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

    How long will this LED last with this battery?

    I have an Led with the following specifications: 3-3.2 V Size (mm) : 5mm Lens Color : Water Clear Reverse Current (uA) : <=30 Life Rating : 100,000 Hours Viewing Angle : 140 Degrees Absolute Maximum Ratings (Ta=25°C) Max Power Dissipation : 80mw Max Continuous Forward Current : 24mA Max Peak...
  2. J

    How to hook up LED to indicate battery is receiving current

    I want to charge up a 12 volt car battery with an AC voltage passing thru a full wave bridge diode and I want my LED to be on when current is being supplied to the battery terminal and if circuit stops producing current for any reason LED will be off and not on as if it where receiving current...
  3. M

    Engineering Thevenin equivalent of an LED circuit

    Homework Statement How would I go about determining the Thevenin equivalent of a simple circuit involving a battery and an LED? I suppose there could be a series resistor to prevent excess draw and burning out of the diode. This question seems very odd since LEDs by definition don't...
  4. B

    How to design a circuit in which an LED turns on when there is a voltage drop

    I want the LED to be off when there is a certain input voltage let's say 5v (the exact value doesn't matter), but when that voltage drops I want the LED to turn on. I would also like the LED to remain on even when the voltage goes back up to 5v. I was thinking of using some sort of logic gate...
  5. C

    LED Lamps for Flashlights: Bulk Availability and OEM Control

    suppose you want to go into business making LED flashlights. Let's say Amazon reviews of existing flashlights say that some are flimsy, others have overly specialized lamp, yet others have small battery etc. So, let's say, you decide to manufacture your own flashlight that would solve these...
  6. F

    Blinking LED: do I use 555 or a flip flop?

    Hello forum. to make an LED blink, would I use a 555 chip or a flip flop and why? thanks fisico30
  7. S

    LED Torch Heads for 12V Miniature Railway Signals

    Hi, newby here, hope I can get some help on this question. I have a project that requires me to use a standard 9 LED torch head, normally running on 4.5 volts (three AA batteries) My project needs me to use 12 volt batteries to supply a control box and finally the 'torch heads' a distance away...
  8. Artlav

    Modulating LED light with sound?

    Hello. I'm trying to make an LED light to carry sound, in a simple blink-it-like-it-arrives way. The problem is, on the receiving end the sound arrives with a lot of distortions, most apparent in the lower notes. Single tones are reproduced faithfully, but anything more complex sounds like...
  9. K

    LED parallel circuits and how they function?

    First off, I'm looking at adding in a few LED's into my iPhone 4s (I'm very limited on space, but there is a pretty open area.) I have found a connection point that gives off 2.8v and is commonly used for lighting up LED's with the screen. I plan to add in a red, green and blue 0603 (or even...
  10. T

    LED Light - Beam Charactoristic?

    For some of the high powered LED lights, the beam seems to have bright and dimmer sections along its length when projected through air. They seem to be regularly spaced rather than random. Some people have described it as looking as though the beam would get thinner and wider along its...
  11. D

    Ultra-efficient LED puts out more power than is pumped in

    Is this for real? Sounds pretty impossible. http://www.wired.co.uk/news/archive/2012-03/09/230-percent-efficient-leds?p=2
  12. N

    Edge detection using LED light source.

    Here's my current project goal ( And what I need help with): I want to use an LED light source, shine it through a 1" x 2" slit and then use a linear array camera to detect the edges of the slit. The problem: Since LEDs are a point source of light emission, my camera has a difficult time...
  13. C

    Can LED Shift Indicators Be Created Without Arduino?

    hello I'm working on a manual shift override on an automatic transmission i have most of my design completed but have no clue where to begin the second half. the idea is to create something to tell me what gear i am in, i wanted to connect a circuit in parallel to the triggers for shifting to...
  14. J

    A Clear LED emitting different coloured light?

    Am I right in thinking the chip controlling the LED is applying more or less power to make electrons go to different energy levels to emit different colours of light? If anyone could clear this up for me it would be much appreciated.
  15. I

    Original problem with maxwell's that led to special relativity

    I've been searching through google and through various sources trying to find more details about the original problem with maxwell's that eventually led to relativity. I'm not sure I understand the problem fully as most sources seem to only talk about it casually before moving on. Is it...
  16. S

    Simple Circuit for high power LED

    What simple circuit that I can design for a 3V high power LED with max current 0.8 amps , I think the component names would help me , I would like to power it on 4.5 to 9 V batteries .Preferably lower voltages. Thanks
  17. F

    Which energy is easier to catch? LED or laser

    Hello Forum, I understand the difference between LEDs and lasers: both operate at optical frequencies, but the LEd has a larger beam divergence and a higher spectral content, less temporal coherence... Assuming we are able create the same beam divergence for a laser as for a LED (using...
  18. Artlav

    What is causing the LED to light up when touched without a direct connection?

    An LED lights up when i touch it. One leg is attached to a piece of metal, other is the one i touch. Polarity does not matter. Amount of metal maters - table frame makes it full bright, half-meter steel ruler makes it dim, a piece of wire makes it just visible. Touching that piece of metal...
  19. K

    Building a Full-Spectrum LED Light Array for My Grow Station

    I recently began making a cabinet into a grow station. It's almost finished, but I'm having trouble with the lighting system. In the beginning the idea was to make a full-spectrum LED light array of no particular voltage. I wanted to mimic this array I saw on LED Lights and Light Fixtures...
  20. Z

    Optical Can I Use One Resistor for Multiple LEDs in a Parallel Circuit?

    Hope I got the right section. First time poster! Hello all! I'm pretty much a Noob so forgive any ignorance. I'm running 31 Orange (2.2v) (24 ma) LED's on a parallel circuit. My power supply is 12v from the DVD power supply of a Xbox 360. I bought a 10 watt 15Ω clay type resistor per a...
  21. Q

    Create a Simple Fire Alarm with Voltage Divider and LED Circuit

    Hi everyone, I'm new to circuits, and was thinking about using a voltage divider circuit to make a very basic "fire alarm." I've attached an image of what I was thinking. The top resistor is a thermistor. I'm having trouble figuring out what this circuit will do. My...
  22. Femme_physics

    Electronics - Op-amps: when will the LED light up

    Homework Statement http://img193.imageshack.us/img193/6627/circuitg.jpg So I got this circuity thingy and I'm told that each LEDs only lights up at 1.4 V. I am asked what should be the vaue of Vin1 where the green LED lights up. Now, I see I have 2 comparators here. Each one is 15...
  23. V

    24v to 12v Interior Led Light

    I have a ceiling fan that has a 24v output. It came with a led circuit board to light, however the light is very dim. I purchased a 12v led circuit board to increase the lighting. Now I know that the light is 24v and the new led board is 12v but it was a direct plug in so I thought I would try...
  24. D

    Using LED in fixture designed for Halogen

    Hello, I have a lighting fixture used in stage and entertainment lighting (HES Trackspot) which was designed to use a 250Watt Halogen bulb (Phillips QT8500). The power supplying the bulb is 24VAC. The bulb has two fans underneath. I have found a LED bulb with comparable lumen output...
  25. B

    Powering an LED Array On and Off at 1kHz

    So I have a question about a circuit I'm making for class. I'm using this PowerSupply is a power supply I'm using in the lab. The 1kHz square wave is 700mV pk to pk with a 350mV offset. LEDarray is a red LED light array (http://www.ledtronics.com/Products/ProductsDetails.aspx?WP=2003). When I...
  26. S

    Dealing with RFI from Expensive LED Lighting: Tips and Experiences

    I have just fitted two (very expensive) UK mains - 14 watt (120 watt tungsten equivalent, 28 watt CFL equivalent) LED luminaires in a building extension. I am now picking up intolerable interference on both AM and FM radios, throughout the house. Considering the cost, CE markings and other...
  27. A

    Advice needed on a laser activated LED

    Hello all First off, I'm afraid I do not have much in the way of electrical engineering knowledge or experience, hence why I am here. I hope you will be gentle with me :) I am trying to determine the process (i.e. components, equipment etc) that I would need to set up an laser activated...
  28. W

    Resistance controlled voltage source (for led array

    hi all, I'm looking for a cheap (and by extension simple) circuit. i have a special pot (Piher's 10mm hex PT-10) that can't be changed. the pots can be physically changed but i have to use this type. the series has a 150mw power rating, with resistances of ...
  29. B

    Why does the LED structure favorizes p-type semiconductor?

    Why does the LED structure "favorizes" p-type semiconductor? Hi all, At first I apologize if my English makes this post harder to understand ;). I am trying to figure out why there is always P-type semiconductor flashing outside in LEDs, both planar and edge ones - P-type region is the active...
  30. Femme_physics

    Op-Amp basic problem with a LED diode

    Homework Statement http://img822.imageshack.us/img822/1859/theque.jpg Given the following circuit, including an Op-Amp and a LED diode. The voltage on the LED diode is 1.4 Volt. In your solution assume that the Op-Amp is idealHomework Equations (In the solution...) The Attempt at a Solution...
  31. P

    [ASK] where to find LED Components Material?

    Hello guys, nice to meet you all. It's kinda awkward since I'm new here and also just a freshmen in my university :) Anyway, I'm conducting a study about the LED components, whom I've already known it is consist of aluminium and Gallium Arsenide (GaAs) or Gallium Phosphide (GaP) or Gallium...
  32. S

    Focus on LED lighting technology, which Master degree?

    Wish to focus on LED lighting technology, Mainly high powered LEDs to illuminate areas such as indoor and outdoor areas. Which masters area should I take into consideration? Should I consider getting a P.E.? Main things to consider when designing actual light fixtures; Optics Heat...
  33. P

    LED specific voltage for specific wavelength

    Hello I am trying to design a precise circuit for LEDs. I have a datasheet from a manufacturer and it says an LED is capable of running 3.0v at 640nm and 3.4v at 660nm. Is there a way to tailor the power (voltage) so that the LED will run exactly or at least approximately at 3.0v or 3.4v...
  34. W

    Engineering LED Circuit Design: Create w/1 Power Supply & 50mA Max

    Homework Statement I need to create a circuit that will take in a Vin, and then for a Vin of less than or equal to 1V, or a Vin greater than or equal to 2V, an led will light up. For this I can only use one power supply of +-5V, and the circuit cannot draw more than 50mA. Homework...
  35. D

    Engineering Electronic circuit, LED turns on if Vin is greater than or less than a value

    Homework Statement Construct a circuit that turns on if it the voltage provided is greater than 3 volts, or less than 2. MUST USE THESE CRITERIA: i<100mA, only one PS. Fewer than ten components. Homework Equations None that I know of, but we've covered resistors, caps, inductors, and op amps...
  36. V

    LED Project in Vehicle: Blown Bulbs & Schematic Questions

    Hello all...I have a led project I have been doing in my vehicle...I have a Bose/Clarion radio that has blown incandescent bulbs. I have already done the instrument cluster & climate control with drop-in led's so I decided to try & fix the radio. My problem is that the radio has soldered in...
  37. 1

    LED flashing unit. - how do I make one?

    Here's my story: I bought a license plate frame for my motorcycle. It has 4 banks of LED lights. I want to wire it to my brake lights. That's the easy part. But, I want them to flash. Can I get them to flash in sequence? at 12v, it takes 0.1 to 0.2 amps to get full intensity. What parts...
  38. S

    Solving LED Dimming Issue: Edward's Conundrum

    Hello folks. My first post on this Forum: I have a conundrum, I have built a LED light fixture in my living room. The issue I have is that the LEDS have dimmed over the last 5 months by about 50%. I did not notice it until I had to replace one the other day, and it was way brighter then the...
  39. T

    Philips Fortimo LED light system?

    Basically am struggling to design a concept, me and my design team have to present a new project in 12 weeks (give or take) and me as part of a 3 man mechanical design team are struggling with research and developing our idea.. Basically we have to use the modern Philips Fortimo 2 LED, and...
  40. M

    Can OBEs be scientifically explained or are they evidence of a soul?

    I joined this forum for one reason, I was researching an experience I had brought on by a traumatic seizure as a child. There was a thread (now locked) on OBE's. I wanted to shed some light on OBE's from someone who had experienced the phenomena. My story: When I was about eight years...
  41. C

    Current mirror for multiple LED driver circuit.

    Hello guys I wonder if you can help me? Basically for a project I’m going to produce a led light source with 12 leds with a single small driver that runs on 24v supply. The LEDs run 3.7v typically so that would require 44.4v that’s a lot more than the led driver can supply but if I run 2x 6...
  42. L

    Creating a square wave with current strong enough to light a powerful LED

    Hello! I haven't touched base in electronics in about a year (only took one course too) I'm currently working on a project and I'm wondering what the best solution might be to creating a square wave which is 5 milliseconds high, 12 milliseconds low (low as in ground not negative voltage)...
  43. R

    Determining LED light intensity from its radiant power

    I have LEDs of 0.7mW, but for my experiments, I want my values to be in light intensity unit - W/cm2. I cannot figure out how to do the conversion.
  44. R

    Causes that led to discovery of GR

    What are the causes that led einstein formulate curvature of space-time? what it has to do, if any, with the discrepancy in mercury orbit.
  45. N

    Having trouble lighting up LED in a breadboard.

    I've got some D.C power supply connected to my breadboard, and there is definitely current going through it as I've put some resistors in series and parallel and checked the values on the multimeter vs my calculations and it seems to be alright. Now I put in a 5mm LED in series with a 100 ohm...
  46. V

    Does Ohmic Contact Affect the Energy Gap Shape of a P-N Junction?

    led chips is a P-N jontion which MQW in middle. And than it bonds metal on P-side and N-side which we call ohmic contact.I had try to draw the band gap graph. Base on theory, when different material bond together, their fermi energy became the the same energy level. I know that the contact of...
  47. T

    LED project power supplies in parallel?

    So I am going to be building an LED light for an aquarium. What I am doing is... 10- 10k 3w LED 3.4-3.6 fv 700ma 10- 455nm 3w 3.4-3.6 fv 700ma I have ordered 6 10w 9-12v 900ma power supplies. I was planning on doing 9 of each blue, and white on 3 circuits each, with a 2.7ohm...
  48. M

    How Can I Make a DIY LED Necklace with Custom Etching and Casing?

    Hello people I am trying to design a birtday presenet for someone and I need your ideas for this. I want to make a LED necklace with a 5mm LED powered by a 3V CR2025 battery. What I can't figure out is where do I put this in to? How can I do the casing and out of which material? I am not a...
  49. E

    Why Does My 1450 nm IR LED Not Illuminate Despite Correct Specifications?

    hi , every body here , I really seek a help , I have an Ir led from thorlaps it's wave length 1450 nm , I followed the specs Forward voltage at 20mA is = 1.2 v typical , 1.5 v Max Max DC forward current = 100mA Power dissipation is 120 mW I tried the following resistance 200 ,220 ,190,180...
  50. R

    Maxim 7221 LED Driver Circuit Help: Driving Higher Voltage Displays

    I need a little assistance sorting a couple of things out. I want to build an LED scoreboard and I am trying to figure out the circuitry to actually drive the LED's with a MAXIM 7221 Display Driver. It's a pretty straightforward problem with smaller 7 segment LED's because they don't...
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