[SOLVED] Principle of working for IR LED

[snishanth512]

Please explain with diagrams....

I am searching for IR LED of 940nm for my project.....

 

[tpetar]

Please explain with diagrams....

I am searching for IR LED of 940nm for my project.....

Explanation with diagram RX and TX :

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940nm is wave length for particular IR LED, there is also other wave lengths...

Do zou plan to make IR Remote Control, Illuminator for CCTV systems, Alarm sensor, Tachometer, .....

You should give more details what you need.

 

[snishanth512]

Why do we use resistor R2 in the diagram(given in the above reply)?

 

[jeffrey samuel]

Why do we use resistor R2 in the diagram(given in the above reply)?

Just to control the Collector Current of the above said design and fix our operating point in the required position

 

[tpetar]

Why do we use resistor R2 in the diagram(given in the above reply)?

Its Pull-Up resistor, and also he limit current and adjust sensitivity of phototransistor.



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If you want to learn more about logic states see this link and use Nvigation field :

https://www.electronics-tutorials.ws/logic/logic_1.html

 

[snishanth512]

So, when the phototransistor receives the photons the output tries to go down to zero.

It acts like an inverter. Right?

I have a one more doubt i.e. what is the difference between photodiode and phototransistor?

What modification should I do for using photodiode in the circuit?

 

[tpetar]

http://hades.mech.northwestern.edu/index.php/Photodiodes_and_Phototransistors

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[faryal]

what is the purpose or R1?

 

[godfreyl]

To limit the current flowing in to the LED to a safe value.