Led Definition and 458 Threads

This thread got me thinking. Incandescent light bulbs were soft banned (as in, cannot be sold anymore) in the EU in 2016 and - if my google-fu is to be trusted - last year in the US. If you go to any store selling bulbs, all of them are LED, which makes sense both from many perspectives.* We are...

I have a bluetooth Logitech M557 mouse with invisible led (it's written "invisible optics underneath) that I had for 5 years and I could use on any surface most often on a pure white bond paper. It can move smoothly. My only problem at present is the buttons are not so stable now due to dusts...

Hi! This question is translated so that's why it might sound a bit weird. I know that the answer should mention the band diagram of the LED, and I think that the answer is to introduce an electrical contact connected to a voltage source. Then when you increase the voltage, it should attract the...

I am thinking about the health aspects of home led lighting and whether it is possible to filter out the shorter wavelength light. I am not sure what manufacturers do in order to produce their 'warm light' bulbs. They claim a lower colour temperature but how are they achieving that?

From the book The Blue Laser Diode: The Complete Story, it said that I am wondering, after 20 years, is this problem still puzzling for scientists? How far have we understood about this problem?

I'm trying to get back to doing engineering work and I want to make an optical alignment jig and put the project on my LinkedIn page. I want to have a small spherical mirror focus light from an LED onto a silicon detector. I'd like to try using PID to make it work quickly. When I read about PID...

Unlike the 2015 outbreak of avian flu (H5N8), the outbreak seen in late 2021 (H5N1) has caused mass mortality for wild birds, which makes the highly pathogenic virus more difficult to wipe out. “Unlike H5N8, this disease is heavily impacting wild birds,” said Johanna Harvey, lead author of the...

A poster on another forum has fitted a large number of 230V 50Hz 24W nominal LED tubes, apparently designed to be plugged straight into the old fluorescent fittings. He has found, by clamp meter measurement, that the new LED lights appear to be consuming 80W, not the claimed 24W. A number of...

Consider the infrared led TSAL7600 which has the following properties: $$ \Phi = 35 mW $$ $$ I_e = 25 mW/sr $$ The half angle is ## 30^\circ ## and: $$ I_r(\theta) = cos^{4.818}(\theta) $$ is a good approximation for the relative radiant intensity. However, finding the actual radiant...

I recently got hold of an LED aircraft landing light after it started taking on water (bad seal on the junction between the front plastic window and the heatsink core structure was letting water in during takeoff and landing), but it is otherwise totally functional. Or it was, until I broke off...

Maybe more of an optics/biology question than electrical, but... My wife wanted some lighting on a cabinet nick-knack shelf. I thought it would be fun/interesting to use a strip of RGB LEDs and a controller to adjust the light color to whatever we wanted, plus the LEDs would be less heat and...

Good morning, I was wondering if I am thinking correctly. I am trying to establishing some step by step to calculate the amount of energy is being absorbed by a water body when a LED pendant is shining right above. Being the parameter that I want to calculate, the energy absorbed by the...

I want to understand if LED's which are used in the vehicles have Peak and nominal current? This is to know the hardware design to support the LEDs with peak currents, if both peak and nominal currents are same we can design a single board else the hardware design shall also consider the peak...

Hello, I'm trying to focus a 275nm (with proper safety precautions) LED that looks to be a few mm in length and width (the light-emitting portion) to a smaller dot size. The LED should probably be fairly close to the surface of the lens to collect more of the light. The dot size would hopefully...

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Hello Forum, I write you with the challenge of calculation the heat dissipation of a LED. The LED in question is http://www.seoulsemicon.com/en/product/spec/SZ5-M3-W0-00/22 a download of the datasheet is possible. The LED binning is 290lm (W4, 5000K) at 700mA, the efficacy is...

I am calculating Responsivity of a pn junction photodiode (a.k.a the target) by irradiating radiation from LED sources. For this purpose, i have two LEDs, one UV and another green LED. Note that LEDs are placed close to the target.UV LED : Manufacturer has given total radiant power to be 20mW...

I am looking for the power in watts, total, put out by and LED. This for example, if I enclosed the complete device in an integrating sphere, what power output would be measured in watts. Unfortunately a lot of the vendors report power in Candela. I could not get a response on this, but I am now...

Summary:: I have a fibre coupled LED light and an achromatic doublet lens, I know by placing the collimating lens at a distance equal to the focal length of the lens, the light will get collimated. But is the a simulation software available where I can input the parameters I can so as to...

I'm going to be adding an IR LED to my Arduino Uno and I'm trying to wrap my head around the math used to figure out the exact resistor values needed to use a PN2222A transistor to drive the LED.I know my LED has a voltage drop of 1.35V and I want to run it at 100mA and that I'll be supplying it...

The bulb/LED is connected to a long cable consisting of two insulated wires. I want to know how is this phenomenon happening in a physical way. I mean, not referring to the quality of used materials. I suppose that for the bulb, it happens kinda Joule effect, and when the circuit becomes...

Hi! I want to measure the heat of LEDs on my DIY LED panel with my infrared thermometer. That means that wrong emissivity could be like +/- 10 C in some cases. Should I take emissivity of white plastic which is 0.84 or are there any better options? Also does IR thermometer care if light from...

Hello Everybody, I'm David from Spain, and happy to be here. We have a LED that needs a FL50mm collimator which is focused to infinite, because we want parallel rays. So the lens is at a distance 50mm (approx) from the led. However, 50mm is too much distance for our design, so the question is...

I have a proportional-only controller LED driver circuit - I need to fine-tune its ##K_P## to 10 for a significant input of -0.2 to 0.2 V in the steady state. In that case, should I use a potentiometer with 10:1 setting? The LED (actuator) can drive voltages between 0 to 4V, so I need to add...

Hi everybody, I'm a mechanical engineer working on a phototherapy project, which includes choosing a LED light source that emits a spectral irradiance of 30 µW/cm^2/nm. however, most of the LEDs datasheets giving you the lumens at best. i was able to calculate the irradiance [µW/cm^2] from...

I've trying to explain this to myself but I know I'm missing something. I tuned the low E string to B. The frequency of that note is about 62 Hz. When I play that note under the led lights in my backyard I can see the string oscillate back and forth. After doing some reading, the LED light...

I use a 2 Relay Motor module to control Direction on a motor (linear actuator). When Relay A is active, actuator retracts. When Relay B is active, actuator extents and Led Module is activated. After some repetitions Led module fail. Cause of the fail? I believe Surge voltage, although i am not...

I'm working with some bare chip diodes for an application where I need extreme luminosity. These are the diodes here: https://www.irtronix.com/leuv-v625a6 I notice that some of the diodes have very significant resistance (on the order of megaohms) from anode to cathode and some have very small...

Hi, I am looking for a suitable method to couple light from 2 LEDs into a fiber and then join both fibers, so that I only have one fiber at the end so that both wavelengths can be emitted from a single fiber. The first coupling step from LED into fiber seems to be more easy, I already heard...

Hi, We are currently working on a project that uses LED chips. Each chip has 4 contacts that need wires soldered onto them. The chip is about 1" x 1", with the contacts being fairly small. What would be the most practical way to accomplish this? Does anybody know any reliable companies that...

One issue I ran across recently involved 24-volt IR LED drivers for IR cameras, in a factory. The LED units were each rated as 0.5 amp loads. The camera was on the same circuit and only pulled about 250 ma. The engineer had specified 2 amp fast-acting fuses to protect the camera circuit and they...

I want to change the the old round 5000 series filament bulbs to led. I attached a picture of some I found on Ebay. I see some led bulbs seem to mention some thing about fan. One way would be cut hole in old glass bulb and glue led in with silicon. Could use glass jar and drill hole in cover...

Our Windows 7 32-bit desktop PC is fitted with an Asus P7H55-M LX motherboard. It was working fine till yesterday evening, but from this morning, it won't turn on. (By this, I mean that it is not even starting the boot; the fan on the processor won't run.) My first guess was the PSU. So I...

Hello Everybody! I am new to electrical engineering and only had 1 formal intro class on the subject (albeit I did very well in it) and have found myself in a position where I need to design a circuit for a micro reflex sight I have been designing. So let me first describe how my competitors...

Could someone please help. i need to connect a 12vdc motor which can draw 16 amps to a switch that has an led on it. the led is rated at 3v 20mA. The power supply i am using is rated to put out 12vdc at 30A I thought of the possibility of adding a resistor to the positive pole of the led. In...

Hi all, If in a room, a lighting design was carried out and the room will contain 4 no, LED luminaries with a total wattage of 80. My query relates to what would a reasonable figure or percentage be to use as heat gain from the light. Of the 80 watts, how much of it would go into heat? I am...

Is there a way to modify a thin overhead LED light fixture that fits over a ceiling box to make the direction of the light easily adjustable? Perhaps add some sort of adjustable shade to it? In remodeling a bedroom, I'd like to install ceiling boxes ( e.g...

Hi all, 25 year electrician here with a strange (to me) issue. I have a science project lamp that has a dimmer, a volt meter and a socket with a bulb in it. The kids can turn on the bulb, rotate the dimmer and watch the voltage go up and down on the meter. Simple enough. Every dimmable bulb...

Most surface mount types of LED’s have a very nearly cosine distribution of light intensity. If we desire to inject light from an LED to the end of a cylindrical optical guide, what is the coupling efficiency as a function of distance (x) from the end of the guide? Assume that the LED is a...

Hello, everyone, I have a LED, 620nm, with a viewing angle of 20°. I would like to bring this light in a distance of about 20cm on a lens with as many photons as possible. My idea is to position a converging lens between the LED and the lens. To be exact, I would position the lens at the...

I was in disagreement with my dad about this and hoped that someone could provide a definitive answer. My take was that a LED driven by a rectified DC power supply will not flicker (provided the rectification is sufficiently smoothed out). Whilst he texted me this, taken from a manufacturers...

Hello, I am looking to build an LED Panel for a film/video application. I have a few specific requirements in mind. 1) Color Accuracy beyond general CRI ratings. 2) Flicker Free to Camera (What specifications in LED drivers should I be looking for to ensure this flicker free application?) 3)...

On older cars made in the 60's I believe flashers work as I drew it out but dropping resistors sold on Amazon are 6 ohm and it states that they go in parallel not to ground seems to me if you was going from high current draw incandescent bulbs to low draw LED one would put one resistor from lamp...

Hello Forum, I am having issue understanding what is going on with the circuit below which is supposed to blink an LED by alternatively pulling the switch up and down which results in opening and closing the circuit the LED is part of (lower circuit portion). This is what I am confused about...

Hi I'm a student working on my last assignment in physics department. now I'm trying to make a radioactive radiation detector with the principle of ion chamber. i want to add some new mechanism which when a charged particle pass through the chamber, an LED would emit a light. is there any...

I am not a physics guy I'm just a husband trying to read in bed at night without disturbing my wife. Does infrared light reading glasses exist?Scientificly, can they be made?

I have been trying to calculate what retinal irradiance value I get with a 1 blue LED system. Since the manufacturer didn´t give the spectral distribution information, I will approximate LED as a monochromatic one (using the 460 nm peak). From the datasheet, the LED intensity range goes from 6...

Hi! Question about LED power supplies. They all have marked ripple voltage. Typically 150mV. How much ripple voltage is human eye capable of noticing when looking at LED strips? And is there difference between 12V and 24V? I have opinion that 150mV ripple on 24V LED strip would give the same...

Summary: Will an external surface reflect light into a more focused beam without using a traditional lens? Hey guys. Just trying to focus the light coming from a 1watt LED light source. It's native beam angle is 130 degrees. I'm hoping to focus it to around 30 degrees. We are creating an...

There has been a large shift from energy inefficient lighting in the last 10 years to LEDs in domestic, retail stores, cars and council run buildings and street lights. The study in the link below by the French government agency support a previous study in 2012 by Sánchez-Ramos published...