(a) Draw the circuit diagram for studying the characteristics of a transistor in common emitter configuration. Explain briefly and show how input and output characteristics are drawn. (b) The figure shows input waveform A and B to a logic. Draw the output waveform for an OR gate. Write the truth table for this logic gate and draw its logic symbol.

A B C
0 0 0
1 0 1
1 1 1
0 1 1
Input characteristics:
Connect the circuit as shown in the circuit diagram.
Keep output voltage VCE=0V by varying VCC.
Varying VBB gradually, note down base current IB and base-emitter voltage VBE.
Step size is not fixed because of the non-linear curve. Initially, vary VBB in steps of 0.1V. Once the current starts increasing very VBB in steps of 1V up to 12V.
Repeat above procedure (step 3) for VCE=various V
Output characteristics:
Connect the circuit as shown in the circuit diagram.
Keep emitter current IB = 20A by varying VBB.
Varying VCC gradually in steps of 1V up to 12V and note down collector current IC and Collector-Emitter Voltage(VCE).
Repeat above procedure (step 3) for IB = 60µA, 0µA.