Led Definition and 450 Threads

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...

So I built this really nice woofer box for my 6.5inch sub. All clear acrylic, and working on sealing and reinforcing the sides and back. My question is this: Given that I purchased a Dayton Audio 25W plate style woofer amplifier, is there any way I can hook this up so that I can plug a string...

This is probably a stupid question but here it is: I am just learning concepts of LEDs. To me, it seems that there is no difference between LED and normal diodes. In normal diodes in forward bias, electrons come from n type and recombine in p type right? In this process photon should be...

Many years having passed since I last looked at an electrical circuit, I been asked to design an electrical circuit at work. We make tonic water, and the idea is to create a holder for bottles with a built-in UV light rigging. Due to the relative efficiency, robustness, cheapness etc, I am...

I want to implement the following very simple logic: Voltage at point "A" is high ==> LED is OFF Voltage at point "A" is low or floating ==> LED is ON and I came up with the attached circuit to implement it. I'm just wondering if there is anything "bad" about doing it this way, or if...

How to design a ciruit that has 2 LED Lights ... I want to design a circuit for the sake of me seing if i can do it. I need the following things 2 LED Lights which are flashing on and off and make noise relative to when there on or off ( like a police siren ) and also i need to house all of...

For my physics class this semester, we had a broad-ranged project to work on. Basically "anything related to physics" was the category. Initially I had wanted to build a percussion synthesizer circuit, but all I could manage to do was pick up a radio station 10 miles from my house, so I...

If anyone could help, that would be amazing. its not homework, its a personal project i am undertaking and just wondered if anyone could give me an explanation or any help if they had any understanding of this circuit! thanks guys! Samm

Hello, I have constructed a 25 Led counter and am having a little trouble. I have cascaded 3 4017's with a 4011 according to how the data sheet shows. I have added a pushbutton along with a 4001 to debounce for a clean count. I get a good clean count with one push of the button from LED 1 to LED...

I don't wish to ask dumb questions about basic LED applications but ... Yesterday I bought a 12 mcd, 5mm Dia, red LED, through hole mount. It was to replace an unexpected failure of the previous unit: supposed to suit 12VDC supply & containing a built in resistor. The application is a 12VDC...

I believe its possbile but wanted to ask if its possible to light a single LED light by and RF signal if its strong enough. I know there are LED's that are as low as 3 milliwatt that could work. Thanks in advance.

Hello, I did an experiment home, i took a power supply 9V and hooked it up in series with 1k Ohm resistor, then after that I hooked it up to a parallel connected 2 LED diodes. So both diodes were on the same voltage drop. I don't know exact calculations behind it but it doesn't matter. Here is...

Greetings, I am rather clueless about this stuff so I'll leave it to you guys to come up with any bright ideas for this. I'm building an array of LED's for my high school that flash to music. I'm using a TIP31C transistor to get this effect. My problem is they're wanting a 1 foot by 1 foot...

I have been trying to make this circuit work for a few weeks now and it is slowly driving me crazy. I have on a veroboard a circuit. When i redo the circuit on Yenka (Crocodile clips) It works perfectly. The circuit is a 555 astable circuit with two LEDs, when i turn it on only one LED...

Ok so I'm going to start this by saying I'm a mechanical engineer and circuits don't make very much sense to me. (So your help is very appreciated) I'm currently designing a board game and I need to be able to program a large amount of led's. Basically, I have 217 holes in a gameboard that...

I'm currently researching for the term paper of my class on black holes and the topic I selected is the one in the title. I've found some good information so far, but I don't feel like I have enough to get an A without a bit more. I'm curious if anyone has any resources that would aid this...

Hi everyone, I am trying to create a data file that contains the intensity of an LED at a particular distance. For each data segment, the distance from the centre point (red dot on my very amateur paint drawing) is d and the distance from the LED to this purple grid is z. So I calculated that...

I bought a LED monitor less than a month ago. Until yesterday I never had any kind of problem, all worked perfectly well. Today while I was away from keyboard but still close to the screen, I saw that the screen suddenly turned all black with large (maybe 100 pixels, I don't really know)...

Simple question for you guys. I am trying to drive an LED with a 5V power source and a resistor in series. I understand how to calculate the minimum resistance needed to drive the LED with maximum current ((voltage supply - forward voltage) / maximum current) but I can't for the life of me...

fastest modulation: laser diode vs LED... Hello Forum, in the telecomm industry, the most common and economical form of modulation is direct modulation, acting on the current operating LEDs or diode lasers. Using an external intensity modulator (OOK), like a super fast chopper, the...

I am not an electrical engineer. Ok, so I am interested in taking a cheap LED flashlight or headlamp (which I don't have yet) and identifying and replacing each individual LED bulb with an LED of a particular wavelength. I've seen you can buy LED's over the internet in bunches so that's no...

Hey guys, I'm currently using as monitor a Flatron ez T730SH. It's been almost 4 years I have it and sometimes it would change the coloration of the whole screen (red to greenish, red-greenish over and over). Apart this I don't have any problems with it and I don't really care about the color...

Can anyone tell me what is the internal resistance of LED? I mean is that very high or low? Usually how much current is drawn from it when it is given 5V?

It will be obvious that I am not a certified Electrical Engineer. I am trying to create a small display and using LED lights to "accent" the display. I was wanting to use 6 to 9 LEDs in a circular fashion. What I am not certain of is: Can I run 6 - 9 LED's just by using a power cord and...

Hello all First time post here. For a Christmas Village display for the houses, I bought a 15 bulb LED light set that is battery powered that I planned to convert to Transformer power so one, it can be controlled by the house voltage timer system I am using for the other lights, and two, so I...

Hey team i need some simple electrical engineering advice. I am a surgery resident and I need battery powered LED that flashes at 8 times a minute. Research funding is about as easy to find as health insurance so I am trying it on my own. I thought about just taking apart a flashing light that I...

Hey team i need some simple electrical engineering advice. I am a surgery resident and I need battery powered LED that flashes at 8 times a minute. Research funding is about as easy to find as health insurance so I am trying it on my own. I thought about just taking apart a flashing light that...

In the following circuit, none of the 7 segment LED's light up when i start simulation. I have been told that I do not need to connect anything to the LT, RBI and BI/RBO ports of the 74247 TTL. Does that affect anything maybe?[PLAIN]http://img708.imageshack.us/img708/390/7seg.png

Hello, I´m wondering if the new LED TV´s use the same energy everytime with independence of the colour. I´m explaining it better. With the "The Cathode Ray Tube" (CRT monitor) you use more energy if the image on the screen is white than it´s black ore dark. Around 15% more of energy. I...

I have a project with two, separately wired high-power LEDs. LED #1 is a 1 watt LED rated at 3-4 Vdc at 350/700 mA LED #2 is a 3 watt LED rated at 2 Vdc at around 350/700 mA According to Resistor calculations, I get: LED #R1 = 4.7 Ohm, 2 Watt rating (for 700 mA) LED #R2 = 8.2 Ohm, 4...

I'm doing a project where I need a sensor to monitor a standard green LED and determine if it is ON, OFF, or BLINKING. I have been considering using a phototransistor or photodiode, but I am not sure how I would use one of these to tell the difference in the LED being on or blinking. Does...

I have a question about making an LED light up when sensing audio. Right now, I'm using Super-Regenerative receivers and testing various components of them. Using a signal generator, my audio speaker squeals, as it should, when on the right frequency. When it's not on the right frequency, I hear...

Hello, Lately I've been trying to gain an understanding of processors/cpu's and the very lowest possible code you can engineer. I decided I would do a thought experiment where I would distill the computer down to the most basic level I could conceive, and decided that such a computer would...

Okay, to cut a long story short, I got hold of a: 16~18V, 30W, White LED, 2100 milliamps. And a 32~36V, 100W, White LED, 3500 milliamps. I got some 6V lead batteries, and I would like to use them to make a crazy flashlight. I tried searching, I came upon quite a lot of solutions...

I made a circuit in which the LED terminals have a potential difference of 0.1V,So how can i amply this potential difference to 6V using an external power supply. I found this circuit : http://www.aldinc.com/pdf/amp_27007.0.pdf I was wondering if this would amply 0.1V or is it something...

The ideas setup is this: There is a LED with solar panel and a battery, from one of the sun-charged nightlights, and an optic fiber (the "mirror") that routes the light from the LED onto it's own solar panel. The effect is that the light dims about half way down. Question: What...

i recently bought a bunch of LED's from superbrightleds.com and wanted to replace the led's that are in my pc's case door. the LED's i ordered are the rl5-r1330. i wanted to know what other parts i would need to pick up from radioshack so that i don't burn them out. i don't know a lot about...

Hey, so I have a large array of LEDs. I think I have 168 of them. I want to power them from my wall in the US (120V AC). The forward bias for each LED is 2.8V. The current rating is 25mA. I plan to arrange them in chains of about 42 to get 117.6V drop over all the LEDs. That leaves me with...

What is in your opinion most promising technology -LED or induction light?

Can anyone kindly help me in using the P channel mosfet as source for switching of LED display? As I've connected it like 16 Mosfets with common source giving 5V from diode b/w power supply, drain is for the16 rows of 32 LEDs. Gate is connected to the shift register. The problem is the...

Ok so I have a flashlight that is 19.2 volts. It used to have a bulb that was 19.2 volts and .6 amps, but I broke it, and couldn't find a replacement, so I decided to try to use an LED and a resistor. The LED is 20 mA (.02 Amps) and 3.5 Volts. If I am correct, to find the resistor I need I would...

Does anyone have ideas about the possibility of (12V) LED units with higher powers and better colour (/spectrum) for domestic situations? I am reluctant to pay the high prices they are asking for the present ones if there is a possibility that something much better is on the horizon. This is...

How many LED's are in a typical LED monitor? For example, how many in a 20in vs. in a 24in, etc? Thanks

Hey. I am currently working on building a circuit that should receive sound input from an electret mic, and then based on the output voltage, light up a certain number of LED's. For example, if the sound is low it should light one LED, and if it's very high 3 LED's. I imagine that 3 LED's total...

Hey I was studying for my test, in my notes it says si cannot be used for led, because it has indirect band gap.Why indrect band gap is not useful for led?

I want to arrange LEDs on a breadboard want to glow SSUET entirely with LEDs. The problem is that I am unable to understand the accurate arrangements to make the circuit. All of my LEDs are not glowing at the same time. Can anyone please explain me the procedure of designing of the...

hi, im looking to connect a 230V AC to an 4V LED. i was suggested a thyristor could be used then a rectifier to convert AC to DC then using a resistor to drop the voltage to 4V. i dan't seem to understand how a thyristor can aid this process. Any suggestions, please help?

Hi, all I've been reading these forums for a while, and now that I have a question, I've finally decided to join. The question I have is school-related, but not really direct coursework since it's very open-ended. I am part of a group (in electronics class) that is building an LED...

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...

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...