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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40 views

7030 SMD LED pad configuration

I have not done a lot of work with SMD LEDs and have a question about the pad layout. I have done quite a bit of research and haven't found much helpful info yet. I am working with 7030 SMD LEDs ...
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66 views

What LED PWM controller has marking AT508CS?

I have an LED worklight with low- and strobe-functions. One click: On - full Power Two clicks: half Power Three clicks: strobe Four clicks: Off The controller is circled: No markings on the top ...
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64 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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37 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 ...
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206 views

Flex circuit solid or hatch copper pour

I have a flex circuit board with 5 LEDs mounted on it. I have large copper areas attached to the LEDs for improved heat dissipation. I read here that "With a hatched plane, the moisture can exit the ...
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96 views

Are common IR LEDs harmful to the eyes?

Is it safe to look at the IR LED clusters on security cameras that are commonly available? They seem to be quite capable of lighting up a distance of 6m. What is their energy density? I'm not sure if ...
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25 views

SK6812, what happens if a pixel fails?

I plan to use SK6812 RGBW LEDs for my projects. There was a question of reliability. What happens if one of the pixels fails? Will the signal go further? If not, which way to look?
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32 views

LED Chaser using counting IC

Total beginner here, I'm trying to build an "LED Chaser" circuit using an IC (CD4022BE) that counts to eight (from zero to seven, and then it wraps around and goes back to zero). Before trying to ...
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60 views

TV Backlight LED's voltages

I have a power supply that is outputting ~300v and 350ma. the LED's in the backlighting are on 11 strips and there are 6 per strip. Can I calculate the voltage per led by dividing 66 LED's into 300v? ...
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71 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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29 views

Can I connect 2 power supplies for 16 meters LED RGB strip?

I've bought 2 sets of 10 meter LED RGB strip (7.2w/m) for a room. Then I've cut them to around 8 meters each to get 16 meters. Everything seemed fine but one thing, because it's 2 separate controllers,...
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46 views

Isolated vs non-isolated boost converter for LED (12v to 24v)

I have a 12v system in my motorhome and planning on installing 24v LED strips, however, I'm unsure whether I would need an isolated or a non-isolated boost converter. I'll be using roughly 5 meters ...
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84 views

PSOC 5 turning on a LED with a switch

I'm trying to turn on a LED using a switch and then turn off the LED after 5 seconds with PSOC. With I run the firmware I wrote, the LED is on and then turns off after 5 seconds. What I want is that ...
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47 views

phoresistor vactrol tremolo noise

I made an optocoupler by shrink tubing a generic photo resistor and a cold white led. Then used it in the following setup to be able to control audio level to achieve tremolo effect: simulate this ...
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54 views

LEDs driven by GameBoy sound

My circuit does not work as I thought it should and I'm really confused now. What I want? Two LEDs which will pulse to audio LEFT and RIGHT channel separately. And same for display BACKLIGHT, but ...
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59 views

NPN / PNP Sound activated LEDs

I have some RGB LEDs (common anode) and I'd like to control them via sound from my stereo (line level). I'd like to be able to switch the two behaviors of the LEDs from flickering off when the input ...
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28 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 ...
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81 views

Indicator LEDs on Arduino current blocking

So I just inherited a project. I am designing a board for a mega32u4 smd microcontroller that has indicator leds on 8 input and output pins (4 digital (3pwm) and 4 analog) that light up green when a ...
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345 views

LM3914 schematic values

I'm trying to study an electronic schema based on a LM3914 but I can not find the same threshold voltage, can you help me? Source of the schematic ...
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54 views

Calculating max peak current at different conditions

I have an IR LED (IR383), and I want to power it with 5v@38KHz. I'm actually calculating the resistor so I need the LED's maximum current. In the datasheet, it says that it accepts 100mA continuous ...
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56 views

design approach for multiple control signals

I built an LED driver based on TI's LM3549, to drive an RGB LED. It works great, but requires that I provide a control signal for each LED: In my testing, I'm using an Arduino to generate the control ...
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63 views

USB charging in place 3 Li-Ion batteries spaced evenly in parallel on LED string

I am a total noob in electronics, and so some other answers to this question are already over my head. I am working off the inspiration of this design of an LED hoop: https://philihp.com/blog/2011/diy-...
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133 views

Modelling a LED Array for SPICE simualtion

I am currently looking to model a whole LED array within LTSPICE. I am working on all of hte logistics right now. I currently have a LED array with about 300 LEDs on the array. Instead of modelling ...
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110 views

MOSFETs are dimming my LED lights - checked other threads but it doesn't work

I'm trying to make an LED strip that I bought off Amazon work with my Raspberry Pi. It works just fine when I connect it through the included adapter which I took apart (shown below): However, it is ...
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213 views

Correct LED derating

I am currently looking at the datasheet of a LED and have snipped out the passage of interest. The question is how do I find out the intensity I can reach at a specific temperature/current by using ...
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92 views

Schematic review for simple LED circuit?

I'm pretty new to circuit design, I am trying to make a small board with a few LEDS that uses a toggle to turn on and another toggle to either show the LEDS always on or to blink the LEDS. I believe ...
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342 views

Two Stage PWM for Power LED Driving and Dimming

Some LED lamps that are used with an external DC power supply use a switching mode current regulator to drive a power LED. I believe that most of them run in the 100-500 kHz range. I want to drive ...
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98 views

Why do blue LEDs have more candelas of luminous intensity than the green ones, in general?

I have been going through datasheets of a lot of LEDs, manufactured by a plethora of manufacturers, like Vishay, Kjell, etc. The Blue LEDs, as per my observation, have more luminous intensity than ...
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128 views

Why does inside of my sphere appear to be getting darker?

This a fully enclosed sphere containing a web cam, white led and photo resistor in exactly the geometric arrangement shown. The led glows dimly (via fixed dropper resistor). It runs at about 9 mA. ...
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78 views

Characteristic of LEDs

I measured with an oscilloscope the characteristic of three LEDs (green, red and yellow) connected in series with a 1000 Ohm resistor. The result of the measurement was this figure: Why do I have ...
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508 views

Multimeter fails to measure forward voltage

I have a MS8233D Multimeter and wanted to measure the forward voltage of some LEDs. I connected the leads directly to the LED and used the Diode Testing Mode. However the multimeter just displays Ol ...
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1k views

Resistor value selection for PWM dimming of Meanwell LED driver

I'm controlling a Meanwell LED driver's dimming function using 0-5V PWM from an Arduino, stepped up to the 0-10V PWM the driver expects. Here is the circuit. '0-5v' is the 5V PWM from the ...
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89 views

Low voltage LED bulb or jump into line voltage?

I'm not even sure if this is appropriate StackExchanage community for this but I wasn't sure where else this sort of question would fit. So I tinker with electronics here and there and primarily it ...
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67 views

Inconsistent values read from PCA9955B error flags

The PCA9955B is a 16-channel LED driver that features programmable PWM and current and has gradation support. It also features open/short detection for all of the 16 channels, which is reported in the ...
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528 views

make an LED blink on rpi2 in assembly

I am trying to make an LED blink on assembly on my raspberry pi 2 model B to debug some startup code. However I don't see anything blink. Could someone tell me what I am forgetting? ...
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411 views

MC34063 boost converter + PWM dimmer unstable output problem

I use NE555 & MC34063 to build a LED driver with dimmer function. The crcuit of NE555 , MC34063 & LED are bridged by a IRF640N NMOSFET. NE555 is responsible for adjusting the brightness and ...
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142 views

Simple IR gate switch

Regards to all I'm totally new with electronic and I need help with some schematics. I find one circuit that fits my needs: simply instantly turn on the LEDs with press of a switch and dims them on ...
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263 views

90 degree phase shift in transistor network

I am analyzing an amplifier circuit that looks like the following: The input signal is provided by the 60 Hz sine wave generator. When I ran the transient analysis on the potential of the signal and ...
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203 views

New WS2801 LED strip fails while old identical ones are working

I'm trying to add an additional 2 LED strips to my current setup of 4 identical ones. Each strip consists of 32 RGB LEDs with a WS2801 chip run by an arduino which connects to a PC. However I'm ...
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248 views

3.3v output voltage on arduino mini

I'm learning to use the Adafruit LSM9DS0 and have cobbled this code together such that an LED will turn on when it detects motion on the accelerometer, specifically when the magnitude is over a ...
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982 views

IR LED power density calculation

I made the basic IR LED circuit shown to augment the existing system on a night vision security camera. No datasheet was found for the LEDs so I just measured the current to extract the power of ~0....
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100 views

Commercial 1.5m / 5' LED light fitting parallel LED arrangement

I am reviewing LED light fittings for an industrial premises refit. As with most of the experienced users on this site I like to understand what I'm purchasing and have opened up a sample fitting to ...
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165 views

Buck Boost Driver to switch 2 LED chains

simulate this circuit – Schematic created using CircuitLab I'm working on a project to turn 2 LED strings (each containing 6 HB LEDs). Here is my question. The Buck Boost driver I'm using is ...
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108 views

Noise being created on Sensor after connecting Power Source to LEDs

simulate this circuit – Schematic created using CircuitLab So I posted this issue on the arduino forums and haven't had much luck getting any visuals on it. I have an arduino and shield of ...
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125 views

Current-Voltage curve of Light emitting diode

Under Real time Applications of LED, I am getting negative current in forward voltage(mili volts)...Please tell me what is the reason behind this and how can i avoid it from getting negative current.
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490 views

Failed attempt to make LM3404 drive a 10W white led

I'm attempting to drive a 10W white led (ebay type, 8-11V, 1A) with a LM3404. I've approximated their reference circuit: I've used a 33uH (1.6A) inductor as L1 and a schottky diode (SS24, 2A 40V) as ...
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448 views

can't change LEDs states using PCA9685

I have a PCA9685 IC connected to i2c of cubieboard like board. Also OE pin is connected to one GPIO pin. I'm using ic2tools to communicate with PCA9685, I can read/...
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243 views

Modifiying SparkFun Uh-Oh Batt. Indicator - TL431 Regulator Diode Based

I'm trying to modify a simple SparkFun Uh-Oh Battery Level Indicator - KIT - 11087 https://www.sparkfun.com/products/11087 It can handle a maximum voltage of 12 or so volts, above that I believe it ...
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71 views

Making a 1m sized 16x24 screen so that the picture is recognizable

I'm thinking about making a flexible LED screen with 16x24 LEDs. I want the screen to be 1m wide so it will have big gaps between the LEDs. Because of the big gaps I think the image may be ...
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518 views

Bottle dynamo (bike generator) rectification and stabilization circuit for LED light

A friend of mine would like to convert her bottle dynamo (bike generator) to run a LED light. The light needs to stay on for maybe 90 secs when the bike is stopped, and needs to blink (using a ...