USB Night Lamp Circuit using White LEDs

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USB Night Lamp Circuit using White LEDs
USB (Universal Serial Bus) are most familiar for connecting external peripherals with our PC and establishing communication between them. Here we are going to use USB for unfamiliar purpose, yes a reading or night lamp. Time to change your old unused USB cables into an low cost miniature lamp which will come handy in several situations. Read How to strip USB Cables

WHITE LEDs:

white-led-light-voltage-drop-current-consumption
White LEDs

LED’s are gradually taking over the lighting industry completely due to its low power consumption and samll size. And white LED is the most employed one when coming to lighting and lamp circuits due to its luminosity and high lighting efficiency. White LEDs drop 3 to 3.5v and current consumption around 30mA.

WORKING OF USB NIGHT LAMP CIRCUIT:

In the above circuit the LED’s are powered by supply through the Vcc pin of the USB cable. The USB offers a regulated 5V power supply so there is no need to add any sort of regulator. The USB is also capable of supplying around 500mA when PC is running in mains supply.

Each LED is capable of dropping 3.5 volts hence i have connected them in a parallel manner. So for a LED of voltage drop 3.5v and current consumption of 30mA the value of the resistor will be 5 – 3.5 V / 30mA. Thus the resistor value we obtain is 50 ohms, so i opted for standard value 56 ohms.

You can increase the amount of LED’s used however care must be taken since over usage may drain the battery when PC running in back up power supply. This is a useful and fun DIY circuit so everybody try this and post your outcome.

 

Related Designs and Schematics

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Frank Donald

Junior Network Engineer at Tata Communications
Frank Donald is an Electronics and Communication Engineer who is very passionate about his subject. Reading, Surfing and Blogging are the things he loves.

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