GAJENDRAN RAO

A14KE0064

Understanding on OPTOCOUPLER

The above IC is the OPTOCOUPLER wich is consisting 6 pins and covered by poxy

Functions

Usually put in between HIGH voltage circuit and LOW voltage circuit These to isolate the HIGH voltage circuit and LOW voltage circuit directly contacted by each

other Moreover, by putting these OPTOCOUPLER between HIGH voltage circuit and LOW voltage

circuit it will prevent the LOW voltage circuit components from destroyed if there is something goes wrong in HIGH voltage circuit.

Its has the same concepts of circuits relay

The optocoupler ic configuration

These ic was integrated by using simple components which is infrared LED which was realy tiny and its work under 1.2 volts and about 20 miliampere.( HIGH voltage circuit is connected to these part)

Its also have phototransistor (LOW voltage circuit is connected to these part)

The OPTCOUPLER working principals

When at input part have HIGH voltage supply the OPTOCOUPLER is connected then other part is connected with LOW voltage circuit.

When the infrared LED receive currents from HIGH voltage supply it will emits infrared lights to the phototransistor.

The phototransistor will detect the emmited light at base cousing it to be switched on and work as normal bipolarjunction transistor

As we see in the circuit above the base phototransistor is connected to a resistor and then to ground this is because to control the sensitivity of the switch on the LOW voltage circuit and make it more stable.

We can also connected the BASE to the ground strainght way but the swicthing of the cuircuir will not stable.