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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. :

On/off Pushbutton Switch with 30 Minute TimeoutI received an email from a Discover Circuits visitor.  He wanted to control power to a LED camping light he was building.  He wanted to turn the light on and off with a small pushbutton switch.  He also wanted a timer so the light would not stay on longer than 30 minutes at a time.  It seems that his kids often turned lights on when going to bed and then forgot to turn them off. . . Circuit by David A. Johnson P.E.-January, 2012

One NiMH
Cell powers White LED
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 . . . Hobby Circuit designed by Dave Johnson P.E.-September, 2009

One-Line Telephone Line Status Indicator This circuit monitors one phone line. . . Circuit by David Johnson P.E.-June, 2000

One-Watt White LED Night LightAs many of you know, I have a pet peeve with poorly made LED night lights.  Often, the light from the LED quickly fades, so within months, the light is useless.  I have posted several versions of modified night lights using higher quality components.  This circuit is yet another version, which produces much more light than those other designs. . . . Hobby Circuit designed by David Johnson P.E.-November, 2008

Plus & Minus DC Power SupplyThis is a classic example of a regulated DC power supply that produces both a positive 15v and a negative 15v from a 20vac wall adapter . . . Hobby Circuit designed by Dave Johnson P.E.-October, 2005


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

Offline Supply Drives LEDs -  04/21/11  EDN-Design Ideas Keep LEDs lit when AC voltage drops. __ Circuit Design by TA Babu, Chennai, India

Old idea, new twist-Magic Lamp -  You have probably seen "magic lamp" circuits in which an ordinary incandescent bulb is lit by a match.  These circuits rely on a hidden temperature or light sensor and are not particularly interesting.  I decided to make a magic lamp,  __ Contact: Charles Wenzel of Wenzel Associates, Inc.

On/off Pushbutton Switch with 30 Minute Timeout -  I received an email from a Discover Circuits visitor.  He wanted to control power to a LED camping light he was building.  He wanted to turn the light on and off with a small pushbutton switch.  He also wanted a timer so the light would not stay on longer than 30 minutes at a time.  It seems that his kids often turned lights on when going to bed and then forgot to turn them off. . . Circuit by David A. Johnson P.E.-January, 2012

One Cell Flashes White LED -  12/11/03 EDN-Design Ideas Many portable appliances and other products that must operate from a single cell are restricted to working at very low voltages.  It is thus difficult to drive white LEDs that typically have a forward voltage of 3 to 5V.  The ability __ Circuit Design by Anthony Smith, Scitech, Biddenham, Bedfordshire, UK

One cell lights any LED -  07/05/01  EDN-Design Ideas The circuit in Figure 1 allows you to light any type of LED from a single cell whose voltage ranges from 1 to 1.5V.  This range accommodates alkaline, carbon-zinc, NiCd, or NiMH
single cells.  The circuit's principal application is i __ Circuit Design by Al Dutcher, Al Labs, West Deptford, NJ

One FET controls LED array -  04/12/01 EDN-Design Ideas White-LED backlights are gaining acceptance because they offer higher reliability and simpler drive circuitry than backlights based on CCFL   (cold-cathode-fluorescent-lamp] and EL   (electroluminescent] technology.  As a result, white-LED backlights are increasingly common in PDAs   (personal digital assistants], cell phones, digital cameras, and other portable devices.  A design __ Circuit Design by Len Sherman, Maxim Integrated Products, Sunnyvale, CA

One Microcontroller Pin Drives Two LEDs with Low Quiescent Current -  02/07/08  EDN-Design Ideas Two simple circuits allow a battery-powered microcontroller to drive two LEDs __ Circuit Design by Antonio Muñoz, Laboratorios Avanzados de Investigación del I3A, Zaragoza, Spain, and Arturo Mediano, PhD, GEPM University of Zaragoza, Zaragoza, Spain

One NiMH
Cell powers White LED
-  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 . . . Hobby Circuit designed by Dave Johnson P.E.-September, 2009

One-Line Telephone Line Status Indicator -  This circuit monitors one phone line. . . Circuit by David Johnson P.E.-June, 2000

One-Watt White LED Night Light -  As many of you know, I have a pet peeve with poorly made LED night lights.  Often, the light from the LED quickly fades, so within months, the light is useless.  I have posted several versions of modified night lights using higher quality components.  This circuit is yet another version, which produces much more light than those other designs. . . . Hobby Circuit designed by David Johnson P.E.-November, 2008

Optical feedback extends white LEDs' operating life -  01/18/07  EDN-Design Ideas PWM-controller loop stabilizes light output __ Circuit Design by Bjoy Santos, Intersil Corp, Milpitas, CA

Optical LED Transmitter -  Schematic only __ Designed by va3iul

Optical Toggle Switch using a Single Chip -  Using dual flip-flop IC CD4027 employ a 555 based monostable circuit to supply input clock pulses.  The circuit described here obviates this requirement.  One of the two flip-flops within IC CD4027 itself acts as square wave shaper

Optimizing Efficiency in White LED Backlight Applications -  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, 21-Mar-07

Ornamental Flashing LEDs -  This circuit can flash three sets of LEDs with different levels of Flashing.  It can be used as Ornamental displays.  The circuit uses a simple Astable multivibrator built around the popular timer IC NE555.  Resistors R1, R2 and capacitor C1 determines the output frequency.  When the output becomes high, Red LEDs lights first.  When __ Designed by D Mohankumar

Our Best LED Torch Ever! -  It's based on a Luxeon Star/O 1W ultrabright LED, runs off two "D" cells and blasts our previous LED torches into the weeds!__ SiliconChip

Our Fantastic Human-Powered LED Torches -  Sure you've seen LED torches before but not like these.  There are no batteries; you just crank the handle to generate light.__ SiliconChip

Outdoor Garden Solar Lights -  This Outdoor LED Solar Garden Lights project is a hobby circuit of an automatic garden light using a LDR and 6V/5W solar panel.  During day time, the internal rechargeable 6 Volt SLA battery receives charging current from the connected solar panel through polariy protection diode D9 and current limiting resistor R10.  If ambient __ Designed by D Mohankumar

Park Aid -  Three LEDs signal bumper-barrier distance; Infra-red operation, indoor use __ Contact: Flavio Dellepiane, fladello @ tin.it

Park-Aid Modification -  Three-step beeps signal bumper-barrier distance; Infra-red operation, indoor use __ Contact: Flavio Dellepiane, fladello @ tin.it

Pathway Lighting with LEDs -  Simple pathway lighting that would provide illumination for the path at night.  Extension for the Solar garden Light.  The torroid is bifilar wound.  The Torroid is 10mm and Cat 5 cable is wound around the same.  Solar panels of 3.5 maybe difficult to procure using 2 2V panels in series could be used.  If you do use 4V panel then __ Designed by Sebastian Kushero

Peggy-A Light Emitting Pegboard Display -  With all the cool things that you can do with LEDs today, there is still one thing that’s lacking: simplicity.  If you want to run a bunch of LEDs at a time, you usually end up spending a fair bit of time worrying about series and parallel combinations, matching brightness, and picking load resistors.  Or, if you’re a beginner, maybe you only get one third of the way through the previous sentence– wondering if you’re already in over your head. __ Designed by © Evil Mad Scientist

Perpetual Candle-White LED Lamp on Ni-Cd -  This is a easy to build LED lamp circuit for Learning and building skills.  This is the first draft schematic V 1.0.  It will need improvements for Higher Power Lighting.  Click to enlarge I will give a short summary, The LM317 here configured for

Philips RC5 IR Decoder using 12 LEDs -  The RC5 IR remote control code, originally developed by Philips consists of 14 bits separated by 1.778 mS, or 24.889 mS for a complete message.   Each bit consists of two half bits where a logic '0' is represented by a 889uS high level followed by a 889uS low level  __ Designed by Bill Bowden

Photo Sensor -  Here's a circuit that takes advantage of the photo-voltaic voltage of an ordinary LED.  The LED voltage is buffered by a junction FET transistor and then applied to the inverting input of an op-amp with a gain of about 20.  This produces a change of about 5 volts at the output from darkness to bright light.  The 100K potentiometer can be set so that the output is around 7 volts in darkness and falls to about 2 volts in bright light __ Designed by Bill Bowden

Photovoltaic switch disables unused LEDs -  03/18/04  EDN-Design Ideas In many applications, it's desirable to disable LEDs used for system verification.  Many options are available for the disabling function, including manual SPST  (single-pole single-throw] switches, enhancement- and depletion-mode MOS __ Circuit Design by Lance McBride, Monterey Bay Aquarium Research Institute, Moss Landing, CA

PIC Controlled 32-LED Knightrider -  A PIC processor simplifies the circuit and gives 12 different lighting patterns for the 32 LEDs.  You can use it as a rear window break light as an eye catching display.__ SiliconChip

PIC controlled Fading Eyes -  Another version of the circuit was done using a PIC microcontroller and a pair of high power 1/2 watt orange LEDs.  The software uses a non-linear scale to generate a more linear visual response.  LEDs are more efficient at lower power and a nonlinear reduction in current seems to obtain a more linear visual effect.  The controller produces a PWM output in 50 steps which is buffered with a medium power transistor to drive the LEDs.  The LEDs are connected to a 12 volt supply so that most any colored or white LEDs can be used in the range of 1.6 to 3.3 forward voltage.   __ Designed by Bill Bowden

PIC Digital Timer (4 timed outputs) -  This circuit uses the PIC16F628 microcontroller to provide 4 timed outputs that can be programmed from 1 minute to 1 week.  An extra 8 bit shift register  (74HC164) is used for the 4 timer outputs and to display four additional indicator lights.   __ Designed by Bill Bowden

PIC Micro LED Projects -  Here is a neat PIC Project  that I created using the 16F84 chip and a neat little bi-color LED from Radio Shack.  The LED can be red or green depending on the bias of the diode.  By using two of the PORT B pins, I can control the bias of the LED.  If the LED is on PORT B, Pin 0 and Pin 1, I can set Pin 0 HIGH and Pin 1 LOW, this would make __ Designed by Jason KE4NYV from Roanoke, Virginia

PIC microprocessor drives 20-LED dot- or bar-graph display -  09/01/06 EDN-Design Ideas Indicator circuit features low cost and minimal component count __ Circuit Design by Noureddine Benabadji, University of Sciences and Technology, Oran, Algeria

PIC microprocessor drives 20-LED dot-or bar-graph display -  09/01/06  EDN-Design Ideas Indicator circuit features low cost and minimal component count __ Circuit Design by Noureddine Benabadji, University of Sciences and Technology, Oran, Algeria

PIC16F628 Digital Clock Timer -  This clock timer uses a PIC16F628 microcontroller to display 3 and 1/2 digit time and control an external load.  The clock includes a calendar with leap year and optional daylight savings adjustments.  The timer output can be set from 1 to 59 minutes and manually switched on and off.  The clock also has a correction feature that allows an additional second to be added every so many hours to compensate for a slightly slow running oscillator.  The oscillator uses a common 32.768 KHz watch crystal and the frequency can be adjusted slightly with the 24pF capacitor on the right side of the crystal __ Designed by Bill Bowden

PIC16F84 LED Chaser -  There are several projects on this page.  Please scroll down to find the LED Chaser.   __ Designed by Jason KE4NYV from Roanoke, Virginia

Picnic Lamp -  You can take this white LED based night lamp on your picnic outings.  The lamp has sound trigger and push-to-on facilities and gives ample light during a walk at night.  It...__ Electronics Projects for You

Picxie 2 8x8 Animated LED Signboard -  The firmware supplied incurrent sourcecode archive is VERY BASIC.  I do intend to draw more patterns.  However, a vast workload coupled with possible emigration has putfinished firmware on hold.  Please do go ahead and build this circuit thoughsupplied firmware is fully functional.  You can have hours of fun designing your own patterns and effects!UsesPIC16F84 __ Designed by Lewin A.R.W. Edwards

Plus & Minus DC Power Supply -  This is a classic example of a regulated DC power supply that produces both a positive 15v and a negative 15v from a 20vac wall adapter . . . Hobby Circuit designed by Dave Johnson P.E.-October, 2005

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


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