I have a Arduino project which controls LED using IR Receiver and Transistor.The circuits works fine,But the problem is the LED is Blinking Brightly only for short range basically between 5-8 cm,but when i used my TV remote it works at for very long range(above 1 m).I have tried giving high voltage to IR Transistor,but no use. Please help to solve this problem!! Thanks in Advance!

  • Are you just using digitalWrite() to turn the LED on and off, or are you modulating it with a carrier frequency?
    – Majenko
    Nov 4 '19 at 16:00
  • What is it you are trying to achieve? It might be better to use a IR receiver instead of an IR phototransitor.
    – Gerben
    Nov 4 '19 at 16:10
  • @Majenko iam using just digitalWrite() to turn LED ON and OFF
    – Arjun Achu
    Nov 4 '19 at 16:16
  • Please add your circuit and your code to the question
    – chrisl
    Nov 4 '19 at 16:18
  • @chrisl iam just using the arduino to turn IR Transistor on and off
    – Arjun Achu
    Nov 4 '19 at 16:20

The reason your TV remote can work over a much longer distance is because it doesn't just turn an LED on and off.

Instead it turns the LED on and off really fast, and then turns that "turning on and off" on and off as well.

In technical terms: the light is modulated with a carrier frequency. Just the same as a radio signal is modulated with a carrier frequency, you can do the same with light.

The receiver then samples the light falling on it over time and passes it through a band pass filter to remove any frequencies in the changes of light intensity that aren't within the frequency of the carrier signal. What is left is then low-pass filtered to recover the overall "on-off" signal that is being transmitted.

Much of that is hard to do using an Arduino, so an IR receiver is used which integrates all the filtering and recovery of the signal. These are sold with different frequency sensitivities, and if you then turn an IR LED on and off at that stated frequency it will be able to "see" it far more efficiently than just having a light on or off.

There is a library for the Arduino that can handle the modulating of the LED at the right frequency for your chosen IR receiver.

  • thanks for the help
    – Arjun Achu
    Nov 4 '19 at 16:34

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