The only electronic website that replies to every comment, and addresses all circuit related issues.

## Simple LED Bulb Circuit

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.

Image credit: http://www.sharplumi.com/en/userfiles/20100913191605380.jpg

Circuit Description

The circuit of a LED bulb explained here is very easy to build and the circuit is very reliable and long lasting. The exclusive surge protection feature included in the circuit ensures an ideal shielding of the unit from all electrical power ON surges.

The diagram shows a single long series of LEDs connected one behind the other to form a long LED chain.

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. These figures are obtained by dividing the rectified 310V DC (from 220V AC) by the forward voltage of the LED. 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.

The power supply circuit used for powering this array is derived from a high voltage capacitor, whose low reactance is exploited for stepping down the high current input to a lower current suitable for the circuit.

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).

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.

Parts List

R1 = 1M 1/4 watt

R2, R3 = 50 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 LED bulb 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, you can refer to the following concepts and implement any one of these in the above simple design:

Using an NTC Thermistor as a Surge Suppressor
SCR Shunt for Protecting Capacitive LED Driver Circuits
High Power Zener Diode Circuit

The following images were sent to me by one of the keen followers of this blog Mr.Ishaan Pathania. The shown prototype of a simple LED lamp was built and tested successfully by him:

•  Stumble

1. Hi Swagatam,

C2 and C3 is electrolytic capacitor?

thanks

1. Yes they are electrolytic caps.

2. In diagram there are two capacitors C1 and C2.

Q1. Both are electrolytic right?

Q2. C1 positive is connected to mains, and negative is to shown point in bridge rectifier. C2 positive is connected to that point between R2 and R3 and C2 negative is connected to point on bridge rectifier. Is that correct?

Q3. What values would change if mains was 110V or 120V? I think R2 will reduce is this correct? Is its value 50 ohms, 1 watt?

Thank you sir
Jay

3. please ignore the above comments they were for the earlier diagram.

C2 is electrolytic, C1 is metallized PPC type.

Your second points are correct, but C1 being a PPC cap does not have any polarity.

Yes with 110V R3 can be made less, however noting is much critical.

Please check the parts list for the component values.

2. Hi,

can i use 20 pcs of LED to this circuit? 10 pcs for each array.

Thanks

1. Hi,
Yes you may use any number of LEDs within 10 and 50 in this circuit with an input of 220V AC.

Regards.

3. hi,
can you tell me the led specifications?coz many type of leds avlbl now.how much it costs?what is the approx cost of 1mfd 400v ppc?what is the o/p ampere avlbl in this circuit? what is the need of 10mfd 400v cap? pls help.

1. I'm not sure about the present rates of the components...., the ampere will be 100mA at the output, the caps are there for filtration.

2. ok thanks..can i use this circuit to drive a 12v 200ohm relay,using 7812 sir?if not , can you pls suggest a transformerless relay drive circuit plss

3. Yes you may connect a relay to the above circuit, 7812 IC won't be required, the voltage will automatically adjust due to low current rating of the supply.

Regards.

4. Hi,
I am trying to learn from your blog sir :-)

Q1. Can I know between which nodes (points) we can connect a relay?
Q2. What would be the purpose of such a connection of relay?

Jay

5. Hi,
you are welcome!!

The relay can be connected across the positive and the negative of the bridge.

On powering the relay contacts will operate....that's all will happen, the purpose will depend on the users plans.

4. hello swagatam

i m a newbie to the analog world and would like to know the role of each and every component present in the above circuit.

thanks...

1. R1,2 = for surge protection
R0 = for eliminating capacitor discharge shock on the 2-pin when removed from the socket.
D1--D4 = for making AC to DC,
C1 = for filtering the above DC
LED resistors = for limiting current to the LeDs so that they don't get damaged from over current.

2. correction.

C1 = for dropping mains current to tolerable limits,
C2 = for filtering rectified DC.

5. What is the power of this circuit?? How mucs is it brighter as a normal filament bulb??

1. 2 watts power, equivalent to a 60 watt filament bulb.

6. hi.. can i use a 5mm white led's for this project???

1. Yes you may use them...

2. hello..i coudnt find some of the values
instead of 1m 1/4 watt i got 1m 1/2 watt
and r3-r7 i got 56ohms 1/4 watt instead of 50ohms 1/4 watt
and c1 i got 104/200v instead of 104/400v
and c2 i got 10uf/450v
are those ok.. if not please suggest me wat to do
i also asked the shopkeeper for c1 if he has 104/600v .. he doest have

3. 1M, 1/2W is ok,

56 Ohm is OK,

C2 is also OK,

C1 will NOT do, minimum volts should be 250 and above.

7. can the leds of 3.2v-3.6v will do in this circuit
waiting
thankyou

1. Yes it will do.

8. hi.. can u please tell me how can i connect 7 parallel of 4led in series, making 28 leds, connecting to 230v ,12v or 6v

1. Make 7 strings of 4 LEDs each by connecting smaller lead of one led to the longer lead of the next led....finally you'll have 7 similar strings of 4 leds which will have a negative and a positive lead terminated at the ends, make all the positive ends common and all the negative ends common. Connect the negative lead to negative of the supply and positive to the positive of the supply. That's it.

Please make sure each string has its own individual limiting resistor....

9. Sir can i use 1W LED for this circuit? or a combination of 1W LED and 15mm white LED? thanks sir..

10. Yes they may be used, but the corresponding resistor values may need some tweaking for optimizing uniform brightness...

11. Sir,
Can I replace C1 with 105/400V instead of 104/400V
I couldn't find the 104/400V
Thanks...

1. Yes you may do it...

12. Hello,
What would I have to do to make this work with the US 120v outlets?
Thanks

1. Hello,

Just reduce 10 LEDs from the series for using with 120V inputs.

13. hi sir,in your Compact 1 Watt LED Driver Circuit at 220V/110V Mains Voltage...can i cunnect power direct to (on birdge)diode's +/- point and a 56omhs restence apply on LED -tiv side

1. No you cannot do that, it will burn the whole circuit instantly.

14. Dear friend.

Thanks for the circuit. Do u have circuit for stable led driver. Because most of time our main supply is not stable. Its going up and down every time. At that time light of the bulb is also going up and down. I am looking for solution for it .

Thank you

1. Thanks!

An smps circuit can be used for powering LEDs which will provide a constant voltage irrespective of input fluctuations. SMPS power supplies are very stable and compact, perfectly suitable for driving many LEDs together.

15. Thanks ,, for ur reply,

Do u have smps circuit that can use to light up 50-100 LED.

1. You can check out the following circuit:

2. but it's very complicated, don't u have simple SMP circuit

3. You can build a transformer power supply for it as shown here:

16. Sir,

R1 = 1M - 2 watt instead of 1M - 1/4 watt
C1 = 474 / 270V instead of 474/400V or 0.5uF/400V PPC
C2 = 10uF/450V instead of 10uF/400V

thank you---

2. Sir,
Thank you,
And I will try to build "LED Tube Light Using Transformer" too, as you shown

Thanks again

17. Sir can you provide me with a flash light circuit by using the flash type bulb used in camera.using 12vDC or 230VAC

1. Do you mean a stroboscope bulb....??

2. OK I'll try to publish it in this blog soon......

3. Thank you eagerly awaiting

1. Hi Kumar,

You can make the circuit shown in this link:

19. Excellent bright,
Sir,
I have a couple of capacitor 105/400V, can I use for this circuit??
Thank you

1. Thanks Kartiko,

That's fine...but a single 105/400V will be enough for this circuit.

2. Sir,
I've made ​this circuit for a 2 bedroom, but I still have some 105/400V, can I use to replace the 474/400V?
I want to make a few more lights with this circuit
Simple and directly lit
Thank you & have a nice day...

3. Yes you can use it, but make R2, R3 = 330 Ohms 1 watt each

20. Hi,
Is the output voltage after the R2 and ground 120VDC?
How can we compute it? For example, I just want 50VDC?

Thanks

1. Hi,

Actually the output voltage is across the bridge positive and negative points.

For getting precise 50VDC you can add a 50v zener across the bridge rectifier outputs.

21. Hi,
Good day Mr.Swagatam, I would like to ask you if I can use a 2uf/400v instead of a 10uf/400v cap.

Jay

1. Hi Jay,

Good Day,

Yes you can use it, it will do the job.

22. hi,
can i use 6 parallel path carrying 2 leds
and the lamp will glow if any of the LED get damaged?

1. no, that won't give sufficient light....it's quite unlikely for any led to get damaged, even if it does, the remaining would still remain illuminated, no worries.

23. Dear Sir

My name is Thusith and Im from Sri lanka,

can you tell me the parts that will sute for lit 60leds

Thanks
Thusith

1. Dear Thusith,

you can use the above circuit for 60 leds also, connect them all in series.

24. hi sir u r doing great work your blog is very helpful
sir pls tell me can i use 30
1w power led with full brightness wit this circuit

1. Hi Vaibhav,

This circuit won't support 1 watt leds, so it won't work....

2. Sir, what will happen if i use 105/400V instead 474/400V,its increase the brightness of all leds?

Sir, the led required for this is 5mm straw hat type but can i use square led like the manufactured corn sample lamp?

4. 105/400v will increase the brightness, but the risk of surge current will increase....

5. the square leds are probably 1 watt type, so cannot be used with this circuit...

6. Sir, like you said its ok to use the 105/400v but risk the surge current..what parts or components need to change to use 105/400v?

7. Use an MOV at the input of the circuit.

25. hi sir.
sir i want to build this circuit for my home. let me know the 150nos of 5mm white led can replace the 20w CFL light?

1. Hi Vaibhav,

yes 150nos 5mm LED will replace a 20w CFL light.... use high bright type

26. thank u so so much sir your blog is very helpful. i m learning lots of things from your blog and you r realy genius and crystel clear heart for sharing your knowledge.
i had build 4 circuit succesfully from this blog. for my home and they r realy working fine. thaknks again sir....

1. you are welcome Vaibhav!

27. sir hight bright type means smd or round type leds?
if u know any part no. of these leds.

1. any 5mm white LEd which is costly and not cheap will be hi-bright type.

28. ok sir thank u.
sir can i drive this 5mm led for long time with transformerless power supply (means 1to2 years)

1. Add an MOV at the supply input points for better safety and guarantee.

2. Use smd led`s for ultra brightness

29. sir can i use 385v MOV to parellel with input capacitor?

1. Don't put in parallel to the capacitor, put it across the input lines (phase/neutral).

30. Hello Swagatam

Dear i have the same capacitor which i had used in 1w circuit one is 1uf 400v and 2nd is 1uf 250v .

can i use the 1uf 400v instead of c1 474/400V and

1uf 250v instead of C2 10uF/400V ?

1. Helo Rajan,

1u will generate more surge currents, so I am a bit skeptical....you better use a 474/400V as the input capacitor for better reliability.

31. MR.Swagatam first of all i need to tell you that your web site is awesome! Thanks to you my knowledge of electronics has been greatly improven.
And secondly i am from Sri lanka and the area which i live in, the Cfl's and the incandescent light bulbs keeps flickering all the time. So will this flickering have any effect on your circuit and the leds??

Thank you
Dilan Leelawardena

1. Hi Dilan,

Thanks!

you may put more number of capacitors parallel to the 10uF/250V, this will help stabilize the voltage fluctuations, and will produce constant illumination.

Regards.

33. Mr. Swagatam, what will happen if i change R1 and R2 to 100 ohm resistors? will the LED's blow up or will they get brighter(cause they are a little dim rite now)?

Thank You
Dilan Leelawardena

1. Mr. Dilan, 100 ohms will slightly increase the light, you can try it, you may try even lower values, it's not critical.

34. dear sir,
Can you explain about most suitable MOV for this circuit...
thanks,
Nandana.

1. Dear Nandana,

2. Alrite thank you bro

35. Mr. Swagatam your circuit works great for 5mm LED's, but when i connect this circuit to a 8mm led its really dim. Anything i can do to make it brighter?

1. Mr Dilan,

you may try increasing the cap value at the input to 1uF/400v, see what happens.

36. OK thanks again. You are a great adviser Mr. Swagatam!

37. Hi,
Swagatam Majumdar,

How can we adjust the circuit with 230V input

1. Hi Ranjith,

The above circuit is designed for 230V only.

38. hiii,
swagatam
i am sunit , i just try this circuit, i give 40 leds in series , as ur diagram shows. and change the r2 & r3 to 150 ohm , 2 watt . but r2 burns every time. how can i prevent this?

1. hi sunit,

I hope you've used 474/400V cap.only

anyway try reducing the values to 50 ohm 2 watt and check.

39. Thank You very much for sharing this circuit with us. I built one just now, and working fine. And please tell me ,the main purpose R1 resistor is using in this for discharging C1 or reducing the the voltage. And thank you again for sharing knowledge with us.

1. Thanks!

R1 is for discharging C1 when the mains plug is removed... to eliminate 220V shock in the form of stored capacitor current over the plug pins.

2. Thank you very much for the explanation.

40. Sir,

I am made this circuit successfully & it worked.

I am Used 12(chain) LED.

I Would request U Please tell me how to measure how many watt use when 12 LEDs are emitting.

1. measure the current by connecting a DC ammeter (DMM set to DC current range) in series with the LED chain, record the reading.

Next measure the voltage just across the LED chain.

multiply the two values to get the power consumption.

2. Sir,

I masure it. It shown 2.2watt..

Now I want to know when I plug it with wall socket after 1-2 minute LED are mightly glowing like Phosporus & also when I turn off the wall socket switch..
WHAT IS THE MATTER...

Thanks.

Avik

3. one of the LEDs might have blown off, check each LED and find the faulty one and replace it with a new one.

4. Sir,
Not a single LED,all LED are mightly glowing Continuously untill unplug from wall socket but I am not powered on the wall socket switch And also after turn off wall socket switch. Is it any ground related problem. But any type voltage not shown in multi meter.

AVIK

5. just reverse the pins of the plug into the socket, and then check.

6. Sir,

I want to add a switch with this circuit. Is it possible PLZ suggest me...

Avik

7. put it in between C1 and bridge

41. sir i want t o operate it using the battery then wht should be the rating of the battery for 40 leds and if there any change in circuit.

thnku sir,
renjith

1. you can use a 12V 7ah battery, make 13 strings of LEDs having 3 series LEDs with individual 220 ohms, connect all the strings in parallel to the battery

42. Anyone plz post a picture of this circuit and how bright it glows.

43. Hi sir
I need put around 65-70 LED s to this circuit. So what the new Values for
R2 and R3
many thanks
I'm Aruna

44. Hello Mr Swagtam
Thanks for this circuit
how can I use 67 LED lights for your circuit. Because my printed board has designed for 67 LED s.
Thank you again
Kumar

1. Hello Kumar and aruna,

use the same circuit which is given above for 65-70 LEds....connect all the LEDs in series, the circuit will then operate at 220v, not at 120V though.

45. Jash from Sri-lanka-

Dear Sir,
Is this circuit works with 01watt 05nos LEDS's in series connection ?
thanks

1. Dear Jash,

No, this circuit will not be able to drive 1 watt LEDs.

46. hello sir
am shail

i would like to know what changes should be done to circuit to make it work in range from 110-220 v
and 50 to 60 frequenct

thank you

1. hello shail,

the above circuit will work for both the voltages, however 120V won't support more than 32 LEDs.

47. hai sir first thank to you.
sir how to construct circuit for 230V/12V 2AMP. WHAT COMPONENTS i will change for changing voltage and current.

1. A capacitive power supply cannot be modified for producing 2 amp current, it can be dangerous and is not recommended.

48. 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?

1. 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 3.3x3 = 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.

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?

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

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?

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?

1. 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.

53. 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!!

1. Hi Dilandki, this problem is the main issue with these kinds of circuits, it happens due to occasional surge currents, you can either use a thermister at the input for cancelling these surges or use an SCR network as shown in this post:

for thermister connection see this circuit:

54. 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??

1. 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 35x3 = around 100V, I tink either one of the capacitors may be faulty in the circuit.

55. 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?

1. 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.

56. 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?

1. 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.

57. 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.

1. I have something in my mind regarding this, will share it soon in my blog.

58. Hello sir,
Sir i want to drive 160 led can i use 32 -32 led's group in parallel with this circuit.plz help me out

1. hello Kapil,

yes you can do that!

59. 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?

1. 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.

60. Sir, can you post a very reliable 10w LED bulb circuit, i wll be very thankful to you

1. you can take the help of the following post for making it:

61. 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

62. Hey Swagatam,

is there any substitute for 200V, 1watt Zener Diode???
plz tell me

1. Hi Bharat,

You can try this circuit, remove D1 and use it for setting any desired surge free output voltage

63. hi swagatam,
I just wanted to know if we can use cob type led for this 'bulb' circuit ?

1. yes SMD leds will also work here.

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

PLZ Suggest me....

1. Yes, you can use it, put it after C1

65. Sir,

Do you have any circuit which provide 12v 100ma power supply.........

1. Avik, you can try the following design:

dimension the input cap for 100ma output

2. Hello sir.....
can i put 10 strings of 4 leds in parallel??
What could be change in the circuit?

66. 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?

1. Hi John, if you want to use a capacitive power supply as explained above, then probably the calculations won't be too critical, still you can refer to the following article for details:

with 3 leds the formula for the resistance would be

R = supply V minus total led forward V divided by LED current

2. i am sorry i dont understand
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

3. my main 220v, i have 1watt LED 45ps, how i can work this LED's 220v ???

4. you did not mention in your first comment regarding 1 watt LEDs...for 1 watt leds,45 nos you will need a 12V 5amp smps power supply and connect with it 15 parallel strings of these leds each having 3 leds and a separate 6ohm 1 wat resistor

5. hi ...swagatam
i dont have smps power supply...i dont want use smps power supply...i have 1n4007 4ps,474/400v 1ps, 10uF/400v 1ps....how connect

67. Hello sir......

Can i put 4 strings of. 10 led in parallel???
What could be change in the circuit?

1. Helo sk,

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

68. sir i need to connect only 10 to 20 leds what changes should be needed?

1. You can use the same circuit which is shown above.

69. Please suggest the exact value of NTC which we can use for Surge Suppressor for the circuit

And please also mention if the require NTC value is 5d-11 for

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 .....

1. 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.

70. 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

1. 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.

71. Thank you very much swagatam

72. Hello swagatam

This circuit at this blog "How to Make a LED "Bulb" work with inverter ?

1. Avik, yes it will work with an inverter output also.

73. 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

1. 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.

74. Appreciate your help swagatam. Regards

75. 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?

1. 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.

76. Hi Sir how r U.....

If I change input capacitor 474k 400v to 105k 400v what change i need...

1. Hi avik,
if you are using 5mm leds, it could get slowly damaged with a 1uF cap.

77. Sir, I want to use 8mm LED

1. 8mm leds are also rated at 20 to 25mA so they will be also vulnerable, using 474/400V will be safer

78. Sir,

As per specification 8mm LED 3.2v & 150mA.

1. for 150mA leds, 105 capacitor will be OK, you may use it.

79. Sir,

sir if i want to use 105 capacitor is it any change need in this circuit....?????

1. no changes would be required!

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

1. 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.

81. 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?

1. 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.

82. 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?

1. 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.

83. 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...

1. 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

2. the zener should be 1 watt rated...

3. 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?

4. As iam using 56ohms 2 resistors i can connect 30 to 40 leds will be fine working?

5. 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.