LED Mood Light -  This circuit makes a nice lamp that consumes little power, runs cool, and has an incredibly long lifetime.  The lamp puts out a warm yellow shade of light, the color may be adjusted by changing the number of red or green LED strings.   __ Designed by Forrest Cook

LED or Incadescent 12 Volt Lamp Fader -  This circuit is similar to the "Fading Red Eyes" circuit    (in the LED section) used to fade a pair of red LEDs.  In this version, the lamps are faded by varying the duty cycle so that higher power incandescent lamps can be used without much power loss.  The switching waveform is generated by comparing two linear ramps  __ Designed by Bill Bowden

LED senses & displays Ambient-light intensity -  11/09/06  EDN-Design Ideas LED doubles as photosensor and visual indicator of ambient-light intensity Design by Dhananjay V Gadre and Sheetal Vashist, ECE Division, Netaji Subhas Institute of Technology, New Delhi, India

LED Sequencer -  The model 4017 integrated circuit is a CMOS counter with ten output terminals.  One of these ten terminals will be in a "high" state at any given time, with all others being "low, " giving a "one-of-ten" output sequence.  If low-to-high voltage pulses are applied to the "clock"  (Clk) terminal of the 4017, it will increment its count, forcing the next output into a "high" state __ Designed by © EETech Media, LLC.

LED Sequencer -  This circuit is the essence of many "chaser" schemes that provide animation in advertising displays, lighting ten LEDs sequentially.   __ Designed by Arthur Harrison

LED Solar Lantern Lights -  Circuit of the LED solar lantern lights presented here is built around one 6V/1W Solar Panel  (PhotoVoltaic Panel) and a 4V/800mAh Lead-Acid Battery.  Here, commonly available 5mm White Straw Hat LEDs are used as the light source.  how does the solar lantern circuit works DC 6V supply from the solar panel is fed to the __ Designed by T.K. Hareendran

LED Strobe -  with high power led's available, their replacement for a xenon tube is viable! __ Contact: P. Townshend EduTek Ltd

LED Strobe & Contactless Tachometer -  This versatile LED Strobe & Tachometer can be used to observe and measure the RPM of rotating machinery.  It offers three different measurement methods and the readout is via a 2-line LCD module.__ SiliconChip

Led Strobe & Tacho Pt.2 -  Last month, we published the circuit of our new LED Strobe & Tachometer and showed how to build the main unit and the strobe light.  This month, we describe the assembly of the optional Photo-Interruptor and IR Reflector Amplifier boards.  We also describe how the unit is used.__ SiliconChip

LED Strobe Flasher -  This little circuit provides a surprisingly spectacular bright strobe flash which is adjustable with P1, the 200K trimmer potentiometer.  P1, R1, R2, and C1 provide the flashrate.  R1 sets the upper flashrate.  The flashrate for the above circuit was measured at 12Vdc.  If the supply voltage is steady or regulated, the flashrate is very stable. __ Designed by Tony van Roon  VA3AVR

LED Strobe Has Independent Delay & Duration -  11-Jun-09 EDN-Design Ideas High-brightness LEDs, with independent delay and duration, find use in a visual-inspection application Design by Michael C Page, Chelmsford, MA

LED Strobe Light -  Schematic + Info + pictures __ Designed by Lennie Zink

LED Torch -  Based on the MAX660, designed to power three 3mm/5mm white LED's from 3V  (1.5V min) , intended for replacing incandescent bulbs in small torches.   __ Designed by Submitted Andre

LED Torch -  A common problem with small torches is the short life-span both of the batteries and the bulb.  The average incandescent torch, for instance, consumes around 2 Watts.  The LED Torch in Fig.1 consumes just 24 mW, giving it more than80 times longer service from 4 AA alkaline batteries  (that is, up to one month's continuous service)  __ Designed by Rev Thomas Scarborough

LED Torchs -  A LED torch is one of the simplest projects you can build and it's very interesting as it uses a super-bright white LED.  In the history of LED production, red LEDs were the first to be invented and their output was so dim you could barely see if they were illuminated.  You needed a darkened room to see them at all __ Contact: Collin Mitchell

LED Traffic Lights -  The LED traffic Light circuit controls 6 LEDs  (red, yellow and green) for both north/south directions and east/west directions.  The timing sequence is generated using a CMOS 4017 decade counter and a 555 timer.  Counter outputs 1 through 4 are wire ORed using 4 diodes so that the  (Red, North/South) and  (Green, East/West) LEDs will be on during __ Designed by Bill Bowden

LED used for near-IR light -  09/01/98 EDN-Design Ideas NOTE :  File has many circuits, scroll down.  You can successfully use LEDs as sources of near-infrared light.  However, when you need a source of light with precisely controlled power, a feedback loop is necessary to compensate for the temporal and thermal changes of the LED parameters.  Standard LED types come with neither these monitoring detectors nor an external monitoring photodiode to detect part of the emitted light and generate a feedback signal.  The situation calls for some mechanical fixture to mount the photodiode. Design by Lukasz Sliwczynski, Marcin Lipinski, Institute of Electronics, Krakow, Poland

LED Blinker uses 4 parts -  EDN-Design Ideas March 26, 1998    [ NOTE : File has multiple design, scroll for this one.]   The circuit in Figure 1 is an easy-to-make attention-getter and runs for a week or longer on two AA cells. In September, I used this circuit for a school fundraiser, and it helped me generate more than $100. My dad showed me a circuit in EDN that did the same thing, but it uses more parts  (see "Alternating LED flasher uses minimal parts," EDN, Nov 20, 1997, pg 104) . Design by Andy Meng, Cincinnati, OH

Led Strobe 2 -  this version has been built and tested and is very simple indeedbased on alien project astable! __ Contact: P. Townshend EduTek Ltd

LED7 Solar Tracker -  Schematic only, no circuit description __ Contact: Duane C. Johnson

LED-flashlight works at voltages as low as 0.5V -  09/23/10 EDN-Design Ideas Extend the life of alkaline batteries.    Design by GY Xu, XuMicro, Houston, TX

LEDs Flasher Alternately -  Classic astable multivibrator using 2 transistors.  Transistor is not critical.  Try these: 2N4401, 2N2222, NTE123A, NTE123AP, NTE159, TUP/TUN and those in your junk box, you may find that most of them will work.   __ Designed by Tony van Roon  VA3AVR

LEDs or Lamps Sequencer -  Very simple, versatile modular design No limits to the number of modules used in the ring __ Contact: Flavio Dellepiane, fladello @ tin.it

Light / dark activated relay -  The potmeter adjust the trigger 'on' level.  The diode in the diagram shows to be 1N914.  This is ok if you have a light-duty relay, also the 1N914 is a signal diode so actually does not qualify.  Use a 1N4001  (Tony van Roon's or better) instead.  A couple of substitutes for the 2N2222 transistor are: NTE123A, ECG123A, PN100, etc __ Designed by Tony van Roon  VA3AVR

Light a white LED from half a cell -  12-Jun-03 EDN-Design Ideas Whether you use them as indicators or to provide illumination, LEDs are hard to beat in efficiency, reliability, and cost.  White LEDs are rapidly gaining popularity as sources of illumination, as in LCD backlights, but with forward voltages typically ranging from 3 to 5V, operating them from a single cell presents obvious difficulties Design by Anthony Smith, Scitech, Biddenham, Bedfordshire, UK

Light an LED without wasting energy -  The circuit in Figure 1 can minimize this waste by using an inductor and an oscillating circuit to control the current through the LED—energy that would otherwise go to waste.  Inductor L1 stores power and channels it back into the LED.    Design by Raju R Baddi, Tata Institute of Fundamental Research, Maharashtra, India; Edited by Martin Rowe and Fran GranvilleApril 21, 2011

Light Bouncer -  A simple chaser from a decade counterbounces a light on 6 bulbs __ Contact: P. Townshend EduTek Ltd

Light Bulb Voltage Regulator  -  The LVR2 and LVR3 work by Pulse Width Modulating the battery voltage and applying that to the light bulb.  In simplier terms it turns the light on and off so fast that the bulb appears to burn smoothly.  The LVR adjusts the time on versus the time off precisely, so that can the bulb maintains the same brghtness even as the battery voltage drops, until the battery voltage is the same as the bulb voltage.  At that point the LVR is on 100% of the time and the bulb grows dimmer with further battery drop. __ Designed by Willie Hunt

Light Chaser -  Schematic only __ Designed by Andres de la Plaza

Light Control Switch -  This is a simple LM311 Comparator based switch which can be used for various purposes: __ Designed by Nina Gajjar

Light Control SystE - M -  It is easy to install a couple of infrared emitter and receiver at the entrance of your room and maybe you connect them to the light, but you cannot control the light in this way! You will never know how many person inside and if the room is empty or not.  In this system, every thing is under control, because it is smart enough to know how many persons inside; and it can identify the direction of them, so the light will be turned OFF when the room is unoccupied; and ON otherwise! __ Contact: IQ Technologies

Light Controlled Switch -  Output a control signal suitable for relay depending on the light level