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Light Emitting Diodes (LED) Circuits
LEDs:   #'s - B     C - G      H - L       M - P       Q - T     U - Z 
 

Last Updated: December 07, 2017 02:05 PM

Circuits Designed by Dave Johnson, P.E. :

 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 Johnson P.E.-February, 2010

 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 3.3 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 from . . . Hobby Circuit designed by David Johnson P.E.-August, 2010

 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 Dave Johnson P.E.-September, 2009

White LED Lifetime Tests  -  All white LEDs fade over time.  I find that some LEDs fade in intensity very rapidly while others fade more slowly but every one I have tested would be worthless in a few months to a year.   To speed up the testing process I have modified my constant current LED driver circuit as shown below.   . . . Dave Johnson, Lubbock TX-DC Magazine - Issue 7 Mar 2010 

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.-May, 2003

 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 Dave Johnson P.E.-December, 2009

Wig/Wag LED Flasher - This simple circuit will flash two LEDs in an alternating fashion. . . Circuit by David A. Johnson P.E.-December, 2004

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 David Johnson P.E.-January, 2011


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

Weekend Projects with Bre Pettis: Make a Joule Thief -  It's a little wisp of a circuit that allows you to drive a blue or white LED from a low voltage.  Normally, if you want to light up a blue or white LED you need to provide it with 3, 3.5 V, like from a 3 V lithium coin cell.  But a 1.5 V battery like a AA cell simply will not work.  But using the Joule Thief, it works like a charm.  Not only does it work with a brand new battery, but it works until the battery is nearly dead-- down to 0.3 V.  That's well below the point where your other toys will tell you the battery is dead, so it can steal every last joule of energy from the battery  (hence the name) .  To learn how to make one, watch the video, which is available in a variety of formats.  __ Evil Mad Scientists Laboratories

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 Johnson P.E.-February, 2010

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? __ Designed by Dick Cappels

White LED Drive. 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 __ Designed by Richard Cappels

White LED Drive. 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 __ Designed by Richard Cappels

White LED Driver -  Efficient circuit runs off 12V and drives up to 30 white LEDs.  It can even switch on automatically when darkness falls.__ SiliconChip

White LED driver backlights LCD & keypA - D -  13-Nov-03 EDN-Design Ideas 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 keypad __ Circuit Design by Fabien Franc, Catalyst Semiconductor, Sunnyvale, CA

White LED driver operates down to 1.2V supply voltage -  09/03/07  EDN-Design Ideas This circuit beats commercially available LED drivers, which bottom out at 2.5V input voltage, by operating at voltages as low as 1V.   __ Circuit Design 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 3.3 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 from . . . Hobby Circuit designed by David Johnson P.E.-August, 2010

White LED driver provides 64 step logarithmic dimming -  10-Jun-04 EDN-Design Ideas 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 current from 1 to 106 mA in 64 steps of 1 dB each.  The driver is a charge pump that mirrors the current ISET (sourced from IC3's SET terminal] to produce a current o __ Circuit Design by William Hadden, Maxim Integrated Products, Sunnyvale, CA

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.   __ Designed by The Electronic Lives Manufacturing-presented Chan

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 __ Designed by Dick Cappels

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 Dave Johnson P.E.-September, 2009

White LED Light Probe for Inspection -  This circuit is useful for inspecting narrow spaces like the inside of the CPUs, monitors, PCB modules and other electronic devices.  The light source is a pencil-thin tube with ultra-bright white...__ Electronics Projects for You

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.-May, 2003

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.   __ Designed by Dick Cappels

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.   __ Designed by Dick Cappels

White LED Power Supply Design Techniques -  TI App Note 

White LED Shines From Piezoelectric-Oscillator Supply -  10-Jan-08 EDN-Design Ideas A piezoelectric ceramic buzzer powers a white LED from a single cell __ Circuit Design by TA Babu, Chennai, India

White LED Step-Up Converter in SC70 & ThinSOT -  LT1937__ Linear Technology/Analog Devices

White LED Stroboscope with Constant Duty Cycle & 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,  __ Designed by Dick Cappels

White LED-Based Emergency Lamp & Turning Indicator -  White LEDs are replacing the conventional incandescent and fluorescent bulbs due to their high power efficiency and low operating voltage.  These can be utilised optimally for emergency lamp and vehicle turning...__ Electronics Projects for You

White LEDs -  In the past whenever something had to be lighted, we have used yellow LEDs (Light Emitting Diodes) , as a substitute for white light.  But now white LEDs are available.  We can finally get rid of those pesky yellows.  Unfortunately the new LEDs are not 100% white ! , they have a small blue shade, which is more notably in pictures than in real life.  As a conclusion the white LEDs are far better than the yellow ones. __ Contact: kenneth @ pallund . dk

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 Dave Johnson P.E.-December, 2009

White Light LED Driver with Gradual Dimming (Rev. A) -  TI Application Note:  Many consumer products using white light LEDs for illumination and backlighting provide gradual LED illumination at turnon and turnoff.  This gradual illumination is usually achieved with the aid of a microprocessor that provides PWM dimming control.  This circuit uses the Texas Instruments TPS61040 white light LED driver to provide gradual illumination at turnon and turnoff without the use of a microprocessor __ SLVA122A–November 2002–Revised January 2008

White-LED driver backlights LCD & keypA - D -  11/13/03  EDN-Design Ideas 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 __ Circuit Design by Fabien Franc, Catalyst Semiconductor, Sunnyvale, CA

White-LED Driver Touts High Efficiency -  12-Jun-03 EDN-Design Ideas 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 __ Circuit Design by Dimitry Goder, Sipex Corp, San Jose, CA

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

White-LED flasher operates from one cell -  05/26/05  EDN-Design Ideas 1.5V circuit flashes white LED __ Circuit Design 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/Analog Devices

Wig/Wag LED Flasher -  This simple circuit will flash two LEDs in an alternating fashion. . . Circuit by David A. Johnson P.E.-December, 2004

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 David Johnson P.E.-January, 2011

Wireless Volume Control -  17-Aug-11 -Design News:   Andrew Morris decided the usual wireless volume controls don’t offer enough functionality, so he created the ultimate volume control that connects between a computer or MP3 player and an amplified speaker system. __ Designed by Andrew R. Morris, Gadget Freak-Case #192

Wireless-Powered LED -  Wireless power is transferred from transmitter to receiver coil using inductive coupling principle.  For wireless power transfer to work efficiently, frequency of the transmitter and the receiver must be tuned to...__ Electronics Projects for You

YoYo enhancement Device -  The original yoyo was equiped with 2 LEDs that lit up whendevice was spinning.  I decided to add a micro to give it some extra pazazz.  The trick here is to makeunit work without a power switch.  The mercury switch is positioned so that it supplies power when unit is spinning.  After about 20 seconds, PIC shuts down in sleep modes,  __ Designed by Luhan Monat-Mesa Arizona

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