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Questions tagged [led]

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.

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59 views

How does a dot matrix led driver know the voltage of an led?

I wanted to make a 7x10 led dot matrix using two 5x7 led dot matrix from lite-on (LTP757KR). I first thought of using shift registers, then I found a 12 x 8 dot matrix led driver with a bunch of ...
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44 views

Power consumption NeoPixels vs. direct control?

At Maker Faire Berlin 2018, an electrical engineer looked at my project which was shown with NeoPixel LEDs (WS2811). He mentioned that the NeoPixels waste a lot of energy. It would be better to build ...
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31 views

How to: Led Dimmer switch to on/off switch

I have a led strip with a wonderful no touch dimmer on the bottom of the kitchen cabinets. What i would like to do is to "link" the inner lighting of the cabinets to the same switch, in a manner that ...
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49 views

How to change ferrite core of transformer

we want to replace EE20x10x6 ferrite core to FED 25 to reduce height of transformer.This is for LED driver ,we have all data for EE20x10x6 means turns for input,output,and auxiliary winding with ...
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69 views

How to use a transistor to drive strings of LEDs from GPIO pins?

This is similar to How to drive a 20mA LED From a 4mA max GPIO Pin except that I need a little more hand-holding in order to understand what is happening. For background, I'm a software engineer and ...
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1answer
51 views

Light bulb LED equivalent of a CFL (Compact Fluorescent Lamp)

If I have a CFL light bulb of 100W what would be (how many watts ) its equivalent in LED. In the place where I live LEDs have taken over and CFLs are no longer available, but I need stron bright ...
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92 views

Control the RGB tape with only one output of the microcontroller

I need to control the colors of an RGB ribbon. This requires 3 PWMs. But I have only one output of my microcontroller available. So for this I need to find a circuit that stays between the ...
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47 views

LED Project: IC that supports different flashing options [on hold]

I am an electronics newbie. I found a number of circuits that allow me to control 10 LEDs using the 4017 IC. The circuits basically allow me to cycle between the LEDs. Can anyone point me to an IC ...
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72 views

Ultra Low Consumption White LED Flasher

simulate this circuit – Schematic created using CircuitLab I need an LED flasher circuit to operate inside small model lighthouses. Ideally the flash needs to be white and the battery needs to ...
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3answers
133 views

Make an LED (20 LEDs) circuit battery efficient

I want to wire up a miniature wargaming figurine to have 20 LEDs. As I've poked around options my concern is the battery life and how often the battery would need to be replaced. Since each gaming ...
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3answers
80 views

Basic resistor question for parallel LED circuit

I'm planning on building an LED circuit to place inside a model miniature for wargaming. The circuit would be in parallel as I'd need a really big battery to power up all the LEDs. I wanted to check ...
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1answer
58 views

Potentiometer min and max value

I purchased several of these to drive high power LEDs on a custom project : https://www.amazon.com/gp/product/B019W4C5IE/ref=ppx_od_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 These LEDs are to be ...
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1answer
120 views

Why is my led not on?

Hello I’m just a beginner and I made a simple circuit with a resistor and a capacitor with a led in between. As I understand the capacitor just accumulates the energy but why is my led not going on? ...
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2answers
156 views

Mystery! LED lights unplugged yet still lights perpetually

I got a string of LED Xmas lights hung behind my TV connected with an extension cord. I want to buy a power bar with a switch to turn it off but for now, I just unplug the strand from the extension ...
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2answers
91 views

How does this LED string work?

I have a LED string with four different lights. The lights are in order red, green, yellow and blue and this pattern is repeated. It has a controller with a button to cycle through fading/blinking ...
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3answers
679 views

How do I figure which LED I need?

I need to replace two LED diodes on a TP4056 board (bottom right corner on the picture). The board is going to be in a box and I want to move diodes to the small holes in the box. There are two ...
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39 views

Multiple input to single output converter and vice versa

First question so please forgive any mistakes. I'm trying to design a system by which multiple LEDs are controlled by multiple switches, but without using as many wires as there are switch/LED pairs. ...
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1answer
15 views

Can a power surge have a different effect on a led driver when floating?

I have a LED driver which has 3 connections on the AC side , L,N and ground. In the event of power surge, can there be a difference in effect if the GND connection of the LED driver is floating or ...
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2answers
35 views

Can I in any way connect +ve side of my led to uln2083a output pin?If no can I do it with M54562 transistor array?

I had conneced my digital pin of arduino to the uln2803a to drive LED. I want to configure my uln2803a such that i can connect +ve side of the led to the output pin of uln2803a IC.
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71 views

What's the required voltage for ws2815? [migrated]

I am working on ws2815 led strip with the esp8266 on arduino 1.6.6 fast led library.Using CD40109B level shifter to convert 3.3V of esp output to 12V .It's working fine upto 31 leds according to the ...
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1answer
44 views

LED Package/Case

I could'not find the packaging searching online. Can you tell me the package/case types of the LED (right) and PD (left) below? Thanks in advance.
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190 views

Constant current source gets heated

I am trying to control some power LEDs using a microcontroller. For this I plan to use a transistor based constant current source to protect the LEDs from getting damaged and PWM on the base of the ...
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2answers
773 views

Why does a 74HC595N work in LED matrices?

I have checked a lot of LED matrices, and mostly a 74HC595N shift register is used. In some cases a TPIC595B like below. Example: Driving LED arrays with Arduino Circuit from above example: I ...
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48 views

5W power led datasheet

Here is a 5W power led datasheet. I have several questions about it : What does "Peak Current (1 / 10 Duty Cycle, 0.1ms Pulse Width) - 1000mA" mean? Does that mean 1000 mA peak current is possible ...
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2answers
109 views

Is the 100w LED I have really 100w?

I bought one of these: https://www.ebay.ca/itm/High-Power-Warm-White-DC-32-34V-100W-LED-light-Lamp-SMD-Chip-9000-10000LM-LM/272210214196 I am powering it with a 12v 8ah battery and a voltage booster: ...
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1answer
82 views

Switch module test circuit design

I am doing a project to make a test box that would to test the switch module in the photo below. Please see circuit diagram below for inside of the switch. Please note this switch is not an ordinary ...
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1answer
47 views

How much voltage I need to light up this led [duplicate]

I have a RL80-UR543 LED 8MM. How much voltage I need if I use a resistor of 100Ohm?
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0answers
28 views

Problem with 5 meter LED strip light and 450W power supply [closed]

I build LED strip lights using old florescent shop lights metal reflectors and used as the heat sink solution for the strip stick on LED light. Total of the LED strip was about 6.5 meters and I ...
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1answer
73 views

RGBW Cree XM-L LED power circuit HELP!

I have 10 Cree XM-L RGBW LEDS and I would like to power them from a 12V power supply. I came up with this idea: A 12V 30 amp power supply powers 3 different step down buck converters (10 amps each ...
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2answers
39 views

USB switch matrix switch to control an externally powered LED? [on hold]

Is there a way to wire the lighting on an illuminated switch so that it's powered by a separate dedicated battery and NOT by the matrix encoder device that the switch is a part of? I have a USB ...
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1answer
59 views

How to choose the right potentiometer for dimming a LED

I have a reading lamp from IKEA. It has a bright LED. Too bright for my taste. So I inspected it and it is composed of a DC power supply unit that outputs 7V and a maximum of 3W. The LED unit is ...
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2answers
58 views

Is it safe to use LED transformers with existing 12v halogen bulbs? [closed]

I am in the process of installing two "Tech Lighting" pendant kitchen lamps (each with their own transformer, but on the same dimmer switch). My question is: Can I use MR16 gu5.3 50w 12v halogen ...
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1answer
63 views

Is there a variable forward voltage diode-like device or circuit construction?

I need to make a test PCB for an LED drive circuit that can drive a variety of different single LEDs. The forward voltage (Vf) of the LED could be anywhere from ~2.2V up to ~6.5V. I'd like the test ...
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1answer
117 views

Why is there no resistor in a christmas LED string light?

I bought a bunch of different LED string lights for Haloween and Christmas. All of them are arranged as 2 sets in parallel. They are either 50 or 100 LEDs. I noticed that most of them have a molded ...
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2answers
99 views

Troubleshooting defective LED bulbs

I bought 10 Thomas Watt LED bulbs and 8 are dead in less than a year (each last about 2-3 months). Soometimes a couple of days before they stop working, they flicker when I switch them on or after ...
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0answers
23 views

Can I connect 2 power supplies for 16 meters LED RGB strip?

I've bought 2 sets of 10 meter LED RGB strip (7.2w/m) for a room. Then I've cut them to around 8 meters each to get 16 meters. Everything seemed fine but one thing, because it's 2 separate controllers,...
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1answer
125 views

555 Timer Stops working after a few seconds

I'm building a LED dimmer using a 555 timer (yeah, lame I know). I'm using it to produce photographic flat frames which require perfect illuminated fields even with shutter speeds as low as 1/1000 of ...
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1answer
77 views

LED indicator - How to show 'on' when circuit is open

I am designing a circuit to replace a problematic computer controlled raise/lower operation for our mobile home bed. The bed uses a 30 amp DC motor (similar to a wiper motor) and simply reverses the ...
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1answer
35 views

Capacitor for 3 minutes off!

I want my led strip lights to turn automatically off after 3 or 5 minutes of turning on. Please, suggest a very simple circuit using capacitors which would block the circuit and turn off the LEDs ...
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1answer
45 views

Wiring a power supply, arduino, and LED strip together?

I've been researching various websites on all of my questions and have found answers to many of them but I am also finding conflicting answers for some of them. I've read that electricity is something ...
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1answer
38 views

LED current source circuit design concerns

TL;DR: Read the bulleted list below. I am designing a simple constant current source to power up some LEDs inside arcade buttons. My project consists of 20 of these buttons. Every button is ...
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1answer
58 views

Why isn't my transistor outputting enough voltage when switched?

So, I'm a software guy, and this is a bit out of my element. I'm working with a Raspberry Pi, and I want to power one of an LED button, a push button with a pair of integrated green LEDs wired in ...
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1answer
41 views

74HC595 Inconsistent Outputs [closed]

I'm fairly new to electrical circuitry, and while trying to test out and use a 74HC595 Shift register I ran into some issues. I'm not using a micro-controller, just push buttons to control to the ...
1
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1answer
49 views

Polarity. What do “C” & “P” signify?

G4 bi pin LED bulb. Silicone coated Hello all. Thanks for the forum. I have some of these: G4 bi pin LED bulbs. Silicone coated dimmable 12 volt DC. They are 1.5watt. Although not visible on this ...
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1answer
117 views

Why does my LM393N (dual comparator) ignore its inputs completely when used with an LED?

I have made the following circuit: Viusalisation (not working): https://i.stack.imgur.com/tDA85.png Circuit (working): simulate this circuit – Schematic created using CircuitLab Left to ...
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2answers
116 views

Two LEDs using, probable problem?

I use a simple circuit to notify user the reverse biased voltage to prevent some issues. Vcc can be -18~+18V, and two LEDs have exactly same reverse voltage (5V), but they have different forward ...
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3answers
101 views

Adding Debug LEDs to PCB

I'm working on the next revision of a prototype PCB board, and from the first one I learned that LEDs would be very helpful instead of having to probe each pin/wire for a certain state. In this ...
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1answer
106 views

What does “Run Power and Ground wires back to the Arduino” mean?

An Adafruit article showing people how to wire up an RGB LED to an Arduino UNO has the warning shown below on its page. For longer strips requiring more than 1 Amp, wire the power directly to the ...
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1answer
43 views

Connecting a 12V LED strip to a 7.4 2s Li-po battery in addition to two motors

I know this is going to be a completely stupid question, but since I'm working with a Li-Po I want to make sure I get this right. What I am building is a modified Nerf blaster that has two motors ...
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2answers
65 views

What am I doing wrong? COB LED with LED Driver

I am relatively new to electronics and I am trying to turn on a Bridgelux BXRC-50C2001-D-74COB LED (Digikey listing, Datasheet ) using a 500mA Mean Well DC-DC LED Driver (LDD-500LW). The LED Driver is ...