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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. :

3 Minute LED Closet Light -  The circuit below is powered by three 1.5v alkaline AA cells.  With a finger tap to the pushbutton trigger switch, a cluster of 6 wide angle white LEDs is turned on.  The lights remain on for about 3 minutes, then will turn off.  The circuit’s standby current . . . Hobby Circuit designed by David A. Johnson P.E.-November, 2010

30 LED Night Light -  This Hobby Circuit uses a capacitor to limit the current through a series-parallel string of 30 LEDs.15 LEDs are wired in series in one direction and 15 more in the other direction.  The capacitor limits the average current to about 20ma.  The 100 ohm metal oxide resistor acts as a fuse.   . . . Hobby Circuit designed by David A. Johnson P.E.

3-Minute Closet Light -  I have a coat closet by my front door.  The thing is very dark at night and really needs some kind of illumination inside.  I could hire an electrician to install a light in the closet ceiling and then wire it to a toggle switch outside the door but that would cost me quite a bit of money . . . Circuit by David Johnson P.E.-December, 2011

3-Minute Closet Light #2 -  The circuit below is powered by three 1.5v alkaline AA cells.  With a finger tap to the pushbutton trigger switch, a cluster of 6 wide angle white LEDs is turned on.  The lights remain on for about 3 minutes, then will turn off.  The circuit’s standby current is only a few microamps.  A set of fresh batteries should last at least 200 light applications.  The circuit uses a Schmitt trigger inverter and two transistors.  When the pushbutton switch S1 is pressed, the 10uF capacitor C1 is discharged . . . Circuit by David A. Johnson P.E.-November, 2010

3v Battery Powered White LED Driver -  The circuit below will drive any LED color, including white LEDs, using a DC power supply ranging from 2v to 3.3 v.  White and blue LEDs normally require over 3v, so the circuit below uses a charge pump scheme to deliver a constant LED light intensity . . . Circuit by David Johnson P.E.-August, 2010

3v Powered Super Bright LED Flasher -  I 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 . . . Hobby Circuit designed by Dave Johnson P.E.-April, 2009

3v Universal LED Flasher -  This low power LED flasher circuit draws about 100ua from any DC power supply ranging from 3 volts to 24 volts.  The 1.0Hz 10ms LED pulsed current is held to a constant 10ma . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

4 to 20ma Current Loop Senses Temperature -  I designed a circuit similar to this one years ago to accurately measure the air temperature inside a building 1000s of feet from a control room.  The circuit uses a very robust current loop method.  It uses a highly accurate semiconductor temperature sensor . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

4_D-Cell_LED_Lantern_Modified -  While shopping at a sporting goods store one day, I spotted a compact LED lantern.  It looked like the kind of lantern I could modify. The lantern LEDs were grouped into three sections of 7 LEDs each, oriented into 120 degree angles.  The LEDs were standard T 1-3/4 epoxy types.  The lantern had a three mode switch which selected between off, full power and half power modes.  At the half power mode, only half of the 21 LEDs were illuminated.  At full power all LEDs were illuminated. . . . Hobby Circuit by David Johnson P.E.-September, 2017


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

3 Flashing LED Doorbells -  Battery Powered LED Circuits:  These circuits combine a buzzer with one or more LED displays.  When the push switch is operated - the buzzer will sound and the LEDs will flash.  When the switch is released - the buzzer will stop - but the LEDs will go on flashing for another 30 seconds or so. __ Designed by Ron J.

3 microcontroller ports drive 12 LEDs -  12/15/06  EDN Design Ideas:  Engine tachometer uses few components and i/O lines __ Circuit Design by Nedjeljko Lekic and Zoran Mijanovic, University of Montenegro, Department of Electrical Engineering, Podgorica, Montenegro

3 Minute LED Closet Light -  The circuit below is powered by three 1.5v alkaline AA cells.  With a finger tap to the pushbutton trigger switch, a cluster of 6 wide angle white LEDs is turned on.  The lights remain on for about 3 minutes, then will turn off.  The circuit’s standby current . . . Hobby Circuit designed by David A. Johnson P.E.-November, 2010

3 pins, 3 LEDs, 3 buttons -  08/18/14 EDN Design Ideas:  Many previous Design ideas [1, 2] have shown how to use the Charlieplexing technique [3] to drive as many LEDs as possible with a minimum number of i/O lines.  This Design idea shows how you can drive three LEDs and scan three switches with only three i/O lines instead of six.  Using the same principle, it will also be possible to manage four switches and two LEDs, or five LEDs and one switch __ Circuit Design by Francois AUGER & Philippe Fretaud

3.6 Volt (cell phone) LED Battery Meter -  This is a similar circuit to the above and provides a 4 LED bar graph indicating the voltage of a common 3.6 volt Lithium - ion rechargeable cell phone battery.  The reference voltage is provided by a TL431 programmable voltage source which is set to 3.9 volts where the TL431 connects to the 1K resistor.  The lower reference for the LED at pin 14 is set with the 5K adjustable resistor.   __ Designed by Bill Bowden

30 LED Night Light -  This Hobby Circuit uses a capacitor to limit the current through a series-parallel string of 30 LEDs.15 LEDs are wired in series in one direction and 15 more in the other direction.  The capacitor limits the average current to about 20ma.  The 100 ohm metal oxide resistor acts as a fuse.   . . . Hobby Circuit designed by David A. Johnson P.E.-January, 1900

30W White LED Automotive Headlamp Driver with Thermal Derating -  The LT3756, LT3756-1 and LT3756-2 are DC/DC controllers designed to operate as a constant-current source for driving high current LEDs.  They drive a low side external N-channel power MOSFET from an internal regulated 7.15V supply.  The fixed frequency, current-mode architecture results in stable operation over a wide range of __ Linear Technology/Analog Devices App Note, Jul 20th 2010

36 LED Chaser -  example of multiplexed display to produce a chaser - LEDs were mounted in a circle __ Contact P. Townshend - EduTek Ltd

3-Channel White-LED Driver Uses Simple Circuit Step-Down DC/DC Converter -  09/13/12  EDN Design Ideas:  Drive multiple LEDs with current mirrors from a single step-down converter.   __ Circuit Design by Nora Jacalan Esteves, Technor Semiconductor LLC, Pleasanton, CA

3D LED Pyramid -  The author ‘just wanted to do a bit of microcontroller programming’.  However, the project rapidly grew into this impressive and visually attractive pyramid.  The circuit consists essentially of a specially-sawn printed circuit board, 23 LEDs and a microcontrollerrequires login to see circuit __ Designed by Published in Elecktor July/Aug, 2010

3-Minute Closet Light -  I have a coat closet by my front door.  The thing is very dark at night and really needs some kind of illumination inside.  I could hire an electrician to install a light in the closet ceiling and then wire it to a toggle switch outside the door but that would cost me quite a bit of money . . . Circuit by David Johnson P.E.-December, 2011

3-Minute Closet Light #2 -  The circuit below is powered by three 1.5v alkaline AA cells.  With a finger tap to the pushbutton trigger switch, a cluster of 6 wide angle white LEDs is turned on.  The lights remain on for about 3 minutes, then will turn off.  The circuit’s standby current is only a few microamps.  A set of fresh batteries should last at least 200 light applications.  The circuit uses a Schmitt trigger inverter and two transistors.  When the pushbutton switch S1 is pressed, the 10uF capacitor C1 is discharged . . . Circuit by David A. Johnson P.E.-November, 2010

3v Battery Powered White LED Driver -  The circuit below will drive any LED color, including white LEDs, using a DC power supply ranging from 2v to 3.3 v.  White and blue LEDs normally require over 3v, so the circuit below uses a charge pump scheme to deliver a constant LED light intensity . . . Circuit by David Johnson P.E.-August, 2010

3V LED Chaser -  There are many 9V chaser circuits that seem to waste about 7V when driving LEDs that are only about 2V.  This project is unique, because it uses only two inexpensive alkaline battery cells totaling 3V for power.  Since most of the waste is eliminated, the cells last a long time.  Unlike the other circuits, this one flashes the LEDs for only about 30ms each, further extending the battery life.  For user convenience, it has a stepper speed control and a brightness control.  At slower speeds and with reduced brightness,  __ Contact IQ Technologies

3V LED chaser using 4017 -  There are many 9V chaser circuits that seem to waste about 7V when driving LEDs that are only about 2V.  This project is unique, because it uses only two inexpensive alkaline battery cells totaling 3V for power.  Since most of the waste is eliminated, the cells last a long time.   __ Designed by Audioguru

3v Powered Super Bright LED Flasher -  I 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 . . . Hobby Circuit designed by Dave Johnson P.E.-April, 2009

3v Universal LED Flasher -  This low power LED flasher circuit draws about 100ua from any DC power supply ranging from 3 volts to 24 volts.  The 1.0Hz 10ms LED pulsed current is held to a constant 10ma . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

3x3x3 LED Cube -  This circuit drives a 3x3x3 cube consisting of 27 white LEDs.  The 4020 IC is a 14 stage binary counter and we have used 9 outputs.  Each output drives 3 white LEDs in series and we have omitted a dropper resistor as the chip can only deliver a maximum of 15mA per output.  The 4020 produces 512 different patterns before the sequence repeats and you have to build the project to see the effects it produces on the 3D cube.  __ 555-Timer

4 DIPs provide as many as 80 sequential-LED outputs -  08/21/08 EDN Design Ideas:  A simple circuit uses HCMOS parts and adds one 74HC540 to multiplex the outputs of two 4017 counters for as many as 80 outputs __ Circuit Design by Greg Carkner, Cobourg, ON, Canada

4 to 20ma Current Loop Senses Temperature -  I designed a circuit similar to this one years ago to accurately measure the air temperature inside a building 1000s of feet from a control room.  The circuit uses a very robust current loop method.  It uses a highly accurate semiconductor temperature sensor . . . Hobby Circuit designed by David A. Johnson P.E.-July, 2006

4_D-Cell_LED_Lantern_Modified -  While shopping at a sporting goods store one day, I spotted a compact LED lantern.  It looked like the kind of lantern I could modify. The lantern LEDs were grouped into three sections of 7 LEDs each, oriented into 120 degree angles.  The LEDs were standard T 1-3/4 epoxy types.  The lantern had a three mode switch which selected between off, full power and half power modes.  At the half power mode, only half of the 21 LEDs were illuminated.  At full power all LEDs were illuminated. . . . Hobby Circuit by David Johnson P.E.-September, 2017

40 LED Bicycle Light 555 Timer 6 Volt -  The 555 circuit below is a flashing bicycle light powered with four C, D or AA cells (6 volts).  Two sets of 20 LEDs will alternately flash at approximately 4.7 cycles per second using RC values shown (4.7K for R1, 150K for R2 and a 1uF capacitor).  Time intervals for the two lamps are about 107 milliseconds (T1, upper LEDs) and 104 milliseconds (T2 lower LEDs)  __ Designed by Bill Bowden

5 Lamp/ LED Flash Driver -  General Description of the following circuit.  This circuit is based around HT–2050 manufactured by HOLTEK semiconductors.  It is a low cost, low-power C-MOS LSI designed for lamp andLED flash driver.  It requires minimum external components.  You can operate it with just two AAA cell or 3v Battery __ Designed by Holtek HT2051

5 MHz Bandwidth Single Transistor Modulator -  The first circuit is useful for modulation up to about 5 MHz and uses a single transistor circuit biased as a firm current source with the LED in the collector circuit.  With the circuit components shown, the high frequency cutoff is about 4 - 5 MHz, limited by the base-emitter forward biased capacitance.  The quiescent DC current through the LED as determined approximately by (Vcc/2 - 0.7) /R5 or about 24 mA __ Designed by M. Gallant

50W White LED Automotive Headlamp Driver -  The LT3755, LT3755-1 and LT3755-2 are DC/DC controllers designed to operate as a constant-current source for driving high current LEDs.  They drive a low side external N-channel power MOSFET from an internal regulated 7.15V supply.  The fixed frequency, current mode architecture results in stable operation over a wide range of __ Linear Technology/Analog Devices App Note, Jul 20th 2010

555 LED Flasher -  This is a small size LED flasher built with the 555 timer IC that is powered from 2 x 1.5V batteries.  The circuit can be used as a flashing metronome, dark room timer, memo-reminder or other similar applications.   __ Designed by Popescu Marian

555 Timer Drives Multiple LEDs from One NiMH
Cell
-  2-Oct-08 EDN Design Ideas:  Using a CMOS 555 timer, you can drive seven high-brightness LEDs from a single 1.25V cell __ Circuit Design by Chuck Irwin, Hendersonville, NC

555 Timer Eliminates LED Driver’s Need for Microprocessor Control -  3-Sep-09 EDN Design Ideas:  A timer provide as programming pulses for lower cost than a microprocessor __ Circuit Design by Michael Day, Texas Instruments, Dallas, TX

555 timer 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

5x5x5 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__ 

5x7 Display -  Sit back and take a big breath.  You are about to take part in one of the best microcomputer (microprocessor) projects you have seen.  It uses a PIC 16F84 micro and you will be shown how to program the chip to create quite amazing effects.  It's a simple project and you will be starting at the beginning of programming, so don't worry if you have never worked with a microprocessor before __ Contact Colin Mitchelltalking @ tpg.com.au

60V, Synchronous Step-Down High Current LED Driver -  03/01/14 EDN-Design Notes   This circuit provide as much better performance and higher power handling than a Zener diode The meaning of the term “high power LED” is rapidly evolving.  Although a 350mA LED could easily earn the stamp of “high power” a few years ago, it could not hold a candle to the 20A LEDs or the 40A laser diodes of today.  High power LEDs are now used in DLP projectors, surgical equipment, stage lighting, automotive lighting, and other applications traditionally served by high intensity bulbs __ Circuit Design by Hua  Walker Bai, also see Linear Technology Design Note 508

6V ultra-bright LED chaser using 74HC4017 -  This is a spectacular but completely useless project.  It lights Ultra-Bright LEDs in a sequence and each LED flashes brightly very briefly.  The LEDs light-up going around and around since they are mounted in a circle (on a CD) , then they pause __ Designed by Audioguru

7 by 10 LED Moving Sign -  This sign uses two LED arrays to form a 7 X 10 matrix.  It produces moving messages or animations stored in an EPROM.  It uses no microprocessor.   As in most electric signs, the LEDs are matrixed, and strobed very quickly.   __ Designed by Boblick

7 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

7 Segment LED Counter -  This simple counter can be used to count pulses, as the basis for a customer counter (like you see at the doors of some stores) , or for anything else that may be counted.  The circuit accepts any TTL compatible logic signal, and can be expanded easily (see Notes)  __ Designed by Aaron Cake

7 segment rolling display using PC -  it is very interesting and convenient to be able to control everything while sitting at your PC terminal.  Here, a simple hardware circuit and software is used to interface a 7-segment based rolling display.  The printer port of a PC provides a set of points with some acting as input lines and some others as output lines.  Some lines are open collector type which can be used as input lines.  The circuit given here can be used for interfacing with any type of PC?s printer port.  Read more: http://www.electronic-circuits-diagrams.com/7-segment-rolling-display-circuit/#ixzz4fil0LLEN
Follow us: @eleczone on Twitter | electronicscircuitsprojects on Facebook__ 

7×5 LED Matrix using Arduino -  Presented here is a simple 7x5 LED matrix circuit vriven by Arduino Uno (Arduino LED).  It can be used to display your name or create any number of patterns.  If the__ Electronics Projects for You

72 LED Clock -  in the circuit above, 60 individual LEDs are used to indicate the minutes of a clock and 12 LEDs indicate hours.  The power supply and time base circuitry is the same as described in the 28 LED clock circuit above.  The minutes section of the clock is comprised of eight 74HCT164 shift registers cascaded so that a single bit can be recirculated through the 60 stages i __ Designed by Bill Bowden

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

 


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