Questions tagged [brightness]

Brightness is an attribute of visual perception

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3answers
65 views

Effect of changing PWM frequency of a light source on perceived brightness

First and foremost, I'm not entirely sure if this is the proper place to post this question, so I apologize if there's a better section for this. I am looking to determine the effect of changing the ...
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1answer
35 views

The 7-segment LED display is too dark when connect to a auto dimming circuit

I'm using the below circuit to build a auto dimming circuit. I was fine when I only use one 7-segment led, but when I connect more 7-segment led (parallel to L1) the light intensity is very low. How ...
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1answer
45 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 ...
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6answers
1k views

Simple LED fade circuit

I've been looking for a simple LED fade in/fade out circuit when power is turned on/off for a 12 V LED. I have tried the following circuits but the problem is that I can't reach the full brightness of ...
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3answers
94 views

Using latching Hall sensor to toggle a LED - brightness issue

I'm using a U18 latching Hall sensor (datasheet) to toggle a LED. I'm driving it off a 6V L1016 battery. My issue is that the LED is very dim. My understanding is that the U18 limits the output ...
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1answer
96 views

Keeping your LED cool with PWM

SO I need to use some 1W and 3W leds for the brightnes, but my application will not allow the start heat sink. I have come across a few articles talking about using PWM to drive LEDs Does pulsing an ...
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2answers
110 views

Undesirable ramping in LED intensity

First time posting on this, so apologies if I mess anything up. I'm having an issue with my circuit that I'm having difficulty figuring out. I am using a TIP120 transistor to turn an LED on/off. The ...
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3answers
1k views

How to compare brightness of different color LEDs (not RGB)?

I wonder - let's assume one would build some user interface using green, yellow and red or just any other available colored LED (not RGB LED) - what would be the proper (aka best) way to compare the ...
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1answer
446 views

How significant is 16bit in 16bit PWM resolution? [closed]

Is there any significance other than the granularity of duty cycle levels?. I'm working on an led driver where the light output levels should be very smooth while dimming. There will be 254 levels of ...
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1answer
60 views

LED perceptive intensity by Color

BACKGROUND I have a panel with light indicators (LED) in RED,GREEN and YELLOW. Since the eye have different sensitivity to different colors, some colors must be brighter than others to be percepted as ...
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1answer
61 views

The brightness of light bulbs in this circuit

What will happen to the brightness of bulb A and bulb B in the circuit shown in the figure when we move the wiper of the rheostat from point x to point y? When the wiper moves from point x to point y ...
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1answer
498 views

The brightness of the bulb

I came across this question in my book, it says: This circuit has three identical bulbs, what will happen to the brightness of the bulb (B), when we close the key (S). (Consider that the internal ...
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3answers
217 views

How can I calculate the current through an LED? [duplicate]

I am trying to find out if increasing current increases the brightness of an LED. I'm pretty sure this is the case now that I have looked into semiconductor band theory physics and p-n junctions. ...
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3answers
352 views

Keep individual LED brightness steady when other LEDs are added or removed

I'd like to use several LEDs on a project, with brightness control (it's a scale model of a street with houses, with LEDs of different brightness in each house, which I've been working on with my son)....
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3answers
2k views

How Is Intensity of Blue Light Measured?

As a hobby project and to help solve issues getting up early in the morning (specially given that it's winter and the sun isn't up until long after I am) I'm trying to find a bright blue light that I ...
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3answers
502 views

How to build a light sensor for PWM dimmed light (for comparison against CC dimmed light)?

I am working on a project in which I need to find a PWM duty cycle to dim an LED to the same brightness level as an LED being dimmed with CCR. Initially, I was considering using a camera for this: I ...
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1answer
309 views

How to create an output for LED brightness control using PWM in PIC

A PIC is multiplexing multiple common anode 7-segment displays. An LED driver is being used so PIC does not have to source/sink a lot of current. To help with multiplexing, each 7-segment display ...
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1answer
101 views

Matching LED brightness from different supply voltages

In an earlier project, I used an LED to indicate power (this 12V model). The PSU delivered +15V. I adjusted brightness with a 5k series resistor. According to the datasheet, this particular white LED ...
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3answers
200 views

How can I decrease the brightness of these BA-15 LED bulbs

I'm looking at these LED replacement bulbs for the interior of my sweet conversion van. I'm looking for a more efficient alternative to the BA15 bulbs that are in there already. These bulbs appear to ...
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1answer
2k views

10x10 RGB LED Matrix Multiplexing with Shiftregisters Bit Angle Modulation

I've build a 10x10 RGB LED Matrix. The LED's are connectet in rows and colums. Thats 40 pins (30 for RGB, 10 for GND). I got myself 5 74CH595 IC's and solderd everything together. I also added a 1A ...
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3answers
1k views

Circuit to create X levels of brightness for a LED

If I'm here today, it's because I need some help for something that is, I think, easy for you. I am quite a newbie in EE but I am trying to improve myself :). Here is the thing, I'll try to be as ...
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4answers
5k views

Dimmer effect (fade) on 12v LED using transistor and Arduino

I am working on a project on which I want to control the brightness of a 12v LED using a transistor and an Arduino board. So far I have used the 2N3906 resistor connecting the collector to the 12v ...
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3answers
206 views

Adding a dimming knob to a step up power supply

I am a ME student with little EE knowledge, and I currently have a setup which includes a 12V SLA battery, a 100W LED chip and a constant-current constant-voltage step up converter. The board can be ...
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2answers
359 views

Measuring display brightness decay

Our device is specified to have a display brightness of 500 cd/m² and it must not decay to less than 50% brightness in 50,000 hours. Now, I can't wait for 5.7 years for that test to finish. I guess ...
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1answer
392 views

If LED's have different bin codes, how can I know what I am buying?

I will start by confessing I am a hobbyiest engineer (ie: still in school) and thus am open to allegations my concerns are not terribly important. However, I have this: I was looking at page three ...
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2answers
85 views

How bright are the dimmest LEDs and what's their typical usage? [closed]

High power extremely bright LEDs are more and more popular in various lighting applications. What about extremely dim low power LEDs? How bright are those and how are they typically used?
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2answers
612 views

Keep brightness high whilst multiplexing [SOLVED]

I have searched a little but I'm a noob to electronics so it was hard for me to understand. So here is my problem. I have made a little 3 x 3 led matrix to test. When powering 1 led it was fine, but ...
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3answers
3k views

shift register RGB led brightness

I'm currently using 74HC595 shift register to light leds. Recently I decided to start using RGB leds instead of simple 1-color leds. Which means that I now have to ...
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1answer
205 views

Does HDMI manage backlight?

I need to manage backlight on a 7 inches touch screen from Chalkboard Electronics that has a HDMI connector and a power jack only. I only need to power backlighting on and off. Can it be done through ...
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2answers
2k views

LED blinking with capacitor and schottky diode?

I saw one circuit which connected one 100uF capacitor and one schottky diode as mentioned in the below circuit diagram. It has a negative logic rectangular pulse at cathode of the LED, which is ...
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1answer
9k views

How to add lumens

I have n bulbs of luminosity k in fixture a. How many bulbs of luminosity l do I need in fixture b for the brightness of a to match the brightness of b? Specifically, I'm wondering how many standard ...
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1answer
83 views

How does area and intensity relate to perceptive brigthness of a light source?

I want to design tail-lights for onboard use in vehicles (mostly bicycles), but I wonder how should I configure the system so as to get the best visual perception from a distance. Each lighting ...
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3answers
7k views

Is there a simple way to diffuse the light of a “super bright” 5mm LED?

I want to put yellow leds inside the turning-signal cases used in motorcycles. The problem is: since the case is not deep enough, when I look from far I can only see the focused, pin shaped LED ...
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1answer
411 views

How to calculate image brightness for use with LED panel

I am using a 64x64 RGB LED matrix for which I'm preparing some content. The existing firmware reads RGB888 video files. I'd like to analyse these files before uploading them, to make sure the overall ...
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2answers
1k views

Applications of PWM?

I know the application of PWM is controlling the brightness of led or DC motor speed, but I don't understand it, why when we change the duty cycle, it change the brightness or motor speed ? Can you ...
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3answers
311 views

What is a suitable candela for a status led?

What is a suitable candela value for a LED to have that doesn't blind you if you stare at it, and will still allow you to view silkscreen markings on the PCB but not to dim that you can see the ...
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1answer
927 views

LED strip brightness and its measurement - did I get ripped off?

I recently bought two 5m rolls of red and blue LEDs for building an hydroponic lettuce light. Each of them is supposed to have the following properties: 300 SMD 5050 LEDS 72 Watts 12 Volts 4500 ...
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1answer
234 views

Capturing brightness on IR Camera in daylight

I am wondering if an IR camera (or a camera with IR-cut) can capture the brightness of a retro reflective tape (high grade SOLAS) on screen in broad daylight. Since the main goal is to capture ...
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2answers
745 views

Will my 12V power supply ever burn these IR leds blinking at 38kHz even without a resistor?

I'm new to electronics, my background is mostly on the software development side... so go easy on me, as this might be a really stupid question. I just want to be sure what is safe to assume and what ...
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3answers
767 views

BJT switch vs amplifier mode

I'm getting really confused about a specific BJT circuit. I want to control LCD brightness and contrast as suggested here. Apprently a capacitor is used to filter PWM output to the contrast pin, and ...
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1answer
1k views

LCD brightness and contrast control with PWM

Is it reasonable to control LCD brightness and contrast directly with the PWM pins of an Arduino, or would it be advisable to use a capacitor/filter to get a constant analog voltage? I assume human ...
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5answers
916 views

EL wire brightness, per m not per m\$^2\$

The datasheets and catalog pages for commercial electroluminescent (EL) wire in hobby quantities, e.g., adafruit's, list brightness in candelas per square meter. That's ok for two-dimensional EL ...
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2answers
2k views

Brightness issues driving 10*11 SMD 5050 LEDs matrix

I'm working on driving a 10*11 LEDs matrix by a µC since a while, and I decided to come to you because I'm a bit surprised/annoyed by my results. So, I first started with simple 5mm white LEDs ...
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3answers
734 views

Regulate brightness over video composite signal

I have a b/w camera that outputs a video composite signal. At night it works very well, but during the day it's so bright everything just turns white. Is it possible to add a potentiometer to be able ...
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2answers
230 views

Choosing an LED

a friend has asked me to help them with a LED billboard type of art piece. It's envisioned to basically be ping pong balls cut in half with LEDs mounted under them. She got some jumbo (10mm) LEDs for ...