- Zener regulator under varying input voltage condition
- It can be seen the input is
- Vo=Vzis constant
- IL = Vo/Rl = Vz/Rl = constant
- And I = Iz+IL
- Now If Vin increases, than the total current I increases. But IL is constant as Vz is constant as Vz in constant. Hence the current Iz increases to keep IL constant
- But as long as Iz is between Izmin and Izmax, the Vz i.e output voltage Vo is constant
- Thus the changes in input voltage get compensated and output is maintained constant.
- Similarly if Vin decreases, than current I decreases. But to keep IL constant, Iz decreases. As long as Iz is between Izmax and Izmin the output voltage remains constant.
- the maximum power dissipation for the zener diode is fixed and given by
- Pd = VzIz max
Miller Crystal Oscillator Miller Crystal Oscillator Similar to modifications in Colpitt's oscillator, the Hartley oscillator circuit can be modified, to get Miller crystal Oscillator In Hartley oscillator circuit, two inductors and one capacitor is required in the tank circuit. One inductor is replaced by the crystal which acts as an inductor for the frequencies slightly greater then the series resonant frequency. The tuned circuit of L1 and C is offtuned to behave as an inductor i.e. L1. The crystal behaves as other inductance L2 between base and ground. the Internal capacitance of the transistor acts as a capacitor required to fullfill the elements of the tank circuit The crystal decides the operating frequency of the oscillator.
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