Wave-shaping and switching circuit
*Concept of wave shaping
Wave shape circuit is used to change the wave shape[ Wave form ] to the desired shape.
They are two types
1. Linear wave shape.
2. Non-linear wave shape.
1] Linear wave shape:- These wave shape are passive component such as resistance,                                                    capacitance and induct-or. In this wave shape but just change phase                                        and amplitude of wave.
                                      Example:- 1. Low pass filter
                                                        2. High pass filter
                                                        3. Alternator
 2] Non-linear wave shape:- These wave shape consist resistance, Capacitance and Induct-or
                                            , Diodes and zen-er diodes. When the input is sinusoidal then                                                  the output waveform is not same shape. 
                                             Example:- 1. Clipper circuit                                                                                                                         2. Clamping circuit
* Transistor as a switch 
Transistor can be employed as an electronic switch. In the circuit a load RC is connected in the collector circuit across the supply vcc. When transistor is used as a switch it is operate cut-off and saturation region.
cut-off region:- When the input base voltage is zero or negative, the transistor is said to be off condition. In this condition base current 
                                                        I [ current ]B- 0
                               Power loss = output voltage x output current
Saturation region:- When the input voltage is made so much positive that saturation collector current flows the transistor is said to be ON condition.
Working:- When the switch S is open, the transistor is in cut-off state and no current flows in the collector circuit. Thus , the transistor behave as an open switch for the collector circuit . when the switch S is closed , base - emitter junction is forward biased and the transistor comes into the conducting state. At this state , current flows in the collector circuit. Thus the transistor behaves as a closed switch.
The transistor is ON state if .
Advantage:-
- It gives noiseless operation.
 - It has smaller size and lighter in weight .
 - It has no moving parts and hence there is little wear and tear.
 - It is cheaper than other switches and requires less maintains.
 
- Transistor is used as switch to drive LED display.
 - Transistor is extensively used as switch in modern inverters.
 
*Switching Circuit 
A circuit (or network) which can turn OFF or ON current in an electrical circuit is known as a switching circuit. 
A switching circuit essentially has the following two parts: 
- Switch
 - Associated circuitry
 
SWITCH:- 
A device which can turn ON or OFF an electric circuit is known as a switch. In general , depending upon the operating mechanism, switches may be classified as 
- Mechanical switches
 - Electro - mechanical switches (relays)
 - Electronic switches
 
- Mechanical switch :-A switch that is operated mechanically to turn ON or OFF current in an electrical circuit is known as a mechanical switch.
 
- Electro- mechanical switch :- A mechanical switch that is operated electromagnetically in order to turn ON or OFF current in an electrical circuit is known as an electro-mechanical switch.
 
- Electronic switch :- An electronic device (transistor or tube) that turns ON or OFF current in an electrical circuit is known as an electronic switch .
 




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