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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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47 views

How to control a lightbar with 20 individual modules? [closed]

The TL;DR version of my question is, how do you control 20 pieces of 12V/1A outputs in the most reliable, compact and cost efficient way, with something programmable? The long version: I got a ...
4
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2answers
94 views

Open-loop Buck LED dimming

About this buck LED driver... TL/DR the questions: 1) I intend to drive the FET from a microcontroller PWM via a suitable FET driver. This open loop control scheme seems too simple. Is it a trap? I ...
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1answer
107 views

Arduino Circuit for High Power LED + Servos

I'm new to the Arduino game, but have experience with electronics in general. I am hoping to hook up two servo's and a high power (1W) LED up to an Arduino, to control them. Due to my inexperience, I ...
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1answer
42 views

What is sitting inside LED array so that I can create my own drivers?

I have a LED array and an app to drive it: https://itunes.apple.com/US/app/id1431362600?mt=8 https://play.google.com/store/apps/details?id=com.yskj.led&hl=en_US I connect to WiFi and I'm able to ...
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1answer
86 views

Led on breadboard burned out why?

Please be kind as I am fairly new to electronics. Anyways, from what I read on multiple forums the rules are fairly straight forward, but I am puzzled as to why my led burnt out. So I connected the ...
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2answers
110 views

Using a resistor to drop voltage for LED

Hoping someone can help me to understand what I am seeing. I have the following: A 5V DC power supply derived from a USB power supply A LED (LINK) with a Forward Voltage requirement of 3.2V (Maximum ...
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0answers
62 views

Flashing an LED with Schmitt trigger

I'm trying to build the above circuit, which is supposed to flash an LED with a schmitt trigger (with the possibility to vary the frequency with the knob of the 47kOhm potentiometer). I don't have a ...
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3answers
92 views

How long can an LED withstand its rated peak current?

I am working with several 7 segment displays HDSP-F103. According to the datasheet, each segment has a peak current of 45 mA, but it doesn't specify for how long in time or in PWM duty cycle. It does ...
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0answers
31 views

LED current rating

I have an unknown LED, I think it was previously run off of ~14vDC. I want to repower it - I have a 5vDC 3A power supply. I dont know the LED rating so I've rigged it up to a simple series circuit. ...
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1answer
250 views

Led blinking with one NPN transistor [duplicate]

I am using scheme as shown below to blink an LED. But I'm using 9V battery source instead of 12V. I tried to use capacitors in range 100uF - 500uF to increase delay between blinks. Questions: ...
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2answers
77 views

Choosing a resistor for connecting a bipolar transistor

I need to run some LEDs using Arduino. The total current consumption is about 190 mA. For these purposes, I found a bipolar transistor PMBT2369 (Nexperia). Transistor characteristics: - Maximum ...
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2answers
108 views

Help with explanation on this transistor behaviour

Hi, I found the above circuit on a website where it was said to produce fade in effect for the LED's. I tested the circuit out in my breadboard with R2 as 1K and C1 as 1000uF and R3 as 100 ohms. ...
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2answers
666 views

LED- Resistor, does the position matter? [duplicate]

I was reading the MAKE AVR programming. One of the chapters suggests to solder resistor to the cathode side of an LED. But in our uni labs it's said to connect the resistor "before" the LED; that is ...
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4answers
102 views

Safe Led resistor path [closed]

I know that Leds in parallel with one resistor is bad. I was wondering if this is still considered bad to do since all power is run through 1 resistor then split and run through other resistors ...
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3answers
80 views

7-Segment Drivers: How do they work/how to handle them?

So I know to drive a 7-segment display you need a TON of pins. However there are 7-segment display drivers (such as the MAX7219) that seem pretty popular. However I'm looking at the datasheet, and am ...
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1answer
107 views

Optical bandwidth and electrical bandwidth

I understand the concepts of electrical and optical bandwidths, but I encountered an example problem that used the following formula to calculate the electrical bandwidth: $$electrical bandwidth = 1/\...
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1answer
39 views

Wiring 3 led lights to a timer switch

My goal is to take a typical white clock and make it light up green at 3pm, yellow and 6pm and red at 9pm I'm guessing I'm going to need 6 red led lights, 6 yellow led lights and 6 green led lights ...
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1answer
83 views

How to calculate current through a resistor and LED?

Question C asks how's to calculate the current over the led and 3k resistor? Can someone please help me understand how to do it?
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1answer
75 views

AL8860 LED driver does not output required constant current

The LED driver circuit i've made here does not output a constant 1A current. With an input voltage of 12V and 9V total Vf on the three LEDs (CREE LED star), the current is only 0.65A. Am I ...
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1answer
74 views

Arduino and 3W LED sharing the same power source, is it possible and how?

I've built a remote control for my 3W power LED with an Arduino UNO and I'm powering the Arduino with a USB cable and the LED with 4x AA NiMh batteries (1.2V). Is it possible to power both my Arduino ...
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0answers
59 views

How to determine wiring of unknown LED scrolling display board

My school has a LED scrolling display board from long ago in the main lobby. When I flip the power switch, it turns on and starts displaying zzzzzzzzzzz... There's a connector on the outside (2x10 ...
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6answers
367 views

led I can stick on a AA battery [duplicate]

I have a toy for my son, it's great but it flies round and round in the dark, I was thinking of sticking an LED on it like we used to do at school - back then LED's were rubbish but they had long ...
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0answers
73 views

Calculating value of a current limiting resistor in a constant current circuit?

I am using 12 leds in series with 3.0-3.4 v forward voltage and 400-500mA forward current (these values are from the datasheet). I am using a constant current led driver(24-40v and 580mA). My problem ...
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2answers
81 views

Using 28 AWG flat/ribbon cable for LEDs

I want to control a lot of LEDs (like 128) in an area of about 1 m2. Instead of using separate wires, could I use a 28 AWG flat cable, and split/cut it wherever needed? E.g. split it in two wire ...
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0answers
59 views

0402 SMD resistance shortcut [duplicate]

I am wiring a small plastic model with 11 yellow 3V 0402 LEDs. I used the resistance calculator to find I need as many 56ohm resisters attached to each LED in parallel to keep them running properly, ...
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2answers
2k views

DIY LED lamp is less powerful than expected

I am making an LED lamp using an LED strip. The LED strip I am using is a 240 LED/m SMD2835 strip, which operates at DC12V, and is supposed to use 18W of power per meter. My lamp is constructed as ...
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2answers
114 views

How does this precision full wave rectifier work?

I am making a VU meter, and I need to rectify the audio signal for the IC comparator chip. I found this circuit in the datasheet, but I am unsure of how it works. I understand that the LF351 op amp ...
1
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1answer
96 views

3.7V Li-Ion battery powered LED step-up/boost driver

Most quality COB LEDs are driven with around 35V. Are there any quality constant current step-up drivers available that allow a 3.7V Li-Ion battery to be used? Or would I have to use TI's WEBENCH ...
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0answers
22 views

110 V LED Light fluctuation based on PC draw from same powerstrip

I apologize as I know this is beneath an engineer's level, however I cannot find a solution. I have 2 110V LED 30W 5000K spotlights which are dimming due to a PC drawing current from the same 110 ...
2
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3answers
152 views

Driving a LED in the most energy efficient possible way [duplicate]

I got into a bit of a challenge with myself, just for the sake of learning something about low power stuff. I want to build a device that has basically two requirements: blink an LED every 5-10 ...
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0answers
51 views

Need help identifying a cable

We bought a LED pendant light, and it turns out that it hangs too high for our tastes. Rather than sending it back, I figured getting a longer cable would be easy enough. (Famous last words...) ...
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1answer
65 views

What resistor do I need?

I have an LED that is rated for 34V at 3A and about 100 watts. I am trying to figure out what power resistor I need with a 36V battery supply. I think I need a 10W 1 Ohm resistor but I am not sure. ...
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0answers
50 views

LED and optocoupler MOSFET switch connected with an inductive load

I want to ask, if this circuit will work. I think the flyback from the inductive load the mosfet is connected to will break the optocoupler. The LED is connected through a resistor which should ...
2
votes
1answer
62 views

Best way to connect 7 x 18650 Panasonic batteries to 2 LEDs

Looking for some help with correct wiring: I have created a custom 7-cell battery (4 cell block in parallel, 3 cell block in parallel and both blocks connected via series) to produce a 7.4V 23.8A ...
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1answer
83 views

Easiest way to control a led remotely [closed]

I was wondering what is the easiest and cheapest way to have a high power led (3 Watt) turn on/off and blink remotely from a distance (60m-100m). I've been looking at some microcontroller solutions (...
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1answer
62 views

Classification of LED type

Out of curiosity, I recently opened a damaged measurement device (it´s some kind of lab spectrometer, but I am not sure) that contains a LED with a package like I have not seen before (see picture). ...
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1answer
33 views

Led strips power supply , consumation and contorller

Hello everyone i am really bad at this stuff, i tried reading a few articles but i can't seems to understand anything. So basically i bought the LED strips from aliexpress that came without power ...
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1answer
30 views

Hooking into Qi charger status LED to power something more

I have a Qi charging module and I want to light up a higher-power string of LEDs when my phone is charging through it. The module has a blue status LED to show it's charging, which I think is where ...
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3answers
84 views

How does an IR LED turn on and how can I test to see if its not broken?

I'm an electronics beginner. Does an IR LED turn on like how regular LEDs turn on or does it only turn on when you've assigned a specific code for it to transmit? The reason why I ask: I bought ...
0
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1answer
18 views

Dimming LED with speed controller

I'm trying to controll 4 parallel 12V DC LED strips with an speedcontroller. I am able to dim the lights from 100% lit to about 5% lit, but it never turns them off completely. My multimeter can't ...
0
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1answer
33 views

Microbit - Control an LED that is powered externally

this may be a bit of a noob question but I am trying to make a motion activated light with my Microbit. I have a 1W superbright LED and its clear the Microbit won't supply the current needed for this ...
2
votes
1answer
71 views

Questions About BJTs in My Circuit

I have an LED multiplexer circuit (inspired by https://www.instructables.com/id/Multiplexing-with-Arduino-Transistors-I-made/) in which I have set the resistor values to maximize the current through ...
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2answers
78 views

LEDs with same current rating but different forward voltages

I have scoured the net for a direct answer but people always end up talking resistor because they don't have constant current. I have a constant current power supply. LEDs are 700 mA and vary ...
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2answers
85 views

How do I model a digital out in a circuit simulation?

I have a PIR: Panasonic NaPiOn AMN34112 that has a digital output. When it detects motion it outputs 4V and 100 uA max. I want to connect this output to a LED using one or more transistor amplifier ...
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1answer
72 views

LED Controller + LED Panel with common cathode

I have a 3-CH DMX controller (5-24V, 5A/ch, common anode) from amazon (don't know if links are desired here) and a 12V 100W MCPCB LED panel, which unfortunately has a common cathode. The panel is ...
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1answer
47 views

Infineon DAVE v4.2.2. XMC1200 Boot Kit 4-Channel DMX Issue

I am using Infineon Dave v4.2.2. to program the XMC1200 boot kit with colour LED card to read a DMX input signal using a rotary dial. For those that don' know, Dave uses a simple UI with "apps" that ...
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1answer
54 views

Series circuit LED controlled by Arduino schematic question

I'm currently making a project with multiple series circuits to PWM control multiple LEDs. I have figured out how to make it work with a transistor, however I was curious if this way would work as ...
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2answers
239 views

How can I use an LED driver (QX5252) to light up 3 different color LEDs (Green, Yellow, Purple)?

I am trying to light up 6 LEDs with the common garden light circuit (2v Solar panel and 1.2V battery). The problem is that I want to light up 2 yellow LEDs, 2 green LEDs, and 2 purple LEDs ...
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1answer
91 views

How can I generate 3 outputs (green/red/off) with a single toggle switch (VERY SMALL)

Disclaimer - I have little to no knowledge of any of this. I'm in over my head and appreciate your help and I appreciate in advance the lamens terms you've chosen to answer with. I'm trying to ...
5
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2answers
1k views

How to solder Christmas lights insulated wire?

I want to fix Christmas lights like these, whose wires got cut near the batteries. The LEDs near the batteries still work. I tried touching the wires from the two parts and I was surprised that the ...