Tuesday, March 04, 2008

220V Line Powered LED Lamp

To connect a single LED lamp to the 220V AC line, the minimum need are a series a high voltage capacitor and a resistor. A diode also in parallel with the LED in reverse polarity connection.

The diode prevents reverse voltage breakdown of the LED. The resistor is needed to prevent in-rush (surge) current to the capacitor if from OFF (discharged). An additional resistor in parallel to the capacitor to bleed the charged voltage when the circuit is OFF to prevent electric shock.

Computing for values:
I(led) = 0.02
Xc = V/I(led) = (220-3)/.02 = 10850
Cmin = 1/(2*pi*Xc) = 1/(2 *pi * 60 * 10850) = 0.24uF = 0.22uF nearest value


Blogger Roger Salgado's Galleries said...


Works fine for me. I was trying to make something like this to work but burned out some leds... Now it's finally done. Thanks allot.

1:42 AM  
Blogger Eythymios said...

I have a problem. How many watts should 1kohm resistor be? I used a 16watts resistor but it gets heated in a short period of time and turn off the circuit because i'm afraid it will be destroyed. Please answer. Thanks

11:46 AM  
Blogger boris said...

I have the same problem, the 1k resistor burns...

3:00 PM  
Blogger Adnimo said...

You can use many in parallel to divide the "work". For instance if you want to use 4 resistors, each will have to be of 4k ohm in this case to get 1k resistance.

8:37 AM  
Blogger alimokoi said...

how about if i will add a series of leds, is it ok, do i have to change the value of the resistor or capacitor?

6:55 AM  
Blogger Panamint Joe said...

Using 220V RMS for the R and C computation will lead to a shortened LED life, perhaps as little as 3 years in actual use. It would be better to aim for a 25 mA peak current, so use 220V x 1.414 = 311V in your computation. Adjust as appropriate for the standard mains voltage in your area. Note to hobbyists in the U.S.A.: In recent years some utilities have surreptitiously raised the mains voltage from the nominal 110V to 120V, even as high as 130V RMS, in order to cause excess current consumption in lights and appliances, thus raising revenues for them and shortening the lives of said lights and appliances. If in doubt, measure the actual RMS mains voltage in your application.

For those of you reporting the 1K ohm resistor burning out, it will be dissipating 0.4W in the given circuit, so it should be sized to at least 2W rating for adequate reliability. (This is operating at 20% of rating; in some industrial applications, resistors are run at no more than 10%, or even 5% of rating for reliability.) If you're still burning out resistors after that, check the capacitor to make sure it's no larger than 0.22uF. The capacitor should have a 600V rating for use with line voltage. The 1K ohm resistor may run warm, but should never run hot. (Don't use your finger to test the temperature, as you are working with potentially lethal voltage.)

3:01 PM  
Blogger Giuseppe-Lucky said...

This comment has been removed by the author.

5:28 AM  
Blogger Giuseppe-Lucky said...

Thank you for posting this circuit. I used a 0.20uF for C1 since that was the closest available. I also used a 5W rating for R1 and 2W for R2.

The temperature I got from R1 was no more than 34C and no more than 35C on C1 after 5 minutes.

Power source is 220V (311V rms) 60Hz.

5:42 AM  
Blogger Geophy said...

This comment has been removed by the author.

9:22 AM  
Blogger Geophy said...

I tried to connect self color changing LED to this circute, but it only emit red light. Will you help me how to connect self changing LED to 220-230v AC Directly for running of colors from the said LED?

9:24 AM  
Blogger Gert said...

The value calculated for Cmin was done correctly, but the formula was given incorrectly Cmin=1/(2*pi*Xc) and should be Cmin=1/(2*pi*f*Xc), the f for frequency was omitted
Thanks a lot for the info!!

12:49 AM  
Blogger Aadhith said...

i'm new to this circuits involving AC.
please help to find a circuit to connect led bulbs to 220 v ac mains.

7:57 PM  
Blogger Aadhith said...

please help me in getting a right circuit for connecting at least 5 led's to 220v ac mains. help me with the values of components to be used and formulas.

8:00 PM  
Blogger alansaki said...

Hey thanks for also share its layout diagram.. I like to design circuit for it.
circuit board

10:24 AM  
Blogger Anir said...

Hi! I am Anirvan and I want to know if a single 8mm white LED can be connected to AC in series with 0.22uF capacitor without any additional resistors?

5:51 AM  
Blogger TEJAS SHAH said...

Fine more hobby circuit at miscinfomedia.blogspot.com

1:31 PM  

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