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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. :

Battery Charge Current Indicator This circuit turns on a LED whenever it detects at least 25ma of battery charge current. . . Circuit by David Johnson P.E.-July, 2006

 Battery Free LED FlasherLED 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. . . Circuit by David A. Johnson P.E.-December, 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


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

Back & Forth Flasher -  for16 LEDs.   __ Designed by Tony van Roon  VA3AVR

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

Bar-mode Lights Sequencer -  Can drive up to 15 LEDs or LED-clusters; Selectable Bar-length __ Contact: Flavio Dellepiane, fladello @ tin.it

Basic 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

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

Battery Charge Current Indicator -  This circuit turns on a LED whenever it detects at least 25ma of battery charge current. . . Circuit by David Johnson P.E.-July, 2006

Battery Equal Charge Indicator -  The circuit below illuminates an LED to indicate unequal charges between two 12 volt lead batteries.  It can be used to verify that two batteries are connected in parallel or isolated since the LED will be off when the voltages are equal within a tollerance, or on if the voltage difference is greater than 100 millivolts.  Three comparators __ Designed by Bill Bowden

Battery Free LED Flasher -  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. . . Circuit by David A. Johnson P.E.-December, 2010

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

BCD to 7 Segment LED Display Decoder -  Most often seven-segment displays are used to display the digits in digital watches, calculators, clocks, measuring instruments and digital counters, etc.  Generally, LCD and LED segments provide the display output of numerical numbers and characters.

Beacon Spinner LEDs -  Our BEACONERB8 has many applications; Manual press the push button to light 8 LEDs in sequence! Automatic, short the switch to automatically light 8 LEDs in sequence, draw attention and have fun! The unique small design will allow you to mount it almost anywhere.  Operate it with 9V battery, 12V car battery, four 1.5V batteries, or via one of our battery simulator kits.  The alternative uses are endless.   __ Contact: Kit from Elich Industrial Development, Corp

Bedazzler: Do-It-yourself Handheld LED-Incapacitator (non-lethal weapon) -  After attending a conference where the $1 million "sea-sick flashlight"    (named "THE DAZZLER") was demonstrated by the US Dept.  of Homeland Security, we decided to create our own version.  For under $250, you can build your own dazzler and we've released the source code, schematics and PCB files to make it easy.  

Bicolor LED Driver Uses Two Leads -  05/13/10 EDN-Design Ideas You can use the circuits in Fig 1 to drive a bicolor LED with only two leads.  This circuit detects the correct closed condition of the left and right side bags in a motorcycle companion.  The bag has two locks that you must close for protection.  When you push the two momentary SPDT   (single-pole/double-throw) switches, they sense the correct closed bag.  One bicolor red-and-green LED indicates the bag’s status, with the red color showing the open-bag condition.  To illuminate the LEDs, you must reverse the polarity of the applied voltage to the LED to change the color  __ Circuit Design by Mario Marcoccia, United Circuits, Fort Lauderdale, FL

Bicolor LED Indicates 10 States -  03/03/11  EDN-Design Ideas Most microcontroller-based devices have several states of operation.  Pushbutton switches often control these states.  To minimize costs, many designs use only one switch; the number of presses sets the microcontroller’s state.  In the circuit in this Design __ Circuit Design by Abel Raynus, Armatron International, Malden, MA

Bi-Color LED Indicates Power/Fault -  Single LED indicates both power on and blown-fuse conditions.   __ Designed by Jim Haggerman, Hagerman Technology LLC

Bi-color LED Project -  There are several projects on this page.  Please scroll down to find the LED Chaser.   __ Designed by Jason KE4NYV from Roanoke, Virginia

Bicycle back Safety Light -  Flashing 13 LED unit, 3V supply; Also suitable for jogger/walkers __ Contact: Flavio Dellepiane, fladello @ tin.it

Bicycle LED POV (persistence of vision display) LED display -  Bicycle LED POV is an electronic LED bar to attach on bicycle wheels.  When riding the bicycle, the LED bar will draw with light, text messages and image animations.  Custom text messages and animations will be drawn on a PC software and downloaded using an USB cable.

Bicycle rear flashing LED light -  No circuit description, schematic only__ CdS Electronic

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

Big 7-Segment LED Display Board with SPI Interface -  Easy build and use, the general purpose Big LED with SPI serial interfacing.  Expandable for multiple digits but still uses only three wires for receiving data from any uC boards.   __ Designed by Wichit Sirichote

Big LED Clock -  The circuit uses a serial-in-parallel out shift register, 74HC595 for receiving serial data from uController board.  See example of U5 in the schematic, SER is for data input, SRCLK is shift clock and RCLK is Latch clock.  Each data bit is shifted into the register on rising edge of the shift clock.  When all data bits are shifted into the 8-bit register, the rising edge of RCLK will clock the data to be latched at each output bit, i.e.  QAQH. __ Designed by Wichit Sirichote

Binary clock using LED matrix to display a binary clock with 6 digits of 4 binary bits each -  Timing and oscillator circuit diagrams / circuit schematics __ Designed by John Main

Binary Coded Decimal (BCD) Clock -  The clock circuit above uses seven ICs and 19 LEDs to indicate binary coded decimal time.  The LEDs can be arranged    (as shown in example above) so that each horizontal group of 3 or 4 LEDs represents a decimal digit between 0 and 9 and each individual LED represents a single bit or    (binary digit) of the value.  Binary digits __ Designed by Bill Bowden

Bi-Polar LED Driver -  Some 2-leaded LEDs produce red and green.  These are called Bi-polar LEDs.  This circuit alternately flashes a red/green bi-polar LED__ 555-Timer

Birthday Heart -  This circuit was made for my wife's birthday.  It is capable of flashing five strings of LED's with different frequencies.  It also has a connector for an 8 Ohm loudspeaker and two connectors for the small PCB's that are contained in musical greeting cards.  In this way the circuit will play alternatingly two room filling tunes at regular time intervals.  After a w __ Designed by Michel Van den Bergh On Electronics

Blink a LED -  For non-embedded programmers the first thing to try on a new system or in a new programming language is to print out "hello world".  The equivalent for microcontrollers and other embedded systems is to blink a LED.  When even the target circuit and the programmer are freshly put together it is wise to start even lower, with a blink-a-LED program written by someone else that is known to be working.  Then when the LED does not blink    (which is likely) there is one thing less to doubt about.  On this page you will find 1 and 2 Hz blink-a-LED    (and some other) test programs for various targets chips and circuits.   __ Designed by © © 2002 Van Ooijen Technische Informatica / Wouter van Ooijen

Blinking Arrow -  17 LEDs in four groups bar-mode sequence. Suitable for shop-windows animation etc__ Designed byFlavio Dellepiane

Bob Blick's Propeller Clock -  A motor spins the "propeller", and a small microprocessor keeps track of time and changes the pattern on seven LEDs with exact timing to simulate a 7 by 30 array of LEDs.  It is an illusion, but it works nicely.   __ Designed by Bob Blick

Bridge-temperature measurement allows software compensation -  08/17/00 EDN-Design Ideas Bridge transducers are notoriously temperature-sensitive.  When the temperature changes, almost everything else varies with some parameters increasing and some decreasing.  The TCS    (temperature coefficient of span) is generally nega __ Circuit Design by John Wynne, Analog Devices Inc, Limerick, Ireland

Bright 10W LED Floodlight -  Light level rivals halogensat MUCH less power!__ SiliconChip

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

Broken-Coil Detector Is Simple Circuit Yet Robust -  03/04/10  EDN-Design Ideas The circuit in this Design Idea was originally designed to detect damaged conveyor belts in the mining industry.  Thin coils are embedded in the conveyor belt.  If the belt suffers damage, it stretches at the affected location, causing one or more coils to break.  The method for detecting the broken coil is to allow a “sensing” coil to magnetically couple with the passing coils in the belt, thus changing the total inductance of the magnetic pair.  The sensing coil is part of an LC oscillator    (Figure 1) .   __ Circuit Design by Juan Pablo Caram, Santiago, Chile

Buck Converter (1 watt LED driver) -  This is an example of efficiently driving a 1 watt white LED from a 12 volt battery using a buck converter.  The LED could simply be connected with a series resistor to get the desired current, but the efficiency would be only 25% since the resistor would drop 9 volts while the LED only requires 3.  The buck converter provides about 90% efficiency. __ Designed by Bill Bowden

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

Buck-Boost Controller Drives High-Power LEDs, Charges High-Voltage Batteries -  08/29/13  EDN-Design Notes The LT®3791 is a 4-switch synchronous buck-boost DC/DC converter that regulates both constant-current and constant-voltage at up to 98.5% efficiency with a single inductor.  It can deliver hundreds of watts and features a 60V input and output rating, making it ideal for driving high power LED strings and charging high voltage batteries when both step-up and step-down conversion is needed.  It can also be used as a constant voltage buck-boost regulator with current limiting and monitoring for both input and output.   __ Designed by Keith Szolusha, Linear Technology Corporation, also see Linear Technology Design Note 501

Buffer Amplifier & LED improve PWM power controller's low-load operation -  09/15/05 EDN-Design Ideas PWM IC is enhanced with discrete components for wider-range operation __ Designed by Gregory Mirsky, LaMarche Manufacturing Co, Des Plaines, I - L

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

Build a LED Dice -  A PIC microcontroller makes the circuit really simple.  We tell you how it was designed and show you how to build it.__ SiliconChip

Build your own LED cube -  This month's featured Gadget Freak is provided by an old favourite of the blog, Peter Griffiths.  He shares all the details necessary to build your own 5 x 5 LED cube

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

 


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