Here is a High power White LED lamp that gives ample light in a room. It is an energy saving lamp and consumes very little power to give sufficient light. The lamp is directly powered from AC hence it is compact and easy to fix inside the switch board box.
The circuit uses 1 Watt White LED as the light source. Luxeon type high watt LEDs are now available. It is rated 3.6 volts and consumes maximum 350 milli amperes current.
1 Watt Luxeon LED
To get sufficient brightness of the LED, more than 200 mA current is required. The AC power is dropped by three 105K (1uF) AC capacitors to low voltage AC. Three capacitors (C1through C3) are connected in parallel to increase current so around 210 mA current will be available. The low volt AC is then rectified by the bridge comprising D1 through D4 and made ripple free by C4. Since the LED voltage is 3.6 V, Zener diode is used to regulate the DC to a safer level. Capacitor C5 act as a buffer to store current to give maximum brightness to the LED. Resistor R1 removes stored current from the AC capacitors when the circuit is unplugged and resistor R2 protects the circuit from transients and inrush current.
Caution: It is important to note that this circuit can give a lethal shock if handled carelessly. Most points are at mains potential, so that take utmost care while handling. Do not construct this if you are not experienced in handling AC circuits. Do not troubleshoot or test when it is connected to mains.
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