Transistor Crystal Oscillator Circuit

1.   What is Crystal Oscillator ?

Ans. Crystal Oscillator is an oscillator that produces electrical Oscillations at a frequency determined by the physical characteristics of a piezoelectric Quartz Crystal.

2. Why is Crystal Oscillator is Used in Radio Transmitter ?

Ans .  1. The Oscillation Frequency of a Crystal oscillator equals the series resonant frequency of the Crystal .

2. Different Oscillation Frequency Can be obtain by simply replacing One Crystal with another.It makes it Easy for Radio transmitter to work at different frequencies.  That is why Crystal Oscillator is Used In Radio Transmitter.

3. Working
 

The naturally occurring quartz is difficult and costly process The basic phenomenon behind working of a quartz crystal oscillator is the inverse piezo electric effect i.e., when electric field is applied across certain materials they start producing mechanical deformation. These mechanical deformation/movements are dependent on the elementary structure of the quartz crystal.  Quartz is one of the naturally occurring materials which show the phenomena of piezo electricity, however for the purpose of resonator it is artificially developed since processing.

                                    4.  A Piezoelectric crystal (a) Symbol
                                                                              (b) electrical model

                      
                                      5. A typical Colpitts transistor Crystal Oscillator Circuit

Some important points about the Crystal Oscillator

1. It make of crystal for  frequency stability.

2. It make used RFC ( Radio Frequency coil) and inductor in its circuit thus more bulky.

3. Higher frequency upto 100 MHz crystal may be used for its operation.