Created by
Created March 30, 2012
Last modified March 30, 2012
Tags led   led-lamp   mains-led-bulb  


This is my LED bulb which runs on AC 240V mains and is deployed on my porch.
The LED used here are 8mm 0.5W 150mA bright White color.


Not provided.


Hi, This is my very first LED lamp, I know it is little bit inefficient, bcoz I feel that I have put more Resistors here.

The values of components are:

Source: 240V AC, 50Hz

C1: 470nF 250V

R4: 1M Ohm 1/4W

R2, R3, R5: 680 Ohm 1W

Bridge: 4 x IN4007 Diodes

LED: 7 Nos, 0.5W 8mm 150mA Super White

My observation:

(1) The LED does not glow very bright...compared to glow obtained when I run 2 LEDs with 7.4V battery.

(2) The resistors R2, R3 becomes hot during operation.

(3) LED doesn't become hot considerably. They are warm after whole night operation.

Please suggest me improvements in this circuit, such that the LED glow upto their full potential with no power loss in Resistors.

by k.rajnikant
March 30, 2012

What's the purpose of the 1 MOhm resistor R4? My feeling is also that feeding capacitor (C1) is too small; if |Z| = AC impedance of capacitor = 1/2pi50*C and i=Vmains/Z the average current yelds to be appox 32 mA try doubling the capacitor before reducing the resistors. Please let me know if that improves somthing...

by ettore_galli
April 24, 2012

hello, I am trying to make a similar circuit attaching the link works well in theory...but in practice i get some 390V DC instead of 46V DC. let me know if something is wrong.

by kumar_rishank
November 28, 2012

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