Electrical Engineering

FET vs. BJT   Advantages: • FET has very high input impedance compared to BJT so that it can be used in amplifiers. • FETs are more temperature stable. • FETs are smaller in size. Limitations: • BJT has higher sensityvitty in change of signals than FETs. This property makes higher current gain in BJT’s output than FETs.

Differential Amplifier   Different input mode: • Single Ended input, v i1 exists, v i2 grounded. • Double ended, both inputs exist. • Common mode, same input signal is applied at both the input terminals.

Operational Amplifier • Number of differential amplifier in cascade. • Integrated circuit • High Gain • High input impedance • Low output impedance Basic OPAMP  

     OPAMP applications   • Linear Application : Output changes in  accordance with input. Example : inverting amplifier, voltage  buffer, non-inverting amplifier, current  controlled voltage source etc. • Non-linear Application : Output wave shape is different from that of input signal.  Example : Differentiator, integrator, Comparator, Schmitt trigger, Zero crossing detector etc.

The AC induction motor is a rotating electric machine designed to operate from a three-phase source of alternating voltage. The stator is a classic three-phase stator with the winding displaced by 120°. Medium construction complexity, multiple fields on stator, cage on rotor High reliability (no brush wear), even at very high achievable speeds Medium efficiency at low speed, high efficiency at high speed Driven by multi-phase Inverter controllers Motor EMI good but... terrible EMI from inverter Sensorless speed control possible Low cost per horsepower, though higher than for 1-phase AC induction motor Higher start torque than for 1-phase, easy to reverse motor Inverter shoot-through' possible, requires dead-time' circuits and compensation

MULTISTAGE AMPLIFIER        Cascaded Connection    Output of one stage is connected to the input of another stage Overall gain A V = V O2 / V in 1   =    A v1 * A V2

Armature Winding : The complete assembly of conductors carried on the armature and connected to the commutator or to the terminals of the machine is called a r mature winding. field winding :   field coil: the electric coil around a field magnet that produces the magneto motive force to set up the flux in an electric machine.