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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24 views

How much radiant intensity does my IR LED need, to be picked up by a camera?

I'm trying to design a night vision system that uses IR LEDs. How do I figure out how much radiant intensity I need, to illuminate an area for the camera to pick it up?
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32 views

Help identifying 5th pin in 5 pin LED connector

I have some RGBW LED strips that I bought for a cabinet lighting project that I did not realize came with their own connectors pre-soldered on. The extension cables it came packed with are sized ...
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1answer
37 views

How to solder WS2812b LEDs(individual,not a strip) to a PCB?

I wanted to do a project using these ws2812b leds, and I find them nearly impossible to hand-solder them because of the tiny contact points. Can someone teach me how to solder these by hand? They are ...
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68 views

Is using a 12.5V PSU ok for a 12V LED? Also would this wiring work?

I am looking to make a small central box to control my LED strips from. However, the switches I've bought are 12V, I only have a 12.5V plug power supply and the LED strips are 5V. I was told a ...
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3answers
98 views

Why are LEDs so tolerant of voltage?

My electricity knowledge is about high-school level or so. Just about enough to be dangerous... Back when I was a kid I used to play around with 4.5V DC power sources, buttons, switches, relays and ...
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83 views

Can an LED be used in paralell of a free wheel diode?

Can an LED be used in paralell of a free wheel diode? All circuit is powered by a 12V alternative. simulate this circuit – Schematic created using CircuitLab I think it can be used like that; ...
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3answers
84 views

Circuit analysis for bicolor LED

I am trying to control two LEDs in reverse parallel, using a signal SIG. SIG is an open collector signal, so it is either high ...
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4answers
74 views

steering 3 LEDs with double button

I want to control 3 LEDs with 2 switches. First switch turns first LED on, second switch second LED, and if both switches are on, all three LEDs are ON. Switches are sharing common input. This is ...
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1answer
29 views

RGB LED Resistor Value and Source Voltage

I am using a Common Anode RGB LED in my project(datasheet is given below) and the different specifications for each LEDs are giving me headache. In my schematics, as shown below, I have used ...
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2answers
75 views

Is it possible to vary an LED from low to high brightness at any frequency without MCU?

I am trying to think of way to vary an LED like in a christmas light where it just goes from max intensity to lowest intensity at any frequency without using an MCU. The reason is I don't want to use ...
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123 views

Brightness of LEDs

I am currently in the design phase of building a digital clock (about 2ft by 4ft in size.) It should be fairly visible from a considerable distance (about 100 ft) and visible during the day. I am ...
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1answer
36 views

How to wire a PPTC polyswitch + blown indicator LED to protect a bi-directional DC motor from stalling?

I have the following setup and it works well as is, except that I would like to protect the 12V DC motors (Reverse High Torque Permanent Magnet 12V DC motor) with a PPTC polyswitch + a LED to indicate ...
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52 views

LED downlight current (amp) usage

I need advice on how to build a battery powered light setup in my house with what I have. Please be kind as I am a DIY newbie when it comes to off-the-grid solutions. Equipment: 1 x 12volt 36Amp ...
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1answer
59 views

Circuit Design - Need 35mA through UV LED using a GPIO controlled switch

I was trying to achieve this using a PNP transistor as a switch circuit and the voltage drop was too significant and I was only able to achieve 13mA. Circuit here I was advised to use a FET instead. ...
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3answers
58 views

ws2812 strips data grounding method & flickering

I know for ws2812 strips (60ppm) you can ground the data line at the far end to reduce the chance for "echos" and improve performance. My question is can you: Short the data tab to the ground tab at ...
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61 views

Change current in steps for pulsed LEDs

I want to control the power consumption and intensity of a IR LED which is fed by a 38kHz signal. Can I add mosfets in series with different resistors (25/250) like in my schematic? Application is a ...
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1answer
30 views

Can I Multiplex with a PWM driver

I really love building LED displays and have a decent understanding of multiplexing at this point. However, everything I've built is just binary, on or off, and I've been interested in building ...
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1answer
46 views

Am I thinking about this correctly regarding 12V, 24V and 120V LED lighting?

Most of the LED light strips I see are either 12V or 24V, which require a driver to step down the power from 120v at the wall (thus the little black transformers that come with them). However... I ...
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42 views

Some of LEDs connected in series remain on

I know that even tiny leakage currents can make an LED glow weakly and there are many answers to similar questions, but my problem is different. I have 6 power LEDs connected in series and they are ...
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1answer
83 views

LED radiation angle appears to be changing with distance

I am trying to measure the radiation angle of an LED. Below are my measurements which I've gone over many times: d is the distance between the tip of the LED and ...
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1answer
36 views

Multisim does not simulate the capacitor charge correctly

If I simulate this circuit in Multisim everything works fine, but in reality the LEDs burn, if I put a 1k resistor in series with the capacitor the LEDs no longer burn I think the LEDs are burned by ...
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0answers
36 views

Converting a circuit/ schematic onto a breadboard? electronics basics [closed]

I need to produce a complete breadboard for my coursework but due to missing school (leg injury) I don't understand how to convert my circuit/schematic into a breadboard after trying to look online I'...
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1answer
486 views

Do dead CFL or LED light bulbs consume power and is it safe to leave them mounted?

Do burned-out CFL or LED light bulbs consume power when the switch is on? Is it safer to keep them in their sockets, removed or slightly unscrewed so the bottom center contact isn't touching? I ...
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2answers
76 views

How can I find a replacement LED to repair RJ45 tester? (re: SMD size, measured with multi-meter)

I'm trying to fix an RJ45 (CAT5/6 lan cable) tester and I need to replace some LEDs and diodes (SMD and not through-hole). The tester has 8 LEDs (one for each wire) and only a few are blown so I ...
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2answers
74 views

(Re) MOSFET as LED current regulator

I would like to use a MOSFET LED Current regulator to source 700mA in 7X Cree XM-L High Power LEDS in series. To test my circuit, i use my workbench powersupply. The image of my circuit is in attaced ...
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1answer
46 views

Wireless RGB led controller circuit with motion sensing - design feedback

Beginner hobbyist here. I would appreciate some design feedback. Purpose of this circuit: It controls an RGB LED strip (5 Meters, SMD 5050) via an IR remote and also automatically powers on/off the ...
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29 views

POV fan display [closed]

I am designing a POV fan display using WS2812 140 LEDs and Arduino. I have tried to know how it works and found that the LEDs are provided serial data input with separate clock of each LED. I want to ...
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3answers
60 views

Trying to understand schematics of a microcontroller (TM4C123GXL)

I have a TM4C123GXL microcontroller with a hwllo-world app. that makes some LEDs to blink. I have done this 'hello-world' by following a tutorial, but now I want ...
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1answer
136 views

Why does this SMD LED only work on AC?

I have basic electronics knowledge and have repaired many things, but I'm a little confused about this. I have a 220 V LED PCB like this: One of the LEDs is burning out and causing the whole array to ...
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0answers
33 views

Using an unknown CLK output to pulse two LEDs [closed]

I am trying to modify a preexisting imaging setup. The setup I have relies on an excitation LED to excite a fluorescing material which will then be captured on a camera. The already existing setup has ...
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0answers
27 views

How to remove sensor controller from LED panel

I have a led panel that is controlled by a touch sensor. Light if off by default, single press turns light on/off, long press changes light brightness. The touch sensor is connected to 3 pins: GND, ...
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1answer
53 views

Defect LED detection for car lights

The schematic beneath is a new project of me. The theory behind this is: My car has a very fool proof bulb failure detection and warning system. CANbus proof LED bulbs can't fool the car and just a ...
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1answer
31 views

In LCD/LED displays, does the back light strobe or remain on?

In LCD/LED displays, like the ones used with computers or for watching TV channels. Does the back light strobe in sync with the refresh rate or does it remain on all the time?
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4answers
45 views

Estimating current when voltage drops > voltage input

Let's say I have a circuit with a 5V battery and a 2V LED and a 100 ohm resistor. Ignoring certain properties of an LED, I can estimate the current by doing: ...
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2answers
48 views

Solving for current with voltage drops

Given the following circuit: Why is the current through the circuit 34.7mA instead of 35 mA? My thinking was that: The LED draws two volts, so it effectively makes the battery 7V instead of 9V. ...
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2answers
143 views

What is causing a white scale buildup at copper pin connection on LED light sticks and how can they be cleaned?

Can someone explain what is causing this white scale to appear on the copper pins and on the block of this LED light connection? The seal at the connection is supposed to be watertight. On occasion, ...
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3answers
91 views

Long battery lifetime light? (LED etc.)

I design some plastic models, and I would like to include a small light (LED or similar). I am looking for a solution with a long battery lifetime. I'm not a electrical engineer but I read that, for ...
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4answers
92 views

Powering LEDs, dim LED in parallel

I want to build an light fixture for my aquarium and decided to use LEDs, almost everywhere it's suggested to wire the LEDs in series. but that will need a high voltage for many high power LEDs. also ...
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1answer
85 views

3D hologram fan display

Did not know where else to ask about this, so if it is off-topic I would gladly take some pointers as to where the correct place would be. I would like to make one of those spinning LED fans that can ...
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0answers
42 views

Want to adapt old dimmer in stove hood to work with LED lights

I have a range hood that came with 4 halogen par20 bulbs. It has a three-position switch for the lights: off, on (full), and on (dim). When I replaced the halogens with LEDs, the dim position caused ...
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1answer
60 views

0603 LED resistor values

I have two LEDs The first one is directly attached to 3V3 and the other one is attacked to the SCK line on AT Mega 328P Here's the datasheet for the led (I am using the same LED) http://www.image....
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1answer
125 views

Current calculations

Emergency lighting solution Continuing from the previous post above. Firstly I know how to calculate current in a DC situation. However, since I am using an inverter that produces 220V at its output ...
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1answer
42 views

Using 12v 50w motorcycle light with two 7.4v RC batteries

I recently purchased two motorcycle lights (12v DC 50w) and only needed one. Now I have some 7.4v 4500mah 45c batteries leftover from my RC hobby a while back. I would like to create a 3d printed ...
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4answers
13k views

Why does current change when adding in an LED?

In the following diagram: The current is 1 mA from: V = IR R = 1 / 1000 = 1 mA However, when I add in an LED with forward voltage 1V: Why does adding in the ...
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2answers
74 views

Dual Coil Latching Relay with LEDs - Opposite LED Triggers on Trailing Edge

This is my first time using dual-coil latching relays (Kemet EC2-5TNU), and I'm running into some strangeness when breadboarding out the below circuit: The coils switch without issue when sending a ...
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1answer
81 views

Drop voltage from 3.3 V to 2.5 V with step-down dc-dc converter or diode

I'm building a status display for a meeting room. The door to the meeting room gets sunlight from the side, so I will hang the lamp turned 90 degrees and the red status light will point towards the ...
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2answers
46 views

WS2812b/Sk6812 flickering on camera

As far as I understood, the WS2812b or SK6812 LEDs use PWM output to drive the diodes. This could cause flickering on camera when the LEDs are dimmed. Does anyone know the output driver PWM rate? Is ...
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1answer
28 views

Driving multiple (variable amount of) LEDs with WS2811

I am trying to control multiple LEDs with the WS8211. According to the specs, RR resistor shall be calculated based on the voltage drop on the red LEDs. So, my first question is: The formula is RR=(...
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1answer
2k views

What are the various 'properties' of a diode?

I have come across various properties of a diode, phrased differently in different places (product sheet, everycircuit, etc.). For example: The wavelength is the simplest and that is the color of ...
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1answer
65 views

What is a three-pronged LED?

I've used two-pronged LEDs and Diodes, but I've come across a three-pronged one: What is this component called, and how would it work?

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