What is Led: Definition and 457 Discussions

LEd (formerly LaTeX Editor) is a TeX and LaTeX editing software working under Microsoft Windows. It is a freeware product.
LEd offers a project manager, powerful editor, integrated spellchecker and thesaurus, built-in DVI viewer, descriptive hints for LaTeX commands, code complete mechanism, word wrapping, code folding, multilingual environment, and more. Nevertheless, LaTeX Editor is a small program.

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  1. S

    Troubleshooting: LED Lighting Tube with 240VAC Input - Fuse Burning Issue

    Homework Statement Im currently doing a LED lighting Tube. I am using 240VAC 50Hz input. The connection will be the Input Source connected through a Rectifier,then a resistor and 68pcs of LED connection. When we try to testing the circuit, all the LEDs did not light up but the 13A fuse...
  2. A

    Need help making a simple flashing LED device

    I'm sure this is very simple for everyone here. I need to make a device that will allow an LED to flash at very specific rates (for example 4 times/sec). I assume I need to use an I/O system that will allow me to program it via computer connected by USB. If this is even the best way to go...
  3. D

    Power usage of LED light using AC adapter

    I have a question about how much power I’m using to run a LED light that I modified to run off an AC-DC adapter instead of 3 AAA alkaline batteries. The light is a Sylvania Lighting Dot It Black Led Swivel, which uses about 1/4 of a watt (4.5 V X 54.7mA) on batteries. The light would dim...
  4. N

    Assembly code microprocessor 8088 for seven segment LED

    Homework Statement i've just started learning microprocessors, and we need to program the 7-segment LED to display numbers 0-9 in increments of 1 i'm trying to get a delay of 1second between each number (and i couldn't get it) e.g., number 1 displays for 1 second, then number 2 displays for...
  5. G

    Help needed: coupling light from a LED into an optical fiber

    First let me preface this by saying by physics-fu is remedial at best. I am a neuroscientist by training, but need a little help with piece of equipment I am designing, so any ideas or input would be greatly appreciated. Basically, I need to figure out a way to efficiently couple a light...
  6. C

    110v Electric motor with led

    In the machine shop where i work they have a coolant system that runs separately from the CNC machine. As of now, they simply plug in the motor and it turns on, however they often forget to unplug it at the end of the day. I need to wire a toggle switch and and LED indicator for when the motor...
  7. S

    Efficient LED Light Design: How to Step Down 240V to 12V for Energy Savings

    Hi all, My question is as below: I wanted to design a LED saving energy light to replace a fluorescent tube.Now since the power supply of our house is 240V,i cannot just connect my prototype(LED light) directly to the power supply.So i need something to step down the 240V to 12V.Is there any...
  8. sophiecentaur

    Domestic LED Lighting: Finding the Right Lamp for Your Home

    I keep looking at adverts for LEDs in the home. None of the LED lamps I have seen in the shops look 'right'. They look like something in The Hitchhiker's Guide. Has anyone actually installed a lamp which looks nicer than (or even the same badness as) a CFL? I get really fed up with the slow...
  9. S

    Pulsating LED to increase current but keep heat down.

    i was thinking of using a 555 timer to create a low duty cycle TTL square wave to power an array of Inferred LEDS at a very high current for short segments of time. basically i want to get really high outputs from an led and keep it from frying itself by turning it on and off really really...
  10. T

    Efficient LED Animation Solutions for Urgent Needs

    LED Animation (urgent) >< I have no idea about the question... A 64 bit ram can just save the pattern of one column, how can it be read again to fill in the second columns and so on... Please click the attachment below to enlarge the photo. Regards
  11. P

    Engineering Will the LED be ON or OFF in this circuit?

    Here is the ciruit. It's a D flip flop http://i45.tinypic.com/jtpjfc.jpg After reset is applied, will the LED be ON or OFF. Explain your answer. The answer is ON but I don't know why.
  12. D

    Why Aren't My New LED Headlights Working?

    Hi everyone, Ive got a question about LED light bulbs for vehicles... I recently purchased a pair, as you can see within my attachment. Last night I got around to installing them but was greatly disappointed when they did not illuminate what so ever. I tried hooking them up to a 6v battery I...
  13. S

    IR led signal distance,Omron PLC reset

    Hi, I have 2 questions here and hope some experts can answer them. Question 1: How to improve the signal distance of the IR led?What parameters in the datasheet that we should look into? I have purchased few IR leds but all of them can't shoot more than 3 metres. I noticed increasing...
  14. rrw4rusty

    Questions on the test that led to Many Worlds

    Hello, This concerns the test where you have a barrier with two slits cut out of it, set in front of a wall or blackboard (or something that will show hits upon it) and devices that will shoot sub-atomic particles. My understanding is this: when particles are shot into the barrier with two...
  15. T

    Need Help Wiring a large LED to Run Off Batteries

    I'm a documentary filmmaker and I am trying to build battery powered china lantern using an 13w Evolux SH LED array light bulb (http://eartheasy.com/store/proddetail.php?prod=EvoLuxSH). I'd like to use something like D-Cell rechargable batteries, possibly from a modified light bulb, although...
  16. J

    Why won't my LEDs light up with 9V and 60 Ohm resistance?

    Hi, I am trying to wire some leds up. There are 5 of them in series VF typ 3.2 V and 30mA. I am using a 9V square battery. 60 Ohm of resistance and an on off switch. Yet it does not light up. Is this because I do not have enough voltage?? P.S. Yes the switch is on! Thanks, Johnny
  17. M

    Trying to wirelessly power an LED.

    I'm part of a Senior Design project involving Wireless Energy Transfer. We are trying to power a standard red LED as a demo, via resonant inductive coupling. Our setup is as follows: We have a 40.64 cm diameter transmitter coil (magnet wire) with 6 turns, hooked up to a signal generator. Our...
  18. J

    LED Project Info: Theory & Resources for CPGE Students

    Hello I am a student in CPGE (Classes Preparatoires aux grandes ecoles) in France (2nd year - specialisation Physics -chemistry) with another student, we are currently looking for information for our project on LEDs. We have to bring in our personal analysis to the subject, and go into the...
  19. J

    Solving LED Power Supply Issues: Tips from John

    Hi, I am trying to link up a series of LEDs and having a bit of trouble calculating the power supply needed. I am actually doing this for a number of applications and wondered if anyone had a system for working this out?? Thanks, John
  20. T

    Circuit with 7 segments led that work with 5dc

    i have a circuit with 7 segments led that work with 5dc but it is not so light up.how can i light up it? it has an 2sa950 transistor.
  21. B

    How would I increase the flash rate of an LED?

    I created an led flasher using a 555 IC, 2 1k Ohm & 1 100 Ohm resistor, and 1 1000uF and 1 .01 uF capacitor. If you need to know exactly how it's wired up I can make a schematic. My question is how would I increase the flash rate? I need a flash of about 3(up to 5) per second. As you can tell...
  22. C

    Troubleshooting LED Lights & Stator System on Off Road Vehicle

    I put LED LIGHTS 60 WATTS on an off road vehicle with a stator not an alternator. When i use my winch or the cooling fan comes on the light goes out. I can turn the light switch off then on and it comes back on. It only happens when there is a fairly heavy draw on the system. Can this be fixed...
  23. D

    How can I prevent my LED lights from blowing out on my car?

    Hi guys, I recently purchased some LED strip lights for my car (like this - http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=150374586680&ssPageName=STRK:MEWNX:IT ) To my knowledge I had them hooked up correctly, they have one positive and negative sire for power. So I found...
  24. D

    Wondering how to wire led series

    Hi there, I have a series of LEDs that I need to get running. i plan to use this series in my car as a cutom LED gauge cluster (you know, speedometer, fuel, engine heat). Anyhow, I've got 17 white LEDs Specs: Voltage Supply = Unkown 17 LEDs 3.1 Voltage 20 - 30 mA I was wondering if...
  25. M

    How can I make my PIC16F84A code shorter?

    Hello, can someone help me in programming our PIC16F84A, we need to make a program that will show only a three output like a traffic light,..but I am not quite familiar in programming this. I examined a 7 output LED program but i can't figure out what to changed.. I also want to changed the...
  26. D

    Perfecting the 555 Timer: Adding an LED Display for Precise Liquid Dispensing

    I want to first thank all of you for your help with my first 555 timer question. With that help and some more reading on the net I have it working perfectly. My next task on this timer project was to include an LED display. My intention was to have a display that would give me a numerical...
  27. A

    Capacitor Charger | LED Illuminate when Complete

    I'm looking to assemble a capacitor charger in a nice, durable enclosure. I already have the DC to HV DC converter. I'm just looking, now, for a way to indicate when the capacitor is fully charged, practically identical to how a flash-enabled camera indicates when its capacitor is charged and...
  28. R

    LED voltages lends to different colors?

    I heard through the grape vine that applying different voltages will emit different colors of light from an LED mainly red, green, white and blue. Is this accurate or is it that the architecture of each LED is different. Are there LEDs that are sensitive to various voltages? If so what would...
  29. DaveC426913

    LED 'ON' light across power switch

    I wish to attach an LED indicator light across the main power to the 12V battery on my boat. This light will let me know from a convenient location whether I've remembered to switch off the main power. How do I wire it up? The LED is obviously 3V. The light would only be ON if the power...
  30. W

    LED Lighting Control: Dimming Channels with Resistance and Microcontrollers

    Hello. I am building an LED striplight for my room. For the device, I would like to have three separate channels so that I can easily color mix Cyan, Magneta, and Yellow. I know the basics of circuitry and wiring the channels, but I am not sure how to control the channels. I was considering...
  31. W

    Help with Inexpensive Pressure-Activated LED Lighting Project

    I am very inexperienced at wiring, and electricity in general, but was hoping to find some assistance in this forum. I am looking for a fairly inexpensive way to wire an LED to turn on when pressure is put on some type of sensor (not sure what would be needed). When there is no pressure, I...
  32. W

    Learn How to Dim an LED Array with a Simple Circuit - No Switch Required!

    Hi. I've got a LED dimmer circuit. When the dc power turns on, the LED will slowly lights up. There is a switch in the circuit that if I "open" the switch, the LED will slowly turns off. The million dollar question is how do I remove the switch and the LED will slowly turns off when the...
  33. J

    LED photodetector IV curves

    I was wondering if anybody could help me understand my measurements. I was interested in measuring the photo current and voltage of a red LED placed in room light and sun light. I measured the voltage across the LED and the current through in both conditions. In the room measurement, I am...
  34. N

    What Determines the Forward Voltage of an LED at low Currents?

    A number of years ago I required a low voltage, extremely low current, voltage regulator. Normal Zener diodes do not function well at low currents. I became aware that the forward voltage of red LED's was approximately 1 Volt at even extremely low currents (less than 1 microamp). My...
  35. P

    How to Connect Multiple LEDs with Different Voltages to One Battery?

    I have tried doing a thorough search through multiple forums as well as the ever popular http://www.google.com" , however my lack of experience has led me to create a post and plead to the experts in such a "noob" fashion about how I would go about setting this up. I am looking to put the...
  36. K

    IR LED not working What gives?

    Hello all, quick question because this circuit doesn't seem to be working at all... I bought a few IR LEDs to attempt a few of the projects located http://johnnylee.net/projects/wii/" and for some obscure reason none of them are working. I hooked a AAA cell (multimeter rates it at 1.2 V) to a...
  37. T

    Why is a current produced when shining light into LED

    Right. Here's how it is, in the past I measured approximate laser power output using diffused LEDs of similar colour wavelength as the laser I was measuring. A multimeter across the terminals showed a current which was proportional to the power of the laser. I once asked my physics teacher...
  38. C

    Need help with Circuit: LED Blinking Problem

    I'm not sure if this is the right forum to put this in and I never took photos of something to put on the internet but I can't get this circuit to work and I need help. The LED is normally on. When I press the switch the LED should blink, slow down until its original condition. Maybe this should...
  39. N

    Powering Our LED Project: Series or Parallel?

    My brother and I have a project where we light up 10 by 5 leds but we aren't sure how to power it the best, and if we should put in series or parallel.
  40. R

    Designing an LED Array Circuit for Real-Time Feedback on Exercise Equipment

    I've modified a piece of exercise equipment so that it generates 12v dc. Max current is almost certainly less than 1 amp (more than that, and the subject (exerciser) poops out fast). Standard (car lighter) plug allows any appropriate device to be powered. Current generation is being...
  41. R

    DIY 12V LED Taillights: Resistor & LED Setup

    I work on cars, and love the led look in the taillgiht of a car or vehicle. I want to learn how to make them, I know how to solder. I have made one just playing around, but am not sure if it is set up right. The first questiong I have is how do figure what type of resistor to use with how many...
  42. L

    Shop 220V MR16/GU5.3 LED Bulbs

    Hi there, I was wondering if anybody could tell me if it was possible to get MR16 bulbs in 220v(I live in Ireland).Do all MR16 bulbs have to have a power supply or transducer to step the voltage down to 12/24 DC or can they just run on mains without the p.supply? Thanks in advance.
  43. M

    Need help to gradually ramp up/down intensity of LED at power-on/power-off

    I am making a high intensity LED light panel for my aquarium. I got 15 1w Luxeon white LEDs rated at 350mA max continuous current and 3.42V forward voltage. The LED driver I am planning to use is Xitanium LED-120A-0024V-10F. Here is a link to the datasheet...
  44. C

    Engineering Calculating R1 for LED Circuit Question with 12V Supply Voltage

    In the circuit the LED's rated current is 20 milliamphers. With a voltage drop across the LED of 1.5 volts, calculate the value of the series resistance R1 necessary to be used if the supply voltage is 12 volts DC. Here is how I answered this, I am not sure if I am right. R1=Er1/Ir1 R1=...
  45. L

    LED and Resistor Circuit WiringWhich resistors should i use?

    i have 20 ultrabright white LED's and i want to get a good brightness out of them. they will be in 2 circuits of 10 leds each. i think i need 1 resistor per led but I am not sure which resistors to use. The LED's are 3.2 - 3.8V and 30mA. i plan to use 9v batteries in whatever combination is best...
  46. H

    Determining supply current/voltage to LED

    Bearing in mind safety margins, how much current and voltage should I supply an LED if it's rated as such: Forward current max: 25mA Forward voltage max: 2.5V Reverse voltage max: 5V Light output min.@ 10mA: 70mcd Light output typ.@ 10mA: 200mcd
  47. Topher925

    Pushing LEDs Beyond Ratings: Can My 25ma LED Survive?

    How far can you push most LEDs beyond their recommended rating before they burn out? I currently have a 25ma, 34k mcd LED that I am planning on putting 50ma through for 10ms durations for 30ms periods. The LED is inside of a aluminum block to help dissipate heat. Do you think and LED like this...
  48. G

    What is the Best Circuit Design for a LED Water Temperature Display?

    Homework Statement I need to design a circuit that measures the temperature of a tank of water (using presumably a thermistor) and then displays the temperature by lighting just one of three led lights. For example, if it is too hot, the only the first LED lights up, if it is too cold only...
  49. C

    Optical DIY LED Lighting: Homebrew Power Supply/Controller Ideas

    I'm currently playing with an idea to convert my living room and family room to LED lighting, however nothing on the market fits my needs so I'm thinking of a homebrew solution. I want to use a computer power supply or other stable 12volt source and then build a current regulator/dimmer...
  50. J

    Help Needed , 110V LED SWICHING CIRCUIT

    I have a simple circuit switching activating a 110V timer but would like to show an LED ON indicator at the switch SW when the switch is closed, I can do this easely enough if I run the wire from the LED to ground but this means I need a ground nearby, so my questions is it possible to place the...
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