Question
- Explain briefly the principle on which a transistor-amplifier works as an oscillator. Draw the necessary circuit diagram and explain its working.
- Identify the equivalent gate for the following circuit and write its truth table.
✓
Answer
- Principle: A portion of the output power is returned back (feedback) to the input in phase with the starting power. (This process is termed as positive feedback)
Working:
As the switch $S_1$ is put on, a surge of collector current flows in the transistor. This current flows through the coil $T_2$. The inductive coupling between coil $T_2$ and coil $T_1$ now causes a current to flow in theemitter circuit.As a result of thispositive feed back, the emitter current also increases. When the current in $T_2$ becomes saturated, it stops increasing. Now emitter current begins to fall and becomes minimum. The whole process keeps on repeating itself.
- AND Gate:
| A | B | Y = A.B |
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
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