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

Last Updated: November 30, 2017 10:29 AM

Circuits Designed by Dave Johnson, P.E. :

 LED Array powered by 24 VA - C24vac 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 Johnson P.E.-December, 2009

 LED Camping Lantern with DimmerA while back I received an email from a Discover Circuits visitor who wanted to build his own LED camping lantern.  He wanted to use a single bright LED powered by 3 large alkaline D cells.  He also wanted to be able to dim the light intensity down to a low night light level, to extend the battery life.  The circuit below performs this task . . . Hobby Circuit designed by David A. Johnson P.E.-December, 2013

 LED Driver using Constant CurrentLEDs are current driven devices.  The light they produce is proportional to the current flowing though them.  One way to maintain a fairly steady light output is to keep the current through the LED fixed, even as the supply voltage may change.  A classic. . . Circuit by David A. Johnson P.E.-December, 2010

 LED Driver-WirelessThe circuit solves this problem by sending power to the LED through the plastic, using a magnetic coupling technique.  The circuit below can route power through plastic enclosures as thick as ľ inch.  The circuit will not work through metal boxes . . . Hobby Circuit designed by Dave Johnson P.E.-November, 2008

 LED Flasher needs only 1.5 VOLTSTo squeeze even more energy from a alkaline battery cell, this circuit adds two transistors to a circuit similar to the above design to boost the efficiency.  A small 1.5 volt alkaline N cell should flash the LED for a full year.  It too uses a "charge pump" technique to provide a LED the needed voltage . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

 LED Flasher that is Battery FreeLED flashers have been used for a wide variety of applications.  Some flasher units have been used in food and hardware stores, to draw attention to sale items and are often attached to boxes which dispense product discount coupons . . . Hobby Circuit designed by David Johnson P.E.-December, 2010

 LED Flasher Universal 3vThe electronic circuit below will flash any LED color with fixed current pulses powered by a 3v battery.  It uses a charge pump approach, which routes a constant current pulse through the LED, regardless of the LED voltage requirement.  Using this approach . . . Hobby Circuit designed by David Johnson P.E.-June, 2008

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

 LED Flasher-Wireless CircuitWhen you would like to flash a LED through a thick plastic case without wires, use this hobby circuit.  It performs this feat.  It draws about 300ua of average current at 5v.  It can be powered from a supply ranging from 3v to 6v . . . Hobby Circuit designed by Dave Johnson P.E.-January, 2011

 LED Flashing Badge #1I have seen numerous flashing light badges at trade shows and conventions.  They are often handed out as gifts to promote some business.  The devices often use inefficient circuits, which cause the battery power source to be quickly depleted. . . Circuit by Dave Johnson P.E.-March, 2002

 LED Flashing Badge #2This circuit uses a CD4013 dual D Flip/Flop IC.  A single lithium battery will provide months of continuous LED flashing.  It also has a tiny push-button switch to turn on and off the light flashing. . . Circuit by David Johnson P.E.-March, 2002

 LED Lighthouse FlasherThis was originally designed for a model in a HO train set.  It simulates the behavior of the light from a lighthouse.  The LED intensity gradually increases, then flashes with a bright light and finally decreases slowly in intensity . . . Hobby Circuit designed by David Johnson P.E.-July, 2006

 LED Lighthouse Flasher for HO Model Train  - HO train sets often have authentic looking scale model homes and buildings.  The hobby circuit below can be mounted inside a model lighthouse.  The electronic circuit drives a single LED lamp in such a way that it produces light which simulates the rotation . . . Hobby Circuit designed by David Johnson P.E.-July, 2006

 LED Pilot Light powered by AC LineThis simple circuit can be used to light a LED indicator lamp, powered from the 120vac line.  I have included component values for 240vac lines as well. . . Circuit by David A. Johnson P.E.-July, 2006

 LED Strings powered by AC LineThis shows 4 different ways to string white LEDs that are powered by a 120vac or 240vac power line.    The circuit was designed by Ken Schultz . . . Hobby Circuit designed by David A. Johnson P.E.-December, 2004


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

LED Driver Combines High Speed, Precision -  08/21/03  EDN-Design Ideas Applications such as turbidity measurement and densitometry require cleanly pulsed light sources with stable amplitudes.  The LED driver in Figure 1 illuminates retinal neurons in a biological experiment that has similar requirement __ Circuit Design by Richard Cappels, Mesa, AZ

LED Driver Delivers Constant Luminosity -  12-Jun-03 EDN-Design Ideas White-LED driver touts high efficiencyThe circuit in Figure 1 is similar in principle to that of a previous Design Idea (Reference 1] but offers improved,reproducible performance.  The output current is almost constant over an input-voltage range of 1.2 to 1.5V and is insensitive to variations of transistor gain.  Transistors Q1 and Q2 form an astable flip-flop __ Circuit Design by Israel Schleicher, Bakersfield, CA

LED driver displays standing-wave ratio -  03/18/99 EDN-Design Ideas -  (Page includes several designs.  Scroll to find this one)  The circuit in Figure 1 uses an LM3914 LED driver to directly display standing-wave ratio (SWR] in a low-cost, rugged instrument.  The SWR-sensing head is derived from the ARRL Antenna Handbookin an article that describes the tandem match.  The forward voltage and reflected voltage (VF+VR ] signal drives Page includes several designs.  Scroll to find this one __ Circuit Design by Richard Panosh,Vista, Bolingbrook, I - L

LED driver doubles as fault Monitor -  08/05/04  EDN-Design Ideas LEDs find wide use as indicators and as light emitters in devices such as optocouplers.  In some applications, the LED or the emitter may be located remotely at some distance from the main unit.  Typical examples are dashboard-mounted automotive indicators and industrial optosensors.  In critical applications, you may require some means of monitoring the integrity of the LED __ Circuit Design by Anthony Smith, Scitech, Biddenham, Berdfordshire, England

LED driver provides oscillator for microcontroller -  16-Sep-04 EDN-Design Ideas The major building blocks for a white-LED driver are an oscillator, a charge pump, and a regulated current source.  National Semiconductor (www.national.com ] produces a device that contains all these building blocks in the highly integrated LM2791/2 IC.  You usually use white-LED drivers in tandem with cellular baseband controllers or microcontrollers __ Circuit Design by Wallace Ly, National Semiconductor, Santa Clara, CA

LED driver provides software-controlled intensity -  09/30/04  EDN-Design Ideas Recent advances in operating efficiency have expanded the use of LEDs from one of mere indicators to becoming driving forces in electronic lighting.  Increased reliability and ruggedness  (versus other lighting technologies] gives the __ Circuit Design by Neda Shahi and Bjorn Starmark, Maxim Integrated Products, Sunnyvale, CA

LED Driver using Constant Current -  LEDs are current driven devices.  The light they produce is proportional to the current flowing though them.  One way to maintain a fairly steady light output is to keep the current through the LED fixed, even as the supply voltage may change.  A classic. . . Circuit by David A. Johnson P.E.-December, 2010

LED Driver with 555 Timer -  This simple LED driver circuit allows us to drive up to seven LEDs by using a single NiMH
  (Nickel Metal Hydride) AA cell.  The circuit produces voltage pulses at a much higher level than the input supply voltage by pulsing the 220 uH inductor.  The inductor must be a high Q  (Q>90) power inductor.  When the input is 1.25 V and the __ Designed by Popescu Marian

LED drivers minimize power dissipation -  02/01/07  EDN-Design Ideas Reference source and pullup resistor improve efficiency __ Circuit Design by Fons Janssen, Maxim Integrated Products Inc, Bilthoven, Netherlands

LED Driver-Wireless -  The circuit solves this problem by sending power to the LED through the plastic, using a magnetic coupling technique.  The circuit below can route power through plastic enclosures as thick as ľ inch.  The circuit will not work through metal boxes . . . Hobby Circuit designed by Dave Johnson P.E.-November, 2008

LED Drives Flash-and-Beep -  06/05/97 EDN-Design Ideas Sometimes, you need an alarm that is both audible and visible in an application that's stingy with space, power, and budget.  The circuit in Figure 1a is compact, efficient, and inexpensive.  The F336HD flashing LED  (part no.276-036 at Radio Shack) is a useful device.  It operates directly from 5V and produces a consistent pulse of light at approximately 1 Hz without a time-constant capacitor.    __ Circuit Design by Dennis Eichenberg, Parma Heights, OH

LED driving & controlling methods including constant current drivers & PWM brightness control -  I decided to write this quick tutorial for two reasons: First because there are many people who would like to know more about driving and controlling LED lights, and second because i was provided an excellent LED driver chip from Farnell for test, and i wanted to put it under the microscope.  So i will place this chip against some other LED drivers to see how good it is. __ Designed by Giorgos¬ Lazaridis

LED Flasher -  A SHORT COURSE in three designs to learn how to use Nutchips from ground up.  You will start making LED flashes.  You will continue learning how to switch outputs with separate START and STOP buttons.  In the last instalment, you will learn how to remotely switch a light on and off.   __ Designed by Projects & Ideas from Nutchip.com

LED flasher -  I made LED flash circuit which is often used as the PIC software making practice.  This circuit controls the blink of eight LEDs with the software of PIC.  The blinking pattern can be changed with five switches -- PIC16F84A __ Designed by Seiichi Inoue

LED Flasher -  This circuit is for amusement only! It flashes three ledís  (possibly of different colours) in sequence.  The frequency of operation depends on the values of the capacitors and resistors.  Try 1M resistors and 220n capacitors.  The integrated circuit is a 4584 hex inverting Schmitt trigger __ Designed by © David Hoult

LED Flasher -  This is a very simple project using a printed circuit board and 8 components.  It will flash an ordinary 3mm or 5mm  (1/8" or 1/4") LED at a rate of about one flash per second.   __ Designed by Collin Mitchell

LED Flasher -  LED flasher with the LM3909 IC and runs from1.5-Volt battery.   __ Designed by Tony van Roon  VA3AVR

LED Flasher -  This two LED flasher circuit uses any DC supply from 3V to 12V.  Flash rate is controlled by R1, C1 and R2, C2.  Larger values create slower fash rates, smaller values higher flash rates.   __ Designed by Evin Devore

LED Flasher -  Based on the MAX660, designed to power three 3mm/5mm white LED's from 3V  (1.5V min) , intended for replacing incandescent bulbs in small torches.)  __ Designed by Submitted Andre

LED flasher & TRIAC pulser work off AC line -  01/15/98 EDN-Design Ideas -  (This File contains several Design Ideas, please scoll to this one)  A flashing LED is an excellent visual alarm.  Unfortunately, the LED is a dc device and requires additional circuitry to operate from an ac source.  Several circuits can perform the necessary function, but the circuit in Figure 1a  is the most efficient __ Circuit Design by Dennis Eichenberg, Parma Heights, OH

LED flasher 2 -  This flasher moves, while lighting of LED drags on.  The brightness of LED is four kinds, bright, less bright, almost dim and dim.  These lighting states are moved with time.  Control of brightness is performed in lighting time of LED like PWM  (Pulse Width Modulation) .  There is no PWM function in PIC16F84A __ Designed by Seiichi Inoue

LED Flasher Checks Fiber-Optic Strands -  7-Jan-10 EDN-Design Ideas Send visible light through strands to check for breaks __ Circuit Design by Edwin A Mack, Port Republic, NJ

LED Flasher Indicates Low Battery Condition -  01/02/97 EDN-Design Ideas Many portable electronic devices could benefit from a visual indication when their battery requires replacement.  Typical low-battery indicators simply turn on an LED when the battery voltage drops below a certain value.  Such circuits actually accelerate the battery's extinction by drawing excessive current.  The circuit in Figure 1 draws a mere 1 m A in its standby mode and averages only 20 m A when activated.  The low current imposes a minimal burden on any battery circuit.  An off-the-shelf, undervoltage sensor IC (IC1) monitors the battery voltage--  __ Circuit Design by David Johnson, DiscoverCircuits.com

LED Flasher needs only 1.5 VOLTS -  To squeeze even more energy from a alkaline battery cell, this circuit adds two transistors to a circuit similar to the above design to boost the efficiency.  A small 1.5 volt alkaline N cell should flash the LED for a full year.  It too uses a "charge pump" technique to provide a LED the needed voltage . . . Hobby Circuit designed by Dave Johnson P.E.-June, 2000

LED Flasher that is Battery Free -  LED flashers have been used for a wide variety of applications.  Some flasher units have been used in food and hardware stores, to draw attention to sale items and are often attached to boxes which dispense product discount coupons . . . Hobby Circuit designed by David Johnson P.E.-December, 2010

LED Flasher Universal 3v -  The electronic circuit below will flash any LED color with fixed current pulses powered by a 3v battery.  It uses a charge pump approach, which routes a constant current pulse through the LED, regardless of the LED voltage requirement.  Using this approach . . . Hobby Circuit designed by David Johnson P.E.-June, 2008

LED Flasher uses Minimal Parts -  11/20/97 EDN-Design Ideas A pair of alternating flashing LEDs makes an excellent visual alarm, this alternating LED flasher is based on one LED with built-in flashing function and two transistors driving  or normal LED.    __ Circuit Design by Dennis Eichenberg, Parma Heights, OH

LED flasher using NE555 timer IC -  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

LED flasher with "Rising & Falling" Brightness -  Here is a Simple Circuit to give a Flashing LED, With a "Rising and Falling" Brightness.  It Uses the Sawtooth waveform from pins 2 and 6 to create the rise and fall.  The Resistor and LED on Pin 3 are Optional.  The 10K Potentiometer give a reasonable range of Speed.   __ Designed by G.L. Chemelec

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

LED Flasher-Wireless Circuit -  When you would like to flash a LED through a thick plastic case without wires, use this hobby circuit.  It performs this feat.  It draws about 300ua of average current at 5v.  It can be powered from a supply ranging from 3v to 6v . . . Hobby Circuit designed by Dave Johnson P.E.-January, 2011

LED Flashing Badge #1 -  I have seen numerous flashing light badges at trade shows and conventions.  They are often handed out as gifts to promote some business.  The devices often use inefficient circuits, which cause the battery power source to be quickly depleted. . . Circuit by Dave Johnson P.E.-March, 2002

LED Flashing Badge #2 -  This circuit uses a CD4013 dual D Flip/Flop IC.  A single lithium battery will provide months of continuous LED flashing.  It also has a tiny push-button switch to turn on and off the light flashing. . . Circuit by David Johnson P.E.-March, 2002

LED Flashing Christmas Tree (No Programming!) In this project i will show how i made my Christmas decoration this year, a 120x80cm Christmas tree with flashing ornaments and guirlande, and the best partabsolutely no programming! __ Designed by Flecks

LED Flashing sweetheart kit -  LED Flashing sweetheart kit __ Contact: Velleman USA

LED Flashlight -  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.   __ Contact: Velleman USA

LED Frequency Counter -  This counter was first known as the Modular Dial developed by Bill Carver, W7AAZ, and published in the Spring 1998 issue of Communications Quarterly. __ Designed by Web David White, WN5Y

LED Illumination for Refrigerators -  The incandescent lamp provided inside the refrigerators glows whenever we open the door.  It suffers from several disadvantages like: 1.  Being a single light source, located in the upper corner, light does...__ Electronics Projects for You

LED Indicates Power Source 08/26/10 EDN-Design Ideas A zener diode lets detects the presence or absence of a power source.   __ Circuit Design by Brian Conley, PE, Circuitsville Engineering LLC

LED Indicates Two Power States -  12/05/96 EDN-Design Ideas  Uses a single bicolor LED to indicate both power-on and blown-fuse conditions.    __ Circuit Design by Jim Hagerman, Hagerman Technology, San Diego, CA

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


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