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Explain the working of transistor as an oscillator using a labelled circuit diagram. |
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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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