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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2answers
45 views

LED MOSFET switching circuit

So here's my circuit for powering 4 LEDs with my arduino. Right now it seems to be working perfectly. I send HIGH to any of the pins and it lights the LED. I was wondering if I take in account the ...
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0answers
50 views

How to blink strings of LED Christmas lights?

For strings of incandescent bulbs, there were blinky bulbs. Is there an equivalent (easy) solution for LED strings? I think that a common blinky bulb will not get enough current flow to operate ...
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0answers
14 views

How to Simulate 10w LED packages in Circuit Lab

I've been messing around buying random electrical components from China and I came across these 10w LEDs and, after seeing how bright just one was when supplied with 12v at 900mA, now I'm looking for ...
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1answer
16 views

The LED energy irradiance (mW/sr) is independent from emission half-angle?

I have two LEDs with the same energy irradiance, 10 mW/sr for a solid-angle of 0.01 sr, but with different emission half-angles: LED A = 15° and LED B = 45°. Can I say that they will emit the same ...
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0answers
35 views

producing spectrum with wavelength of 755nm [on hold]

I need an LED or something else to procuce infrared waves with the wavelength of 755nm. the closest LED which I found on the web has 740-750nm waves
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0answers
18 views

Spot light LED bulbs (MR16) flash once when turned on. If I put 1 normal halogen in then it solves the problem. Why? [on hold]

I have 5 spot light bulbs in my bathroom. All use MR16 connection. I replaced them all with 5w LEDs and when I turn on the switch they flash once then go off. If I remove one so there's only 4 then ...
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0answers
24 views

Motorcycle LED Headlight modulator help req! [on hold]

first time asker here! First of all, I can use a soldering iron, and I have a basic knowledge of electronics.. I ride a motorcycle and have fitted it with high power CREE headlights. I'd like to ...
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0answers
69 views

100Khz 150W LED Switching

My test Circuit is 5V VCC + LED + n-MOSFET(Controled by OPAMP for constant current) + n-MOSFET(For ON/OFF) +(feedback)+ Shunt Resistor + GND. 5V/30A SMPS. If there is no n-MOSFET for ON/OFF. It's just ...
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2answers
3k views

Why are SMD LEDs shipped in a sealed bag containing desiccant?

I had a selection of 0805 LEDs in my last Mouser order and was a bit surprised to discover they arrived in heat-sealed (rather than folded and taped with sticker) bags containing a desiccant bag and ...
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2answers
84 views

Would the frequency of LED be equal to that of microcontroller

Suppose I have a simple LED driving circuit i.e. an LED and a resistor in series which is driven by a pin of a microcontroller. Now I set the frequency of this pin to say 1Khz, will the LED flash with ...
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0answers
25 views

Can I connect the current sink pins of a linear LED driver?

I am designing a little battery powered LED necklace/button kind of device, which has a matrix of 42 LEDs. Each column of the matrix is driven by one CAT4002A to achieve a defined current and to allow ...
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2answers
48 views

How can I invert this current control?

Below circuit is an emitter follower supplying current to an LED. A DAQ board is outputting 0-10VDC voltage to the base and cannot supply more than 5mA. Thats why the LED is not directly hoked up to ...
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0answers
54 views

Buck Boost Driver to switch 2 LED chains

simulate this circuit – Schematic created using CircuitLab I'm working on a project to turn 2 LED strings (each containing 6 HB LEDs). Here is my question. The Buck Boost driver I'm ...
0
votes
1answer
47 views

LED switch with externally controlled current from sinking output

My device has sinking output (Vcc=3.3V), the LED current (and voltage) is controlled by another device (a voltage controlled constant current source) as indicated at VLED. The LED IV curves (as ...
-1
votes
3answers
55 views

Proximity Sensors with feedback changing LED brightness [on hold]

I am trying to create several devices that track the proximity of one another, with a feedback that brightens a LED as the devices become closer (one device will brighten as it comes closer to any of ...
0
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1answer
19 views

For 12X8 LED array with any 1 LED glowing at a time, should we charlieplex or use 74HC595n?

Apologies in advance for probably missing a lot of things. I'm pretty new to electronics. I'm building a 96(12X8) led (monochrome ultra bright, white) multiplexed array, driven by an Arduino nano. ...
-4
votes
0answers
45 views

I'm trying to build a Slayer Exciter [closed]

I've been trying to build this exact same Slayer Exciter circuit, but I'm running into problems. The only difference between my circuit and his is that I'm using LEDs instead. The circuit should work ...
0
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1answer
28 views

What resistors to use for 60, 8000mcd LEDs, with 4 * 1.5v battery source? [duplicate]

I currently have 60 LEDs in a parallel circuit. I am using 4 1.5v batteries as the source. The LEDs have a forward voltage of 3v-3.4v (8000mcd, wavelength 460nm). My questions are: Can I just use ...
-6
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0answers
48 views

What is that red led in front of cpu [closed]

There is a red led infront of my cpu just beside the power led which flashes at times when i run the computer.what is it and what does it indicate.
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2answers
191 views

LED circuit is draining AA batteries REALLY fast

My question is long, rambling and weirdly specific. I hope I'm not violating like 50 stackexchange rules, but I'm completely lost. Long-time lurker, first time asker and pretty new to circuits in ...
0
votes
4answers
108 views

Oops! N-channel Mosfet on sinking output

I have designed a simple circuit to drive LEDs using a MAX6964 I2C LED driver/GPO chip. Unfortunately, I somehow missed missed that the outputs are open-drain current-sinking outputs. This is not ...
-4
votes
0answers
24 views

Use Arduino to get on and off reading from 32 LEDs for Serial communication in Processing [closed]

I have 32 ultrasound proximity controlled LED lights that is each connected to an Arduino and turns on and off individually. However, I also want to connect them all together in some way, so that I ...
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2answers
42 views
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2answers
87 views

Why can a 74HC595 drive 8 LEDs?

I don't understand, I have seen many people use the 74HC595 to drive 5V across 8 5mm green LEDs via 220Ohm resistors at the same time, whereas the datasheet says that the maximum Vcc current is 70mA. ...
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0answers
6 views

Arduino continually resets when connected to external power supply, but not USB [migrated]

I'm working on a seemingly simple Arduino project which plays a sound and flashes an LED when provoked by some trigger. The problem: When powered by an external power supply, the Arduino continually ...
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0answers
53 views

Simple 1.2->12V, 5A current limiter circuit with limit indicator

I have a voltage source which varies between 1.2 and 12V, and I would like to limit the current between 1mA and 5A. The voltage source is a switch mode power supply, and the current limiter has to be ...
-3
votes
0answers
59 views

Better way to run 10 - 1W LEDs? [duplicate]

If I want to run 5 to 10 1Watt LEDs from battery, which is the better method ? connect the LEDs direclty to a 3.7V 3000mAh battery or Use a cheap DC stepup circuit with a a 3.7V 3000mAh battery ...
0
votes
1answer
49 views

How to control a common-cathode RGB LED matrix with Arduino?

I have the Arduino Uno board, and I want to create a 17x31 RGB LED matrix. Unfortunately, I wasn't patient enough and already bought the LEDs, and I purchased common-cathode LEDs without doing much ...
0
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0answers
40 views

Phototransistor modulation and 50Hz interference

I've got an LED being modulated at 1kHz. This then points towards a phototransistor (LPT80A) which is wired up in a common emitter configuration with a collector resistor of 1k. The output of this ...
0
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4answers
144 views

How to limit current to LEDs

I have understood that this is a bad way to do it: Since some LED can draw more current than others. So lets say I would power some high powered LEDs, like say 10 x 3W LED with a DC forward ...
0
votes
1answer
54 views

Strange current reading, LED's in series

I have a 19.4v/2.37A power adapter. I have 5 LEDs (3.2v-3.4v 20mA) connected in series. When I measure the current, the reading says 0.08A, which is total of 4 LEDs, not 5, but close enough. ...
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2answers
84 views

Sending PWM signals down cat5 cable

I working on an LED lighting project where I will be installing 20 boxes in a space, each containing 4 LEDs (RGB and IR.) I want to connect all of these boxes to central board which will drive all of ...
0
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1answer
59 views

High currents LED switcher circiut for WS2811?

I am making one High Amp for WS2811 RGB LED driver in range 2 Amp, SO base on it's Datasheet the driver working by this way: there are some switcher circuit similar to this : But this kind of ...
0
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2answers
82 views

Resistor for 20 LED's in series

I am reverting here for some advice on a LED panel circuit that I am trying to build as I cannot find any concrete answers anywhere else online. My apologies as my understanding of electronics is very ...
0
votes
1answer
43 views

Lighting LEDs from high current source [duplicate]

I have an circuit with six high torque servos connected parallel to power brick that provides 5V @5Amps. Everything is running fine. But I wanted to add few LEDs to circuit but I dont know how do I do ...
0
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1answer
22 views

TPS61196 LED Driver chip for high Voltage Backlight applications: What to do for proper backlight driving?

I need to design a Backlight Driver which has to have high brightness. These are the equipments I have in the design: My Backlight String combined of 2 parallel of 28 serial LEDs(2 * 28 = 56 LEDs) ...
2
votes
2answers
240 views

Deciding On A Resistor For an LED

Let me preface: This is my first post on this exchange, so I will try to provide as much context as possible. If some details are lacking, or I've left this question overcooked, I apologize. So, I am ...
0
votes
1answer
78 views

Set ADC input to high impedance

On a early version of the system I'm working on, an Arduino Mega was being used to read some analogue values using its ADC. Something critical to the application was for the ports to be always in high ...
1
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2answers
62 views

LED radio display - How to control multiple segments at a time?

I have a display from an old radio (I think it was a Watson). Now, there are different wires connected to it: Let's call the first two A and B and one of the others (it seems to be not so important ...
2
votes
2answers
49 views

Festival light sculpture LED power question

Hi im looking for some guidance for a temporary outdoor lighting installation at a festival. I want to run 18 x 10m lengths of low voltage LED fairy lights these ones. I have some large 12v batteries ...
0
votes
1answer
45 views

Design recommendations for an array of different forward voltage LEDs

I'm putting together a custom aquarium lamp as a hobby project and I'm not sure of the best way to configure the LEDs. All the LEDs are Cree and I am looking to push ~800ma through them. 5x whites ...
0
votes
1answer
39 views

Dimming LED lights with PWM, driver quite far from LEDs, noise considerations

There were a few questions like this before, however I haven't found ultimate answer yet. I'm going to drive LED lights in my house with multi-channel driver (PWM controller + MOSFET Transistors), ...
0
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3answers
98 views

When will parallel LED voltage drops become an issue

The following circuit will cause problems because of voltage drops: simulate this circuit – Schematic created using CircuitLab It should be changed to look like this: simulate ...
3
votes
1answer
71 views

Is there a limit to the number of parallel LED if each has its own resistor?

I am building a circuit with 6 parallel LEDs, powered by 5 volts through a transistor array which can provide 300ma. If each LED is allowed 20ma (by setting the correct resistance for each), I should ...
3
votes
3answers
188 views

Are there side effects to using too much resistance for an LED?

I have a 9v battery and a standard red led from reference 1.7v drop and I want it to draw 20 ma also from reference. so id need a 365 resistor. to my understanding if i have too little resistance then ...
0
votes
1answer
100 views

LED light dimming, TRIAC vs PWM?

Many days ago, I published a question here asking about dimming an AC LED using and Arduino and TRIAC, and I was told that most LEDs that support dimming should work with the circuit I linked to them. ...
2
votes
1answer
69 views

Power Efficiency of Embedded system

I am designing an embedded system and I am hoping to achieve maximum power efficiency as the system will be running off of 2x CR1620 batteries. In addition to power efficiency, I would like to keep ...
1
vote
1answer
98 views

conditional switch for classic car [closed]

I am would like to add a small buzzer or led light to the dash of my old MGA which activates only when: a) the ignition is off AND b) I have forgotten to shut off the battery cut off switch. (This is ...
3
votes
1answer
131 views

Dimensioning smoothing capacitor for China DIY LED lamp

My first question here so bare with me if I'm a bit "off" or so regarding the level of knowledge etc. My purpose is to try to learn things. So I started off by buying some LED lamp DIY kits of this ...
1
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2answers
70 views

Calculating resistor for LEDs with different Forward Voltages in series

I need to work out what resistor I need for a series circuit containing 3 LEDs of 2 different types, and a 9v battery. I can do the maths, but I need to check I'm doing it right as I'm trying to ...