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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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2answers
108 views

Do i need a resistor in this led circuit?

I have made a circuit with two (3v) LEDs in series. Connected to a 5v supply from an adapter with usb. (1.5Amp) I belive in series circuit each led gets around 2.5v which was enough to light them. ...
2
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0answers
21 views

Control LED panels via a relay and a PIR sensor

I bought 6 x 48W LED panels and a PIR motion sensor to light a shed/workshop area. All 240V rated. I did not appreciate that the LED drivers have a high inrush current. My question is whether I can ...
1
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3answers
62 views

How would I drive about 440 LED's without breaking the bank?

Alright, I'm trying to create I guess an LED matrix display(?) so that I can make essentially a text display using 8x5 LEDs per letter, to make 11 letters in total. I'm definitely willing to learn a ...
2
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1answer
123 views

Is electricity saved by switching off the lights when leaving a room?

Incandescents are very energy inefficient for sure so they have to be turned off whenever you leave the room. But I have tried to find the answer for CFL lights, some say that it's more efficient to ...
3
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2answers
75 views

TLC5940 - with 200LEDs from car battery

I'm working on project that involves 100 white and 100 RGB leds, controlled with 25 TLC5940. I've managed to connect three TLCs to Arduino MEGAv3 and so far so good. I've found out that I have to ...
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2answers
69 views

Powering two 3-LED lamps with battery/Battery pack - Multiple questions

I have seen many questions along these lines but I don't think any is an exact match (if that's incorrect, please just point me to the right match, that would be great and save everyone some time). ...
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1answer
52 views

LED behavior during 24 VAC negative half cycle

I don't understand why the green portion of LED3 is able to conduct. Since the path marked in green represents the negative half-cycle of the 24VAC isn't the green LED reverse biased therefore no ...
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4answers
208 views

What is the RGB value of Edison Light Bulbs? [on hold]

I've been doing a little electrical engineering (outside of my lane a bit). I'm trying to get the RGB values for Edison light bulbs. Can anyone provide me with those?
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2answers
78 views

Why is my LED flickering when it is connected to a variable resistor, and it's resistance is at the minimum value

I am doing a simple breadboard circuit, with an LED, 3.3V power supply (a microcontroller connected to the PC will be the voltage source), a potentiometer, and a Voltmeter connected across the LED. ...
0
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1answer
57 views

Leds in series with buzzer without resistor

So I'm pretty new at this, so I'm sorry for any dumb questions/statements. I'm trying to build a puzzle box where you activate a circuit with a reed switch using a hidden magnet. Activating this ...
0
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1answer
46 views

PSU for led fixture

My cousin gave me a LED fixture for which the power supply is no longer working. He threw it away so I cannot look at the specs in the PSU. He says he measured 78v out of the PSU before throwing it ...
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0answers
51 views

How to Programm a PIC12F508 to light LEDs? [closed]

im new to programming and feel quite overwhelmed with googling it myself, i just have a simple project that i want to do and hope you can teach and show me the code i need. The plan is to have a ...
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2answers
2k views

Why does this simple circuit oscillate? (Ekasi oscillator)

Why does an Ekasi oscillator oscillate? From my research, I learned that when this is first plugged in, the capacitor is charging, so the LED doesn't shine. When the capacitor reaches 12v, then the ...
0
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3answers
50 views

Convert Battery to AC @ same voltage

I have some LED fair lights that run on 30V @ 0.4A supplied from an AC mains supply. They have been wired to flash using some form of notification to the AC (I'm not interested in them flashing). I ...
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0answers
37 views

9 volt battery in a 6 volt led cicrcuit [closed]

]3I have a 6 volt night light that has about 100 little led's in it. The battery housing fits 4xAA(1.5v) batteries (6v total obvs). I thought I was clever putting in a 9 volt battery when I ran out of ...
1
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3answers
78 views

How to improve an elegant design for an LED dimmer, low-powered with LDO

I am building a sunrise alarm clock. The LED is supposed to get brighter over the course of 30 minutes, then remain fully lit for another 30 minutes, then switch off. I am using a digital pin on an ...
2
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3answers
147 views

Designing brake light with specific luminous intensity

I am currently designing a brake light for a Formula Student car and I am looking into existing solutions on the market for inspiration. The two specific solutions are this, and this. The LED I found ...
2
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2answers
134 views

Cheap way to power blue LED on coin cell

I need a cheap way to take a 3v nominal coin cell and power a 3.3 forward voltage blue led. It needs to be cheap in production on a large scale, so a rudimentary joule theif won't work. Ideally it ...
0
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1answer
44 views

Reverse phase dimming - LED driver buzzing [closed]

I've been experimenting with an LED panel and different dimmers, trying to find a dimmer that wouldn't make the LED buzz, or at least not buzz too loud. I found that this dimmer (it's a universal ...
22
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4answers
3k views

Why does an LED have to be a diode?

I know LED stands for Light Emitting Diode; but why does this component need to be a diode to emit light? My question assumes that the "leds" we see everywhere (for lighting, screens, etc) are ...
1
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0answers
25 views

How to indicate different FSR pressure sensor measurements without Arduino?

I want to build a circuit that indicates the different pressures applied to an FSR sensor. I thought of indicating the different pressures using 3 LEDs to indicate no pressure, medium pressure and ...
1
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1answer
37 views

Do thermal cutoffs exist that would work with a line that is 40-75V 0.5A and a max temp of ~85°C?

I have a bunch of COB LEDs that I am going to wire in series using an LED driver. The driver gives off between 40-75V and 0.5A max. The circuit should run around 70V and 0.5A. Due to space ...
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1answer
84 views

Voltage drop when switching FET

I am working on a project which will be switching LED strips with a max of 2A. As a test I have connected a 20W hallogen light. When I try to switch it I get a voltage drop as can be seen in the ...
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2answers
138 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
61 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
67 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 ...
0
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1answer
68 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 ...
0
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1answer
61 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
74 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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2answers
19 views

Alternating 3 LED wiring question

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. I am trying to figure out a ...
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1answer
67 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 ...
0
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1answer
32 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 ...
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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?
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0answers
59 views

Turning on LED circuit when input resistance drops below 50 ohms

I trying to build a circuit where the circuit monitors a variable resistor and when the variable resistor drops below 50 ohms it turns on an LED. The system voltage is 10-15volts DC. Any assistance ...
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0answers
31 views

How to connect led strip to be powered by charger and batteries part 2

Li-ion batteries are nominally 3.6V and three in series will not supply 12V very long if at all. You could use four series batteries and a 16.8V charger rather than 12.6V then add a 12V buck step ...
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3answers
43 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 ...
0
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2answers
63 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
70 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 ...
0
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2answers
48 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
82 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
75 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
61 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 = ...
0
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3answers
94 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
votes
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
102 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
votes
2answers
96 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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3answers
84 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
47 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
40 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?
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0answers
36 views

How can i calculate the battery life a an led strip?

I have made an led strip powered by a nimh battery, battery: 3600mAh, 7.4v LED strip: 2m, ~60Leds, I believe they are 5050 leds I need to calculate the battery life.