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LED light Answered

Hello! First of all I want to say hi to everyone as this is my first post! I hope to learn some interesting things from all of you. 
On the topic now. I want to make a USB LED night light for my sister. I wanted to make it USB powered with RGB (or whatever they are called. I'm not too familiar whit all this stuff) LEDs that you can control in computer. Is something like that possible without expensive controllers and what not? Every answer will be appreciated. 
Thank you!

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Goodhart

5 years ago

It would depend on whether you want the light to be manually turned on, OR if you need it to fade in, and fade out, turn on only when motion is detected, etc.
A computer aided on off like iceng has listed isn't hard.

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iceng

5 years ago

Someone asked something similar.

This works to lite up in the dark using only 20ma to drive the LED.

When the ambient light comes on the LDR turns on the MOSFET which robs the 20ma current from the LED, D2 and D3 turning the nite-lite off.

The zener protects the FET gate if you chose a higher voltage.

R2 is dependent on that voltage and the LDR ( Light Dependent Resistor ).

LDR-LEDriver.JPG