needs to be installed over the proposed housing.

The circuit of a LED bulb explained here is very easy to build and the circuit is very reliable and long lasting.

The reasonably smart surge protection feature included in the circuit ensures an ideal shielding of the unit from all electrical power ON surges.

How the Circuit Functions

  1. The diagram shows a single long series of LEDs connected one behind the other to form a long LED chain.
  2. To be precise we see that basically 40 LEDs have been used which are connected in series. Actually for a 220V input, you could probably invorporate around 90 LEDs in series, and for 120V input around 45 would suffice.
  3. These figures are obtained by dividing the rectified 310V DC (from 220V AC) by the forward voltage of the LED.
  4. Therefore, 310/3.3 = 93 numbers, and for 120V inputs it's calculated as 150/3.3 = 45 numbers. Remember as we go on reducing the number of LEDs below these figures, the risk of switch ON surge increases proportionately, and vice versa.
  5. The power supply circuit used for powering this array is derived from a high voltage capacitor, whose reactance value is optimized for stepping down the high current input to a lower current suitable for the circuit.
  6. The two resistors and a capacitor at the at the positive supply are positioned for suppressing the initial power ON surge and other fluctuations during voltage fluctuations. In fact the real surge correction is done by C2 introduced after the bridge (in between R2 and R3).
  7. All instantaneous voltage surges are effectively sunk by this capacitor, providing a clean and safe voltage to the integrated LEDs at the next stage of the circuit.

CAUTION: THE CIRCUIT SHOWN BELOW IS NOT ISOLATED FROM THE AC MAINS, THEREFORE IS EXTREMELY DANGEROUS TO TOUCH IN POWERED POSITION.

Circuit Diagram#1

led bulb circuit using high voltage capacitor

Parts List

R1 = 1M 1/4 watt
R2, R3 = 100 Ohms 1watt,
C1 = 474/400V or 0.5uF/400V PPC
C2, C3 = 4.7uF/250V
D1---D4 = 1N4007
All LEDs = white 5mm straw-hat type input = 220/120V mains...

The above design lacks a genuine surge protection feature and therefore could be severely prone to damage in the long run....in order to safeguard and guarantee the design against all sorts of surge and transients

The LEDs in the above discussed LED lamp circuit can be also protected and their life increased by adding a zener diode across the supply lines as shown in the following image.

The zener value shown is 310V/2 watt, and is suitable if the LED light includes around 93 to 96V LEDs. For other lower number of LED strings, simply reduce the zener value as per the total forward voltage calculation of the LED string.

For example if a 50 LED string is used, multiply 50 with the forward drop of each LED that is 3.3 V which gives 50 x 3.3 = 165V, therefore a 170V zener will keep the LED well protected from any sort of voltage surge or fluctuations....and so on

led bulb circuit with surge suppression

Video clip showing an LED circuit circuit using 108 numbers of LED (two 54 LED series strings connected in parallel)

High Watt LED Bulb using 1 watt LEDs and Capacitor

A simple high power LED bulb can be built using 3 or 4nos 1 watt LEDs in series, although the LEDs would be operated only at their 30% capacity, still the illumination will be amazingly high compared to the ordinary 20mA/5mm LEDs as shown below.

LED bulb circuit using 1 watt LEDs

Moreover you won't require a heatsink for the LEDs since these are being operated at only 30% of their actual capacity.

Likewise, by joining 90nos of 1 watt LEDs in the above design you could achieve a 25 watt high bright, highly efficient bulb.

You may think that getting 25 watt from 90 LEDs is "inefficient", but actually it is not.

Because these 90nos of 1 watt LEDs would be running at 70% less current, and therefore at zero stress level, which would allow them to last almost forever.

Next, these would be comfortably working without a heatsink, so the entire design could be configured into a much compact unit.

No heatsink also means minimum effort and  time consumed for the construction. So all these benefits ultimately makes this 25 watt LED more efficient and cost effective than the traditional approach.

Circuit Diagram#2

Surge Controlled Voltage Regulation

If you require an improved or a confirmed surge control and voltage regulation for the LED bulb, then the following shunt regulator could be applied with the above 3 watt LED design:

surge shunt regulator for LED bulbs

Video Clip:

In the videos above I have purposely flickered the LEDs by twitching the supply wire just to test ensure that the circuit is 100% surge proof.

Solid State LED Bulb Circuit with Dimmer Control using IC IRS2530D

A simple yet efficient mains transformerless solid state LED controller circuit is explained here using a single full bridge driver IC IRS2530D.


Highly Recommended for you: Simple Highly Reliable Non-Isolated LED Driver - Don't Miss this, Fully Tested


Introduction

Normally LED control circuits are based on buck boost or flyback principles, where the circuit is configured to produce a constant DC for illuminating an LED series.

The above LED control systems have their respective drawbacks and the positives in which the range of operating voltage and the number of LEDs at the output decide the efficiency of the circuit.

Other factors like whether the LEDs are included in parallel or series or whether they need to bedimmed or not, also affects the above typologies.

These considerations make these LED control circuits rather dicey and complicated.The circuit explained here employs a different approach and relies on a resonant mode of application.

Though the circuit does not provide direct isolation from the input AC, it has the features of driving many LEDs with current levels as high as 750 mA. The soft switching process involved in the circuit ensures greater efficiency to the unit.

How the LED Controller Functions

Basically the mains transformerless LED control circuit is designed around the fluorescent lamp dimmer control IC IRS2530D. The circuit diagram shows how the IC has been wired up and how its output has been modified for controlling LEDs in place of the usual fluorescent lamp.

The usual preheating stage required for a tube light utilized a resonant tank which is now effectively replaced by a LC circuit suitable for driving LEDs.Because the current at the output is an AC, the need of a bridge rectifier at the output became imperative; this makes sure that current is continuously passing through the LEDs during every switching cycle of the frequency.

The AC current sensing is done by the resistor RCS, placed across the common and the bottom of the rectifier.This provides an instant AC measurement of the amplitude of the rectified LED current.The DIM pin of the IC receives the above AC measurement via the resistor RFB and capacitor CFB.

This allows the dimmer control loop of the IC to keep track of the LED current amplitude and regulates it by instantaneously varying the frequency of the half bridge switching circuit, such that the voltage across the LED maintains a correct RMS value.

The dimmer loop also helps to keep the LED current constant irrespective of the line voltage, load current and temperature changes.Whether a single LED is connected or a group in series, the LED parameters is always maintained correctly by the IC.

Alternatively the configuration may also be used as a high current transformerless power supply circuit.

Circuit Diagram#3

solid state LED bulb with dimmer circuit

Original article can be found here

SHARING IS CARING!


About the Author

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!



203 thoughts on “3 Best LED Bulb Circuits you can Make at Home”


  1. Howdy, Friend! Interested to Learn Circuit Designing? Let's Start Discussing below!
  2. Hi Swagatam,

    I am trying to learn more about SMD transformers to use them in led powering circuits, Which are mostly found in led light bulbs or trimmers. Can you share me a link or a website where I can find more design based information on it?
    Or can you make me explain more on it?
    I have used those normal transformers in many college based projects, but now I would love to learn more on smd transformers. I am not getting more designed based information on it. Also getting confused with the number of pins those different transformers has.
    Any help would be really appreciated, I have just cleared my B.E so still a student not a professional guy! 🙂

  3. Hello sir I have 5mm 9v leds dome dip I have to connect 50 leds in series to 230v ac main wat will be the circuit for that

    • Hello Abdul, can you please specify the current rating of the LED, and is it an assembled module with a resistor, or is it a single isolated LED without resistor?

      • Hello sir it’s current amps is 20ma ……and it is not assembled with resistor …..it is single isolated led without resistor

        • OK in that case you can try the second circuit from the above article. Put all the LEDs in series, and for the zener diode use a 160V 1 watt zener diode.
          The zener number is NTE5101A

      • Sir, I would like to make a transformer less power supply with 2.2mfd/400v capacitor. I hope i will get aprox 140ma.current. the op voltage is to be lowered to 50v. Here what value of filter capacitor is to be used?

  4. Hello,
    I need to build led driver .Please help me for the circuit to make it.Is it possible to make led driver with both possibile input AC/DC?
    1
    INPUT VOLATAGE RANGE
    70-140 VDC / VAC
    2
    OUTPUT VOLTAGE
    15 VDC
    3
    OUTPUT CURRENT 1
    3 Amp
    4
    OUTPUT CURRENT 2 (WITH DIMMING FUNCTION)
    2.5 Amp
    5
    SURGE PROTECTION
    1.8KV, 1.2/50 µsec
    6
    WORKING TEMP
    0°C to 85°C
    7
    PROTECTION :
    Short circuit

    7.1
    open circuit

    7.2
    reverse polarity input

    7.3
    over voltage

    7.4
    under voltage

    7.5
    EMI / EMC PROOF
    8
    OUTPUT WATTAGE
    15VDC X 3 AMP = 45W

    • Sorry I do not have a 3 amp SMPS circuit with me at the moment, I would rather suggest you to buy one ready made and reverse engineer it and identify its full construction details

    • Rishabh, it could be either the LEDs are of bad quality and therefore not illuminating or they are burnt due to surge current….please use a zener diode as suggested in the last circuit, and also an NTC if pssible

  5. Dear Sir,

    Could you please tell value of inductor coil used in Philips 5 watts led bulb (which is burnt due to power fluctuation)

    • Dear Ravi, without practically checking the design it can be difficult to understand the correct specs of the coil…

  6. Dear Sir,
    I have made your circuit to power up my 100LEDs with 25LEDs in series and 4×25 LEDs in parallel. Its working fine. Just a concern. Shall I put a current limiting resistor on every 25LEDs branch. I tried putting 6.8K 1W and its getting quite warm. I am using the christmas Light LEDs C6 E10 0.1W 15mA. Your advise is greatly appreciated.

    • Dear Reeko, I am glad it's serving the purpose for you…however the 474 capacitor won't generate more than 25mA, therefore it's strange if the resistor is getting warm.

      Don't use 6.8K because it's too high, use 100 ohm 1 watt and see the difference.

      alternatively, you an make just two channels each having 50 LEDs, that would make the design even more efficient, cooler and brighter.

  7. If I have to reduce the no. Of LEDs to 4 hence what is the resistor I have to connect in series??
    Can you please give the calculation if possible ckt diagram.

  8. Dear Swagatam,

    I made this circuit and its absolutely working fine.

    I am an electronic hobbyist and want to learn in electronic and enhance my knowledge on field of electronics and circuit. Please could you recommned any book or tutorial. I was not PCM student.

    Thanks again.

    Rgds
    Sagar

    • Thanks Sagar, I am glad to know this.

      There are plenty of books and tutorials online, you can elect any of these as per your convinience

  9. I want to drive 3v 150ma leds. I have connected 3 leds in parallel and have connected 24 such parallel leds in series. I wanna know whether this circuit will suit my requirement?. Also kindly tel me the current output of your circuit.

    • No it won't….you will need to connect all the LEDs in series for making it work with this circuit…and for 150mA you may have to use 1uF/400V x 3 capacitors in parallel instead of the shown 474/400V

  10. Sir i want to make a sign board like "Welcome" with 555 and 4017.I will need seven strings ,each consisting of max 38 LEDs in series.Can i use this supply circuit ? Can you please refer me to such a circuit diagram…

  11. hello Swag good morning. pls am new here and my questions might sound so childish but i really want to learn from this blog. please Sir i want to design a 36W LED bulb with 220-240V input without a transformer. please advice kindly. thanks

  12. hello…..please suggest me….how can i calculate the valve of c1,c2,r1,r2…for different watt level of led bulb….how can i built transformer less rectifier circuit…????

  13. Please reply how to make led in home use 3volt, 5 volt, 9volt, please reply and what's the parts needed, to make it

  14. Help sir ,how to connect 8 mm 50 nos led,s to 220 AC supply.which value resistance ,capacitor and diode for need that connection.

    • Kiran, you can use the same circuit which is shown above if the current rating of the LEDs is 20mA, if it's more then you may have to increase the input capacitor value accordingly

  15. Hi Sir … I see this is an old post, but I want to know:

    Here in Mexico we only have 120v. What changes I need to do to this circuit to make it work?

    Thanks!!

    • Hi David, you can use the same circuit for 120V supply also, but more than 40 LEDs cannot be accommodated in series, ….upto 40 LeDs will work nicely

  16. Hi, I find your circuit interesting and I modeled it up in everycircuit with 16 LED's (5630 type). But in the simulation the current through the LED's is far too high, this is only resolved if I reduce the 500nF capacitor to about 1.2nF.

    everycircuit.com/circuit/4562220067848192

    Can you explain how this works, I can see that the input capacitor's reactance is being used as a voltage divider, but then surely the capacitors value needs to be adjusted for the number of LED's and the unput voltage?

    • Hi, that's why I consider simulators useless….and I never use them.

      0.47 is supposed to provide around 35mA current to the indicated 20mA LEDs, the excess 15mA could be dropped by the series resistors, in fact it could drop the current below 20mA I have not calculated it….but 0.47 is an optimal value…..

      for 5630 LEDs, even the 0.47uF won't be sufficient, since these are rated at 1/2 watt and would require around 150mA current…that's huge and could call for a capacitor as high as a 2.5uF for achieving optimal performance in the above circuit.

  17. Respected sir.,
    1. pleas tell me i want now the difference between ntc and vairistor(mov)?
    2. Can i use 10D431k mov ?

    • Satheesh, both are surge suppressors, NTC is connected in series with one of the mains input supply lines while MOV is connected between or across the supply lines.

      the specified MOV is not a good choice due to its higher clamping voltage spec (700V)…..it should be around 300V not above this.

  18. HI Friend…
    I want to ask something here, you mentioned 40 Led's (white 5mm straw-hat type) on your circuit,
    my question is:-
    1. Can I use 1w led's instead of 5mm straw-hat type?
    2. If yes then how many 1w led's I can use with this circuit? (without any changes circuit parts)
    3. What is the minimum & maximum life of this circuit?
    4. This circuit can handle low voltage?? (Due to rainy season you know sometimes we get low voltage in home. or If E.B workers works on the sreets and sometimes they try to connect line and we can see the voltage flick 2,3 times)

    Thanks in advance…

    • Hi friend,

      yes you can use 1 watt LEDs, anything between 40 and 90 LEDs in series can be tried….but you may have to increase the input capacitor value to 3uF/400V.

      the circuit life is permanent, but the LEDs can get burnt if an NTC or any other suitable surge limiter device is not included..so you need to include one at the input

      The low voltage handling range will depend on how many LEDs are used in series….40 LEDs will allow upto 140V AC input drop…and so on

    • Thank you SM, for vry quick reply,,
      I have few little doubt, I hope u will clear.
      1. I don't know what is my 1w led current, generally 1w led current is 300 to 350ma, but mine I don't know whether it is really 300/350ma or what…. so how to know the led current value? any calculation?
      2. you told me to put NTC at the input, :- what value of NTC I have to put? I mean what rating of NTC?? & and I am confused where to put NTC exactly….
      This circuit is work well with 5mm @20ma normal led's… but I want to run 1w led's. pls clear my above doubts

    • Oh thankssssssssssssss.
      I got it… ur great… I got it, the NTC should be put before c1(c1 and r1 as shown on ur above link article 1st picture).. you shown NTC value is 5D 11 (5ohm 11mm). you mean I an use NTC 5d 11,, Ok I will do and check, if any issue, I will free to text you.
      Thank you very much friend….

    • yes, according to me you can use 5D11 NTC for your application….the link is not opening because you might not have toggled the "share" option….tick the box and resend the link

  19. hello Swagatam
    Please I need your help for a diagram for a LED grow lamp ,direct power 220 volts
    4 red 1 blue all 3 watt LED , I would like to have 200 LED to create 600 watt

    • hello walter, I think I have answered to this question somewhere previously,
      anyway, you'll need an SMPS for driving 3w LEDs, you can't drive directly from 220V

  20. Dear sir.
    I'm SHRiNiVAS,
    first of all, I've no words how to thank you for all this. Bcoz I'm art student so electronics is thousands of miles away from my academic career. Bt your blog made me able to build circuits with full understandings.
    I've made this circuit with 90 LEDs. I'm getting so good illumination. I've also made your 1W single LED 220V AC circuit. Both are running very well. Now I want to attach only single 5mm LED to this 1 watt circuit. Actually I have posted you this requirement in the comment in that 1W circuit page bt maybe it couldn't reach to you or you may angry with me. Bcoz I couldn't got your reply. Well, if you got this message, please suggest some modifications in your 1W 220V AC circuit to attach only single 5mm white LED with safe brightness according to its durability.
    I hope my this effort won't be wasted.
    Thank you sir.

    • Dear Srinivas,

      I have replied to your previous comment also….please press the "load more" button to see hidden comments on pages which have more than 200 comments.

      for a single 5mm LED you just need to change the input capacitor value to 0.33uF/400V that's all….

  21. Hi friend,
    exactly i was waiting for this…….
    I seen ur 1st diagram, you shown 40 led connected in series. i want to ask you that if the single led 1w x 40 (3v) (in series) = 1w, 120v. Ok means watt will be the same only volt increased, but by my thinking its equal to 40w brightness… am i right??????
    next question is: which is the best?? >>> led in series or led in parallel ???
    next question is: this above circuit is durable? (long lasting) (if all parts purchased new from market, not from recycle)
    Thank you,

    • Hi friend,
      1watt led will not provide enough light because the current is too less in this circuit.

      but if you connect 5mm LEDs and use 50 LEDs then that would provide equivalent to 3 watts of light…so it's better to use 5mm LEDs than 1 watt LED

      use an NTC….or an MOV at the input f the circuit…then it'll be long lasting and reliable

      in the above type of designs, series is always better, but for 12V adapters parallel is better…

  22. Hi much respect to you for answering all the questions.
    I have 1cm square 12v 10w leds, can I use this circuit or would I need to change some values?
    Thank you

    • thanks time&space, the above circuit is only for low current LEDs, for a high watt LEd such as yours, a 12V 1amp SMPS would be recommended

    • Thank you for your reply, so if I want to put 30x 12v 10w should I put them in parallel with a 12v SMPS?

    • yes you can do that, but the 12V SMPS will need to be above 30 amp rated, or you can even try a 0-12V/50amp transformer for the same after aptly rectifying the output to a pure DC.

      a current controller circuit would also be required, but you can skip this by making use of a fan cooling behind the LED heatsink.

  23. Hi, yes you can use 20 LEDs with the shown circuit.

    no changes would be required in the circuit, if you see the resistors getting warm reduce it to 10 ohms each.

    connect a 80V/1 watt zener across C3.

    NTC/MOV can be used for extra safety, although technically the zener alone would be enough for the protecting the LED from current surges.

    NTC/MOV may be rated to control 100V (clamping voltage)

    • Thanks Sri, you can simply increase the input capacitor value to 2uF/400V for getting 150mA.

      However make sure to use an NTC thermistor at the input and also if possible a 200 to 500 turn coil over any iron core in series with the LED string

  24. Hello sir I want to run 300 leds of 5mm or 8mm to 230v AC main of 6 series in parallel each series of 50 leds so wat will be the changes for the circuit

    • Hello Basit, for this you may have to increase the input cap value to 2uF/400V by connecting two 105/400V in parallel, rest everything can be left as is.

      make sure each string has its own series a 22 ohm 1 watt resistor or any value between 15 and 30 ohms

  25. How much nos of smd led will work for this circuit and if I want to connect 100 nos of smd leds what will be the changes for the circuit

  26. Sir how much number of smd led will work for this circuit and if I want to connect 100 nos of smd led in series wat will be the changes for this circuit

    • Basit, since the maximum available voltage from the 220V input after rectification will be 330V so dividing this by the forward voltage of the LED gives 330/3.3 = 100

      so yes 100 LEDs will be just OK and can be connected in series,

      no changes will be required in the design.

  27. buna ziua domnule swagatam.cum pot face o lampa la 220v cu banda leduri auto de 12v.un exemplu de conectare leduri.multumesc anticipat.

  28. Dear sir.
    I build this circuit successful.but switch off time bulb instal in bulb holder. then bulb very very dim illuminate .
    1.why did it happen?
    another matter
    2.can I increase bright in the circuit?

    • Dear Hassan,

      i did not understand your query: ….."but switch off time bulb instal in bulb holder. then bulb very very dim illuminate"

      use more number of LED in series to increase the illumination…use at least 60 LEDs to make it bright and safe.

      also use a coil in series with the positive line….the coil can be made by winding 200 turns of 0.5mm magnet wire over an iron nail or bolt…this will prevent the initial surge current from entering the circuit

  29. hello dear mr Swagatam Majumdar
    first of all i want to thank you for making such good blog and let us know how to make incribble things.
    i have some question from you i hope i could have my answers.
    i maked this circuit and two other circiuts too
    i want to choise best and the one that is smallest and taking little space
    first of all i want to ask : can i run 20 or 18 or 38 smd leds (5730 model)on this circut?
    if i want to reduce leds to 18 what prameter should be change?
    if the leds goes up there will be changes in cureent and volatage too.
    but i want to this circiut delevery me 19 mA and 3.2 v for every led.
    you said cureent output will calculated by ractounce formula : Xc = 1/2(pi) fC
    if circuit eleverys 70ma out put will this burns leds?
    how should i controll the amp that pass leds? should i use resistor?
    if i use resistors thre will be voltage drops too. you said useing output cureent will drop mains from 308 to 0 !
    i`m a little bit of confused i`ll be thanks ful for your answrs.
    thank you again for your time.

    • thanks Hz021,

      you can use the number of LEDs as per your requirement, just make sure the current requirement of the LED string matches with the capacitor's current delivering capacity.

      This can be calculated using the reactance formula which I have comprehensively covered in one of my recent articles.

      Resitor can be used for controlling current but calculating the capacitor value correctly is recommended for ensuring proper efficiency and safety of the LEDs.

      All's been explained in the following article

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

      Additionally you may also want to include an NTC thermistor in order to arrest the switch ON surges which sometimes become the major cause of LED burning problems in these circuits.

  30. I bought a corn cob led lamp it won't work on DC only AC, I think because of the capacitor that would block DC. tyvm for sharing merci beaucoup

  31. Hi swagatam,

    I want to build this circuit. You said that if you used ntc thermistor the leds would last longer.

    So what is the value of the ntc?

    Sorry if my question is wrong as i'm a new electronic hobbyist who just visited your blog lately. But could you give me little light about that ntc thing for this project?

  32. sorry for asking too much… finally made with 40 leds, working fine bright,due to absence of zener, i got a 33D NTC from electronic ballast , it was present at i/p of supply in ballast. i used it in series with leds… lit very brightly n some leds gone. 33D cannot be used?
    necessary to connect it at 230v i/p of ckt?

    • replace the input capacitor with a 0.22uF/400V and check the response, if the brightness is good continue with it in the circuit, it will also reduce the surge current and stop the LEds from blowing off, without the need of an NTC. if possible use a coil in series with the LED chain for better protection. The coil could be made by winding 200 turns of 0.3mm magnet wire over any ferrite rod.

  33. Hi.. 🙂
    my name is Hz021 and i`m a guy how loves your blog!
    it`s full of treasure for me… XD
    but i have some questions about this circuit i hope you can help me.. (please)
    Q1: i want to use 20 smd leds each needs 20 mA and 3.4 volt for high bright. can you help me about value of caps and resistors? and please help me to learn how calculate the value for any other uses and situations.
    thanks again…

    • Thanks Hz021,

      Typically a 0.47uF/400V would also work for your application but if you are interested to know the exact capacitor value, it will need to be calculated by first calculating the reactance of the capacitor and then by using ohms law to find its current capacity.

      Once you find the reactance use it in place of resistance in Ohms law, voltage will be 310V after rectification, the third parameter "I" can be easily calculated then.

  34. Thank you sir…. i will use some 30 leds with 56ohms r and a 50v zener , i hope zener can be of any watt. 50v zener would be available in markets , also please give any substitutes if any…

    • If you don't find a 50V zener or any other closer value, then you can use two 24v zener in series for the same result

    • hi sir, i got 2nos 27v 1w zener instead. The zeners should be connected in series & then in parallel with led string, the +ve of zener to +ve of led & the banded to -ve of led string?

    • Hi Rohith, yes the zeners can be put in series and used….the banded side will connect with the anode end of the LEd string and the other side of the zener will connect with the cathode end of the LED string.

    • wow really awesome…. its really working bright…. at first it doesnt illuminated when i removed the zeners its working , i used 30 leds then 40. iam having 33D NTC can i use?
      thank you sir for posting such awesome circuits….

    • Thanks Rohith,

      yes you can use the mentioned NTC for suppressing surge.

      actually for 30/40 LEDs, the zener should be a 150V rated.

      My previous suggestion was for your earlier comment where you intended to use only 10 LEDs.

  35. As iam having 56ohms r2,r3 how many leds would be needed?
    1) how can i calculate the no of leds to be connected?
    2) if iam using a no of leds how to calculate resistance for this ckt?
    3)50v zener would be sufficient for any no of leds?wattage of zener?

    • lower resistance would increase surge current risks if the LEDs are small in number.

      at least 30 LEDs would be require if 50+50 resistances are used.

      however with a zener diode installed the risks could be completely prevented.

      multiply 3.3 with the number of LEDs and add 10 to it this would roughly give you the zener value for the particular number of LEDs.

  36. Hi sir, i got c1 as 6H474K 2L D its 474 /400v? i got it from shop. also R2,R3 56 ohms c2,c3 4.7mF/250v and planning to use 10 leds to this. can i proceed?
    also please tell what value of ntc to be connected for safety? ntc connected to ac supply input?

    • Hi Rohith, I am not sure about the capacitor number, you'll need to try it practically to confirm.
      for 10 leds use 1k/1watt for R2, R3……C2, C3 is fine.

      NTC won't be required for such a small circuit according to me, if possible connect a 50V zener parallel to the LEDs series end leads.

  37. how many led cant carry this circuit ? now i have 100 leds straw hat white ? can't the circuit apply with 100 leds !!

    • 100 x 3.3 = 330V. after rectification the ac should reach this values so I think the circuit would be able to handle all the 100 leds with a 220V input.

  38. sir what kind of pcb we used for making circuit for led bulb/tube?
    how much is life of these circuit?
    how can we increase life of these circuits?

    • You can include an NTC thermister at the input for increasing the life of the LEDs and the circuit.
      A glass epoxy PCB would be fine for this project.

  39. Good evening swagatam i your knowledge very valuablemthan you for sharing! Iwill take lus m advise as my country power is 110v also, but i have 5mm round superbright leds at 30ma 3.2v can i still use the same circuit or i habe to change something else? Kind regards

    • Hi Paula,
      you can use the same circuit as given above even with 110V inputs, just make sure the total LED count in the series does not exceed 30nos. otherwise the illumination could get weaker.

  40. Hello swagatam.
    Could you help me with the values of r1,r2,r3. The values and types of ci and c2, the values for d1,d2,d3,d4 for 110v ac. i am using the same 40 leds 3.2 v 30ma thank you in advance.
    Ps congrats you have the best circuit in the net

    • Hello Lus,

      You can use the same circuit which is given above for your application also, nothing needs to be changed except may be R2/R3 which can be reduced to 50 Ohms each.

  41. Please suggest the exact value of NTC which we can use for Surge Suppressor for the circuit
    https://homemade-circuits.com/2012/04/how-to-make-led-bulb-circuit.html

    And please also mention if the require NTC value is 5d-11 for
    https://homemade-circuits.com/2013/02/using-ntc-resistor-as-surge-suppressor.html

    And if time allow please elaborate in Surge protection circuit which we can design from component available in market. I read your topic on surge protection but exact value are not mention ( like for MOV ) so it difficult for beginners …. Facing very difficulties due to voltage fluctuation in my village town. many led bulb are stopped working. so kindly please reply. looking forward to hearing from you …..
    posted on your fb wall too, plz reply,, really needed your help

    • There's a big range of NTCs and MOVs ithe list and it's difficult to suggest a particular value because they are so closely differentiated, so it would be better to consult with your local electronic dealer regarding the correct one.

      If you want to avoid an NTC, you can use a transformer power supply in place of capacitive power supply and use a 7812 or 7824 IC for getting a well regulated power supply.

    • Helo sk,

      Parallel srings will result in low illumination, so it's not recommended, you should connect all the LEDs in series only.

  42. Good afternoon friends.
    My name is john, my passion to design an LED star lighting system is very intense but i don't have the complete knowledge yet, that is why i decided to access the internet to acquire more knowledge, in search i found your blog, with what i saw i was amase and as well happy because i know i can get some aid from you.

    My question is if my main is 220V , i want working 45-50 LED, i dont know value of resistor and capacitor . if you dont mind plz tell the electricity diagram

    can i know the value of resistor to use in series with the 3-LED?

  43. Sir, Can i use 250v MOV in parallel in front of input voltage in this circuit for high volt protection……

    PLZ Suggest me….

  44. Tanks Mr. Swagatam, I've done with this circuit. My Question is what kind of LEDs to make a real bulb, I mean not corn bulb, so we need less LEDs (3-10) & can I appy this circuit to do that? #reallysorry'boutmyBadEnglish

  45. Hello sir, i want to launch LED Bulbs in the market at low cost and also want to provide 1 year guarrenty with it.

    So, is this circuit suitable for this?

    • Hello Deepak,

      I am not quite sure about the life of this circuit, however by putting a 200V/3w zener diode parallel to C2 can make the circuit much reliable.

      • Sir,
        Please describe by a circuit diagram,i don’t understand ,what is (310V / 2 watt zener diode across the supply lines after the bridge rectifier).
        What type of wire I will use for series.i have no idea on electronic,please sir help me for understand.

      • Sir,
        What is (310V / 2 watt zener diode across the supply lines after the bridge rectifier) ,I don’t know ,please clarify me by above circuit diagram.

        Which type of wire I will be use for series led connection.

        Sir please help me, thanks

  46. ohh i see….. so do you have an awesome circuit to drive 1 watt power LED's? I searched your site but i couldn't find it anywhere. It would be a real help if you could post a circuit for 1 watt led's.

    Thanks in advance!!

  47. so if i changed the main 474k 400v cap to 3 uf, and the 1 uf cap to 100uf will i be able to drive 12+ 1watt led's in series with maximum brightness?

    • Unless you make the forward of the LEDs equal to the output voltage of the capacitor, it won't work.

      you will have to connect at least 60/70 LEDs in series only then you might be able to reach full illumination.

  48. Oh another thing Mr. Swagatam if i were to power 12, 1watt LED's in series(with maximum brightness, what changes do i need to do to your circuit?

    • capacitive power supplies are well suited for low current high voltage type devices, 1 watt LEDs do not come under this category and therefore will not work efficiently with the above circuit.

  49. OK I'll do that, thanks for the advice.

    One more thing Mr Swagatam, I made another one of these circuits, and when I checked the output voltage my multimeter reads 27 volts is that correct? or is something wrong with my circuit?

    And on another occasion i built your circuit it worked fine for a couple of days, but then it stopped working. My bulb has 35 led's in series, I checked the led's, all of them were fine. Then i started to power the leds 5 at a time, and they DID light up. When i reached 20 the leds were dim, and above 20 led's none of them would light up. This is strange cause all 35 led's were working 2 days ago(very bright too), and now the circuit doesn't have enough juice to power all of them. Could you tell me why this happened??

    THANKS IN ADVANCE!

    • Without load it should read equal to the bridge capacitor value, therefore the bridge capacitor should be rated at the highest possible value. lower values will slowy damage and leak the capacitor.

      for 35 LEDs, the output should be 35×3 = around 100V, I tink either one of the capacitors may be faulty in the circuit.

        • Jindro, a fan capacitor could be quite bulky, but you can use it. Try with a single a capacitor first, and check the brightness, using 2 might increase the risk of switch ON surge current and LED damage.

  50. HI! Mr.Swagatam i built your awesome circuit and it was working fine! After a couple of months it started to flicker. Now after 2 days of flicking it's stopped working. Could you tell me why this could have happened, could it be that one of the caps has gone bad?

    Thanks!!

  51. Thanks for your reply sir.

    Q1. If my supply voltage is 220v, does this means that the FWD voltage for 1LED is 2.2v?

    Q2. How can i get the LED current?

    • FWD voltage and current are fixed parameters as per the particular LED specifications, check out their datasheets for it.

      For example a 5mm LED normally has 3.3V as the FWD voltage and 20mA as the operating current.

  52. Thanks for your reply sir.
    What i am asking is, how will i know the values of the resistors to use in series with the 3-leds connected in series in the circuit constructed by Mr.Ishaan Pathania if i am to construct the same circuit?

  53. Thanks for the reply.
    The circuit i am talking about is the one constructed by Mr.Ishaan Pathania your follower.
    How can i get the value of the resistor he used?

    • The prototype used a 12V supply, the formula mentioned above is standard for all supply voltages, and may be used for the prototype also.

  54. Good afternoon swagatam.
    My name is kelvin, my passion to design an LED lighting system is very intense but i don't have the complete knowledge yet, that is why i decided to access the internet to acquire more knowledge, in search i found your blog, with what i saw i was amase and as well happy because i know i can get some aid from you.
    From the prototype above 3-LED was connected in series with a resistor.
    My question is if my main is 220V how can i know the value of resistor to use in series with the 3-LED?

    • Hi Kelvin, thanks!

      You can use the following formula:

      Supply voltage – LED fwd voltage divided by LED current

      With a capacitive power supply, after rectification the output would be 330V, 3 LED would have 3.3×3 = 9.9V as the FWD voltage and with 5mm LEDs the current for the series would be 20mA or 0.02 A,

      Therefore 330 – 10/.02 = 16000 ohms or 16k is the resistor required.

      But practically any smaller value resistance works with the above type of circuit because the current input from the capacitor is too low and therefore has little strength to burn anything.

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