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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 using a series resistor, or it can get more complicated, involving PWM and multiplexing.

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LED blinking in parallel circuit

I have build simple circuit which have 2 LEDs and 2 resistors. The total power for circuit 1 = 0.38 W. Current 7.92 mA. I used two resistors, 4.7 kΩ and 1.6 kΩ. Total resistance for resistor is 1.02 ...
Kim's user avatar
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1 answer
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Why don't LED datasheets specify a maximum rated voltage?

I understand that (i) LED's have forward voltage drops (Vf) and (ii) that exceeding the dissipation wattage or max current can damage the device; thus one uses a series resistor to limit the current. ...
KJ7LNW's user avatar
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How to short time delay controller?

I have an old keyboard which I use for decorative purpose. It has RGB lights which turns on for few seconds when a key is pressed. I want to keep them on at all times. How to achieve this? Can I ...
Saransh Bairagi's user avatar
-1 votes
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65 views

my cooling pad is not working can anyone help me? idk bout any electronic stuff [closed]

**so the problem is I bought cooling pad around 6 months ago and it was working perfectly fine but today when I started it it was working normally but soon after it stopped working than I unplugged ...
Dishant Jadav's user avatar
0 votes
2 answers
39 views

Can I safely use the GPIO or opto-IO pin from Basler industrial camera to drive a 64 mW LED?

I've got a Basler aca2440-20gm industrial camera. This camera has configurable GPIO and opto-IO pins. If it's possible to do so without damaging the camera, I'd like to drive a 20 mA 3.2 V LED with ...
RJDB's user avatar
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2 answers
61 views

turn on an LED with a pressure switch but it will not turn off until you reset the switch

So first off I'm new to all of this electronic stuff. I understand the basics but that is it... so this is what I'm attempting to do. I want a pressure switch that will turn on an LED light, but i ...
Dan Hladil's user avatar
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2 answers
85 views

Designing a simple toy dashboard

I would like to make a "car dashboard" simulator as a gift for my kid. Nothing too complicated. Here are my initial thoughts, and I would like to hear your opinions - where I was wrong, what ...
vtomic85's user avatar
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Digital Dice Roller [closed]

I am working on a project to create a Digital Dice Roller. Below is the suggested component connection to implement the circuit diagram. However, I am confused start as my background is not in ...
Yerfdog's user avatar
2 votes
1 answer
65 views

Why do I have to increase the current by 2V when I am using a transistor?

I have a 3V 3W LED, which I would like to control with an ESP32. For controlling the LED, I have chosen a TP122 transistor. Here is my 'schematic': (The Arduino is an ESP in real life, and the 3 V ...
Marci's user avatar
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2 answers
62 views

Toggle switch from button and capacitor

In my head I see it something like this: What it must to do? When I push button first, capacitor will charge and LED will emit(B->C in transistor). Before capacitor will be discharged and while ...
bazylevnik0's user avatar
-1 votes
1 answer
90 views

Communication does not occur when connecting an LED to the UART line

I attached LEDs using transistors to UART RX and TX as shown in the attached photo. But the led doesn't work and the uart doesn't work either. If I remove this circuit the uart works fine What's the ...
bomdong2230's user avatar
0 votes
3 answers
126 views

Calculating current through a diode in a voltage divider circuit

I have a voltage divider circuit which I use to drive two LEDs with different luminous intensity. I understand that this is not the best way to do it but I wanted to control two LEDs with the same ...
Nikhilesh's user avatar
0 votes
1 answer
85 views

LED without resistor?

I have an LED with a 3.3v supply and 3.2v forward voltage. The cathode is being grounded (very sparingly) by an STM32 which can sink up to 20 mA. Can I get away without a resistor?
marc6bbs's user avatar
0 votes
2 answers
35 views

Using 5-in-1 dimmable power supply with PWM dimmer for LED strip

I hope my question is not too basic. I'm confused as to how I am supposed to connect a PWM 24V dimmer with my 24V 5-in-1 dimmable power supply. The 5-in-1 has AC inputs (neutral and load), LED- and ...
Marc-André Lafortune's user avatar
1 vote
0 answers
58 views

Buck-Boost fault mode on startup and gradual current decrease

I am using the TPS92692 in buck-boost mode with an analog signal to set Iadj and PWM. When I start the circuit, it consistently goes into fault mode and the fault pin is periodically set low. However, ...
msch's user avatar
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1 vote
1 answer
43 views

A simple visual indicator (LED light?) when a USB fan is on

I have a USB fan, some distance away from me, which I use occasionally. It's plugged into a charger and it has a manual switch. I sometimes forget to turn it off, because it's very quiet so I can't ...
MrSparkly's user avatar
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2 answers
68 views

What happen if both sides of LED connected to positive?

Question 1: If we connect both ends of an LED to the positive terminal of a battery, will it create a short circuit and damage the LED? Question 2: If connecting both ends of an LED to the positive ...
Furkan KARADENİZ's user avatar
1 vote
0 answers
41 views

How to test Keychron K3 Pro PCB LEDs

After plugging Keychron K3 Pro keyboard to USB port on Tesmart KVM switch (used not original power adapter maybe it worked not stable), after 10 min of working keyboard and mouse unplugged and light ...
Lion's user avatar
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1 vote
1 answer
45 views

Can I control Neopixel LEDs with this circuit? Is this a viable level shifter?

I recently purchased a microcontroller board (Pimoroni's Automation 2040 W) and I would like to control Neopixel-like LED strips (WS2815) which work with 12V. Since I am using a 3.3V microcontroller (...
ElectroEnthusiast's user avatar
0 votes
1 answer
42 views

DC LED flickering - connected to Solar Panel (DC) with fan (DC)

I have set up a 100% DC system for my house; solar panel (400 W, 10 A, 40 V) and the circuit connects to two LED fans in series (DC - 12 V) and radiator fan (DC - 24 V). I'm an arts student and self-...
noobie electric's user avatar
0 votes
1 answer
131 views

How can I properly use PWM to observe hopefully >= 2x normal efficacy, seeing the theoretical max of 1700 lm/W scotopic efficacy?

In a Wikipedia article on "Scotopic Vision", there is a section that states: The maximum scotopic efficacy is 1700 lm/W at 507 nm (compared with 683 lm/W at 555 nm for maximum photopic ...
MicroservicesOnDDD's user avatar
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0 answers
28 views

Designing an LED strip driver [duplicate]

I have a pretty long (5 meters) 24 V LED strip with four connectors for RGB and ground and lets say it needs 300 mA. I need this circuit to be controlled by a microcontroller. I've looked around ...
cr1tical1's user avatar
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1 answer
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I am currently running a part of a series parallel 12 V LED strip current 200 mA from 12 V adapter. Can I add 3 LED single bulbs in parallel?

I made an infinity mirror and it has a 2 ft. part of an LED strip which is UV light it is a series parallel strip that draws 12 V. I have it powered by a 110 VAC to 12 V DC 700 mA adapter. Voltage ...
Mike's user avatar
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56 views

3528 RGB LED common anode but + on pin 1

I have a gaming controller (nacon; mid tier) which have 3 damaged LEDs. They are 4 pin RGB LED 3528 size in common anode. But the positive common is on pin 1 (the LED marked pin) and all the LEDs ...
jetuaime81 's user avatar
1 vote
1 answer
78 views

How to implement a blinking led circuit that is dependent on its voltage input?

I am designing a circuit with two LEDs, where one LED will blink when the output voltage (Vout) is 5V and the other LED will blink when Vout is grounded. I am confident in the functionality of the ...
Ewheel's user avatar
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0 votes
2 answers
92 views

Powering LED's From Two Different Relays? (Complete Novice)

I am attempting to install auxiliary reverse lights in my vehicle and have come to the end of my useful knowledge. I am confident I could simply install new LED's splicing a relay into the existing ...
Wire_licker's user avatar
3 votes
3 answers
886 views

How can I use a transistor to control the segments on this 7-segment display?

Pictured here is a 4-digit 7-segment display: Datasheet I'm designing this to have a microcontroller controlling it through a shift register (2, actually). The shift register doesn't have much power ...
Steam Ranger's user avatar
0 votes
3 answers
63 views

3 buttons and 3 LEDs circuit with mutual exclusion

I want to create a simple game for 3 players with 3 push buttons and 3 LEDs. Each button turns on a specific LED. The challenging part is that I need mutual exclusion. Only the LED corresponding to ...
Drakell's user avatar
1 vote
1 answer
76 views

How do phosphorescent panels compare to LEDs for whole of night low level lightinhg

Modern phosphorescent materials are used for applications like emergency exit signs and evacuation markers. I'm wondering if the best of these may be acceptable for low level all night low level ...
Russell McMahon's user avatar
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0 votes
1 answer
89 views

The LED that is series with relay is destroyed after a couple of activations

I've tried to make a bidirectional relay circuit with a pair of relays that work with 24 volts. I tested the circuit and it works fine and both LEDs turn on when the relay is activated. After a ...
hrsk2002's user avatar
2 votes
4 answers
274 views

What are these 6-pin LED-controlling SMD components called?

In a post from March 2014 regarding candle-flicker circuits, Passerby included a photo of the sort of thing that manufacturers pair with LEDs to produce LED "candles". This is the original ...
BirdsInMyBrain's user avatar
1 vote
1 answer
61 views

Can someone help me with a LED light fixture puzzlement? [closed]

I have been buying and using LED bulbs from the Dollar Tree for many years. I have never had an issue with them in the past. Just the occasional burn out in my home office fixture because it stays on ...
russT's user avatar
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1 vote
0 answers
86 views

LED driver schematic

Working on building a driver for an LED headlight, there is a low beam and a high beam circuit that I need help figuring out either a schematic or a pre-existing driver for. The low beam side would ...
Matt Fiddler's user avatar
0 votes
3 answers
107 views

Help with LED VU meter

In this circuit, when in bar mode all LEDs light up, in dot mode only LD10s. Overall it doesn't react to the audio input at all. I wanted to use a half wave rectifier before the LM3914 for better ...
Status Re's user avatar
  • 225
0 votes
2 answers
37 views

AP3012 Running away with current draw

I am using Diodes AP3012 to boost Li ion battery voltage up to 5V. I have a I2C LED driver to drive LEDS. When I get current draw on the output of my boost converter, the output of the boost converter ...
Eyurk's user avatar
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0 votes
1 answer
52 views

String of 5 WS2813B LEDs flashing White on power up or reset

I'm using an ESP12 to drive 5 WS2813b RGB LEDs, in the code I use the Fastled library and switch off the LEDS straight away but there's always a white flash of all the LEDs on power-up and reset (the ...
user avatar
0 votes
1 answer
95 views

How to keep the voltage of an LED constant while using a MOSFET as a switch?

I need help with a project involving an Arduino and a high-power LED. I am using a MOSFET as a switch to control the LED, with the gate of the MOSFET connected to the output of the Arduino. The ...
user3369353's user avatar
1 vote
2 answers
71 views

Is there a standardized process for Inductor selection calculation for boost LED controllers?

Through numerous datasheets that I've gone through in selecting an LED controller to use, I've come across two different methods that are used to estimate the needed inductance: Based on the ripple ...
roaibrain's user avatar
  • 407
1 vote
1 answer
39 views

Is brightness for WS2812B LED voltage dependent?

I understand that this would be true for any other regular LED. The doc states that it accepts +3.5~+5.3 V. I was wondering if it is somehow internally converted to operate at the same level as long ...
somerandomusername's user avatar
0 votes
1 answer
66 views

How does this LDR circuit work? [closed]

All I know is that when I turn the lights off, the LED should light up, but I don't know how and why it works. Can you help me? I'd like to know how it works. The 10k there is a potentiometer. The ...
fireBreaker_2007's user avatar
1 vote
1 answer
71 views

Most energy efficient way to make a LED blink using a multivibrator [duplicate]

I'm using this LED. I want to make this LED blink at MAX brightness (100 mA) at 1 Hz. I need to use a multivibrator and therefore can't use any IC chips. The circuit is powered by a 3.7V battery with ...
Simon Mayr's user avatar
0 votes
3 answers
86 views

EMC considerations for external LEDs PCB

I am developing a PCB that has mounted LEDs and their current-limiting resistors. The PCB is 2-layered (bottom layer for GND, top layer for signals and components). It takes the LED control signals ...
irag10's user avatar
  • 71
2 votes
4 answers
113 views

Selecting resistor value for PWM LED driving

I want to create a circuit to drive some LEDs with PWM. The circuit consists of a PMOS switch at the high-side and the gate driven by the MCU PWM pin that is configured open-drain. The LEDs have ...
irag10's user avatar
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0 votes
1 answer
46 views

I want to know R2 value wrt Vin and Vout of HCNR201 circuit

I'm trying to learn this circuit, it is HCNR201 (Source - HCNR201 High Bandwidth Evaluation Board User Guide). I want to calculate value of R2 w.r.t. Vin, Vout and HCNR supply. Specially trying to get ...
Bhushan Waghe's user avatar
1 vote
6 answers
161 views

Series/parallel LED current limiting resistors

Suppose I have a voltage regulator acting as a high-power current source (basically a constant-current driver), with a resistor to set the output current. This drives 27 high-brightness white LEDs, ...
lemon's user avatar
  • 590
0 votes
3 answers
75 views

How do constant-current drivers implement voltage limits?

Suppose I have a constant-current LED driver providing a stable 700mA between 8 and 10 volts. From my understanding, the current is kept the same (hence constant current) by increasing and decreasing ...
lemon's user avatar
  • 590
3 votes
3 answers
166 views

How to light up a rocker switch powered by a battery of only 1.5v?

I have a small hobby project for which I wired 4 AA batteries in parallel to achieve the desired result, which comes to 1.5V, as the batteries are in parallel, which is what works for my project. My ...
electrical's user avatar
5 votes
3 answers
629 views

LED as a flyback for a 3V relay?

I have a 3VDC SPDT relay. I don't have a fly back diode but I do have an LED. Can I use the LED as a fly back diode if it's just a 3V relay? The relay is a HRS4H-S DC3V.
Zipho Lunika's user avatar
0 votes
0 answers
17 views

Ceiling fan dual color lighting switching

Some ceiling fans now have two different sets of LEDs, of different color temperatures, which are selected by switching the power on/off. I would like to know how this switching circuit works, it has ...
Thiago Rodrigues's user avatar
0 votes
2 answers
92 views

How to calculate resistors on PCB for white LEDs [closed]

Thanks for closing my post... once again. Instead of helping it gets instantly closed. I somewhat got the answer thanks to AnalogKid's answer! I dont get how he calculated the 2mA but thanks to his ...
TJCDE's user avatar
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