Questions tagged [brightness]
Brightness is an attribute of visual perception
45
questions
0
votes
3answers
55 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 ...
0
votes
1answer
34 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 ...
0
votes
1answer
40 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 ...
5
votes
6answers
971 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 ...
0
votes
3answers
90 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 ...
0
votes
1answer
93 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 ...
0
votes
2answers
108 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 ...
2
votes
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 ...
0
votes
1answer
416 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 ...
0
votes
1answer
59 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 ...
0
votes
1answer
60 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 ...
0
votes
1answer
433 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 ...
0
votes
3answers
214 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.
...
0
votes
3answers
334 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)....
3
votes
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 ...
1
vote
3answers
479 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 ...
0
votes
1answer
304 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 ...
0
votes
1answer
99 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 ...
0
votes
3answers
184 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 ...
0
votes
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 ...
7
votes
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 ...
2
votes
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 ...
0
votes
3answers
204 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 ...
3
votes
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 ...
1
vote
1answer
360 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 ...
-2
votes
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?
1
vote
2answers
586 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 ...
0
votes
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 ...
0
votes
1answer
199 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 ...
6
votes
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 ...
2
votes
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 ...
4
votes
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 ...
3
votes
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 ...
2
votes
1answer
408 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 ...
0
votes
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 ...
2
votes
3answers
294 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 ...
3
votes
1answer
919 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 ...
-1
votes
1answer
226 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 ...
1
vote
2answers
727 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 ...
2
votes
3answers
762 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 ...
0
votes
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 ...
3
votes
5answers
901 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 ...
2
votes
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 ...
2
votes
3answers
696 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 ...
4
votes
2answers
228 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 ...
