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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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53 views

Nautical map model navigation lights

I would like to create navigation light sequences on old admiralty map of my local area. There are lighthouses and channel markers in area with mix of flashing and times. The single flashes I can use ...
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51 views

Constant Current Regulator position in a series circuit

I'm designing a circuit with 3 LEDs, a CCR (NSI50350), and a power supply in series. My question is: Does it matter where I place the CCR? Can I design my circuit this way: +V--LED1--LED2--CCR--LED3-...
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92 views

Noob question: blinking leds with pn2222A and 9v battery

I'm kind of new here. I've been roaming around the forum for a while trying to figure out how to finish up this circuit I'm building and really need some help. I'm trying to build a blinking LED ...
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1answer
49 views

WS2812B LED Strip Not Drawing Full Amperage

I recently purchased one of these LED strips. Now I have read all about how these are notoriously known for drawing a lot of current from its power supply so I bought one of these power converters ...
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1answer
52 views

Amplification of a Microphone with a LED Array and speaker: Grounds? [closed]

This is the circuit I'm trying to build: Circuit on falstad.com I feel like everything works in theory, but I'm having trouble implementing the grounds on the actual circuit. I do not know where to ...
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1answer
28 views

Combining two led strips with separate controllers

Out of practice and have forgotten basic principles but would like to combine two led strips to one controller so they operate in sync. Have combined output from sensor into control box but outputs ...
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1answer
50 views

(Backlight) LED Driver maximum number of LEDs

I've been tasked to find a suitable backlight led driver for a Mitsubishi LCD panel (AA104XF12-cf1) which is PWM dimmable, but in my search I've only found confusion. In nearly all datasheets it ...
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1answer
73 views

Faulty temperature sensor on PCB - lights keep blinking, how to replace this?

I’ve been working on a broken continuous operating high power LED system - it starts blinking when powered. This was an indication of overheating and it was clear that the cooling fans have stopped ...
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61 views

PCB dual LED emitter, TIA and voltage regulator (beginner)

Does this PCB look good for this operation? The schematic is attached. I have a voltage regulator connectected to an LED emitter. Voltage regulator to TIA . TIA then is attached to active high pass ...
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4answers
141 views

How to connect multiple 0402 leds to an Arduino for a 1:87 model

I want to replicate lighting a 1:87 scale police car with the aid of an Arduino Pro Micro ATmega32U4 powered by a 90mAh 3.7V LiPo which is connected to a TP4056 5V Lipo battery charger which is ...
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1answer
37 views

How to read multiple sensors, store into an array, sort and then do something with the results—Arduino

I have a small project that I could use help understanding how best to move forward. I have a set of 8 batteries of different voltages and age. I’d like to read the voltages of all, assign an ...
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3answers
167 views

12V 10A linear LED supply keeps failing; need a better design

I homebrewed a flashing LED landing light for my high performance experimental aircraft. The details are here Because I was afraid of electrical noise (which could impact communications or ...
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1answer
51 views

Is Power Factor only relevant at rated load in Light Equipment?

As you might know, LED lamps over 25W require a minimum 0.9 power factor in Europe. I have designed a PSU for a specific LED lamp which is rated about 50W. There is a PFC-stage (crm) in order to ...
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3answers
82 views

dc voltage control for LED lights?

I'm looking for a little bit of help on a project I'm working on. I need to find some way to make led light bars (18w and 120w) to automatically start out dim and gradually brighten to full ...
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2answers
90 views

Very low current (<10 microamps) darkness detector circuit that turns off in light

I've made a device that lights an LED at a very low current (<10 microamps) as a very dim indicator for use in the dark. At its simplest, the circuit is a 3V coin battery + resistor (300K-1M ...
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1answer
72 views

How do alternating Christmas tree lights work?

I saw these alternating Christmas lights: The top image has all lights on, the bottom left image has odd-numbered lights on, and the bottom right image has even-numbered lights on. The LEDS are ...
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1answer
725 views

Why are these LED current limiting resistors so big?

I'm looking at the charging circuit for a lithium ion battery that was made by Adafruit. Here's an excerpt: If there's a 5V rail from the USB port and a 470 Ohms resistor, is that limiting the ...
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2answers
43 views

4x CREE XP-E2 M2/M3 on 23mm star PCB

i´m still running into connecting problems with the "4x CREE XP-E2 M2/M3 on 23mm star PCB". https://www.led-tech.de/en/4x-CREE-XP-E2-M2-M3-on-23mm-star-PCB Can someone help me out how do i need to ...
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0answers
65 views

Anybody recognise this connector on an LED module?

I purchased a handful of these Luxeon K16 LED arrays a while back, they are surplus units from a Toshiba DLP projector if I'm not mistaken. They have solder pads onboard, but also feature a Molex-type ...
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1answer
129 views

Help Identifying a CMOS optical mouse sensor?

I'm working to repurpose the trackball assembly of a Logitech Trackman wired mouse for use in an experimental rig. I assumed that Logitech would use Avago's ADNS series of optical flow sensors, but it ...
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1answer
52 views

Using 1 IR receiver for 4 LED controllers

I've purchased 4 cheap LED controllers from China for controlling 20m LED stripes. After setting the system up, I encountered the problem that at least 1 of the 4 LED controllers doesn't respond to ...
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5answers
155 views

Finding LED specs

I received from a friend a bunch of 1W/3W (??) LED. The thing is, I can't find any specs for them. For sure I have a method to test them and find Vf/If, but is that method any good? I need EE's advice....
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1answer
45 views

ATtiny45 program/reset issue

I'm pulling my hair out trying to get this ATtiny45 to work, hopefully someone out there can help. The ultimate goal is to drive an RGB LED strip using PWM, but I'm getting some unreliable behavior ...
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0answers
85 views

Bare LED light flickering on constant voltage pover supply

I have this LED light which started blinking under some use. So, I desoldered the SMD LED component and hooked it up to a variable power supply. When I apply 6V, the LED starts to emit a little bit of ...
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3answers
136 views

LM339N - Comparator #4 not working as expected (always low)

I've designed a circuit for a battery indicator for my 18V Li-ion battery pack, based off this example here: https://www.electroschematics.com/8347/24v-battery-level-indicator/ I have it laid out on ...
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2answers
88 views

How to fully shut off an LED indicator when used with a Smart Switch?

Update See added comments at end of question. I am working on a project to implement a remotely lit indicator when triggered through a wireless connection. To make this work I am trying to use ...
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1answer
65 views

DIY Use 18650 in place of 18500

I got a (relatively inexpensive) SmartYard LED Solar Spotlight as a gift, and have been playing around with ideas to extend the battery life. It uses a 3"x5" solar panel, and comes with a 3.7V, ...
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3answers
65 views

Diode (LED) forward voltage in series and parallel

As a preface I am just a hobby electronics enthusiast and not an electrical engineering student, and I am just starting out at that, so these may be obvious answers for even a first year student. As ...
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1answer
79 views

100W LED - Arduino controlled Driver

I have a project which requires me to drive a 100W LED (32V, 3A, CC). The only catch being, is that dimming control is required via Arduino. I couldn't find a conclusive method of doing this via ...
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1answer
43 views

Can I use a 12V switching power supply to power a G4 LED bulb?

I'm trying to convert a broken halogen lamp to LED using a commonly available G4 bulb. I have a lot of orphaned universal power supplies from various electronic accessories. Can I use a 100-240V => ...
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1answer
102 views

What kind of led would be used for this keyboard [closed]

I have a project that involves this keyboard, it has 12 sections on the pcb marked UX (X being 1-12) for what I guess are for leds. If I'm correct what kind of led would I buy for it? Something like ...
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1answer
72 views

How to solder SMDs on metal core PCB?

I have a bit of soldering experience but look for instructions on how to solder on an aluminum core PCB. The PCB is for high power LEDs that dissipate a lot of great, hence the metal core. The ...
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1answer
60 views

Trying to wire in LED to show cooker element is on/off

Hi I'm a mechanical engineer so please bear with me. I'm trying to wire in an LED to show whether a cooker element is on or off. Looking at the diagrams below, the easiest way to do this would be to ...
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2answers
193 views

Constant current led dimming

I have a few panel lights which come with normal non-dimmable constant current drivers. I want to add a dimming feature to them, please suggest me a circuit that I can use with Arduino/ESP8266 to ...
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0answers
61 views

Constant Current LED Driver Output Control using PWM

I want to control the brightness of a led which is powered by a constant current driver. On utilizing a MOSFET and pwm signal from an arduino uno the led starts to fade in as the duty cycle ...
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2answers
55 views

How much power is dissipated as heat in a 12V MR16 Led Bulb

I just installed a dimmer for a set of (non-dimmable) MR16 bulbs wired in parallel. The dimmer sits between a 12V power supply and the bulbs. My observation when trying to dim the non-dimmable bulbs ...
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1answer
26 views

led SMPS converter

Which type of converter is best for an LED light for getting better efficiency and high colour rendering index? We want to design a converter up to 80 Watts which gives indirect lighting and less ...
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1answer
588 views

Capacitor in parallel with a resistor between live and full bridge rectifier

I have an LED light bulb and dismantled it to look at the circuit inside. I made some google search for pcb but couldn't find any relevant info about FST-855 or FST-854: After drawing the schematic,...
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2answers
185 views

LED Blinking after replace

For clear any mistake, the question is: Why the LED started to blink after being replaced? The goal was to replace the blue leds with red leds, after replacing the leds one of them started to blink, ...
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1answer
110 views

Is this LED cover a commercial product?

I am trying to build a fork sensor. While I am OK at electronics stuff, for the first time in my life I took active role in making a finished product. Looking at our competitors designs, I noticed a ...
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2answers
111 views

LED circuit Driver question

I’m trying to set up a circuit with one single LED (NICHIA NV4L144AR Specs: Forward current 700mA, forward voltage 11.9V, 8.3W max power) and a piece of LED strip 0.4 meters long (Specs:input 12VDC ...
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3answers
121 views

I have 3.1V LED 20mA and wire 20 or more [closed]

How you calculate how much Volt battery you need? Like: 20 x 3.1V = 62V ....or is it something else? I want to wire them in series manner.
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1answer
26 views

2 levels of brightness for led illuminated switch

I'm think of using a switch in my car. The switch has 5 leads ... +, -, C, NO, NC. 12 V to the + and - light the led (brightly). What I would like it to do is light up the led dimly when the dash ...
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3answers
78 views

Variable wavelength IR Diode?

I was thinking of building a DIY IR Spectroscope but for this, I need to find an IR diode that can do variable wavelengths. So far I have looked at Farnell and Mouser but all the diodes I have looked ...
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2answers
2k views

Why are OLEDs used in screens insted of LEDs?

I was trying to google this question and couldn't find any information. And from reading some info on how they work i didn't find any significant difference asides from OLEDs being made out of organic ...
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2answers
73 views

Worst Case Analysis of the LED circuit - Reg

I need to perform the Worst case analysis of the LED circuit attached. The value of the resistor has already been chosen and I am doing the calculations for min, typ and max current. Please bear with ...
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2answers
62 views

Combining a light therapy LED lamp with a light alarm clock - programmable dimmer

I live in a place where there is little daylight in winter, so I would like to use a light therapy lamp. Also, I would like to use it to wake me up, gradually increasing the intensity of the light ...
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1answer
59 views

Understanding replaced leds brightness behaviour (keyboard backlight)

I've followed this tutorial to replace some broken leds on my keyboard. The leds I used are: ...
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2answers
88 views

How does a dot matrix led driver know the voltage of an led?

I wanted to make a 7x10 led dot matrix using two 5x7 led dot matrix from lite-on (LTP757KR). I first thought of using shift registers, then I found a 12 x 8 dot matrix led driver with a bunch of ...
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2answers
94 views

Power consumption NeoPixels vs. direct control?

At Maker Faire Berlin 2018, an electrical engineer looked at my project which was shown with NeoPixel LEDs (WS2811). He mentioned that the NeoPixels waste a lot of energy. It would be better to build ...