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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. :

 9v Battery Voltage MonitorThis circuit turns on a LED whenever the voltage of a standard 9v battery connected to the circuit drops below 7.2 volts.  It uses a LTC1440 comparator, which also contains a 1.18v reference diode.  In standby mode, the circuit draws only 4uA. . . Circuit by Dave Johnson P.E.-July, 2006

 AC Line Powered LED FlasherSome of the latest LEDs are amazing.  They can produce a surprising amount of light with very little current.  In the light flasher application shown below I take advantage of a nice surface mounted LED from King Bright.  This flasher circuit draws only about 3ua of average current from the AC power line to flash this green LED.  This flasher might be used as a power indicator light . . . Hobby Circuit designed by David Johnson P.E.-December, 2008

 AC Line Powered LED Pilot LightThis 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 . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

 AC Line Powered LED StringsThis shows 4 different ways to string white LEDs that are powered by a 120vac or 240vac power line.    This hobby circuit was designed by Ken Schultz.. . . Circuit by David Johnson P.E.-December, 2004

 AC Power Loss AlarmIíve been having a problem with my instant hot water system lately.  This system circulates electrically heated water throughout my house using a small pump.  The pump is wired into a ground fault interrupter   (GFI) module.  Every now and then, the GFI trips, leaving me without hot water. . . Circuit by David A. Johnson P.E.-March, 2009

 Active AC Power Line IndicatorThe circuit below is designed to detect when a power cable is active   (hot) .  When the flat sensor end of the device is held near an active AC line, the bright green LED on the top of the housing will glow.  It is powered by a 3v CR2032 lithium coin cell.  I. . . Circuit by Dave Johnson P.E.-May, 2005


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

8 LEDs Make a 100-Division Voltmeter -  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

8 Stage LED VU Meter -  The circuit below uses two quad voltage comparators    (LM339) to illuminate a series of 8 LEDs indicating volume level.  Each of the 8 comparators is biased at increasing voltages set by the voltage divider so that the lower right LED comes on first when the input is about 400 millivolts or about 22 milliwatts peak in an 8 ohm system.  The divider voltages are set so that each LED __ Designed by Bill Bowden

80x32 pixel DIY LED matrix display -  The LEDMATRIX additionally includes a simple speaker allowing to e.g.  notify the user of a new message being displayed.  Furthermore a TSOP1736 IR receiver can optionally be connected.  This device receives and decodes the IR signals used by ordinary TV remote controls.  By returning informtion about received IR signals to the controlling PC, the displays contents may e.g.  be remotely changed using a simple spare IR remote control. __ Designed by Till Harbaum <Till @ Harbaum.org>

81-LED Chaser Light using CD4 017 -  This is a simple 81-LED chaser light using two CD4017 decade counters.  NE555 timer is used for clock generation for CD4017.  We have used only two CD4017 ICs to construct the...__ Electronics Projects for You

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

8x85 RGB POV Display. Part 1 -  Brads electronic projects This was my first attempt at a nice and colourful RGB LED POV Display.  POV stands for persistence of vision.  The circuit uses just 8 RGB LEDs which are mounted vertically and when spun horizontally it gives the illusion of __ Designed by Radio LocMan

8x85 RGB POV Display. Part 2 -  The drawing process is really quite simple.  The pic microcontroller puts 00000000 00000000 on the eeproms address bus    (selects the first address) This byte of info    (at that address) is now placed on the data bus and all RED GREEN AND BLUE __ Designed by Radio LocMan

8x85 RGB POV Display. Part 3 -  Things to note in the source code: You can easily define how many frames of animation are in your animation loop by changing the total_frames variable to how ever many frames you have.  The flying animation example has 178 frames.  If you only have __ Designed by Radio LocMan

8x8x8 Programmable LED Cube -  Club Jameco's all-time best selling kit. __ Contact: Jameco Electronics

9 Second Digital Readout Countdown Timer -  This circuit provides a visual 9 second delay using a 7 segment digital readout LED.  When the switch is closed, the CD4010 up/down counter is preset to 9 and the 555 timer is disabled with the output held high.  When the switch is opened,  __ Designed by Bill Bowden

9 Second LED Relay Timer -  This circuit provides a visual 9 second delay using a 7 segment digital readout LED.  When the switch is closed, the CD4010 up/down counter is preset to 9 and the 555 timer is disabled with the output held high.  When the switch is opened,  __ Designed by Bill Bowden

94% Efficient 25W White LED Automotive Headlamp Driver -  The LT3956 is a DC/DC converter designed to operate as a constant-current source and constant-voltage regulator.  It is ideally suited for driving high current LEDs.  It features an internal low side N-channel power MOSFET rated for 84V at 3.3 A and driven from an internal regulated 7.15V supply.  The fixed frequency, current-mode __ Linear Technology/Analog Devices App Note, Jul 20th 2010

9v Battery Voltage Monitor -  This circuit turns on a LED whenever the voltage of a standard 9v battery connected to the circuit drops below 7.2 volts.  It uses a LTC1440 comparator, which also contains a 1.18v reference diode.  In standby mode, the circuit draws only 4uA. . . Circuit by Dave Johnson P.E.-July, 2006

A "persistence of vision display" (POV display) using LEDs -  A "persistence of vision display"    (POV display) has only a single line of LEDs blinking on and off.  The display mechanically sweeps it across a person's field of view, giving the illusion of a 2D display.   

A 25 LED Chaser (Sequencer) -  A Fairly Simple C-Mos Circuit.   __ Designed by G.L. Chemelec

A 34W LED Driver with Robust Output Short-Circuit Protection -  Figure 1 shows the LT3796 configured as a boost converter to drive a 34W LED string from a wide input range.  The LED current is derated at low input voltages to prevent external power components from overheating.  The front-end current sense amplifier monitors the input current by converting the input current to a voltage signal __ Linear Technology/Analog Devices App Note, Jun 29th 2012

A CharliePlexed RGB LED Dice -  The project uses 7 RGB LEDs arranged in the form of dice.  Each RGB LED has three separate LEDs inside so that makes a total of 21 LEDs and they have been controlled by 4 I/O pins of ATTiny13V Microcontroller.  But according to the theory of

A Low-Power, long life LED flashlight -  Scouring the Internet for information on LEDs, I accidentally stumbled upon a PDF detailing a flashlight made from PVC.  For the torch, he biases ultra-bright LEDs with ballast resistors as described in my LED lighting guide.  This is a simple solution, but a with a slightly more complicated circuit we can extend battery life by over ten times!

A Moving Message Display -  It's easy to build, easy to program, easy on the pocket and easy on the eye.__ SiliconChip

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

A Seriously 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

A Simple Circuit Musical Light -  The circuits for musical lights available in the market are highly expensive and based on microcontrollers.  Also, their programming is very difficult.  Here is a simple and cheap circuit for a...__ Electronics Projects for You

A Smart Mixture Display for Your Car -  A 10-LED display indicates the fuel mixture, while a small buzzer sounds if the mixtures go dangerously lean.__ SiliconChip

A Step-Down Conversion Concept for a PWM-Mode Boost Converter -  TI App Note 

A Voice Controlled LED Light Show using a VRStamp -  A voice controlled LED light show.  Train your board with your voice, then control the LED animation by saying commands!   This project is fitted to the mikroC RSC-4x compiler small memory model : no mikroC licence is needed, just to show the power of the demo version!__ Bruno Gavand

AC LEDs -  Some useful Circuits with LEDs using the AC voltage.     (5/28/2006)  __ Designed by Jose Pino

AC Line Powered LED Flasher -  Some of the latest LEDs are amazing.  They can produce a surprising amount of light with very little current.  In the light flasher application shown below I take advantage of a nice surface mounted LED from King Bright.  This flasher circuit draws only about 3ua of average current from the AC power line to flash this green LED.  This flasher might be used as a power indicator light . . . Hobby Circuit designed by David Johnson P.E.-December, 2008

AC Line Powered LED Pilot Light -  This 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 . . . Hobby Circuit designed by Dave Johnson P.E.-July, 2006

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

AC Line Powered LED Strings -  This shows 4 different ways to string white LEDs that are powered by a 120vac or 240vac power line.    This hobby circuit was designed by Ken Schultz.   __ Designed by Ken Schultz, drawn Dave Johnson 12.18.2004

AC Line Powered LEDs -  The circuit above illustrates powering a LED    (or two) from the 120 volt AC line using a capacitor to drop the voltage and a small resistor to limit the inrush current.  Since the capacitor must pass current in both directions, a small diode is connected in parallel with the LED to provide a path for the negative half cycle __ Designed by Bill Bowden

AC Power Loss Alarm -  Iíve been having a problem with my instant hot water system lately.  This system circulates electrically heated water throughout my house using a small pump.  The pump is wired into a ground fault interrupter    (GFI) module.  Every now and then, the GFI trips, leaving me without hot water. . . Circuit by David A. Johnson P.E.-March, 2009

Accurately Simulate an LED -  EDN-Design Ideas 10/07/10    A transistor that simulates an LED lets you test the driver circuit.   __ Circuit Design by Jon Roman and Donald Schelle, National Semiconductor Corp, Santa Clara, CA

AC-Powered LED Lamps Without Rectifiers -  Usually, LED lamps require rectifier when connected to the AC mains power supply.  Electrical isolation of the LED lamps from the mains is also required in most cases.  But rectifiers create...__ Electronics Projects for You

Active AC Power Line Indicator -  The circuit below is designed to detect when a power cable is active    (hot) .  When the flat sensor end of the device is held near an active AC line, the bright green LED on the top of the housing will glow.  It is powered by a 3v CR2032 lithium coin cell.  I. . . Circuit by Dave Johnson P.E.-May, 2005

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

 


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