Led Definition and 458 Threads

Hi all, I have a problem of understanding the concept of radiant intensity, in particularly I’m interested in LED characteristics and confused with specification in LED datasheet. For example in the datasheeat for the VSMY2850 LED from Vishay it is stated that typical radiant intensity is 100...

Hi I'm not having a huge problem, but it bothers me. Today I noticed the indicator led in my power button doesn't work. I'm using an Acer 7750G laptop not entirely sure how old (funny how quick we forget and get used to such things). Is there any software method of testing this LED? I'm using...

Homework Statement You wish to use an LED (D1) which provides essentially zero resistance and is rated to accept either a maximum of 75 mW of power or 30 mA of current. In the following two circuits, what range values for resistor R1 will be acceptable in each case if the voltage provided by V1...

Hi there, how one can compute the spectral power distribution of white LED ,i,e like black body radiator that has a formula of calculation.. regards

I want to make a solar simulator with LEDs. I want to get a net intensity of 1 Sun(1000 W/m^2). My LEDs have the following specifications: LUXEON S LXS8-PW30 Luminous flux at 700 mA, 85°C* 1315 lm Radiant flux at 700 mA, 85°C 4113 mW 1931 CIE color points at 700 mA, 85°C (0.4304, 0.4030)...

Hi, I want to make a solar simulator with white LEDs as a part of my project. I searched net about it, but couldn't get much details about it? Can some one help me with the basic schematics, no. of LEDs required and the design? Regards, Jefin

Hi guys, I'm a total greenhorn so please bear with me. I'm designing a circuit in which I use a lot of tri-state buffers. All ICs in the circuit will be powered with 5V, but I need to pass 12V (and up to 15A) from the input to the output of the tri-state buffers when the buffer is enabled...

Hello, I am new to any type of engineering and just have been working with Arduinos and other microcontroller lately for fun. I am creating a prototype for a project that requires me to use a 9V power supply with 1Amp to power the Arduino(note, the arduino only needs around 300mA to run). I...

why nobel prize is awarded for blue led invention even though it was invented before? i bought this blue led 2 years back i.e on 2012,

Can I use a thermocouple which has a temperature difference of 1 degree to generate current to run a very small led.

Why do some LED bulbs show clear utility frequency flicker, while others don't? Is it there, but not visible for the weaker lamps because of less amplitude? Is the diffuse bulb coating fluorescent and smooths the flicker away? Here a comparison of some IKEA LEDARE models, slowed down by factor...

I am a senior in high school researching sonoluminesce. Me and my teacher were hypothesizing the mechanism that could cause it and discussed the possibility of the bubble and water system having LED-type qualities, as an LED is light emitted by electrons falling into holes when excited by...

Hello,I'm new to the physics forum.I have a question regarding fluorescence,and I didn't know where to post it exactly,so I decided to do it here... I like growing plants,and am forced to grow them under artificial lights during winter.I am always on the lookout for more efficient lights,that...

This is probably a simple matter. I have tried to find an answer on the web without success. All published data on current-limiting resistor values is for LEDs with current rating less than power source. I am putting together an array for a museum of high brightness LEDs rated at VF 4.2, IFM...

Homework Statement The asker needs to know the angles to mount three LEDs inside a traditional mains powered light bulb shaped enclosure "to get even radiation from the LEDs", and also the position of the covering plastic sphere in relation to the LEDs. (I was thinking that the position of the...

Hi, I'm a freshman in college and a beginner in electronics. Does anyone know of a way to use a micro analog thermometer to change the color of a small LED light once it hits a certain temperature. I am looking to make this on an extremely small scale.

Did Led Zeppelin Plagiarize 'Stairway'? A Penn. Judge Will Decide http://www.npr.org/2014/10/26/358903514/did-led-zeppelin-plagiarize-stairway-a-penn-judge-will-decide I think they are sufficiently different.

Hi everyone, This may seem like a really silly question, so I apologise in advance, but how do I go about creating a basic RGB LED circuit using a micro-controller like this one: http://www.jaycar.com.au/productView.asp?ID=ZZ8540. Will a breadboard suffice to make the circuit or will I have to...

Hi everyone, So, I am involved in a solar project for the developing world involving solar lights. What I would like some confirmation on is how to figure out how bright a LED light is going to be? I need the light to be bright enough for a child to study by, but unsure how to ensure this...

when is the LED on for the circuit shown? (Construct a truth table) btw that part that's cut off at the top says 5 V but i don't think the voltage or resistance matters in this problem. how many low and how many high inputs do i need to get that LED to light up?

I'm a total noob when it comes to electronics and you are going to lol at me. Please don't lol too hard. Becuase I'm not really good at this stuff its going to be hard for me to explain but Ill do my best. I have circuit board for an ecig that I want to use a led anti vandal switch for it like...

anyone know what the metal fin-like structures are? i see these on a lot of LED bulbs. they look like heat sinks but if conventional bulbs don't need heat sinks why would an LED bulb need one? besides! i thought the conductivity of semiconductors was proportional to temp.

In a simple series circuit there is a 12V supply battery, 12μ6 F capacitor, a Resistor, and a 2v drop LED with an imax of 30mA. frequency is 10Hz Calculate the resistance of the resistor so that the LED just stays on. Homework Equations Resistance of Capacitor Xc = 1/2∏fC P=VI V=IR...

Hello, I am new here so my apologies if I have posted in the wrong place. I am trying to amplify the radio waved I get from a receiver to power led that will ultimately be used as a remote for the AC. I have contemplated "charging" a capacitor until it has enough power to power the led...

Hello. I'm trying to design a AC to DC LED driver with PWM dimming. I have a design that I can use with the LM3406HV but I would like to design something that I can wire up 110V AC mains line. With the LM3406HV I need a DC power supply. I was thinking about using a switching power supply but if...

Hello. I'm learning about high power LED's. I would like to design a high power LED driver for a DIY project I'm working on. I'm planning on using an LED driver to provide constant current and have dimming control through PWM. I'm going to be using 3W high power LED's in a series configuration...

I currently have a 40-in Sharp LCD Aquos (5 years old) and I want to upgrade to a 50-in or 60-in LED or Plasma TV. My 40-in Sharp has a very clear picture when using the HDMI inputs. I am looking at Samsung, Panasonic, LG, and Sony models. Won't the picture (that I am used to on my 40-in screen)...

If i have a LED which drops 3V, and 30mA through each LED and i need 8 LED in series.. does it mean that i need a total of 24V and 30mA from power supply or less? And if i use the same circuit in parallel, does it mean i will use 3V but much more current like 0.24A?? or least current?

Hi, While experimenting with various LED's in LN2, I noticed some strange behaviour from my green LED's. As expected all LED's (except the green one's) emitted light with a shorter wavelenth (for instance, my yellow led turned to red etc). However, my 2 (different manufacturer type LED)...

Hi, I recently designed a PCB in EAGLE, and I got it manufactured and I had all the pieces Sufrace Mounted on it, put it in the oven, everything seems fine and dandy, but I already killed 3 LEDs because of some weird thing going on. I have 5 different LEDs conneced to my circuit, the leds run...

How does one measure the etendue experimentally (when the area of the emitter and the angular distribution is not provided) in order to compare the focusing strength of two LED sources in an optical setup? Thanks!

Hey Guys, I have no background or experience in electrical engineering. I have not been able to find any information regarding the wiring application I am trying to achieve. Any help would be greatly appreciated. Is it possible to do the following; I want to run a 6 inch LED strip that is...

Hi, I am new to this site, but it seem like there are some very intelligent people posting on this forum and I was hoping someone could help me out. I am trying to build a LED light. I would like to string 10 of these lights together and plug them into the wall. 5 watt 430nm (hyper...

This is a LED lighting project that will go into a high power rocket shaped like saucer. Because this is a high power rocket, it must be launched at a certain distance from spectators for safety reasons. The launch pad will be at least 200-300 feet from spectators and rocket may go as far as...

Hello, my name is Mike, and I have just enough electrical engineering knowledge to be dangerous. This season I have inherited a programmable LED Christmas light set up from my father-in-law who is no longer with us to help guide me with his EEngeneering knowledge. Here's the issue. I have...

Hi guys, I'm trying to design circuits that include mostly ohmic devices with the exception of some LEDs. In particular, I'm having trouble coming up with an effective voltage drop across an LED. This is the datasheet for the particular LED that I'm trying to include in the circuit. It has a...

Hi there, I'm a material's design student and I have an idea to a project.. This idea needs an electrical circuit , with a led and a timer, but it has to be really really small, because it is for small objects. How can I mount this type of circuit, with a timer that will fire a red light...

Hello everyone! I'm currently working on something and am finding myself a little stuck. I am trying to determine how to use a photodiode to brighten leds in low light conditions and dim in bright light conditions. I was able to do this with a simple pnp transistor, however, i need to be able...

My son is working on his science fair project. I had told him that LED bulbs produce voltage in sunlight and he's been exploring that and is trying to see if he can charge a cell phone using LED bulbs under a light source. Using dozens of small LEDs, he is producing about 5v under a light...

Circuit Design -- Comparators to light an LED Homework Statement I need help designing a circuit that takes an input voltage and then lights a single LED if and only if V in is greater than or equal to 2V and less than or equal to 1 V. It can only use 1 Power Supply unit, +/-5V Circuit must...

Hey all, Wanting to create an up/down counter that uses a photogate as a trigger, and a 12 segment LED bar graph to display the count. It will need to begin at full illumination, turning off one at a time on activation of the photogate. Will also need a reset switch, though I'm thinking a...

I really don't know much about circuit design, but I have built a device and it requires a LED indicator when power is applied to the load. I also need a very low parts count. The Problem. As I have designed it the LED glows ever so dimly when ac voltage is removed and when power is...

Homework Statement Design a circuit with three momentary, normally open, button inputs and one LED output. The LED must light anytime exactly two (2) of the buttons are pressed simultaneously. The LED has the following characteristics: Vf = 0.83 If = 14.2 - Draw a neat schematic diagram for...

Hi, Why is there negative current in an LED at low voltage(set up in forward voltage)? Why is there luminescence of an LED at negative current as described above(when LED is in forward voltage)? How would the I-V curves of LEDs of different colours vary? Why? The questions I've asked all...

Sony 32R420 vs Samsung UE32F4000AWXXH They have similar, almost same specifications. But Sony is a little bit expensive. I need advice about specifications and which of them is better in picture reproduction and other specification.

I machined my own 7-segment display out of clear polycarbonate, each segment is about 1.5" long (it's a rather large display) and now it's time to add the LEDs. Turns out that the usual LEDs with the epoxy lens focus the light too tightly on one spot, so I get more of a dot rather than...

I was wondering if anyone could help me with this. I have a 200mm LED fan that currently has blue LEDs in it. I would like to swap them out for tri-color LEDs and run a switch through the LED loop to control which LED would turn on. I want to mount the switch into a PCI slot in the back of...

How do these LEDs conduct ? With this board: the associated schematic is: P1 (with pins 1 and 2) represents a motor. OUT1 and OUT2 are the conduction paths. LEDs L2 and L1 will illuminate depending on which way the H-Bridge is conducting. My question is how are is that the...

Would it be possible to add a transistor in between the LED and the driver, as shown in the application photos, to PWM and fade the LED with 0-5V logic (Assume the LED has a forward voltage of 3V)...

I have a 3x3x3 foot box that I want to light up in a place that does not have access to electricity. The box will ideally be as well lit as a regular room in the evening with red, green or blue light. We anticipate using the box 4 hours a day for 7 days. Given these parameters I am trying to...