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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Making a simple solar-powered lighting system, a few concerns

I'm building a fairly simple solar-powered lighting system to use at home, which charges up a battery by day and then the battery powers a few bulbs at night, switching automatically. So far, I got ...
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36 views

keil stm32f4 led example

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1answer
35 views

MOSFET Switching without gate voltage / LED Strip

I have ordered logic-level MOSFETS of the type IRLZ34N (for the sake of working on a Raspberry Pi) but I have problems in Wiring it up. I have so far connected: +12 to the +12v lane of the switch ...
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2answers
80 views

LED for High frequency/blinking application

Which parameter in the datasheet of the LED defines the turn on time and turn off time? What kind of LEDs are used for high speed switching applications? Thank you
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1answer
82 views

Discrete LED Driver Topology

I have drawn the above schematic by reverse engineering a locally available LED Bulb. I was expecting to find an IC in the driver board but instead found this discrete circuit. Googling "Discrete ...
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0answers
68 views

Customized torch/flash light using a perfboard with an attiny

I am currently working on customizing the flashing frequency of a torch light (customized intervals between on&off). To program the individual frequency I have made use of an attiny 85 ...
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0answers
57 views

Reusing a old non perfectly regulated 12v powersupply

12 volt power supply shows 16.8 volt Not long time ago i made a simple low voltage rgb pwm circuit to test with raspberry and arduino. Now after a while of reusing old chagers and recycled ...
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4answers
65 views

Can two LED circuits with a shared ground use a single resistor? [duplicate]

I wonder if anyone can help me, a complete beginner, with a very basic question? I currently have a red LED connected to a GPIO pin on a Raspberry Pi, and a green LED attached to a different GPIO pin. ...
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1answer
63 views

Is this diagram correct? [on hold]

I have created the below mentioned circuit diagram: I just wanted to know that have I drawn a good/correct diagram or should I make any changes to this diagram? I have not added the resistors in ...
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2answers
49 views

TSOP382838 IR receiver keeps outputting signal even if no infrared light is present

This is a beginner question. This is my first time using an ir receiver. The one I have is a TSOP38238. I have setup a simple circuit that consists of a visible led and receiver. When I have no ...
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1answer
56 views

Can I Reverse/upside-down mount SMD LED

I've seen reverse-mount LEDs which are meant to have the light shine through a hole in the PCB, instead of straight off. Is it possible to just add a drill hole for normal LEDs and just place them ...
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1answer
34 views

MOSFET choice for 12v LED Strip and 3.3v Logic

I'm currently planning a project on a low-cost WiFi-enabled RGB LED controller and could use some help in looking over my parts list and general concept. What I'm wanting to do is a build a ...
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4answers
58 views

Inerfacing switch & led with any controller

I am trying to interface switch and led. I want to write a program in which if I press and release the switch led should glow and if I again press the switch led should turn off. I am not able to ...
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23 views

movement decision taken upon the light seen by a line follower robot

I'm working on a line follower robot and it has to check traffic lights every estimated distance and a decision of whether to move or wait is to be taken upon the current state's light of an external ...
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2answers
56 views

How To Build A POV Display Clock? [on hold]

Hi I'm looking to make a pov display clock. The problem I am having is finding plans because I want it to rotate on a horizontal axis. I'm wanting to attach it to a magnetic rotor such as ...
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1answer
54 views

SMD LED footprint

I want to use small SMD LED in my PCB just for indication purposes (Rx/Tx pins, power rail). I have found this one; I think it will do the job. However, the footprint is obscure What does this ...
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1answer
65 views

Constant current driver - direct pwm dimming

I recently picked up a cob bulb of Ebay that came with a constant current driver. Tried to dim it using a mosfet and PWM signal of an Arduino, but it resulted in a very loud ringing/humming from the ...
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6answers
2k views

How can voltage burn out an LED?

I understand how a current higher than what the LED is rated for can burn out an LED, but how does something equivalent happen with voltage? If the correct current is on an LED but the voltage is too ...
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3answers
69 views

Driving an LED with a low amplitude square wave as an input of MOSFET switch

I am trying to drive an LED with a square wave. I've made a circuit like below: The problem is, an equiment can generates a square wave with a limited amplitude up to 1.7 V. After some experiments, ...
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3answers
78 views

Will connecting two batteries in parallel increase current drawn in simple led circuit?

I have a resistor diode circuit that I'm powering with a 9V battery. The circuit diagram below is a simplified version of it. The real one has 4 LEDs, 8 resistors. I want to deliver 30mA to the ...
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2answers
53 views

Transistor not supply enough current

I am trying to run a 100W 32V Led with a DC-DC boost converter from a 6 volt battery, and I want to make it so it will shut off when the battery voltage gets low. So I am using a TIP122 transistor ...
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3answers
69 views

can dropped voltage be greater than forward voltage?

What I know is: forward voltage, Vf = The minimum voltage that is required to start current flow across the LED/Diode dropped voltage, Vd = The voltage that is used/lost across the LED/Diode. My ...
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1answer
56 views

Narrowband LED performance compared to Laser for Spectroscopy

I am currently building my own Raman spectrometer and I am in the process of choosing a light source. I am deciding whether I should be using LEDs vs traditional laser modules. These are my ...
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0answers
24 views

Ethernet 15+ Inch Amoled Display [closed]

I am a Software engineer and I need to make some program (TCP/IP client) that connect to Ethernet with more than one Ethernet display devices (LED or OLED 15+ inch) (TCP/IP Server) The program will ...
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1answer
51 views

Why does a resistor in my Neopixel data line work at all?

Adafruit's best practices for their Neopixel LED strings say, "Place a 300 to 500 Ohm resistor between the Arduino data output pin and the input to the first NeoPixel." Someone asked about the ...
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1answer
65 views

Driving IR LEDs using PWM - measuring current & current source questions

For a project I'm currently working on, we're trying to drive 940nm IR LEDs (Kingbright L-934-F3C) using PWM, regulated by an Arduino Uno. We've run into several issues during our prototyping process ...
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4answers
454 views

What is the total resistance of a LED array?

First time poster and a hobby EE enthusiast here. I want to turn on a LED array with a transistor switch and I'm having trouble with determining what will the total resistance on my transistor ...
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1answer
70 views

What is a purpose of BJT in an LED driver circuit with MOSFET?

I am trying to turn an LED on and off repeatedly with a square wave. Yesterday, I've checked the following circuit works: (Please note that, the figure has one voltage source ...
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1answer
40 views

WS 2811 lights flickering

I'm working on a project involving a bunch of daisy-chained WS2811 lights and I'm noticing significant flickering on the ones at the end (lights #16-30 in a chain of 30). Right now, the circuit is a ...
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0answers
41 views

Single resistor with same characteristics parallel LEDs? [duplicate]

This type of question is asked many times I believe, but what differs my question is that in this case all LEDs are same. So there is no chance that one LED will draw all the current and others won't ...
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1answer
117 views

LED indicator for DC voltage

I am planning to using a buck / boost converter to run a DSLR camera from my USB powerbank AND other power sources. For that module I want to build with the buck / boost converter, I need a simple LED ...
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1answer
75 views

Led driver circuit 3.3v & 5v

Not long time ago, as i couldn't find a proper Mosfet to drive a high wattage led strip ( 5050,5630), i asked how to create a circuit that allows me to turn on properly the mosfets i already own. ...
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0answers
34 views

CREE LEDs - Copper vs Iron Lead Frame

http://www.cree.com/LED-Components-and-Modules/Products/High-Brightness/5mm-Oval-P2/5mm-Oval-Color-Series CREE offers LEDs in copper and iron lead frame. What does it refer to? Are the actual leads ...
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1answer
36 views

How is it possible to use TRIAC dimming with an 110v input LED T-8 Tube light?

I have seen T8 or T10 Led Tubes made for entertainment lighting that can plug into a Triac dimmer and be dimmed down to approx 10% with no flicker and no color shift. Attached is a picture of the ...
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1answer
47 views

fading out effect on a bunch of LEDs [duplicate]

I am trying to make a bunch of LEDs fade out when they are turned off. The task is quite simple for a single LED by using a 1000uF capacitor to produce a time delay as in the following circuit: The ...
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2answers
48 views

Rotating a motor according to calculated output [closed]

I have 13 photodiodes. Positive connection from battery is connected to the positive end of each photodiode. The position of photodiodes is as shown below: ...
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1answer
34 views

Determine supply voltage for led from current limiting resistor

Everyone knows how to calculate the resistance of a current limiting resistor for a LED but is it possible to go the other way? (aka determine the supply voltage from the resistor's value) I ask ...
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2answers
67 views

How to control on/off with multiple LEDs without traditional multiplexing

first post here but I've been doing some research and cant find a definitive answer. Goal: Use some type of voltage-controlled switches in parallel (similar to schmitt trigger) that will accept PWM ...
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0answers
47 views

dimmer on demand

I am trying to make a "dim on demand" for my aquarium (freshwater planted aquarium/shrimps) There are 24/7 timers/dimmer out there, but I have weird schedule everyday. Press an ON button Light ...
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1answer
67 views

LED and light bulb in series

I have this electrical system: a switch connected to a 120V 60Hz 21W light bulb. I wanted to add two outlets one for a LED, another one for something else like a laptop or a fan. I tried to plug in ...
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3answers
57 views

shift register RGB led brightness

I'm currently using 74HC595 shift register to light leds. Recently I decided to start using RGB leds instead of simple 1-color leds. Which means that I now have to ...
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1answer
98 views

Driving a large array of LEDs (~600)

A colleague and I had the idea to build Conway's Game of Life in a large 8x8' form factor using a 50x50 grid of RGB LEDs (RGB so that the grid can be re-purposed in the future). The idea is to build ...
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1answer
52 views

Use SCR dimming info to feed 1-10VDC line

Hello I am modifying an electronic lighting fixture to use LED instead. I have everything I need already, 80W LED, Power Supply, etc. There are just two issues I cannot resolve. The original fixture ...
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1answer
69 views

Why the voltage of supply got stuck when connected with leds?

I was working with some smd LED's trying to make their V-I curve. For that purpose, I connected two segments parallel to each other each containing two leds as shown, to a regulated dc power supply ...
6
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1answer
157 views

Why do Infrared LEDs come with different coloured lenses?

I'm just starting a project to build a universal Engineer's Remote Control Unit [EG. able to send the Panasonic 0xF2 code, etc.]. I have seen that IR LEDs come with (at least) three distinctly ...
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2answers
109 views

Is resistor on LED's necessary after voltage drop?

Let's say we have perfect 5V DC 0.1A power supply. Obviously for one LED we would need a resistor (I'm well aware of Ohm's law), BUT what if we connect bunch of LED's in series. And the current drain ...
2
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2answers
47 views

How many lumens does an incandescent halogen bulb provide?

I got my hands on an old slide projector (the kind that projects cel slides onto a wall). The light source, is a 24V, 150W incandescent halogen lamp. As a little pet project, I'm thinking of ...
4
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4answers
721 views

Can a photodiode distinguish between daylight and white/blue LED?

I am working with a photodiode that is supposed to detect very tiny amount of LED light(the light will be programmed by an attiny 85). Using different kind of lenses I succeeded amplifying the light ...
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2answers
88 views

NPN transistor: collector current flowing to emitter without connecting base?

I have a circuit where a LED has its cathode connected to the collector of my C8050 (or SS8050) NPN transistor, with the emitter grounded. Even though the base is left floating, the current is still ...
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3answers
112 views

What are the basics I need to know to power LEDs with RF at a range of 30 feet?

I would like to light up a path in the woods with hundreds of LEDs using RF. The idea is that I would carry a RF transmitter powerful enough to light LEDs. As I approach the LEDs would get brighter, ...