Help with Circuit: Identifying Transistor Usage

[jaffer]

Hi

Can anybody help me in telling me what the two transistor in the picture of circuit i attatched are being used for?

Thanks in advance

 

[sophiecentaur]

They are both being used as 'drivers' to supply more current to the LED and Buzzer than the Integrated Circuits can deliver. Look up " electronic driver circuits" to see more examples.

Is this a Homework Question?

 

[jaffer]

nope it's just a general question and thanks for the quick answer.