NPN + PNP Transistor Current Amplifier
Category: Transistor Logic
Designer: RANA MUHAMMAD ADNAN KHALIL
Notes
In this circuit you will understand how a transistor pair (npn + pnp) is used to amplify the current signal. Before understanding this circuit, it is recommended that first see Single Transistor Current Amplifier in Transistor Logic category. 1. The basic equations of any transistor are Ic = beta*Ib Ie = Ib + Ic 2. In this circuit output can be taken from emitter of Q2 or collector of Q2 transistor. 3. The input current signal is given at base of Q1, which is amplified and collector of Q1 is connected with the base of Q2. 4. Current meter is placed in series of every path to verify the equations of transistor. 5. You can see that for Q1 (NPN transistor) Ic_Q1 = beta_Q1*Ib_Q1 Ie_Q1 = Ib_Q1 + Ic_Q1 6. Similarly for Q2 (PNP transistor), Ic_Q2 = beta_Q2*Ib_Q2 Ie_Q2 = Ib_Q2 + Ic_Q2 7. Where, Ib_Q2 = Ic_Q1 Applications: 1. This circuit is used as current amplifier for very small input current. 2. This circuit can also be used to test transistor as an amplifier. 3. This circuit can also be used to verify the transistor equations. Note: More circuits are coming soon. If you like this app than please rate us 5 stars. Thanks