Monday, November 24, 2014

White LED Light Strip

The white LED light strip    


Three white LEDs in 3258 SMD footprint in series with a 150-Ohm resistor are powered by 12V.  Ten of there are connected in parallel.  They can be cut or soldered together to make short or long string.  On the back is the 3M stick tape, which makes installation easy on any place.  The forward voltage of the white LED is specified 2.8-3.6V at 20mA. In this configuration, the current draw is about 16mA; 20% of the power is wasted as heat dissipation in the resistors.  I suppose such construction is to make the power supply simply, just a constant 12V.

This type of white LED strip is not very bright; it is good for decorative lighting.  For serious illumination, high power LEDs are needed.