• White LED Life Tester   NEW
  This simple circuit is designed to plug into a standard AC electrical outlet.  It uses four super bright white light emitting diodes (LED) in conjunction with a capacitor coupled full wave rectifier circuit. The LEDs are mounted in a box and are angled slightly to bounce the light off of a nearby wall.  The light should last about 10 years.  The circuit draws less than one half of one watt of power and can therefore run continuously.  In spite of the low power, the LEDs provide sufficient illumination for most night light applications.  Circuit component values for both 120vac and 240vac are shown.

• WHITE LED NIGHT LIGHT
  This simple circuit is designed to plug into a standard AC electrical outlet.  It uses four super bright white light emitting diodes (LED) in conjunction with a capacitor coupled full wave rectifier circuit. The LEDs are mounted in a box and are angled slightly to bounce the light off of a nearby wall.  The light should last about 10 years.  The circuit draws less than one half of one watt of power and can therefore run continuously.  In spite of the low power, the LEDs provide sufficient illumination for most night light applications.  Circuit component values for both 120vac and 240vac are shown.

White LED drive from 1.5V:    How do you get 3.5 volts to drive a white LED when you only have a 1.5v battery?...(schematic / circuit added 6/07)

White LED Driver Backlights LCD and Keypad:    11/13/03 EDN Design Ideas  /  (added 1/05)  Designers widely use white LEDs to backlight color LCDs and keypads in handheld devices, such as cell phones, MP3 players, GPS navigators, and PDAs. Their spectrum and brightness represent near-ideal light sources. One possible configuration for a phone or a phone/PDA combination is to have a group of three LEDs to light the display and six LEDs for the

White LED Driver in Tiny SC70 Package Achieves 84% Efficiency:    Linear Technology Magazine Design Ideas August 2002 (app note added 2/05)

White LED Driver Minimizes Space Maximizes Efficiency and Flexibility:    Linear Technology Magazine Design Feature December 2003 (app note added 02/05)

White LED Driver provides 64 step logarithmic dimming:    06/10/04 EDN Design Ideas  /  (added 1/05)  The circuit in this Design Idea is designed for portable-power applications that require white LEDs with adjustable, logarithmic dimming levels. The circuit drives as many as four white LEDs from a 3.3V source.

White LED Driver Touts High Efficiency:    06/12/03 EDN-Design Ideas / (added 7/03) White LEDs, the most recent addition to the LCD backlight, find common use in providing backlight for color LCDs. Thanks to their size and white-light output, they appear in small, portable devices with color displays, such as PDAs and cellular phones. Like other LEDs, a white LED needs a constant-current source—typically,....

White LED Head Lamp:    A white LED head lamp which can operate with only two AA batteries. The LEDs are driven in constant current, so that the brightness is maintained until end of battery life.  (added 10/05)

White LED inductorless drive from 1.5V and 3V:    The operating voltage of white LEDs coupled with my emotional need for low cost for a given function, motivates me to make LED drivers suitable for battery operated lanterns that can run from a small number of cells. White and Ultraviolet LEDs available at the time of this writing, require higher voltages than colored LED's. In the case of the ones I bought most recently, from 2.8 to 4 volts, depending upon operating current and the individual device....(schematic / circuit added 6/07)

White LED Power Supply Design Techniques:    TI Application Note  (added 2/06)

White LED Step-Up Converter in SC70 and ThinSOT:    Linear Technology LT1937 (app note added 02/05)

White LED Stroboscope With Constant Duty Cycle and Constant Current Drive :    Finally, white LED's are bright enough to use in a practical stroboscope. This circuit can operate as a bench-top stroboscope that, in conjunction with an oscilloscope or frequency meter and bench top power supply can accurately measure rotational speeds, or it can be operated hand-held from a single 9V battery, using a marked scale to estimate rotational speeds. Its a nice iinstrument to have on or around the workbench. Besides that, its fun to use...(schematic / circuit added 6/07)

White Light LED Driver with Gradual Dimming:    TI Application Note  (added 6/06)

White-LED Driver Touts High Efficiency:    06/12/03 EDN Design Ideas (added 1/05)  White LEDs, the most recent addition to the LCD backlight, find common use in providing backlight for color LCDs. Thanks to their size and white-light output, they appear in small, portable devices with color displays, such as PDAs and cellular phones. Like other LEDs, a white LED needs a constant-current source—typically, on the order of 15 to 20 mA....

ZXSC100 Single cell DC-DC converter LED driving applications:    Zetec Semiconductors  Applications Notes ZXSC100 single cell DC-DC converter offers an ideal solution to driving white LEDs in flashlights, enabling operation from a single NiCd or NiMH cell.   (app note added 6/07)