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White LED (White Light Emitting Diodes) Circuits
White LEDs:  #'s - D         E - O         P - S         T - Z         LED Circuits

 

Last Updated: October 18, 2017 05:04 AM

Circuits Designed by Dave Johnson, P.E. :

1-Nimh Cell powers White LEDThere 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 . . . Hobby Circuit designed by David Johnson P.E.-September, 2009

1W White LED Night LightAs many of you know, I have a pet peeve with poorly made LED night lights.  Often, the light from the LED quickly fades, so within months, the light is useless.  I have posted several versions of modified night lights using higher quality components.  This circuit is yet another version, which produces much more light than those other designs. . . . Hobby Circuit designed by David A. Johnson P.E.-November, 2008

24V DC Powered Beeper with 4 Separate Inputs24vac 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.  This hobby circuit below is one method to efficiently power a cluster of 7 white LEDs from 24vac. . . . Hobby Circuit designed by David A. Johnson P.E.-December, 2009

3v Battery Powered White LED DriverThe circuit below will drive any LED color, including white LEDs, using a DC power supply ranging from 2v to 3.3 v.  White and blue LEDs normally require over 3v, so the circuit below uses a charge pump scheme to deliver a constant LED light intensity. . . Circuit by David Johnson P.E.-August, 2010

Bidirectional Solid State RelayThe circuit below can switch up to 4 amps of current with a peak voltage up to 20v.  It is fully isolated using two inexpensive red LEDs.  One LED forms a red light source, which illuminates a second red LED.  The circuit takes advantage of the 1.5v. . . Circuit by David Johnson P.E.-May, 2009

Control Variable LED IntensityThe circuit below uses power from four rechargeable AA NiMH cells to drive 3 white LEDs.  A potentiometer varies the duty cycle of a pulse width modulator circuit to vary the intensity of the LEDs from 0% to 100%.  The beauty of the circuit is that when the . . . Hobby Circuit designed by Dave Johnson P.E.-September, 2009


Links to electronic circuits, electronic schematics, designs for engineers, hobbyists, students & inventors:

1 Cell Flashes White LED -  12/11/03 EDN-Design Ideas Many portable appliances and other products that must operate from a single cell are restricted to working at very low voltages.  It is thus difficult to drive white LEDs that typically have a forward voltage of 3 to 5V.  The ability __ Circuit Design by Anthony Smith, Scitech, Biddenham, Bedfordshire, UK

1.5V battery powers white-LED driver -  30-Sep-04 EDN-Design Ideas Although white LEDs are common in a variety of lighting applications, their 3 to 4V forward-voltage drop makes low-voltage applications challenging.  Charge pumps and other ICs are available for driving white LEDs, but they generally don't work with the low supply voltage of 1.5V in single-cell-battery applications __ Circuit Design by Steve Caldwell, Maxim Integrated Products, Chandler, AZ

12V White LED Driver -  DC powered LED lighting circuits can vary from trivial single LEDs with series resistors and LEDs with simple analog current regulators to more complicated switching power supply circuits such as this project. There is a tradeoff between simplicity and circuit capabilities. This more complex circuit adds features such as regulated light level across a wide range of input voltages and automatic circuit shutoff on low input voltage. __ Designed by G. Forrest Cook

18 LED dimmable LED lamp -  This circuit is a dimmable white LED lamp array with 18 LEDs.  The lamp brightness is regulated as long as the input voltage is above 10.5V.  A low-dropout analog voltage regulator is used for a simple and relatively efficient __ Designed by G. Forrest Cook

1-Nimh Cell powers White LED -  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 . . . Hobby Circuit designed by David Johnson P.E.-September, 2009

1W White LED Night Light -  As many of you know, I have a pet peeve with poorly made LED night lights.  Often, the light from the LED quickly fades, so within months, the light is useless.  I have posted several versions of modified night lights using higher quality components.  This circuit is yet another version, which produces much more light than those other designs. . . . Hobby Circuit designed by David A. Johnson P.E.-November, 2008

20mA LED Ballast -     (corrected text) I use this circuit for general use to power white LEDs, like a headset light I use on my desk and a keyboard light for my computer.  I built it into a tiny Radio Shack project box    (270-288) , which y no longer sell.  I put heat-shrink tubing  __ Designed by Andrew R. Morris

24V DC Powered Beeper with 4 Separate Inputs -  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.  This hobby circuit below is one method to efficiently power a cluster of 7 white LEDs from 24vac. . . . Hobby Circuit designed by David A. Johnson P.E.-December, 2009

30W White LED Automotive Headlamp Driver with Thermal Derating -  The LT3756, LT3756-1 and LT3756-2 are DC/DC controllers designed to operate as a constant-current source for driving high current LEDs.  They drive a low side external N-channel power MOSFET from an internal regulated 7.15V supply.  The fixed frequency, current-mode architecture results in stable operation over a wide range of __ Linear Technology/Analog Devices App Note,

3-Channel White-LED Driver Uses Simple Circuit Step-Down DC/DC Converter -  09/13/12  EDN-Design Ideas Drive multiple LEDs with current mirrors from a single step-down converter.   __ Circuit Design by Nora Jacalan Esteves, Technor Semiconductor LLC, Pleasanton, CA

3v Battery Powered White LED Driver -  The circuit below will drive any LED color, including white LEDs, using a DC power supply ranging from 2v to 3.3 v.  White and blue LEDs normally require over 3v, so the circuit below uses a charge pump scheme to deliver a constant LED light intensity. . . Circuit by David Johnson P.E.-August, 2010

50W White LED Automotive Headlamp Driver -  The LT3755, LT3755-1 and LT3755-2 are DC/DC controllers designed to operate as a constant-current source for driving high current LEDs. They drive a low side external N-channel power MOSFET from an internal regulated 7.15V supply. The fixed frequency, current mode architecture results in stable operation over a wide range of supply and output voltages. A ground referenced voltage FB pin serves as the input for several LED protection features, and also makes it possible for the converter to operate as a constant-voltage source. A frequency adjust pin allows the user to program the frequency from 100kHz to 1MHz to optimize efficiency, performance or external component size.
 __ Linear Technology/Analog Devices App Note, Jul 20th 2010

7 by 10 LED Moving Sign -  This sign uses two LED arrays to form a 7 X 10 matrix.  It produces moving messages or animations stored in an EPROM.  It uses no microprocessor.   As in most electric signs, the LEDs are matrixed, and strobed very quickly.   __ Designed by Bob Blick

7 Component Regulated LED Lamp -  This is a minimal parts lamp made with four white LEDs.  It features regulated light output from 10V to around 20V and works well as a flashlight.   __ Designed by G. Forrest Cook

AC Line Powered LED Strings -  This shows 4 different ways to string white LEDs that are powered by a 120vac or 240vac power line.    This hobby circuit was designed by Ken Schultz.   __ Designed by Ken Schultz, drawn Dave Johnson 12.18.2004

Atmel AVR Tiny13V for driving a white LED -  LED headlamp projects: Tiny13V microcontroller as step up    (boost) or step down    (buck) voltage converter for driving a white or high power LED.     (pdf file) Desgin equations and source code included.   __ Designed by Steven Weber, KD1JV

Bidirectional Solid State Relay -  The circuit below can switch up to 4 amps of current with a peak voltage up to 20v.  It is fully isolated using two inexpensive red LEDs.  One LED forms a red light source, which illuminates a second red LED.  The circuit takes advantage of the 1.5v. . . Circuit by David Johnson P.E.-May, 2009

Buck IC Boosts Battery Voltage for White LED -  04/24/03  EDN-Design Ideas White-light LEDs are finding their way into many markets that incandescent bulbs once served.  Flashlights are among the newer applications in which reliability, ruggedness, and ability to control the power draw of the LEDs make these devices attractive.  With incandescent bulbs, the power management for the device is a simple on-off switch __ Circuit Design by Robert Kollman, Texas Instruments, Dallas, TX

Buck regulator controls white LED with optical feedback -  10/25/07  EDN-Video Design IdeasBy using optical feedback, you can stabilize the output level of a high-intensity LED __ Circuit Design by Dhananjay V Gadre, Netaji Subhas Institute of Technology, New Delhi, India

Buck/Boost Charge Pump Regulator Powers White LEDs from a Wide 1.6 Volt to 5.5 Volt Input -  App Note #1021__ Maxim Integrated

Build a Bright-White LED Torch -  You get high brightness, a cool white light and very low battery drain.  And you'll never have to replace the bulb again.__ SiliconChip

Charge Pump & Step Up DC DC Converter Solutions for Powering White LEDs in Series or Parallel Connections -  App Note #1037__ Maxim Integrated

Circuit Delivers Dimming Control for White-LED Driver -  10/28/04  EDN-Design Ideas The demand for power in color cell-phone handsets is constantly increasing.  New applications steadily emerge, making it imperative to reduce power consumption in the design.  Examination of usage data shows thatthan 50% of the power __ Circuit Design by Wallace Ly, National Semiconductor, Santa Clara, CA

Circuit drives latching relays -  02/01/96 EDN-Design Ideas Figure 1 shows a low-parts-count circuit that can drive one- or two-coil latching relays.  Latching relays are useful in sensitive analog designs.  The 74ACT174 hex flip-flop has ample capability to drive the Aromat TQ2E series of latching relays.  Both windings for the TQ2E-L2-5V two-coil relay are on the same magnetic element, so the windings' fields add.  You __ Circuit Design by Roy McCammon, 3M Austin, TX

Circuit drives mixed types & quantities of LEDs -  10/03/02 EDN-Design Ideas Portable systems often use LEDs of different colors and in varying quantities of each color.  Some examples are white for the display backlight, green for keypad illumination, and red for power.  Typically, the LEDs derive power from at least two power supplies  one for "standard" LEDs (red and green] and one for white LEDs __ Circuit Design by Mark Pearson, Maxim Integrated Products, Sunnyvale, CA

Circuit Drives White LEDs -  11/23/00 EDN-Design Ideas Newly available white LEDs are replacing CCFLs  (cold-cathode fluorescent lamps] in handheld applications using a back-lit LCD.  These applications include PDAs  (personal digital assistants], digital cameras, and cellular telephones,  __ Circuit Design by Eddy Wells, Texas Instruments

Compact Inductorless Boost Regulates White LED Bias Current -  App Note #1116__ Maxim Integrated

Constant current, constant voltage converter drives white LEDs -  09/02/04  EDN-Design Ideas LEDs usually take their drive from a constant dc-current source to maintain constant luminescence.  Most DC/DC converters, however, deliver a constant voltage by comparing a feedback voltage to an internal reference via an internal error amplifier.  The easiest way to turn a simple DC/DC converter into a constant-current source is to use a sense resistor to convert the output current to a voltage __ Circuit Design by Keith Szolusha, Linear Technology Corp, Milpitas, CA

Control Variable LED Intensity -  The circuit below uses power from four rechargeable AA NiMH cells to drive 3 white LEDs.  A potentiometer varies the duty cycle of a pulse width modulator circuit to vary the intensity of the LEDs from 0% to 100%.  The beauty of the circuit is that when the . . . Hobby Circuit designed by Dave Johnson P.E.-September, 2009

DC/DC Converter Drives LumiLEDs White LEDs from a Variety of Power Sources -  DN340 Design Notes__ Linear Technology/Analog Devices

Deliver Dimming Control for White-LED Driver -  10/28/04  EDN-Design Ideas The demand for power in color cell-phone handsets is constantly increasing.  New applications steadily emerge, making it imperative to reduce power consumption in the design.  Examination of usage data shows thatthan 50% of the power __ Circuit Design by Wallace Ly, National Semiconductor, Santa Clara, CA

Drive latching relays -  02/01/96 EDN-Design Ideas Figure 1 shows a low-parts-count circuit that can drive one- or two-coil latching relays.  Latching relays are useful in sensitive analog designs.  The 74ACT174 hex flip-flop has ample capability to drive the Aromat TQ2E series of latching relays.  Both windings for the TQ2E-L2-5V two-coil relay are on the same magnetic element, so the windings' fields add.  You __ Circuit Design by Roy McCammon, 3M Austin, TX

Drive mixed types & quantities of LEDs -  10/03/02 EDN-Design Ideas Portable systems often use LEDs of different colors and in varying quantities of each color.  Some examples are white for the display backlight, green for keypad illumination, and red for power.  Typically, the LEDs derive power from at least two power supplies  one for "standard" LEDs (red and green] and one for white LEDs __ Circuit Design by Mark Pearson, Maxim Integrated Products, Sunnyvale, CA

Drive White LEDs -  11/23/00 EDN-Design Ideas Newly available white LEDs are replacing CCFLs  (cold-cathode fluorescent lamps] in handheld applications using a back-lit LCD.  These applications include PDAs  (personal digital assistants], digital cameras, and cellular telephones,  __ Circuit Design by Eddy Wells, Texas Instruments

Driving White LEDs -  The 555 is capable of sinking and sourcing up to 200mA, but it gets very hot when doing this on a 12v supply.  The following circuit shows the maximum number of white LEDs that can be realistically driven from a 555 and we have limited the total current to about 130mA as each LED is designed to pass about 17mA to 22mA maximum.  A white LED drops a characteristic 3.2v to 3.6v and this means only 3 LEDs can be placed in series.  __ 555-Timer

Dual Full Function White LED Step-Up Converter with Built-In Schottky Diodes -  LT3466__ Linear Technology/Analog Devices

Dual White LED Driver Features Integrated Switches & Schottky Diodes in 3mm × 3mm Dfn Package -  DN1010 Design Notes__ Linear Technology/Analog Devices

 

White LEDs:  #'s - D         E - O         P - S         T - Z         LED Circuits

 


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