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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4answers
148 views

Why won't this circuit work?

I made this circuit. I calculated everything, but all I get is THE LED JUST WONT TURN ON. simulate this circuit – Schematic created using CircuitLab
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1answer
63 views

How do I find the right resistor for an LED panel? [closed]

I purchased one of these cheap LED panels to light a room. One review suggested that it's important to put a resistor on it, to keep it from frying itself. But, he didn't list what resistor to use. ...
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1answer
61 views

SK6812 - LED Flickering

I am facing a strange issue while building a simple LED matrix. I am using the SK6812 LEDs and an ESP8266 controller. The LEDS will be controlled over Wifi. My matrix contains about 180 LEDs on a PCB ...
1
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1answer
70 views

LED intermittently fails but works when voltmeter applied

I have an LED in a home project. It's in a simple loop with a resistor and the GND and V+ ends connected to appropriate pins on a microcontroller. The LED works properly for extended periods of time ...
0
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1answer
53 views

Help me to build some devices for measuring LEDs optical power[mW] with range (1 -100)mW included [closed]

I have an application of photoactivation device with 10-20 LEDs for every color; with the following wavelengths : red 630-670nm ;yellow 575-595nm , green 510-540nm . In order to obtain an uniform ...
0
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1answer
55 views

Power multiple parts of one project from one wall wart

I'm building a project with a high-power 10W RGB LED controlled by PWM from a microcontroller. Right now I'm using a wall wart to power the LED, and powering the MCU through my computer's USB. My ...
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3answers
76 views

How Much Current is Usually Used with IR Transmitting LEDs, in Remote Controls?

If you take various Remote Controls from your home, such as for a TV, Audio System, TV Box, etc, and measure the current that is supplied to the IR LED in the remote, what would be common current ...
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2answers
152 views

Can i use I2C level shifters to power digital LED strips

Can I use I²C level shifters to power digital LED strips, more specifically, WS2812B strips? I can only find I²C level shifters, are they ok?
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1answer
75 views

How is this LED light guide made?

I need to know how LED status lights like these on my Bose Q35 headphones, are made? Is it a light guide? some kind of foil or what?
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1answer
42 views

ESP8266 circuit with an LED

I'm building a project where I use an ESP8266 module to control a LED with my smartphone. For my project I want to battery power the ESP8266 and the LED so I'm using two Lithium Ion batteries. I've ...
0
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2answers
76 views

Using a LED with an ESP8266 module

I'm building a project that uses a high power LED (3 Watt) in connection with an ESP8266 module using the module as an access point and connecting to it with my smarthpone. I've successfully managed ...
0
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2answers
95 views

LED driven by MOSFET is dim

I have this schematic: I had to replace T1 transistor with a MOSFET (because D4 on an ESP8266 has to be high at boot time and the transistor reduces the pin voltage, so the ESP doesn't boot - see my ...
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0answers
39 views

I have RGB LEDs but I need an external power source [duplicate]

I have WS2812b RGB LEDs for a project but I don't have an external power source. I heard that you can use a power bank for charging phones and things. I cut the end of a micro usb but wouldn't know ...
0
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0answers
37 views

What does define LED spectral response

Trying to understand more about the LED process and seems there are quite limited resources online. From some sources, it is made on MOCVD reactor by doping a silicon wafer with different types of ...
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1answer
116 views

What connector is this on an LED strip light?

I managed to find some scrap LED strips. I noticed that these have some peculiar connectors on them. Does anyone recognise what connectors these are?
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2answers
71 views

Parallel circuit with LED on one path and resistor on the other

I'm a beginner to circuits. Unlike many other questions, my circuit involves a parallel circuit with a LED on one path but a resistor on the other, as shown in the picture. Q1: assuming the LED has ...
1
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1answer
40 views

LED s calculation of beam area, dosage and energy from data sheet information

I have an application with LEDs with following data sheet LED631E 635 nm optical power 4 mW half angle 20° FWHMa 10 nm, Could you help me with calculation of beam area at the distance ...
0
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2answers
133 views

Is wearing LEDs dangerous? [closed]

Wearing 1 LED isn't much of a problem. It only requires a few volts and ~25mA of current. But what about 100+ LEDs? It depends on the number of LEDs in series or parallel (or both), but would it be ...
2
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1answer
111 views

Driving IR led from 3.3V GPIO using 2N2222 transistor

I am using the following circuit to drive an IR led from a NodeMCU. simulate this circuit – Schematic created using CircuitLab However, im seeing the following on my scope. (Please ignore the ...
0
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1answer
32 views

Camera LED in phones - PWM or analog current controlled?

The LED illuminator/flash that is used on cellphones with cameras is also controlled by flashlight apps. Is the light level controlled by pulse width modulation or is it analog current controlled? In ...
2
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2answers
761 views

If Manufacturer spice model and Datasheet give different values which should I use?

I'm trying to simulate an LED circuit but I am getting a large difference in results from the simulation vs calculations done using the datasheet information. In this case both the spice model and ...
2
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2answers
405 views

How to add power-LED to my small amplifier?

I have a simple PAM8403 that I use to amplify sound, The volume switch also works as power-off, if I slide it all the way down it makes a click and its off. My girlfriend is the user of this device ...
0
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2answers
35 views

Reducing current in a circuit without reducing voltage [duplicate]

I didn't find a solution in the other similar posts or maybe I don't understand them. Here is my problem : I've got power supply with an output of 5V and 8A to feed 128 leds drawing 5V and 50mA each. ...
0
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1answer
90 views

LED-drivers FAN5331 and FAN5333

I have a question about the following LED drivers: FAN5331, datasheet http://www.mouser.com/ds/2/149/FAN5331-92198.pdf FAN5333, datasheet https://www.onsemi.com/pub/Collateral/FAN5333B-D.pdf They ...
0
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1answer
39 views

How to bypass minimal load limitation on a power switch?

I got a power switch which seems to have minimal load that makes it incompatible with LED lights. Schneider GUPA1411BSS 1 Gang 1 Way PIR Switch — after unpacking I found it has only L, L1 and earth ...
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0answers
31 views

What size resistor to light 3.3V LEDs from a 3.3V circuit? [duplicate]

I have some blue LEDs that are listed at having a Vf of 3.3V @ 20mA. If I want to drive them from a 3.3V source, do I need a dropper resistor? Methinks I do, but R = (3.3 - 3.3) / 0.02 = 0 Ohms! I ...
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2answers
59 views

Diode meter of my DMM does work for red LEDs but not for white LEDs

I have a diode meter on my DMM Powerfix Profi and I want to measure the forward voltage. (actually it is not so profi at all). So I tried the steps needed, and found the Vforward of a red led to be 1....
5
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4answers
930 views

High voltage LED indicator 40-1000 VDC without additional power supply

I would like to make an indicator to show that DC bus (700VDC) capacitors are charged (be careful!). What is the best way to make a LED indicator, which will work for a long time from 40VDC to ...
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1answer
63 views

Lamp is dim for ages when turning on straight after turning off [closed]

My bedside table lamp is plugged into a powerboard and is using a 9.5W Mirabella LED bulb on a 240V circuit - in Australia, i.e. with the Australian plugs. We can't buy incandescents here as they are ...
1
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1answer
60 views

LED : calculation of optical power[mW] from luminous intensity[mcd] [duplicate]

I have an application with LED with given optical power. I found on ebay some LEDs but it appears just intensity [mcd] How can I determine optical power of LEDs in mW ?? Please, mention some clues. ...
0
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1answer
29 views

Wiring sets of 2, 15" LED strips to illuminated switch. 12 sets total — to power supply

Ok, Hoping you guys can help me. I have a screen printing machine for printing t-shirts. The machine has 12 arms that extend out from the center. Under each of these arms I want to put 2 15" white LED ...
6
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1answer
1k views

Will a Schottky diode save my LEDs against reversed voltage?

Consider the following schematic: simulate this circuit – Schematic created using CircuitLab Main question: 1) I am accustomed to use Schottky diodes to protect my circuits against reverse ...
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2answers
54 views

Do the optical power and energy of LED vary with distance?

I have an application with LED and It requires a bigger beam . I could obtain a bigger beam by incresing the distance between LED and surface. But îs there the possibility to decrease the energy ...
1
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1answer
67 views

Current source with multiple “taps” for driving different LEDs

I'm building a light source for a (one-off, hobby) 8mm film scanner that will be taking several exposures of each frame with different color (R, G, B, and possibly IR) light. I'd started with high-...
0
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1answer
57 views

How do you deal with operating ranges of low current LEDs?

I'm looking at using an IN-S85AT5UW in an upcoming hobby project. I'm pretty sure it says that with the white LED, I'll get about 180 mcd and that the maximum continuous forward current is 5ma. That ...
0
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1answer
61 views

Connecting 4-pin RGB led

Ok, I feel like this question is a bit underqualified for this site but I couldn't find anything better. Anyways. I have almost no knowledge about electronics, so sorry for the stupidity. I want to ...
0
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1answer
45 views

Why does an UDN2981 lower the current?

I want to use a UDN2981 8-channel source drivers IC (see UDN 2981 datasheet) for a matrix multiplex light. I connected the UDN2981 this way: pin 9 (VCC) to 5V pin 10 (GND) to GND pin 6 to VCC with a ...
0
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1answer
71 views

Using a MOSFET to turn on/off LEDs which could get reverse voltages

I formerly asked about a LED circuit a long time ago. The circuit I want to make is 'reverse-voltage notifier'. If the input is reversed, then a LED(below, D2) will lit. Of course, if the input is ...
0
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1answer
64 views

Connecting an IC to LEDs - would I use a transistor?

I have this breadboard circuit, which is basically a 65C02 CPU that has 16 Address pins. I want to wire these up to LEDs. Below, I've connected them directly, which is likely all kinds of bad (Too ...
0
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2answers
139 views

Why is the threshold voltage kept large in an LED?

My book says ... But the threshold voltage are much higher and slightly different for each color. The reverse breakdown voltages of LEDs are very low. While I understand that the reverse breakdown ...
2
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3answers
151 views

PUT relaxation oscillator doesn't work

I'm following instructions from Charles Platt's "Make" and trying to mount PUT oscillator. Strangely, it blinks only once when I switch on the DC current, no oscillation was observed. I have tried ...
1
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1answer
84 views

Debouncer with LED inside

How It's possible to add a LED to a line that it's debounced (switch) with an RC circuit. If I place 2 LED, one on ground and one on VCC to know button position. Will they remove my charge/discharge ...
0
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1answer
84 views

How to drive 2/3 color LED's and circuit schematic

I need to use 2 or 3 color LED for my circuit.(preferably 3 color one). I am going to use PIC18F26K83 to control the LED. However, I am confused how am I going to make it change colour. I think I ...
0
votes
3answers
70 views

LED series-parallel and parallel-series combination circuit

I'm designing some LED strips to use to grow plants along a long wall. There will be hundreds of LEDs run by a constant-current high quality LED driver (Meanwell brand or similar). All the commercial ...
1
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4answers
87 views

Inverted LED driver circuit

I am looking for an LED driver circuit that would illuminate when a voltage is at zero, and which would gradually shut off as a voltage rises to 3.3v, with a (somewhat) direct relationship between ...
1
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1answer
37 views

Powering same LED strip from 2 drivers - diode?

So I'm looking at adding some LED mood lighting to our bedroom. End game is to have a single LED strip controlled by 2 different switches Currently, I have 2 switched 240V AC outlets, one either side ...
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2answers
76 views

Finding resistor values with a high power LED on an Arduino (Limited experience with circuitry)

I am having difficulty determining resistor values on a 3W LED circuit. It's running off an AT85 Tiny, and being powered by a 9V battery. We want to be able to monitor the battery level, as well as ...
0
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1answer
78 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 ...
0
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1answer
71 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 ...
0
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0answers
45 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?...