A printed circuit board (PCB) is an or insulating board on which a circuit design is printed. Space is left for various components on the circuit board and conductive links are etched on the circuit boards to connect different components on the circuit board electrically to realize a circuit. As mandated by the application, the circuit boards consist of different components. A few of the essential components are discussed here.
Power source and voltage regulators
The power source is responsible for catering to the power requirements of the components and the circuit. There are different types of power modules available in different dimensions according to their power offering capability (in terms of voltage and current). The ratings of components should be kept in mind while choosing a power source. Additionally, they come in AC and DC. Choice is based on the requirement of the circuit.
Voltage regulators are used to draw a fixed voltage from the power source as long as the power source is having voltage value greater than the rated value of the voltage regulator. They are used for giving voltage isolation partly or whole of the circuit.
They are sacrificial protection devices. They are placed in a circuit in order to protect it. In case of heavy currents that can damage the circuit components, the fuse breaks the circuit by damaging itself and thus protects other components.
Resistors are used to limit the current to a circuit. They offer hindrance to the path of electrons and the resultant power loss is released in the form of heat. Resistors come with color codes, which is helpful in determining their value. The cross section of the resistor is decided by the wattage of the resistor. If it has to dissipate more heat, the wattage will be more and its cross section will be more. The leads of resistor do not have polarity.
Potentiometers are variable resistors. They come mostly with three legs. Two legs are for the power source and the third leg is the tapping leg. Potentiometers of different values are available in the market. A knob is generally provided to change the tapping of the middle leg.
Capacitors are responsible for storing charges. Capacitors are two legged components and come in different shapes, sizes and rating. The cylindrical ones are called electrolytic capacitors. They possess polarity. Ceramic capacitors do not possess polarity in legs.
Inductors store energy in the form of a magnetic field. They are in the form of coils.
Diodes, transistors and rectifiers
Diodes and transistors are switches. A diode is an uncontrolled switch whereas a transistor is a controlled switch. A transistor can be used as an amplifier as well. Rectifiers are circuits that consist of diodes and converts AC into DC.
Crystal oscillators are used to enhance the frequency performance of a circuit. It consists of a piezoelectric crystal. The rating of the crystal oscillator is clearly marked on the crystal.
Relays are electromagnetic switches. They react according to voltage or current changes and change the position of the internal plunger to divert the circuit and switch currents or voltages.
These are heavily architectural and miniaturized circuits. They are meant for a specific purpose and can also be programmed to do certain functions.