Electrical engineering

The two basic types of communications systems are: Analog communication systems, and Digital communication systems. An analog communication is a system in which the information signal is transmitted and received in an analog form means a continuously varying signal such as sine wave.  Here, both the information and the carrier are analog signals. In digital

When the field winding of a d.c machine is connected in parallel with the armature, as shown in Fig (a), the machine is said to be shunt wound. If the field winding is connected in series with the armature, as shown in Fig (b), then the machine is said to be series wound. A compound

Power in three-phase loads may be measured by the following methods : One-wattmeter method for a balanced load Wattmeter connections for both star and delta are shown in Fig. Total Power = 3 × wattmeter reading Two-wattmeter method for balanced or unbalanced load A connection diagram for this method is shown in Fig for a

A three-phase supply is generated when three coils are placed 120° apart and the whole rotated in a uniform magnetic field as shown in Fig (a). The result is three independent supplies of equal voltages which are each displaced by 120° from each other as shown in Fig (b). The convention adopted to identify each

There are a number of situations when digital signals have to be converted to analogue ones. For example, a digital computer often needs to produce a graphical display on the screen; this involves using a D/A converter to change the two-level digital output voltage from the computer, into a continuously varying analogue voltage for the

If both inputs of the op amp shown in Fig. 1 are used simultaneously, then from equation, the output voltage is given by: Vo = Ao(V2 − V1) When V2 > V1 then Vo is positive, its maximum value being the positive supply voltage + Vs, which it has when (V2 > V1) ≥ Vs/Ao.

Operational Amplifiers (usually called ‘op amps’) were originally made from discrete components, being designed to solve mathematical equations electronically, by performing operations such as addition and division in analogue computers. Now produced in integrated-circuit (IC) form, op amps have many uses, with one of the most important being as a high-gain d.c. and a.c. voltage

Networks in which electrical energy is fed in at one pair of terminals and taken out at a second pair of terminals are called two port networks. The network between the input port and the output port is a transmission network for which a known relationship exists between the input and output currents and voltages.

The maximum power transfer theorem states: The power transferred from a supply source to a load is at its maximum when the resistance of the load is equal to the internal resistance of the source. Hence, in Fig when R = r the power transferred from the source to the load is a maximum. Typical