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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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140 views

LEDs in household outlet

The output of the household outlet is AC. But when repairing one of those, I found that there was a LED (used as indicator) in there. Since LED is a diode, it must switch on 60 times and switch off 60 ...
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1answer
119 views

How to control LED brightness with mosfet as switch and potentiometer

I am designing a circuit to control a high current LED string. Most of the time the led string will be ON. Where should I place a potentiometer to control the brightness of the LED when it is on by ...
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2answers
80 views

Getting trouble powering a LED strip with battery

I'm trying to build a portable LED light and things are happening not the way I wish to. I have a Sumbulbs 12036 LED COB Strip. This LED works with DC 12-14V voltage, it has 10W power and recommended ...
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1answer
74 views

RGB led weird color behaviour (blue except when touched to skin)

I have an RGB LED, which I belive to be the diffuse version of this one: https://www.sparkfun.com/datasheets/Components/YSL-R596CR3G4B5C-C10.pdf, though I am not completely sure, as I bought it some ...
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1answer
65 views

Do 12V MR16 LED bulbs contain active components? [closed]

I was wondering if, unlike GU10 (230V AC) LEDs, GU5.3/MR16 (12V DC) LED bulbs typically contain any active voltage regulating components? Or do they directly connect the LEDs to the 12V line so there ...
3
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2answers
91 views

Alternating 3 LED project

I am making a Halloween costume for my son and it needs some light. Basically he's a character from the Mario Bros universe that carries a traffic light on a fishing pole (Lakitu in Mario Kart). I am ...
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1answer
69 views

Can I use a USA Led Bulb in Europe? [closed]

I am a software engineer working with an IOT company in the states, Right now I am located in Europe for a month and a half, and have some hardware (light bulbs) that I need to use to finish some ...
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1answer
55 views

Simulating 3 phase mosfet bridge with LEDs

I have a commercial 3 phase BLDC motor driver board (TI DRV8323 BoostXL) and I want to write a firmware from scratch. For testing, I want to make sure I open/close the mosfets in correct order. I am ...
6
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3answers
2k views

Does a dimmed LED lamp draw less power than one at full brightness? [closed]

Does a dimmable 6W LED lamp, dimmed to 50%, draw c. 3W? Or does it still draw the full 6W?
1
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3answers
77 views

How to connect LED strip to be powered by charger and batteries

I plan on using it mostly plugged in, batteries are there just for extra mobility and won't be used most of the time. Don't know lot about batteries so in first scheme I added a switch (pos. 1 ...
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2answers
71 views

LEDs and static

We been seeing some "random" LED failures and some someone suggested static electricity could be the cause. I've never heard static electricity is a problem with LEDs. Anyone have any comments?
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1answer
82 views

How to connect a LED G13 Tube directly to a power socket?

I am trying to build my own cheap lighting for my greenhouse. I have found a couple LED tubes that would be perfect for the task, only they are supposed to be mounted on a lamp of some sort. They have ...
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2answers
51 views

Connect VGA cooling fan (12vdc - 0.1A) to constant current driver (120Vac to 12- 22vdc @ 0.3A)

I have an AC driven COB LED which can be connected directly to the AC main in house (120v). I would like to attach a cooling fan to the COB which requires 12vdc @ 0.1A. I have a constant current ...
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2answers
85 views

LED light strip vs. incandescent light bulb power consumption ambiguousness [closed]

Formula for power is: P = I * U or Power (Watt) equals Current (Ampere) * Voltage (Volt). For my LED strip (5 m in length), it says power consumption is 18 ...
2
votes
1answer
90 views

Calculating the resistance for the base of a transistor

I'm building a circuit for my little niece's birthday (I'm already overdue with a couple of days). I started building it before I well understood enough about transistors and no I'm running a little ...
1
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2answers
141 views

Is 22AWG wire appropriate for 144-LED WS2812B strips?

There is a question on a 1m set of WS2812B LEDs at 144 LEDs/meter (60mA/LED at peak brightness) about what gauge wire is used. The seller replies that the wire is 22 AWG (linked above). 144 * 60mA = ...
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3answers
156 views

LED Fault in PCB - Some strings of LEDs intermittently dim

I have a university project that involves working with surface mount LEDs. For some reason, some of the rows of LEDs, when lit up, are dimmer than they should be. This problem is only intermittent ...
6
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6answers
2k views

LED not achieving max current

I have a project that is powered by a 12v power supply. I need as bright of an LED as possible and decided to use this 9v LED. According to the datasheet, its max current is 1A, which is what I would ...
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1answer
110 views

Light source that withstands extreme conditions [closed]

I am designing an aircraft obstruction light, and Federal Aviation Administration (FAA) requires crazy requirements for their standards. One standard goes as following (From FAA AC 150/5345-43H): 4....
2
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2answers
105 views

Sewable LED Ribbon - 1m, 50 LEDs (Blue)

I am looking to integrate these sewable LED ribbons into a project. https://www.sparkfun.com/products/14138 I am wondering how it is possible to power 50 Blue LEDS in series with only 2x 3V coincell ...
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votes
3answers
121 views

Are IR emitter frequencies adjustable? Can modulation of the emitter variate material absorption properties?

A common LED emitter, Gallium Arsenide, apparently has a wavelength of about 760 nm. Then on the receiving end, there is a filtering circuit to eliminate ambient IR and to demodulate the message. Can ...
1
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2answers
55 views

Smaller apa106 led, more smd style [closed]

This is going to sound like a childish question as it is not a very long one, but is there anything like a apa106 led or at least follows the same protocol coding wise that is more smd style and ...
0
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1answer
54 views

led driver negative output and GND

If I connect the positive output of a LED driver to anode and cathode of LED is connected to power ground (Negative output of driver is remain unconnected), whether the LED Will work or not?
5
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1answer
472 views

Replacing two LEDs with a 2-pin, bicolor LED, using a circuit that reverses polarity based on two inputs

I'm working with a commercially available circuit that can optionally be configured to disable its internal LEDs and use two external LEDs. This post discusses the use of external LEDs. One LED or the ...
1
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3answers
76 views

Powering a PC monitor with batteries

So, this is where I am at currently( no pun intended). I am assuming that with an inverter for both components and 3 - 4-18650 cells in series - in parallel rated at 4800mAh would be good enough? Ill ...
1
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1answer
121 views

Vertical ghosting on 64x32 1/16 RGB LED matrix panel

I have been working at driving some of those generic LED matrix panels found all over the web for sale (such as this one), 64x32 I've struggled a lot with the lack of real documentation, but I've ...
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2answers
66 views

LED Driver Choosing help

Newbie here, I am working on a project with a panel of 12 - 15 LEDs(std 5mm through hole LEDs) in paralell. I am currently using a 5V 1A SMPS. I used 330 Ohm resistors for current limiting. It works ...
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1answer
83 views

Bypass LED with switch (why)?

I have a schematic attached that appears to show a switch bypassing an LED, or the other way around. In the working device operating the switch lights the LED and engages (as in turns 'on' a 'normally'...
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3answers
148 views

High power LED strip power distribution

I want to power 20 RGBW LEDs. Each of these lamps and each color channel should be individually controllable with PWM. Since it concerns pure LEDs without internal control I would like to use a ...
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3answers
64 views

MAX485 Receive Output pin current sufficient for optocoupler LED?

I want to recreate a project found at this link where an optocoupler's LED is a driven by the receiver output of a MAX485. Now, my question is, the LED series resistor (R5) value is 470ohms, if my ...
2
votes
3answers
42 views

Setting current on Diodes Inc PAM2863 LED driver IC, with external resistor AND driving different voltage to VSET

I'm looking to use the Diodes Inc PAM2863 DC-DC LED driver in a project. The datasheet gives a V=IR method for setting the average output current with an external resistor, where Iout = 0.1 / Rs. ...
1
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1answer
94 views

How to build a multi LED blink circuit triggered by vibration sensor?

I'm wondering how to build a module just like the ones that are in kids shoes that light up. I've taken a few of these out and would like to make my own circuit but I'm not sure if it is possible. I'...
6
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2answers
256 views

Philips 9 W luminaire quotes 7 A for 300 ms inrush!

In his answer to Will repeatedly turning a light bulb on and off damage it? @Bradicul stated, An example of inrush current is an LED downlight fitting with 9 W (0.0375 A at 240 V) will have any ...
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1answer
49 views

Night vision led [closed]

What is the best night vision (type not brand) IR Led for night vision on a car camera for driving at high speeds without headlights? (I'M A RALLY DRIVER BTW AND SOMETIMES HEADLIGHT GET DAMAGED AND ...
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2answers
94 views

make LED 12v light fixtures

I would like to remove the n27 sockets from household light fixtures and replace them with LED lights used in the automotive industry. I would like to put a reasonable amount of LEDs in the fixture to ...
2
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4answers
193 views

Use current from SMD LED to switch larger current

I've got a bluetooth receiver with blue SMD LED's on that flash to indicate connection status. I would like to take that status LED and replace it with the white LED that's in a switch I have. The ...
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1answer
71 views

Keep spare LED bulbs or increase dimming? [closed]

I have a luminary with 12 light points for standard E14 bulbs and a LED dimmer in the wall. Using Calex bulbs, I only need 6 bulbs, which I run most of the time at 80% light output (measured with the ...
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1answer
82 views

If I connect 10 3mm or 5mm blue LEDs to 3 AA battery power source, do I really need resistors?

Looks like this is a good forum to ask this basic question. I would like to connect 10 LEDS 3mm blue lights together and the power source is 3 AA batteries. Do I really need a resistor?
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3answers
384 views

Connecting multiple Fairy lights in parallel to single power source

The above diagram shows how I'm about the connect the LEDs, info regarding the drop forward voltage been taken from: Calculating forward voltage for a string of fairy lights: multimeter shows "1&...
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1answer
76 views

9X9 RGB Led matrix, design suggestion

I need to drive 80 RGB leds (so 240 individual leds), physically and conceptually aligned as an 8x8 matrix + an additional vertical line and an additional horizontal line. I'd like to drive the ...
23
votes
3answers
3k views

Is the LED drop voltage difference between colors linked to the different wavelength energy?

To me appears that LEDs that emitt light with less energy (e.g. IR and red) have less voltage forward drop than the ones with more energy associated to their wavelength (such as blue or UV). That ...
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3answers
480 views

ws2812b 5050 60 led per meter 300 led strip power issues

I'm having issues trying to power my 5 meter 300 led 60 led per meter strip and I'm using the sp105e magic controller to control them. I cannot get them to light up correctly. I have a 4.5V 100mA ...
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1answer
57 views

pwm after constant current switching driver

I have searched, but cant find an answer for my specific setup. I have a Xl4015 switching contant current source for my 10w LED set at 1000mA. I would like to add a pwm dimming circuit to switch a ...
0
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1answer
99 views

What is the function of this npn transistor?

I see that the R306 resistor is trying to limit current when the npn transistor is on. I am not sure what the resistance offered by the npn is but it looks like the current through the 47k resistor ...
0
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4answers
127 views

How can I use Charlieplexing with common anode RGB LEDs?

I've an ESP32-based dev board (LoLin32) which has 26 digital I/O pins. I want to connect 25 common anode RGB LEDs to it. Connecting them in the 'normal' way would require 75 I/O pins, which I don't ...
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3answers
77 views

Wiring up a current limiting resistor with an IR LED burns of the LED

I have a 5V DC supply and i am trying to wire an IR led with a resistor in series to it. I have wired it up to a bread board as shown in the pic The current limiting resistor value is ~ 216 Ohm. ...
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1answer
70 views

LEDs to indicate Data being transferred

just asking for some reassurance really, probably a novice question. Thank you in advance for any advice. I am building this project: https://github.com/brianmarkpeters/CHIP_BASED_SYNTHESIZERS/tree/...
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5answers
207 views

PCB Design for High Powered LED

I need to design a breakout board for this Cree XHP50 LED. It is a 12V LED that I would like to run at 1.5A. It will be turned on by this ON Semi NSS12201LT1G NPN transistor, which is connected to a ...
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3answers
198 views

What makes same wattage led light bulb brighter than the other? [closed]

I noticed that one 10 W LED light bulb was 800 lumens and the other 1000. Both were warm white, 4000K, 80 CRI. What exactly makes one brighter than the other?
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1answer
34 views

LED Dimmable 2 of the 8 turn off when others are dim [closed]

So I just had Integrated LED Recessed Retrofit Ceiling Light Fixtures installed on a Lutron Toggler 150-watt Double Pole 3-way White Toggle Indoor Dimmer (rated for LED lights). When the dimmer is ...