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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. :

  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


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

Jumbo Flashing LED Lights -  This is a flashing led lights circuit powered from a 12V DC power supply that uses the well known 555 IC.  Flashing lights have many and varied applications in life.  They are used as warning lights on highways to increase road safety, as beacons on towers, as advertising signs on shop windows, and so on.  Mechanically operated __ Designed by T.K. Hareendran

Kitt car scanning LED sequencer -  Most people are familiar with the adventures of a certain black Trans-Am with 5000 Megabit memory.  This car started life as emotionless and argumentative but by the time it smashed its way through the first episode, everybody wanted to own it __ Contact: Collin Mitchell

Knight Rider Lights-LED Chaser -  I don't know why, but people like blinking lights.  You see LED chasers everywhere, in TV shows    (Knight Rider) , movies, and store windows.  This schematic is my version of a simple 10 LED chaser.  There is no 555 timer used because __ Designed by Aaron Cake

Knight Rider Look-a-like Lights -  12 Volt Knight Rider, "Look-A-Like", Lighting Systems Revised "JAN.2, 2008"  (Errors on Knight-3, Corrected)  __ Designed by G.L. Chemelec

Lamp Flasher -  This circuit adopts the rather unusual Bowes/White emitter coupled multivibrator circuit.  The oscillation frequency is about 1Hz and is set by C1 value.   __ Contact: Flavio Dellepiane, fladello @ tin.it

LCD Power Supply Provieds +/-15V LED Power -  Magazine Design Idea  s May 2004__ Linear Technology/Analog Devices

LCD-bias supply provides precise tracking -  05/03/01 EDN-Design Ideas Small monochrome LCD systems often require split  (dual) -bias supplies with precise voltage tracking to prevent plating of the LCD.  The circuit in Figure 1 provIdeas±18 to±20V adjustable LCD bias voltages with 1% tracking accuracy.  The circuit operates from a single 4.2 to 2.5V Li-ion cell for portable monochrome LCD applications.   __ Circuit Design by David Kim

LDR & LED Smoke Detector -  Smoke detectors are generally used in advanced alarm systems.  Most of this professional devices use gas-detectors, ionization rooms or radioactive elements as sensors.  In this circuit we are not using any of this complicated components.  Instead of these, we are using two LDRs and one LED.  LM1801 special-purpose IC , which is designed especially for smoke detectors, provides us building this circuit by using the minimum number of components.  It includes one internal zener supply, two reference voltage outputs, one voltage comperator, fixing diodes and one 500mA output transistor.  

LED 12 Volt Lead Acid Battery Meter -  In the circuit above, a quad voltage comparator  (LM339) is used as a simple bar graph meter to indicate the charge condition of a 12 volt, lead acid battery.  A 5 volt reference voltage is connected

LED AM meter -  Measures current up to 10A with selected 100mA, 10mA and 1mA resolutions.  

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

LED as Light Sensor -  Usually light-dependent resistors  (LDRs) and photodiodes are used as light sensors to activate or deactivate circuits based on the presence or absence of light.  But a common transparent LED can also...__ Electronics Projects for You

LED Audio UV Monitor -  The circuit is completely conventional, and is based on the App Note  From National Semiconductor.  The circuit is shown in Figure 1 and as you can see it uses a single IC and a few discrete components.  The extra diode  (D3) is included to ensure that the DC to the LEDs is almost unfiltered __ Designed by Rod Elliott  ESP

LED bargraph ammeter for your car -  It's easy to build and even easier to connect.__ SiliconChip

LED Bar-Graph Display Represents Two Digits -  09/22/11  EDN-Design Ideas Use a counter IC to drive two sets of four LEDs.  The circuit in this Design Idea makes a voltmeter that reads to 0.99V.  The idea uses a counter IC to drive two sets of four LEDs  (Figure 1) .  Each of these two sets represents a BCD  (binary-coded-decimal) value.  With all of the LEDs off, the voltmeter reads 0V.  With all of the LEDs on, the reading is 0.99V.  Op amp IC1A generates a predictable voltage ramp. __ Circuit Design by Raju Baddi, Tata Institute of Fundamental Research, Pune University, Maharashtra, India

LED Bargraph Optical Tachometer -  For the electric R/C enthusiast, a tachometer can be a very useful piece of equipment.  When I first built this tach back in 1995, it was essential, as there were very few off-the-shelf electric R/C power systems that just worked.   __ Designed by Stefan Vorketter

LED based transistor teste -  Here is the circuit of a very simple transistor tester which used two LEDs for displaying the condition of a transistor.  Both PNP as well as NPN transistors can be tested using this circuit.  Quad 2 input CMOS NAND gate IC CD4011B is the heart of the circuit.  Out of the four NAND gates inside the IC, only three are used here and they are used as NOT gates by shorting their input terminals.  Gates U1a, U1b, resistor R1 and capacitor C1 forms a square wave oscillator.  

LED Battery Condition Indicator -  In the circuit below, a quad voltage comparator  (LM339) is used as a simple bar graph meter to indicate the charge condition of a 12 volt, lead acid battery.  A 5 volt reference voltage is connected to each of the  (+) inputs of the four comparators and the  (-) inputs are connected to successive points along a voltage divider.  The LEDs __ Designed by Bill Bowden

LED Battery Meter -  will measure any low voltage battery on a 10 led scale! __ Contact: P. Townshend EduTek Ltd

LED Bicycle Light Revisited -  NOTE : Must register on this site __ Designed by Published in Elecktor July/Aug, 2010

LED Binary Calculator -  You can't calculate binary values as is on most handheld calculators and using the windows one is just a pain, so i decided to make my very own  (binary only) calculator.  This calculator supports all the basic functions like : NOT, OR, AND, XOR, 

LED Blinking for Embedded Systems -  Smart hardware design can simplify the embedded software and make it more reliable.  Designers use blinking LED signals to indicate different status and for inbuilt testability.  Making an LED array blink...__ Electronics Projects for You

LED brightness control -  It's easy to alter the brightness of an LED simply by varying the current through it.   __ Designed by Richard Torrens

LED Camping Lantern with Dimmer -  A 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 Chaser -  I don't know why, but people like blinking lights.  You see LED chasers everywhere, in TV shows    (Knight Rider) , movies, and store windows.  This schematic is my version of a simple 10 LED chaser.  There is no 555 timer used because __ Designed by Aaron Cake

LED Chaser -  This is the circuit of a simple LED chaser.  The LEDs lights one by one for a period of 1second and the cycle repeats giving the running light appearance.  The circuit uses two ICs (one is 555) to drive the LEDs.  IC1  (NE555) is the popular timer IC wired in the Astable Multivibrator mode.  Resistors R1, VR1 and capacitor C1 act __ Designed by D Mohankumar

LED Chaser -  A sequential light chaser using the PIC 12F629.   __ Designed by Jose Pino

LED Chaser II -  LED Chaser Version 2, Improved.  Use it as "LED chaser" or "Third Brake Light".   __ Designed by Jose Pino

LED Chaser Provides Three Game Functions -  This circuit is essentially a light chaser but it can also be set to provides heads or tails  (Two Up) or a Dice  (die) .  It also has a speaker to simulate the sound of a spinning roulette wheel.  Note that the dice and heads/tails features can be deleted if required and rules for the games created to suit individuals; eg, betting can be used or the numbers recorded and then totalled to get the highest score per game__ Learning Electronics

LED Christmas Tree with 64 LEDs -  The Holidays are once again upon us and we wanted to give our readers the edge in decorating this year.  Continuing our all-digital-hardware theme to coincide with our Kickstarter for a Digital Electronics Course at PyroEDU, we have created an LED Christmas tree controlled entirely by digital logic __ Designed by PyroElectro

LED Clock Using Pic (Microcontroller) -  Now you can always know the exact time.  With this design you can have an atomic clock in your room.  Isn’t that great? Read on to know more.  First of all, it is not about any radioactive elements here.  This is about building a clock display that can get the time from the DCFF77 facilities

LED Counter -  This circuit is the 12-bit binary counter which used 4040B.  The number of the pulses of the input can be confirmed by seeing it with the eyes by putting the light-emitting diode to the output of the counter.  It is the function only of it but it is useful.  Because it is the 12 bits, the highest rank counter __ Designed by Seiichi Inoue

LED Current Regulator -  Here is a circuit that will allow LED's to glow at a constant brightness throughout battery life or varying power supply voltage.  This circuits is capable of saturating, allowing the battery voltage to get within 0.3 volts of the LED voltage before the L __ Designed by Andrew R. Morris

LED Dazzler: a Driver Circuit for Really Bright LEDs -  Caution: these LEDs are so bright they will burn your eyeballs!__ SiliconChip

LED Decibel Meter -  The circuit below responds to sound pressure levels from about 60 to 70 dB.  The sound is picked up by an 8 ohm speaker, amplified by a transistor stage and one LM324 op-amp section.  You can also use a dynamic microphone but I found the speaker was more sensitive.  The remaining 3 sections of the LM324 quad op-amp are used as __ Designed by Bill Bowden

LED Dice -  This project has two advantages over previous dice circuits.  It produces a realistic readout as well as a 'slow-down' feature.  These combine to make it one of our most popular games projects.  As can been seen in the photo, the 7 LEDs are positioned on the board in the same positions as the spots on a dice  (die) .  When these are activated, they simulate the rolling of a real dice as it rolls across the table.   __ Contact: Collin Mitchell

LED dice based on a 4060 chip -  Every self-respecting DIYer makes his own electronic dice with LEDs as spots.  Then you don’t have to throw the dice anymore – just push the button.  The electronics also ensures that nobody can try to improve his luck by fiddling with the dice.  Too bad for sore losers! This circuit proves that an electronic die built using standard components can be made quite compact.  The key component of here is a type 4060 digital counter  (IC1) .__ Learning Electronics

LED dice using PIC16F88 -  No circuit description, schematic only__ CdS Electronic

LED dice with fast roll -  No circuit description, schematic only__ CdS Electronic

LED Dimmer -  This circuit will adjust the brightness of one or more LEDs from 5% to 95%.  __ 555-Timer

LED dimmer -  Find out how to put together a simple but efficient PWM dimmer circuit for LEDs.   __ Designed by REUK-Renewable Energy UK website

LED dimmer uses only two lines -  03/21/02 EDN-Design Ideas The circuit in Figure 1provIdeas 32 steps of brightness control-from 0 to 100%-for a backlight or instrument panel, using just two general-purpose-microprocessor signals.  In addition, the circuit requires little board space, because it uses only three SOT-23s and one µMax package __ Circuit Design by Jerry Wasinger, WallyWare Inc, Norcross, GA

LED display digital Voltmeter -  This is an easy to build, but nevertheless very accurate and useful digital voltmeter.  It has been designed as a panel meter and can be used in DC power supplies or anywhere else it is necessary to have an accurate indication of the voltage present.  The circuit employs the ADC  (Analogue to Digital Converter) I.C.  CL7107 made by INTERSI - L. __ Designed by © Smart Kit Electronics

LED doubles as emitter & Detector -  08/16/01 EDN-Design Ideas Every junction diode exhibits some degree of photosensitivity when it receives light comprising an appropriate range of wavelengths.  The spectral response of a junction diode depends on a variety of factors, including material chemistry, junction depth, and packaging.  The packaging of most devices aims to inhibit sensitivity to radiant flux to maintain the intended function of the device __ Circuit Design by Kyle Holland, LI-COR Inc, Lincoln, NE

LED Driven Tail/Brake Light Cluster -  LED driven tail/brake Light Cluster Constant current circuitry 12V Battery operation __ Contact: Flavio Dellepiane, fladello @ tin.it

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


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