The design of the LED night lamp circuit (bedroom light) is similar to that of many commercially available products. However, the light circuit does not use any kind of bulky and noisy stepdown transformers, but a capacitive potential divider is inserted in a simple manner to provide a constant current for driving the light source. Here a high-efficiency, low current blue LED is used as the light source. The design is safe, simple and stable!
When input power (AC 220V) is available, capacitor C2 is charged through C1 and R2 and bridge rectifier assembly D1-D4. Zener diode D5 limits the voltage across C2 to a safe value of near 15V. This low voltage dc supply is then fed to the LED (D6) via current limiting resistor R3. When the input supply is removed, LED stays on unchanged for a short time and then diminishes gradually. No instant darkness when the supply is switched off!
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After construction, enclose the circuit in a small plastic box. Drill a 5mm hole in the centre of the enclosure and fit the LED in a suitable LED holder in the 5mm hole. Finally fit a supply input socket and, optionally an on/off switch at the rear/side of the enclosure.
WARNING! Great care should be taken when working with this led night lamp circuit since it is connected directly to the fatal mains supply.