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Explain the use of a junction transistor as an oscillator. |
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Answer» Solution :An L-C circuit can be USED to produce oscillations of desired frequency. It consists of a tank circuit consisting of inductor L and capacitor C connected in parallel. The frequency of the tank circuit is given by `v=(1)/(2pisqrt(LC))` Due to the resistance of inductive coil, there occurs a small but constant energy loss and oscillations thus PRODUCED are damped. To transmit speech or music, we require undamped electromagnetic waves called carrier waves.  To do so an L-C circuit is coupled with transistor in such a way that there is a proper feedback to the L-C circuit at the proper timings so that the energy of L-C circuit REMAINS the same throughout oscillaitons. When key K is pressed, the collector attains positive POTENTIAL due to which a weak collector current will start rising in `L_(1)`. The increasing magnetic flux is linked with `L_(1)` and hence with L. |
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