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

Last Updated: October 24, 2017 02:55 PM

Circuits Designed by Dave Johnson, P.E. :

 Simple Circuit for White LED Night LightThis 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. . . Circuit by David A. Johnson P.E.-July, 2003

 Simple Circuit Negative Supply CircuitThis simple circuit consists of two LEDs and a photo diode.  It generates a negative voltage with a current level of a couple milliamps.  It is ideal for supplying a negative rail to low power “rail to rail” op amp circuits, which need to have a true zero volts output.  Note:  This circuit is not particularly efficient . . . Hobby Circuit designed by David Johnson P.E.-July, 2006

Solar Fireflies In Jar Light -  When I was a kid, growing up in Illinois, I remember catching fireflies and putting them into a jar.  I loved watching them flashing away at night.  Later, I would let them out to live another day. . . . Circuit by David Johnson P.E.-September, 2017

Solar Mason Jar Light -  I have modified several commercial solar garden lights over the years.  I switch out the LED, solar panel, battery pack and control circuit.  The result is a much better overall light.  One of my disappointments in using store-bought garden light assemblies is their construction.  They are built so cheaply that over time, water and insects get inside, killing the light operation. . . . Circuit by David Johnson P.E.-September, 2017

Solar Powered Lighthouse -  While at a discount store one day, I spotted an interesting tall lighthouse.  It had a tiny solar panel and an equally tiny LED light.  The LED was pointing downward, at the center of a rotating light reflector.  I thought it might be turned into an interesting addition to my wife’s garden. . . . Circuit by David Johnson P.E.-September, 2017

Solar Powered Quartz Clock -  Connect a solar panel to a quality AA size 1One of my homes in Colorado had a large battery powered quartz clock above the fireplace.  It was powered by an AA size 1.5v alkaline cell.  The battery would run the clock for about a year or so, then I would have to break out a tall step ladder and replace the battery for another year or so of operation. That gave me a great 10:1 energy margin. . . . Circuit by David Johnson P.E.-September, 2017

Solar Powered Flood Light using NiMH
Cells
There are many solar powered garden lights available.  Most of the devices offered at the home improvement stores have very poor performance.  Their batteries are too small, the light launched is weak and the solar panels are undersized.  None of the devices I have tested would operate through a typical night. . . Circuit by Dave Johnson P.E.-December, 2013

 Solar Powered Infrared 1W Security Camera IlluminatorMany security cameras are equipped with an array of infrared LEDs to illuminate an area in front of the camera with invisible light for night time surveillance.    However, there are times when a remote area, well away from the camera, needs additional infrared light.    The circuit below uses a modified solar powered path light to bathe a fairly large area with 850nm infrared light. . . Circuit by Dave Johnson P.E.-June, 2014

 Solid State Relay that is BidirectionalThe 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 . . . Hobby Circuit designed by David A. Johnson P.E.-May, 2009

 Sound Triggered Night LightA while back, I received a schematic from a guy by the name of Karl.  He described a situation he and his wife found themselves in aboard a cruise ship in the Caribbean.  They were staying in a room toward the inside of the ship, which did not have any port holes, windows or a balcony. . . Circuit by David Johnson P.E.-August, 2013

 Super Bright 3v Powered LED FlasherI have posted several kinds of LED flashers over the years.   This is yet one more flasher, designed to flash any high power LED of any color.  It hits the LED with a 25ms 250ma pulse once every 2 seconds.   This works out to an average current about 3ma.  It. . . Circuit by Dave Johnson P.E.-April, 2009

 

 

     

 


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

SAA1064 display Module project -  This isn't a complete project really.  Actually it is a display module that I like to use in "quick and dirty" projects that need an easy to use display module.  This page is meant as a reference for myself, and for you if you want to build one of my projects that uses it.

Safety Flasher -  This circuit alternately flashes two high-brightness LEDs as a safety measure during jogging or walking.  The LED’s can be mounted on clothing or a belt.  The circuit draws a precisely controlled 10mA in order to conserve battery life.  Also, the battery vol __ Designed by Andrew R. Morris

Safety Light -  My 1200 square foot metal shop only has one small entrance door and no skylights.  If the lights are turn off while inside, there is not enough light to safely find the door to exit the building.  On a couple occasions, while I was quietly working at my test bench, my wife would walk into the shop, grab a garden tool and rush back out, turning off the lights and closing the door without thinking . . . Hobby Circuit designed by Dave Johnson P.E.-November, 2004

Schematic & breadboard layout for reversed LED color sensor using an opamp -  If it seems complex at first, don’t panic.  Note that there are a lot of extra parts to provide an interactive experiment. __ Contact: David Cook

Scheme provides high-side current-sensing for white-LED drivers -  19-Feb-04 EDN-Design Ideas White LEDs find wide use in backlighting color-LCD screens in most portable devices, such as cellular phones, PDAs, and MP3 players.  Multiple LEDs often connect in series to ensure that the same current flows through every LED.  To forward-bias these LEDs, a voltage of 10 to 16V comes from an inductor-based boost regulator, such as an SP6690 __ Circuit Design by Dimitry Goder, Sipex Corp, San Jose, CA

Secondary Colors from Multicolored LEDs -  07/24/03  EDN-Design Ideas One disadvantage of generating a yellow color by mixing two primary-color light sources is that the LED must use twice the current because both the red and the green LEDs must be on.   __ Circuit Design by Claude Haridge, Stittsville, ON, Canada

Self-Oscillating H Bridge Lights White LED From One Cell -  26-Nov-09 EDN-Design Ideas Circuit operates on batteries as low as 0.6V __ Circuit Design by Luca Bruno, ITIS Hensemberger Monza, Lissone, Italy

Sequential Bar Graph Turn Light Indicator for Car -  The article illustrates a simple yet innovative, fancy car turn signal light circuit which produces a rising bar graph sequence effect when switched ON. __ Designed by Swagatam Majumdar

Sequential Brake/Turn Lights -  Bar-mode LED-cluster sequencer.  Can drive up to 16 clusters.   __ Contact: Flavio Dellepiane, fladello @ tin.it

Sequential LED Flasher -  for 10 LEDs.   __ Designed by Tony van Roon  VA3AVR

Serial Comms to LED Driver -  This document describes the HSETI PCB.  This PCB is a small simple application for the Atmel AT89C2051 microprocessora 20 pin 8051 variant, with FLASH  (reprogrammable) program memory.  The board has just two chips on it, the CPU and a driver/buffer.__ Airborn Electronics, Australia

Serial COMs to LED driver -  This document describes the HSETI PCB.  This PCB is a small simple application for the Atmel AT89C2051 microprocessora 20 pin 8051 variant, with FLASH    (reprogrammable) program memory.  The board has just two chips on it, the CPU and a driver/buffer.  __ Airborn Electronics, Australia

Series Connected Voltage Boost for a Battery Operated LED Lantern -  A circuit that goes in series with a white LED and a 1.5 volt cell to make > 3 Volts to drive a white LED __ Designed by Dick Cappels

Seriously Bright 20W LED Floodlight -  Last February, we published a DIY 10W LED Floodlight, which has been enormously popular.  We said that one was almost blindingbut to paraphrase Croc Dundee, that's not bright.  THIS one is BRIGHT!__ SiliconChip

Set LEDs’ Hue From Red to Green -  10/21/10 EDN-Design Ideas By varying the current through red and green LEDs, you can vary the hue in 32 steps.    __ Circuit Design by Marián Štofka, Slovak University of Technology, Bratislava, Slovakia

Seven Component Regulated LED Lamp -  This is a minimal-parts lamp made with four white LEDs. It features regulated light output from 10V to 20V and works well as a desk lamp or flashlight. The lamp is still working perfectly 16 years after it was first built. __ Designed by G. Forrest Cook

Seven 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

Seven-Colour LED Lighting -  Presented here is a simple circuit that uses six red, green and blue  (RGB) LEDs to generate a running-light effect in seven colours—blue, green, red, cyan, yellow, magenta and white.__ Electronics Projects for You

Shop Safety Light -  My 1200 square foot metal shop only has one small entrance door and no skylights.  If the lights are turn off while inside, there is not enough light to safely find the door to exit the building.  On a couple occasions, while I was quietly working at my test bench, my wife would walk into the shop, grab a garden tool and rush back out, turning off the lights and closing the door without thinking . . . Hobby Circuit designed by David A. Johnson P.E.-November, 2004

Signal Processor Adds LED Display -  6-Jun-96 EDN-Design Ideas Designers using the Texas Instruments TSS400, a versatile 4-bit sensor-signal processor, may find the circuit in Figure 1 useful as a replacement for, or an adjunct to, the IC's built-in display capabilities __ Circuit Design by N Thomas Christman, Zablocki VA Hospital, Milwaukee, WI

Signboard -  On this page, I will introduce the electronic signboard with PIC16F84A.  The message is displayed to flow on the left from the right.128 LEDs are used for this board __ Designed by Seiichi Inoue

Signboard 2 -  Iwill introduce the making of the electronic signboard which used PIC16F84A on thses pages.112 LEDs  (7 x 16) are used for the display of the message.50 LEDs are used as the design of the edge.  Latch registers by CPLD are used for the display of the LEDs.   __ Designed by Seiichi Inoue

Simple Circuit Battery-Status Indicator Uses Two LEDs -  08/12/10 EDN-Design Ideas Use LED brightness to indicate battery charge.    __ Circuit Design by Abhijeet Deshpande, People’s Education Society Institute of Technology, Bangalore, India

Simple Circuit current limiting for LED flashlights -  I have modified my 3-White LED 3-AA cell flashlight by adding filament bulbs in series with the LED's to form a "ballast" utilizing the positive resistance-vs-temp characteristic of tungsten as a simple current source.  I did this to increase the battery life  (at the expense of initial brightness) , and to increase the lifetime of the LED's.  The flashlight, which was given to me, appears to be an early C. Crane unit. As in most of these simple lights, the 3 LED's are wired in parallel on a tiny circular PC board and connected directly to the 3 AA Alkaline cells.

Simple 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

Simple Circuit for 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. . . Circuit by David A. Johnson P.E.-July, 2003

Simple Circuit LED Constant Current Lighting -  There is a lot of effort going on to improve the technology of LED  (Light Emitting Diode) lighting. The reason is that LEDs are much more efficient than standard incandescent or CFL light bulbs.  They also last longer than either of the alternatives and don’t have issues with disposal like CFL bulbs.  LED lighting has a lot going for it except one thing. It is still pretty expensive __ Designed by Gary C. Sutcliffe

Simple Circuit LED Constant Current Source -  Chip manufacturers are always coming up with ever more sophisticated constant current driver chips for LEDs.  We have included this design for those of you who prefer a more cheap and cheerful solutionmust register on this site __ Designed by Published in Elecktor July/Aug, 2010

Simple Circuit LED flasher -  This circuit has a lot going for it.  For one thing, it only consists of two transistors, two capacitors and four resistors.  That also means it consumes very little power.  You can control the flash rate by changing the size of the 100k resistors    (100k makes for a pretty slow rate) .  You can also control the duty cycle by using resistors of different values on the two sides __ Designed by Colin Pringle

Simple Circuit Logic Probe uses Bicolor LED -  03/13/98 EDN Ideas -  (File has several circuits, scroll to this one) A project posed the challenge of replacing existing analog potentiometers  (used to set brightness and contrast levels]in video monitors with digitally controlled potentiometers.  The different brands and models of monitors presented widely varying voltages across the potentiometers.  The design.    __ Circuit Design by Mark Shill, Burr-Brown Corp, Tucson, AZ

Simple Circuit Negative Supply Circuit -  This simple circuit consists of two LEDs and a photo diode.  It generates a negative voltage with a current level of a couple milliamps.  It is ideal for supplying a negative rail to low power “rail to rail” op amp circuits, which need to have a true zero volts output.  Note:  This circuit is not particularly efficient . . . Hobby Circuit designed by David Johnson P.E.-July, 2006

Simple Circuit Photodetector -  I´ve designed this simple circuit to test a photodetector.  I got the detector from an old 5 1/4" disk drive.  If you can get one, you will find two photodetectorts: one is used to sense the density  (double density or high density) 

Simple Circuit RF signal meter with LEDs -  The simple but effective circuit presented here converts an RF input signal into a visible LED indication.  Only discrete components are used.  The circuit can be used as field strength analyser or RF Wattmeter when a 50 ohms resistor is connected between ground and HF  (J1) .  Calibration required.  Of course you can add extra LED stages in case you want to extend the range.  The second picture shows how the circuit can be build on a very small piece of vero-board.   __ Designed by Ron Zoetermeer, JO22gb, Netherlands

Simple Circuit single-cell white-LED driver uses improvised transformer -  15-Feb-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

Simple Circuit two transistor lights LEDs -  9-Apr-09 EDN-Design Ideas A previous Design Ideas describes a circuit that uses an astable multivibrator to drive an LED (Reference 1].  The circuit in Figure 1 uses a simpler alternative approach.  The circuit uses a 2N3904 NPN transistor and a 2N3906 PNP transistor, which operate as a high-gain amplifier __ Circuit Design by Barry A Tigner, Michigan State University, East Lansing, MI

Simple Circuit Voltmeter Monitors TTL Supplies -  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.   __ Designed by Texas Instruments App Notes, 2-Oct-02

Simplest LED Flasher -  This may be the simplest LED flasher circuit you can build, with the notable exclusion of LED's with integrated flashing circuits.  This might be a good replacement for the LM3909 in some applications. 
 __ Designed by Dick Cappels

Simplified PC Connections for Gpib Instruments -  Application Note__ Aligent

Simplified white-LED flasher operates from one cell -  26-May-05 EDN-Design Ideas 1.5V circuit flashes white LED __ Circuit Design by Anthony H Smith, Scitech, Biddenham, England

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LEDs:   #'s - B     C - G      H - L       M - P       Q - T     U - Z 

 


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