Who think LEDs Are simple?

This is my first Topic in this community :slight_smile: Today i wanna explain some thing about Light Emitting Diodes (LEDs)

A Light emitting diode (LED) is essentially a pn junction diode. When carriers are
injected across a forward-biased junction, it emits incoherent light. Most of the
commercial LEDs are realized using a highly doped n and a p Junction.


=>Generally LED is simple , but if we add just Arduino Uno3
without any electronic component we can use it for security for example when it’s detect light in dark , turn on alarm :smiling_imp: i was use it in school :sweat_smile: in my cell :sweat_smile: … anyway we can use this idea in much. it will work like Ultrasonic send waves and if a object in domain waves, will turn on alarm

But the problem, we know LEDs
just output Light not input Light by diode.
The Actual Idea we will write a code make for us LED output light and input light in same time then logs changes in Serial Monitor
Tools :

  1. 2 LED // LED1 Receive Light (input) and LED2 (Output)
  2. Arduino Uno3
  3. Arduino IDE
  4. and your mind, because i will not be explain some parts. :relaxed:
    Source code :
    This is a Video maybe will explain what i mean :blush:


great thanks to all member community :wink:


Welcome man! Congrats on your first article :slight_smile:

Speaking of LEDs, my room is fitted out with them, they make for an edgy and cool hacker space :grin:


Interesting article. I have been working with LEDs with my arduino and they amaze me how simple yet intriguing they are.

Nice article and welcome to the community!


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thank you brother :wink:

:smile: yep they light help us for thinking :blush:

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@Techno_Forg and your welcome thank you man

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@pry0cc :blush: thank you too

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Using LEDs as inputs is pretty interesting! Didn’t know that was possible (and it’s actually useful for me), thanks for the article.

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What is the sensor you use on the A3 pin?

hmmm so this is a bot post?

thank you @Leeky I hope the article helps you a lot

@fxbg Yes :slight_smile:

but you still havent said what the input on a3 is

:smiley: just when you will see A3 its mean input in ANALOG IN exactly A3

yes i know what the analog inputs are lol i was asking what sensor you used on a3

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