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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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60 views

Why is my RGB not drawing more current?

I've got a 3-9W RGB LED (https://www.adafruit.com/product/2524). It's connected to a breadboard with a power supply that tests as giving 4.9V and 2A on a short circuit. I've got 5W resistors at ...
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1answer
59 views

LED dimming circuit

I have a MeanWell IDLV-65A-12 LED driver that I would like to control brightness via the 0-10 VDC dimming circuit. Spec sheet here. I have a basic understanding of electrical circuits, and ...
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35 views

Connecting several 6v LED fairy lights to one power source

I have a pile of fairy lights on individual 6v battery packs. Something like these https://www.amazon.com/gp/aw/d/B07L2RPV3B/ref=psdcmw_3742221_t1_B07L2S2N1J My hope is to connect several (at least 3?...
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1answer
34 views

Energy delivered by a LED in Joule

Please help me with calculation I read in the link https://www.thorlaser.com/LLLT/calculating-LLLT-dosage.htm A 500mW laser with a beam area of 0.25Cm2 used for 20 seconds delivers 40 J/cm² A 200mW ...
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1answer
102 views

What is this cable/device?

I hope I'm on the appropriate site. Does anyone know what this thing is? It has a mini mono plug. The white square is slippery..but it is not covering double-sided tape. A white LED did not light up ...
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37 views

Finding resistance value [on hold]

I have LED circuit of 12 volt and 240 mA. My Power source is 12 volt 5 amps Transformer What resistance and power of resistance should be the best for works well Thanks
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0answers
17 views

NeoPixel THT: Varying pinouts

I am in the process of designing a PCB for a solder kit that receives NeoPixel type LEDs, the ones with the short head: Now, there seem to be different pinouts: Ordered on Amazon.de as WS2811 LED ...
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1answer
22 views

Using internal regulator DVDD pin to power up external devices

I am designing a H-Bridge PCB and using DRV8323 as the driver. This chip has a pin name DVDD which from my understanding, from the below statement, is used to ...
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0answers
25 views

TLC5940 SOUT/SIN signal broken after 4th daisy-chained IC

I have a PCB with 5 TLC5940's daisy-chained. The first 4 work fine, but the fifth doesn't work. The LEDs connected to that one just go on at full brightness and that's it. When I measure the SOUT to ...
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0answers
16 views

Can I use a single clock line for 6 parallel addressable rgb data lines?

I am making a PCB with the dimensions of about 60 (height) mm by 320 mm (width). The PCB contains 5 Letters and 1 logo. The idea is to have 6 datelines in parallel. This way I can have different ...
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0answers
23 views

Low power flashing led with phone battery

I want to make a circuit that flashes a series of leds and that lasts as long as possible from a tablet battery. The battery has a voltage of 4.2 when fully charged and 3.8 when discharged, and has a ...
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2answers
53 views

What happens if LEDs do not get enough current? [duplicate]

I'm building a lighting fixture using big led panels. The LED panel says it requires 7 amps @ 12 volts, but the power supply I have is only rated to 4 amps @12 volts. What will happen? Will it ...
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1answer
32 views

Using Diode As a Solar/Lightbulb Cell

...hi :) a few days back I saw this Instructables.. https://www.instructables.com/id/Using-Diode-As-a-Solar-Cell/ ...so I started to experiment how this can be used to charge a cellphone or a ...
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1answer
39 views

LED lights with a dim light in open circuit [duplicate]

I was installing new LED lamps on my kitchen, which seemed to be functioning well. After turning off the lights, the newly installed lamps still had a dim light, that kept itself for quite long. I've ...
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1answer
110 views

Single Cell LED boost Converter

I am planning on powering 10 white LEDs (LUXEON 3014) from a single AA rechargeable battery with Vin min=0.9V, Vin max=1.4v VLed=2.8v @ 23mA so total Vout for 10 LEDs Vout=28v, iout=23mA I found this ...
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2answers
57 views

Arduino pin connection basic

In the Arduino Uno's basic manual, connections for fading led are given. They have connected led on breadboard. The positive of led is connected through a resistor to the pin no 9 (pwm) and negative ...
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1answer
66 views

Finding the broken cicuit in an Xor Gate

I am new to this particular stack site but I feel that this is the most appropriate place to ask my question. -Background- I've been following an online web course called Nand2Tetris that takes you ...
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1answer
83 views

Why would Discontinuous Conduction Mode be desirable for an LED driver?

I saw this press release where DCM was listed as a feature for a new Infineon driver chip. Source: led-professional.com I'm involved in LED driver design for Horticulture where DCM is undesirable....
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0answers
22 views

Current leak LCD PCB IT-net vs TN-net

I have a LED with LED PCB mounted on a metalic plate that is connected to earth ground. The driver is a cl.2 driver with no earth wire and it's a constand current driver. The lamp is connected to ...
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4answers
759 views

Constant Current LED Circuit

In the below circuit, the circuit maintains a constant current on LED. My question is after the LED there is a voltage of 18V, still, need to be dropped. Will the NPN Transistor heat up while ...
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1answer
45 views

5V vs 12V addressable LED efficiency

Despite hours of googling, I could not come to clear understanding how efficiency of 5V addressable LEDs compare to their 12V counterparts. If 5V is supplied to WS2812, and the red LED only needs 2....
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2answers
63 views

Best way to power LED strip (180 LEDs)

I'm assembling this addressable RGBW LED strip setup that is 3m long and 60 LEDs/m. I have found no answer to my two questions on other sites or youtube. (This is the strip I'm using: https://www....
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1answer
57 views

Unexpectedly high voltage drop in the transistor

I'm driving an LED with a microcontroller through a transistor with a PWM signal. When the gate is grounded, no current flows, as expected. As soon as I start to drive the transistor (1% duty cycle), ...
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4answers
2k views

Can I use USB data pins as a power source?

I'm trying to build a circuit as seen below, where a sequencer controls the flashing of some LED sections, and an SPDT switch controls power to either the left or the right section of LEDs. However, ...
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1answer
45 views

LED selection for my application

I need to select LED/LEDs for a light source in my project. The requirement is that the light source should approximately be able to project light beam of 1.5m diameter on a surface, from a distance ...
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1answer
64 views

ADC Selection Pulsed Measurement

I am planning to measure the voltage of an rgb LED pulsed with an ADC. The pulse is around 20ms long. The pulse is necessary so the self-heating is within reason so it won´t affect the any ...
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2answers
56 views

Charging capacitor to power LED with a low current source

I have a 10000uF 6.3V capacitor, and my source is generating 3.3V and 15uA of current. How long will it take to charge it enough so i can pulse a standard 5mm LED for lets say 1 second?.
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2answers
45 views

Powering multiple WS2812B strips from different sources, are all grounds connected?

I'm looking to confirm if I need to connect the ground of 2 LED strips which have different power sources. Adafruit says The key is to have all of the ground pins among the strips connected in ...
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4answers
78 views

Will switching a LED on and off at a said frequency reduce or increase heat loss?

In my case, a 50W 34V LED is being used to light a small box. To reduce heat generated by the LED, we are switching it on and off at 50Hz. But I was wondering will this actually help? In the case of ...
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2answers
71 views

Does connecting LEDs in parallel use more current then connecting them in series in my circuit?

Sorry if this is a dumb question, I need a sanity check on this stuff. Is it possible to give LEDs varying current, without sacrificing efficiency? Basically I have 4 LEDs which could all use ...
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2answers
57 views

Brightness when using 3.7v battery for powering 6 LEDs rated at 5v in a series

I am using 6 LEDs in a series (APA102C spec) these specifically powered by some atmega chip, and am having trouble finding a sufficiently small battery that will allow me to run the LEDs at maximum ...
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1answer
72 views

Calculate the turn-off delay of an LED in parallel with a capacitor

I am trying to create a Custom turn off delay for an LED. For this I take an Capacitor in parallel to an LED My Idea so far was: I have the General Equation for an Capacitor. And the General ...
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1answer
74 views

Blue 5mm flashing LED flashes for a while then goes static

This isn't my strong point by far so please bear with me! I have some 5mm blue flashing LEDs 4.5v - 6v operating voltage and my power source is a 12v 1A mains adapter (for CCTV camera) over CAT5e. I ...
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1answer
65 views

Mosfet: gate voltage 0 but still led strip on

LED strip: DC, 4W Mosfet: IRF740 (datasheet) To Do: Use wall socket (AC) to run DC led strip and also turn it on/off with MOSFET and arduino. AC to DC is done with rectifier and transformer. So ...
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3answers
119 views

Off grid LED solar lighting without batteries

I have 2 COB LEDs (12-14V DC, 50W, I think with 3,75 A in data sheet). I need to run them with a solar panel, it should only run when there is sunlight no batteries needed. Using a 270W panel (open ...
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1answer
19 views

Implementing led lighting with SR-ZG9101FA-RGBW

So I have this device: SR-ZG9101FA-RGBW I'm trying to properly connect it, but so far I'm having issues such as being unable to detect device in philips hue app and only two color channels are being ...
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1answer
43 views

LED switching: Circuit reacts unexpected

I have my current circuit in LTspice and am trying to simulate it. The idea is the following: I have a UV LED (360 nm) which I want to switch off in at most 6ns. For this I have my LED in parallel ...
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1answer
67 views

Different led voltages for different colors

It's probably going to simple for someone to answer this one but I haven't done electronics in about 15 years now so please be kind with the answers I'm sure when I used to do this there was an led ...
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1answer
31 views

How to get the continuous current rating of a power led from the spec sheet?

I am looking at an Osram OSLON® Black, SFH 4715A Infared LED. Is this LED rated for continuous operation? The spec sheet lists: Total radiant flux (IF = 1 A, tp = 10 ms) (typ) Φe 770 mW Does the ...
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1answer
149 views

How to add LED effects to PCBs? [closed]

I don't mean LEDs for indication, debugging, etc. I mean LED effects like on the MSI Z370 Motherboard, where entire sections of the board are illuminated by continuous strips of light. How is this ...
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1answer
69 views

Powering LED strip from Arduino

I want to power a 5V white LED strip (50cm) from an Arduino (Leonardo, connected through long USB cable to my PC permanently). The idea is to have the LEDs dimmable through the Arduino pwm signal. I ...
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0answers
49 views

UDN2981 maximum output current too less

For a LED 'matrix kind of' project I want to use UDN2981's for sourcing, and ULN2803's for sinking. I want to use 5mm LEDs, being able to use 100 mA (10% duty cycle). Since the ULN2803 can handle ...
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1answer
48 views

how to wire BC547 LED flashing circuit in EAGLE?

I'm studying electronics and I'm trying to grasp the usage of EAGLE. I got an assignment where I must first make this schematic and then wire it on a 3cm x 3cm board. There is a condition where the ...
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3answers
97 views

LED when soldered doesn't work, but when removed it works

I have this kit https://www.amazon.ca/gp/product/B07GRYNV6F/ref=ppx_yo_dt_b_asin_title_o02_s00?ie=UTF8&psc=1 soldered everything correctly (checked multiple times, the right element in the right ...
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2answers
58 views

Why do iluminating LEDs flicker?

I recently got a Milwaukee compact floodlight, which is a powerful LED hand light. The light from the device appears constant, but if a scene illuminated by the light is viewed with a scanning imager,...
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1answer
38 views

LED ULN2803 thermal / heatsink questions

I'm intending to use LEDs of 5mm, which have a max forward current rate at 30 mA, or a value of 100 mA, with 10% 1 kHz duty cycle, in a circuit like the one below except some changes: STM32F103C8T6 ...
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2answers
52 views

How do I interpret an RGB LED max amperage given as a range e.g. 30mA-70mA?

I have some LED's I got in a mixed package and the RGB LEDs instead of a single max amperage just list a range. One example is I have a common cathode RGB LED with ratings listed as 1.9-3.4v and 30mA-...
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1answer
94 views

3 simultaneous led chaser using only 555 and 4017

I've to design a circuit which consists of 30 LEDs in a row (RED, BLUE and GREEN) followed by a led matrix which spells out IN. Conditions which I've to follow: When the circuit is powered, ...
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0answers
44 views

Some more problem caused by EMI

Before, I asked some ways to solve the EMI problem and I got some useful answer from here: Really occasional malfunction of the Schmitt-trigger input - Really occasional malfunction of the Schmitt-...
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2answers
53 views

Improve Brightness in LED Multiplex

I’m doing a 16 rows & 48 column LED matrix design. The attachment shows only one row & some columns. I’m scanning rows @ 1/16th rate. Designed for 4mA average current to the LEDs. I’m doing a ...