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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.

8
votes
4answers
10k views

Is it OK to attach an LED directly to a 5V Attiny?

From the datasheet, I though the AT90S1200 had current-limited pins and when running at 5V would sink the proper amount of current through a green LED attached to + (0 turns on the LED, 1 turns it off)...
8
votes
5answers
14k views

Best way to control 75 LEDs with Arduino

I need to control 25 groups of 3 LEDs or 25 RGB LEDs. Each group will be dismissed from the uC by up to 20 cm (about 8 inches). 20 cm is very safe assumption but I think it will be 10 cm or less. ...
10
votes
7answers
760 views

How to identify LED markers by modulating their brightness?

For a project of mine I need to use infrared LED markers to identify locations of points in space with stereovision algorithms and multiple IR cameras. I also need each LED marker to have a unique ...
4
votes
4answers
19k views

Turn-on voltage for LED

I have a bunch of green LEDs (not super bright), the plastic around the actual LED is physically green, but they did not come with a turn on voltage. 3V seems to work but they're not too bright, is ...
7
votes
2answers
180 views

LED changing colour over time

Can a LED change colour over time? I've had a blue LED set up for some time and it use to be a much brighter (ultramarine blue) now it's heading to a more greenish dull colour. How is this happening?...
2
votes
3answers
349 views

Current source for CREE XLamp XP-G

Looking to play around with the CREE Xlamp series LED and was wondering what would I need to drive them off 110V household power? Output current needs to be in the range of 800-900mA. EDIT: I am ...
26
votes
15answers
25k views

Controlling 500 LEDs with PWM

I'm considering taking on a project that would involve individually addressing 500 LEDs, optimally with PWM support for each. I'm planning on using an Arduino since I already have one, but I'm open ...
5
votes
4answers
6k views

Arduino PWM controlling high-power LED

I'm wanting to use one of the Arduino's PWM output to control a high-powered LED. I can't remember the exact specifications, but it was considerably more current than the ATMega328 can provide. I ...
33
votes
5answers
6k views

Detecting light with an LED

How do I detect light with an LED?
9
votes
5answers
6k views

Red Green Blue LED

Do you need to use different resistors against each of the colours on an RGB LED?
8
votes
5answers
10k views

Is there a single IC that can control a 8x8 RGB LED Matrix

I was wondering if there was a single IC like the MAX6960 that could control a whole 8x8 RGB LED Matrix because the MAX6960 can only control a RGY.
4
votes
2answers
209 views

What does 'cathode-row' mean?

"The MAX6960–MAX6963 are compact cathode-row display drivers" What does cathode-row mean?
8
votes
4answers
3k views

LEDs for full daylight

I'm working on making a sign that will be outdoors in full sunlight and I want it to have the longest range visibility. This is a project for uni and I will probably need 100 LEDs or so - I need the ...
18
votes
5answers
9k views

current sourcing, current sinking

I'm a student studying electronics and I'm having trouble understanding the concept behind current sourcing and current sinking. We've covered it in a lab using a 7404 and an LED and all that. Just ...
7
votes
4answers
9k views

How to hook up a 5x7 LED matrix to Arduino?

What is the best way I can hook this 5x7 LED matrix to an Arduino board?
29
votes
11answers
16k views

I'd like to learn how to make my own USB gadgets

I've been writing Linux character device drivers for other people's stuff for some time. I'd like to find a new hobby and the thought of making my own USB gizmos seems really neat. I would be ...
6
votes
11answers
7k views

Using diodes to limit current to LEDs

I'm setting up an attiny2313 to drive an array of LEDs and blink them in different patterns. Rather than putting a series resistor in line with each LED (they'll be controlled separately, so I can't ...