White LED Array that is Lined Powered  -  There has been a lot of excitement lately in the lighting industry. Some companies are beginning to manufacture general lighting fixtures, which replace incandescent and fluorescent lamps, using LED lights. When proper heat management is designed . . . [Hobby Circuit designed by David A. Johnson P.E.,  02/28/10]

White LED Drive Circuit. Part 1  -  How do you get 3.5 volts to drive a white LED when you only have a 1. 5v battery? Be Careful About Peak Current A note of caution: These LEDs are comparatively expensive, so I suggest putting a small resistor (1 to 10 Ohms) in series. . .  [by Richard Cappels]

White LED Drive Circuit. Part 2  -  Alternative Types of Cores If you can't find a ferrite core, or even an old rusty nail, all is not lost. You can still make a pretty good white LED power supply by using a non-magnetic core. It sounds like an oxymoron, but a. . .  [by Richard Cappels]

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?. . .  [From Dick Cappels' project pages]

White LED driver backlights LCD and keypad  -  11/13/03  EDN Design Idea   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 con. . .  [by Fabien Franc, Catalyst Semiconductor, Sunnyvale, CA]

White LED driver operates down to 1.2V supply voltage  -  09/03/07  EDN Design Idea   This circuit beats commercially available LED drivers, which bottom out at 2. 5V input voltage, by operating at voltages as low as 1V. . .  [by Dave Wuchinich, Modal Mechanics, Yonkers, NY]

White LED Driver powered by a 3v Battery  -  The circuit below will drive any LED color, including white LEDs, using a DC power supply ranging from 2v to 3.3v. White and blue LEDs normally require over 3v, so the circuit below uses a charge pump scheme to deliver a constant LED light intensity from . . . [Hobby Circuit designed by David A. Johnson P.E.,  08/15/10]

White LED driver provides 64 step logarithmic dimming  -  10-Jun-04 EDN Design Idea   The circuit of Figure 1 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 and adjusts the total LED cur. . .  [by William Hadden, Maxim Integrated Products, Sunnyvale, CA]

White LED inductorless drive from 1.5V & 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 LEDs. . .  [From Dick Cappels' project pages]

White LED is Powered By One Nimh Cell  -  There are a lot of white LED driver circuits floating around. A popular circuit called the “Joule Thief” can drive one white LED from a single 1. 2v or 1. 5v battery cell. Most of these circuits use one or two transistors to form a voltage boost circuit . . . [Circuit by David A. Johnson P.E.,  09/26/09]

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.  . . . [Hobby Circuit designed by David A. Johnson P.E.,  05/27/03]

White LED Night Light for the Home  -  This project uses lethal voltages. If you are not experienced in working with lethal voltages, read this project, but don't build it. You only have one life, and AC power can take it from you very quickly, or leave you with terrible injuries. . . .  [From Dick Cappels' project pages]

White LED Power Failure Light  -  Where I live most of the time, the AC power drops out upon occasion. This used to leave me groping around in the dark for a flashlight. I could have bought a battery-backed up "emergency light" for about US$35, but being basically metal boxes with floodlights attached, they would make my living room look more like a prison. And besides, I make things like this for fun, so thinking about the problem eventually lead to the solution on this web page. The power failure light that I eventually designed and built is housed in the plastic case from a wall-mounted power transformer. I had accidentally destroyed the transformer by shorting its output, and had kept the plastic case for years, just waiting for a project like this one. Since its mounted in a hand-sized enclosure, when the power fails, it is a simple matter to walk over to the light, unplug it from the wall, and use it like a flashlight to walk into other rooms to retrieve a flashlight. This particular lamp dims after a few minutes, and is down to a dull glow after about 15 minutes. The glow can last for hours after that. I suspect that this is at least partly the result of using rechargeable batteries from a surplus store. . . .  [From Dick Cappels' project pages]

White LED Stroboscope With Constant Duty Cycle & Constant Current Drive   -  Finally, white LEDs 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, . . .  [From Dick Cappels' project pages]

White LEDs powered by 24V  -  24vac is a popular voltage. It is often used in low voltage lighting systems and industrial controls. It is much less dangerous than 120vac/240vac line voltages. The circuit below is one method to efficiently power a cluster of 7 white LEDs from 24vac . . . [Circuit by David A. Johnson P.E.

White Light LED Driver with Gradual Dimming  -  TI Application Note. . .   

White Light LED Driver With Gradual Dimming (Rev. A)  -  LED lighting designers are challenged with meeting their efficiency and reliability goals faster in advanced LED lighting designs. LED lighting customers seeking the latest in innovative and affordable LED lighting solutions can benefit from TI's broad product portfolio of LED drivers, AC/DC, DC/DC, power management devices, wireless and wired interface control and embedded processors. LED designers have the option of not only controlling the power stage, but regulating LED currents as well, eliminating the need for multiple components and reducing system cost. . . .  [Texas Instruments App Notes, 10-Jan-07]

White-LED driver backlights LCD and keypad  -  11/13/03  EDN Design Idea   A simple circuit uses transistor junctions to monitor multiple temperature zones (Figure 1). The temperature sensors are ordinary, general-purpose, low-cost, diode-connected transistors. The well-known diode equation VBE = (kT/q) ´ln (IC /IS ) shows that the. . .  [by Fabien Franc, Catalyst Semiconductor, Sunnyvale, CA]

White-LED Driver Touts High Efficiency  -  06/12/03  EDN Design Idea   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. . .  [by Dimitry Goder, Sipex Corp, San Jose, CA]

White-LED driver uses improvised transformer  -  02/15/07  EDN Design Idea   Minimal component-count circuit boosts a single cell's voltage to light an LED. . .  [by Jim Grant, Scientific Controls, Orlando, FL]

White-LED flasher operates from one cell  -  05/26/05  EDN Design Idea   1. 5V circuit flashes white LED. . .  [by Anthony H Smith, Scitech, Biddenham, England]

Wide Input Range 1a LED Driver Powers High Brightness LEDs with Automotive & 12 VAC Supplies  -  DN1012 Design Notes (Linear Technology). . .  [Linear Technology]

Wideband Low Noise Amplifier Drives 50 Ohm Loads  -  10/23/97 EDN Design Idea   The circuit in Figure 1 is a wideband, high-gain amplifier with two useful features not often found in combination.  The input-referred noise is 2. 6 nV/ (square root Hz], yet it can deliver 27 dBm into a double-terminated 50 ohm load or 30 dBm into a single-terminated load. The circuit uses two monolithic op Amps. . .  [by Mitchell Lee, Linear Technology Corp, Milpitas, CA]

Wideband, High Input Impedance, Gain = 1000 Amplifi er  -  The gain is distributed equally between four amplifier sections in cascade, so the gain of each section is about 5. 6. Distributing the gain uniformly provides the best bandwidth. Trimming of the final stage corrects for resistor variances so that overall gain is 1000x. . . .  [Linear Technology App Note - , Jun 21, 2011]

Wideband, low-noise Amplifier drives 50V load  -  10/23/97 EDN Design Idea   The circuit in Figure 1 is a wideband, high-gain amplifier with two useful features not often found in combination.  The input-referred noise is 2. 6 nV/ (square root Hz], yet it can deliver 27 dBm into a double-terminated 50 ohm l. . .  [by Mitchell Lee, Linear Technology Corp, Milpitas, CA]

Wig/Wag LED Flasher  -  This simple circuit will flash two LEDs in an alternating fashion . . . [Circuit by David Johnson P.E.,  12/18/04]

Wireless LED Flasher  -  There are times when you would like to flash a LED through a thick plastic case without wires. The circuit below performs this feat. It can be powered from a supply ranging from 3v to 6v. It draws about 300ua of average current at 5v . . . [Circuit by Dave Johnson P.E.,  01/09/11]

xTimer V1.0  -  Easy build 4-channel timer, suitable for energy saving, simple hardware and nice firmware with c coding. Automatic power down mode, simple settings, optional buzzer for sound alarm. . . .  [Wichit Sirichote, designer]

Zener level-shifter drives high-side switch  -  06/16/2014  EDN Design Idea    simplify a high-side driver by replacing a transistor with a Zener diode. Microcontrollers, the heart of all modern electronic gadgets, are increasingly powered with sub-5V power supplies. This complicates the control of external loads powered by higher voltages. . .  [by Dhananjay Gadre & Nidhi Sharma]

ZXSC100 Single cell DC-DC converter LED driving applications  -  Zetex Semiconductors Applications Note:   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. . . .   

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