An LED is a light-emitting diode. Lighting an LED is considered the "Hello world" of a circuit design, and it can be as simple as putting a series resistor or can get more complicated, involving PWM and multiplexing.

learn more… | top users | synonyms

-2
votes
0answers
32 views

Snake game on 8x8 matrix using shift registers [on hold]

we have displayed a led snake on led matrix and have moved left and right. we are unable to detect its head so that we can control it to move up right left etc.. any help would be appreciated..
0
votes
2answers
75 views

Want LED to stay on once it is triggered

Have built the Seattle Univ cell phone detector to locate hidden harassment devices around my home, especially the auto tracker presently installed somewhere in my car. Circuit works well, and LED ...
1
vote
1answer
83 views

LEDs driver circuit

I was wondering what is the role of this type of circuit connected to LEDs. I found it in a LED torch supplied by 2xAA batteries. Is it an oscillator? Is it only an energy trick? What are the ...
0
votes
1answer
59 views

Can use 17 resistors with 16 rgb led's?

I always see an rgb led ran with 3 resistors, for example a 20ma led on 5v power uses 150ohm's for red due to it's lower voltage but only 100ohms for green and blue. I am running 6 shift registers off ...
1
vote
4answers
82 views

Photodiode - Turn Digital Input pin into 1 with little light Input

Currently I am trying to work with a photodiode(SFH 203) that is supposed to detect very small amount of light. Using the digital of an arduino the photodiode cannot turn the pin to 1 due to the low ...
0
votes
2answers
80 views

LED lamp increased power consumption after installation: Why? [on hold]

I'm new here, but I've been checking your forum few times before, never registered. Anyway... I have a problem at my home. I'm not very electrical kind of guy, so these questions may be easy to answer ...
-1
votes
0answers
30 views

Remote LED dimmer

I have a question about LED dimmers. I'm using a 12v-24v LED single color remote dimmer with a Output Power: < 96W & rated Load Current: < 8A, it was working with a lower powered LED but ...
14
votes
2answers
1k views

What are the 'knuckles' on through-hole LEDs and photodiodes for?

I am using an IR LED and a photo diode, and I have designed the PCB according to the specifications that I found on the datasheet - i.e. hole sizes for the pins being 0.6 mm. However, on these ...
4
votes
1answer
42 views

How does area and intensity relate to perceptive brigthness of a light source?

I want to design tail-lights for onboard use in vehicles (mostly bicycles), but I wonder how should I configure the system so as to get the best visual perception from a distance. Each lighting ...
1
vote
3answers
74 views

Removing flickering of LED lightning

I am trying to install recessed, dimmable LED lightning in the living room. We're talking about an end solution of maybe 15-20 spot lights. My home has 120V/60Hz. Currently I am experimenting with a ...
0
votes
2answers
52 views

LEDs and External Quantum Efficiency (EQE), how to find Light Output Power with test results? How to find power?

I'll try explain everything as clearly as I can as it's slightly complicated. I really need help as I'm quite new to this kind of experiment and work so any help would be extremely appreciated. I did ...
0
votes
1answer
38 views

No output from programmed attiny2313

I flashed a simple led blink program to an attiny2313 with a usbasp type programmer. Avrdude confirmed that the chip was programed, but the led is not blinking. I tried switching the led, varying ...
0
votes
1answer
63 views

How does this USB capacitive touch light circuit work? You can touch anywhere and it turns on, not just the electrode

Here are some pics of the circuit board. Now I'm not asking how the circuit works, I understand that. There is a capacitive touch sensor IC where the shiny electrode you see on top connects to the ...
0
votes
1answer
106 views

PWM with Oscillator does not dim LED display as expected

I have a fairly successful attempt so far at driving an LED display with an Arduino Mega 2560. The Display sequences work well on their own and the Arduino seems to be doing its job sending the ...
-1
votes
1answer
69 views

how to design high power LED light circuit,

I am new to electronics, want to prototype a LED light with 3 red led, 3 blue led and 3 white led. All the led are 1W high power LED. Each group of color can be controllable respectively and I want ...
1
vote
4answers
117 views

Minimizing PCB size of a 192 RGB LED array

I'm working on the design of an LED lamp house for my film scanner. I need RGB LEDs, plus IR LEDs. I'm figuring on a 2"x2" grid of SMD LEDs. Datasheets for the ones I'm using below. The current design ...
1
vote
1answer
44 views

help with 555 timer to dim led driver

I am trying to build some DIY LED fixtures to light my saltwater aquarium. They need to be dimmable, and I want to dim them with Pots for convenience versus a controller. It will probably be clear by ...
1
vote
1answer
52 views

Control LEDS with PWM and transistors

I have three transistors that are each connected to 5 LEDs like so. I am attempting to increase and decrease the current through the LED's in a linear fashion by increasing the current in the base ...
0
votes
1answer
25 views

Need to add blinker module to relay trigger

simulate this circuit – Schematic created using CircuitLab I have a simple light controller box. I have a 2 channel relay that controls a red and green light by magnetic switch. so we can ...
0
votes
0answers
43 views

how i powered an LED with 220 AC [duplicate]

can anyone suggest a simple circuit which lights up an LED with 220V AC. I am trying to make something without the use of transformers. Maybe a bridge rectifier and a resistance connected with LED. ...
-2
votes
1answer
42 views

How can I understand the interface to connect from motherboard to lcd display?

I want to connect motherboard directly (without controller) to lcd display, i.e. this: http://www.panelook.com/LP173WF1-TLA2_LG%20Display_17.3_LCM_overview_18016.html Please give me the manual how ...
1
vote
2answers
161 views

How to control the current output from usb slots of computers?

Is it possible to control output from a computer usb port so, for instance if I have a usb led I can make it blink or do whatever with it. Whenever I send a high signal it would glow and whenever I ...
0
votes
2answers
52 views

AVR-C turning led off after number of blinks with interrupts

so what I am trying to do is that I am trying to make the led blink for a certain number of times before it turns off. I want to avoid using delays so I tried utilizing the interrupt and I also used a ...
2
votes
1answer
65 views

Questions about a simple LED circuit using the ULN2003A

I'm a newbie, and am trying to drive several independent LEDs using a transistor array in a 5-volt CMOS circuit. Here's what I've come up with, showing only the first LED: In the schematic, ...
0
votes
2answers
82 views

Led's in series light power degradation with strange results

I am doing life cycle test for 7 led's connected in series with current limiting resistor.(picture for reference) I am measuring light power(mW) with Thorlabs photo resistor for each led. Led's ...
0
votes
1answer
49 views

Help wiring multiple different colored LED lights

I am working on a project right now, and it is the first time that I have worked with wiring anything. I have 70 LED lights. 10 red, 10 orange, 10 yellow, 10 green, 10 blue, 10 purple, and 10 pink. I ...
1
vote
1answer
67 views

Controlling multiple RGB leds with PWM from a Atmega328P using one transistor per color

I want to be able to control 9 RGB leds, each color from a potentiometer. Each color needs 20mA, so when all the colors are present the leds will need 540mA (9*3=27, 27*20mA=540mA). My RGBs leds are ...
0
votes
2answers
42 views

how the LIFX or Hue generate millions of colors?

I see the Philips Hue and LIFX led bulb can generate the millions of colors, I can find . can anyone tell me how this light works to generate millions of colors, what is the yellow LED light and ...
0
votes
1answer
60 views

RGB gets wrong values

I have Arduino which output 3 pwm signals into the gate of a irf731 FET transistors. Their ...
0
votes
2answers
61 views

Timer for turning LED's on for 4 seconds and then off for about 200 seconds

I want to build a very small, low power timer that will allow several LED's on for 4 seconds and then off for about 200 seconds, then repeat. 4.5VDC. No programming. Help please - thanks.
1
vote
2answers
118 views

Trouble converting 12VDC incandescent to LED: lack of resistance

I'm converting two, independent, incandescent bulbs (OEM 212-2) fixtures to use LEDs for automotive map reading. Each incandescent bulb (12-volt/system) measures 1.5 ohms with a meter; however, there ...
1
vote
1answer
84 views

Is it Possible to Produce Any Color Temperature?

I see it is possible to purchase many different color temperatures in light bulbs from 3500K (in the red spectrum) to 6500K (in blue spectrum) all the way to 10,000K and even 20,000K or higher. All ...
0
votes
0answers
47 views

looking for 300mA cree led driver circuit

I need help or need basic circuit of cree LED driver with the following info: Voltage input: 12v Output : 3.3v at 300mA Thanks for any help.
0
votes
1answer
75 views

Power an LED from 120v

I'm building a lamp and want to integrate an analog voltmeter (0-300 volts AC) in to the circuit. It has an LED backlit dial that requires a separate, 6.3v power supply. Any suggestions on how an ...
1
vote
2answers
42 views

Lighted SPST switch waiting problems

I am trying to put together a model rocket launcher for my son and am having issues with wiring. He wanted it to look "cool" so I have two SPST switches that light when powered, and a single SPST push ...
3
votes
4answers
233 views

Semaphore using one microcontroller pin

I'm trying to make a semaphore using to LEDs green and red, controlled by one arduino pin. Idea is when pin is low red LED is on and green LED is off, when pin is up green LED is on and red LED is ...
-2
votes
1answer
66 views

What circuit is used to power up a 3W LED light

What circuit should I use to power up a 3W common anode RGB LED direct from mains (220V)? I am working on a 3W rgb led which has 3 diodes connected in parallel with their + terminal as common anode. ...
0
votes
1answer
70 views

Makeshift way to drain a battery?

I have a 3.8V mobile-phone battery that I need to discharge. However I don't have any electrical components (say led) with me. What is a crude way to do this using household items?
0
votes
3answers
48 views

IR LED for night vision LED driver necessary?

I am working on a project that requires a night vision camera. I have a small camera placed on the PCB and 4 IR LEDs placed around it to illuminate the dark room. The rooms are about 20-30qm. I have ...
0
votes
2answers
75 views

Confusion over a simple 4060 LED blinker

I'm trying to build a simple LED blinker using a 4060BP binary counter, as per the following: and (Originals here and here). When I have built either circuit, the LED (I'm just using one for now) ...
0
votes
2answers
64 views

9x 1W LED's parallel + series resistor calculation help needed

I am struggling with the calculations of the current limiting resistor for my circuit so I wanna ask you guys for help. I've tried doing this calculations on online calculators and by myself with math ...
2
votes
3answers
71 views

Is there a simple way to diffuse the light of a “super bright” 5mm LED?

I want to put yellow leds inside the turning-signal cases used in motorcycles. The problem is: since the case is not deep enough, when I look from far I can only see the focused, pin shaped LED ...
4
votes
3answers
271 views

Why is PWM used to control LEDs even when they're only used On or Off?

I've noticed on cars with LED tail lights that they have a flicker to them - I presume because they're PWM controlled. But I've seen it on vehicles where brake lights and tail lights are separate ...
0
votes
1answer
53 views

How hot do High Power 1-3W LEDs get

I'm thinking of Using 3W RGB high power LEDs for a project. I will only have one color on at a time so I'm pretty sure that it would be 1W of ussage at a time. (please correct me if I'm wrong) My ...
0
votes
1answer
109 views

Help on transistors or MOSFET in 8x8x8 LED cube

I am on a project to build a 8x8x8 LED cube having common cathodes in each layer. I have built the cube and now I have to build the main circuit. I am using my Arduino Mega 2560 to control it. I ...
1
vote
2answers
346 views

Resistors with arduino

simulate this circuit – Schematic created using CircuitLab I'm using Arduino Mega Pro 5V. Pins use a max of 40-50mA. I'm connecting 3 RGB super bright 5mm LEDs. Currently wired in ...
1
vote
2answers
417 views

LED emergency lighting - relay activated

I've designed the following schematic for my LED emergency lighting project; I'm planning on building it soon, my knowledge in electronics is short right now (I started learning electronics by ...
1
vote
1answer
87 views

quick charge but slow discharge of a capacitor

I'm trying to find a circuit that will quickly charge a capacitor with a load(led) in the circuit but slowly discharge it (keep the led on longer than it took to turn on). Is this possible? Does ...
0
votes
2answers
80 views

How much voltage to give my IR LED?

I got a new IR led, emitting light at 850nm. It says 5v reverse voltage and 1.5 forward voltage. How many volts should I give it? I have DESTROYED three other IR LEDs because of giving them too ...
0
votes
1answer
51 views

How to find places to add power indicator light in simple DC circuits?

I build a lot of little hobby circuits and I usually place them inside of some kind of project box. Right now I'm working on the "Atari Punk Consol" by Forrest Mimms. It looks like this: I tried ...