Optocoupler Types, Applications with Examples and Circuit Diagrams



Optocoupler is a component which uses light energy to connect two different electrical circuits or transfer energy from one circuit to another circuit. Two circuits are completely electrically isolated to each other that means there is no electrical connection between them. In this article, we will discuss 
Optocoupler Types, Applications with Examples and Circuit Diagrams





Optocoupler has also some different names such as Opto-isolator, optical isolator, photocoupler, etc.

Optocoupler mainly comes within ICs. IC 4N35, IC PC817, and other 4NXX series ICs are examples of optocoupler ICs.

Let's see what inside an optocoupler IC.


Optocoupler Construction



Optocoupler


As you see in the above figure the Optocoupler IC divided into two sections, one is the Light emitter section and another section is a light receiver or light sensor. The optocoupler mainly has two elements one is a light source, it may be LED, LASER, Infrared etc. Another element is a light receiver such as it may be a Phototransistor.


We know that when a light is applied to the base of the phototransistor it conducts current. This principle is used in the optocoupler. So when we give electricity to the optocoupler then it creates a light which may be visible or Infrared and it is false upon the base of the transistor hence the transistor starts conducting current.
When the applied light is off then the transistor stops conducting.




Different Types of Optocoupler



1. Photo-Transistor Optocoupler



Photo-Transistor Optocoupler, Optocoupler Types and Applications


As you see in the above diagram the photo-Transistor Optocoupler has an IR LED as a light source and a phototransistor as a light sensor or light receiver.
In Six terminals optocoupler, the 6th no pin is connected to the base of the transistor to control the sensitivity.



2. Photo-Darlington Optocoupler



Photo-Darlington Optocoupler, Optocoupler Types and Applications


In Photo-Darlington, two transistors are used. When IR light falls upon the base of one transistor it turns on the other transistor.






3. Photo-SCR Optocoupler



Photo-SCR Optocoupler, Optocoupler Types and Applications



As you see in the above figure, the Photo-SCR Optocoupler uses an SCR inside it. When the light falls upon the gate of SCR it will turn ON. To control the sensitivity the gate terminal of the SCR is connected to 6th no. pin.



4. Photo-DIAC Optocoupler



Photo-DIAC Optocoupler, Optocoupler Types and Applications



5. Photo-TRIAC Optocoupler



Photo-TRIAC Optocoupler, Optocoupler Types and Applications




Examples of Optocoupler ICs


Example of Photo-Transistor Optocoupler IC, PC816, PC817, LTV817, K847PH

Example of Photo-Darlington Optocoupler IC, 4N32, 4N33, H21B1, H21B2, H21B3

Example of Photo-TRIAC Optocoupler IC, IL420, 4N35

Example of Photo-SCR Optocoupler IC, MOC3071, IL400, MOC3072

Example of Photo-DIAC Optocoupler IC, MOC3020, MOC3021





Applications of Optocoupler


1. The main application of optocoupler is to isolate two different electrical circuits.
2. Optocouplers are used in solid state relays.
3. Optocouplers are used for ground isolation purposes.
4. Optocouplers are used for high voltage monitoring and sensing circuits.
5. Optocouplers are used in lamp dimmer circuits.
6. Optocouplers are also used in Motor control circuits.
7. Optocouplers are used in lighting control circuits.
8. Optocouplers are used in switch mode power supply(SMPS)
9. Optocouplers are used in DC to DC converter circuits in automobiles.




Motor Control Circuit using Optocoupler


The motor control circuit using Photo-DIAC optocoupler is given below.


Motor Control Circuit using Optocoupler, Optocoupler Applications


You can see in the above circuit diagram, the pin 1 and 2 of the optocoupler are connected to a DC source through a switch and a resistor.

The motor is connected to the AC supply through a TRIAC. Here the Photo-DIAC optocoupler is used to trigger the TRIAC.

When we turn ON the switch, the IR LED inside the optocoupler will turn on and the light falls upon the DIAC. When the DIAC starts conducting, the TRIAC will be triggered, therefore the motor will turn on.

As you see the high voltage AC circuit and low Voltage DC circuit is isolated to each other by the Optocoupler.






Read Also:




Thank You For Visiting the Website. Keep Visiting for more updates.

Optocoupler Types, Applications with Examples and Circuit Diagrams Optocoupler Types, Applications with Examples and Circuit Diagrams Reviewed by ETechnoG on 08:05 Rating: 5
Powered by Blogger.