A LED is a light emitting diode. Lighting a 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.

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2answers
60 views

Quick and dirty LED power from AC

I have some extra 1n4007 diodes, and was wondering whether, instead of using a power supply to drop the voltage, could I could power LEDs by just making a full wave rectifier, Using a capacitor to ...
0
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0answers
61 views

How do filament LED bulbs work, looking very similar to incandescent bulbs?

Filament LED bulbs use very narrow strips containing the LED, which look similar to filaments of an old incandescent bulb. Here's a good picture: http://www.aruana-led.de/ They look like a normal ...
0
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4answers
101 views

Why are mostRGB LED strips common anode instead of common cathode?

Why are most RGB LED strips common anode instead of common cathode?
0
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1answer
66 views

Can LED be controlled using PWM pin without using a FET in LT3475?

I am designing a LED driver circuit using LT3475EFE-1#PBF IC for controlling two LEDS. I have a signal from an I/O pin for LED ON-OFF control which is tied to PWM input (as recommended). Typical ...
0
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3answers
55 views

Use of ULN2003 for LED current drive

I'm trying to use de IC ULN2003 to logically drive the current of different LEDs from a logic input. I have searched for the data sheet but i don't understand how the IC works. I know that there is a ...
0
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0answers
54 views

Help with ICs, 2-digit 7-segment displays, 74HC4515

Can someone show me how to connect two DC56-11YWA 2-digit 7-segment LED displays to an Arduino Uno or Mega2560 using two 74HC4515s? Is there another IC that I will need in addition? I want to display ...
0
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0answers
38 views

Designing a pluggable current/information circuit

I'm trying to solve a technical problem for a project I'm working on, and being from a computer programming background I'm having trouble getting the electrical engineering part off the ground. Please ...
-1
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1answer
58 views

Am I doing this right? (LED's to music)

simulate this circuit – Schematic created using CircuitLab I have been charged with designing and making a circuit that makes LEDs brighten or dim to an audio source. At the time I ...
0
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2answers
54 views

Arduino and several leds

Can an Arduino turn on multiple leds at the same time?. I want make a home made lamp with several less controlled with an Arduino UNO light sensor and i already have the light sensor, also i know how ...
0
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1answer
97 views

How do I solder a LED in place of an earphone?

I have a super basic bluetooth headset. I've taken off the earphone, and want to put a very low power, basic LED in its place. I plan on just soldering the anode to the red wire and the cathode to ...
-1
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1answer
61 views

LED on open circuit [closed]

This circuit is not working where the transistor value is BC556B. Any ideas?
6
votes
5answers
645 views

How to control three LEDs with two uC pins using just passive components?

I only have 2 (3-state) pins available on a microcontroller and need to control 3 red LEDs, uC is running on 5V. I can only use passive components in addition.
0
votes
4answers
92 views

How to drive LED when sinking current to MCU?

Hopefully a simple one. Should I always control by writing to the GPIO digital output? Or should I always leave it low and then tri-state the output? LED turns on when MCU pin sinks current: In ...
1
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2answers
69 views

Serial Data Input through Microcontroller to Output Voltage

I am new here and new to programming, so I thought maybe some of you might be able to help me in the right direction. I am looking to design a circuit that receives serial data from an RS232 port on ...
1
vote
1answer
81 views

LED wiring questions with 9v battery as power source

My son is working on a project in which he is using 36 total LEDs consisting of 7 different LED's. There are 6 different solid colored LEDs varying from 1.88v to 3.2v and one color changing that is ...
1
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0answers
81 views

How to detect failed LED? [closed]

I am a little puzzled by the situation that I have. I have four 12W led lamps on my ceiling. They are all connected to a Meanwell HLG-100H-42B dimmable power supply in parallel. The lamps are really ...
0
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1answer
75 views

Is it possible that LED power supply is interfering with my webcams USB connection?

Not sure it is a right place to ask this question but I'm pretty out of options. I'm building DIY home-studio LED lights out of multiple 12V LED bulbs. I'm using a dedicated power supply connected to ...
3
votes
10answers
415 views

Uniformly illuminate an array of LEDs: how to get the most homogeneous output?

Please note: this question refers to the electrical engineering part of the design, optical configuration is not request (advices are however welcome) I'm trying to design a LEDs lamp with ...
1
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0answers
67 views

Obtaining maximum light from IR led for distance sensing

I'm working on a project and I'm using IR LEDs and photodiodes to measure the reflected signal. At the moment the IR LEDs are always on and drawing 100mA. It works really well except for times when ...
3
votes
2answers
117 views

How to “deserialize” a digital output to 4 digital outputs

I am working on a small test project for my Arduino and as part of it, I want to display a number on a 7-segment LED system. My first setup involved just direct links to the 7-segment display and ...
1
vote
1answer
78 views

Wild AC to DC for Arduino and high power leds

I've seen some similar posts but none did exactly match. I'm looking to power a Arduino Uno and 1x 10W + 4x 3W LEDs (Using BUZ11 from Arduino output) from a very wild AC source which is on a very ...
3
votes
3answers
57 views

Working with a cathode-based LED seven-segment display

I have recently purchased an Arduino micro and am using it to learn more about electronics and embedded systems. I have a numeric LED display HDSP-H101 with the following circuit diagram, and I am ...
1
vote
1answer
96 views

High speed flashing LED Lightbulb for data transfer? [closed]

I am currently trying to experiment with Visible light data transfer with On-Off Keying. I have trouble finding LED that could flash up to 1-2 MHz. Currently, I use the following LED lightbulb: ...
0
votes
1answer
42 views

Phototransistor responsivity does not match datasheet?

I am making a basic circuit to test the responsivity of a phototransistor. I made a basic circuit using a phototransistor connected to 5V and a 22kOhm resistor. On the other side of the ...
1
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2answers
122 views

Simple circuit reacts to touching a node

I am trying to repeat a circuit from this post. For some reason it does not work properly, and trying to fix it I figure out strange behavior. LED turns on if I touch R3 with my finger or with ...
1
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1answer
73 views

Which diodes for 12v indicator light circuit?

Which diodes for 12v indicator light circuit? I have a car whose signal light audio indicator is too soft to hear. I would like to set-up an visual indicator on the dash for when the signal lights ...
2
votes
3answers
91 views

EL wire brightness, per m not per m\$^2\$

The datasheets and catalog pages for commercial electroluminescent (EL) wire in hobby quantities, e.g., adafruit's, list brightness in candelas per square meter. That's ok for two-dimensional EL ...
6
votes
1answer
1k views

Replacing incandescent bulbs with LEDs, unexpected behavior

I have an over-the-stove microwave/ hood vent combo with 2 adjustable-brightness lights. The lights appear to be 12V lamps with a G4-style connector, and they burn out all the time... like every 4 or ...
0
votes
2answers
54 views

N-Channel MOSFET Selection - SOA & determination of VDS - LED Application

To begin, I've thoroughly searched for answers to my question/s and have yet to find any clear & concise data. I'm in the progress of determining an appropriate N-Channel MOSFET to be used as a ...
0
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0answers
44 views

When using Arduino to multiplex a 10x10 grid of RGB LEDs ( TLC5940NT ) do you need extra power?

When using Arduino to multiplex a 10x10 grid (100 LEDs) using a few TLC5940NTs will I need power above and beyond that of 3 LEDs considering there will only ever be 3 LEDs lit at any given time?
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votes
2answers
66 views

Constant current led drivers shared ground

I have 4 constant current led drivers with PWM. Here's 300-1500mA LED Driver datasheet. I want to use 3 of these drivers to power each color of a 90w rgb led. I was under assumption that I could ...
1
vote
4answers
138 views

Powering 28 LEDs in series by 220VAC - simple stabilizer

I have a home-made thingy that I would like to use as a lightning in my living room. It contains 7*4=28 LEDs (red, 1.86V, ...
2
votes
2answers
508 views

What happens when supplying an LED with too low voltage?

What happens when supplying an LED with too low voltage? Will it just emit less light? I'm making an octocopter, and need to cut away as much weight as possible. I need to run the LED without cooling ...
1
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3answers
99 views

Reference to understand LED data sheet specification, characteristic and way to use them

I'm trying to build my own IR-led light with multiple LEDs. I've bought a TSAL6100 IR led but I'm not sure how to interpret the data sheet, I can't find any reference in internet. Can anybody tell me ...
0
votes
2answers
66 views

Large LED Matrix Display of 10 lines of 12 rows x 128 columns

I need help to drive 10 LED matrix display each of 12 rows x 128 columns. I am unable to find LED driver that can drive 12 x 128 LED matrix display. My project requirements are: 1. All 10 LED matrix ...
0
votes
3answers
136 views

Colour Sensor from discrete components?

I am participating in a robotics competition that requires colour detection using discrete components. The aim is to detect red and green lights of traffic signals. I have tried making a sensor ...
1
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1answer
56 views

dimming an Ikea Jansö with Arduino

I have a bunch of LED Lamps from a yellow swedish furniture market. At that time they are connected with wireless power switches (Based on 433MHz). That is quite nice because I can control them from ...
0
votes
2answers
42 views

LED module on Arduino - driver needed?

That an arduino can power some simple led's is basic knowledge. But what about an SMD RGB LED. I cannot find some datasheet for the module I purchased from ebay (I want to use this LED for ...
0
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0answers
44 views

Controlling a TLC5927 LED Driver

I am trying to control TLC5927, with no success. I have read the whole datasheet, but I still can't figure it out. I tried to simulate it, with no success too. Can someone draw me a timing diagram ...
0
votes
1answer
111 views

LEDs in series but only one glowing

I have the following setup: simulate this circuit – Schematic created using CircuitLab (The LEDs are actually some generic UV leds without a known part number, so I didn't edit the ...
3
votes
2answers
368 views

How do I make an LED turn on when my output reaches 5v?

I'm a hobbyist and pretty new to many of the components involved, so I hope you guys can help me here. I'm trying to keep the circuit as simple as possible. I made a small variable power supply with ...
1
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1answer
107 views

Dimming power LEDs with Arduino

I used the following circuit to dim power LEDs with Arduino: I used TIP120 or IFR610 as Q1 instead of IRF510 and I found that if I use IRF610 the current is much more lower than expected. In case ...
0
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0answers
60 views

Keeping current constant during PWM dimming of a LED string

simulate this circuit – Schematic created using CircuitLab I'm looking for a good control method for PWM dimming a string of LEDs and keeping the current through the LEDs at a constant ...
2
votes
3answers
90 views

Switching LED with a transistor

I would like to switch a 350mA LED with a transistor. Switching is done by a 5V microcontroller and the main voltage is provided by a 24V power supply. To play around and see what works I used Yenka, ...
1
vote
1answer
82 views

Count the number of flashes on a yellow LED with 1-wire

I would like to count the number of flashes generated by a yellow LED in my Schneider Me4ZR power meter. This power meter produces 100 flashes for every kWh. I would like to use One Wire protocol to ...
0
votes
1answer
135 views

LED glows on low port is set to 0?

I have an Arduino UNO board with a ATMEGA328-PU and am trying to control the LED on output 13 that is on the processor pin B5. I have a switch connected on the Arduino port 7, which is on the ...
-3
votes
1answer
59 views

Circuit design for variable number of leds [closed]

I am very new to this field and turned onto it by adruino and raspberry pi. So for my next project I am looking to create, I wanna have 6 leds (20mA 3v) in a line. Now depending on my output from ...
0
votes
2answers
47 views

Problem with Optek OP265AA infrared LED

I can't seem to get the op265AB infrared LED from OPTEK to light up. I'm using my phone's camera to look for light. This works with Radio Shack part 276-0142 but the OP265AB just isn't lighting up. ...
1
vote
3answers
186 views

Smallest, simplest possible (randomly) flashing 2-3 LED circuit

I am trying to randomly flash 2-3 LEDs using the smallest possible circuit using 1 or 2 CR2032 batteries. Can I power 2-3 3mm (3-3.4v, 20mA)(amber, white) flashing (slow 1Hz) LEDs using one CR2032 ...
1
vote
4answers
197 views

Highly accurate constant current source

I want a continuous and highly stable light from an LED for around a couple of hours, for which I need a highly constant and highly stable current source. I prefer an opamp-based circuit for the same. ...