The Schmitt-trigger is a circuit which creates hystereses and which is useful in digitizing an analog signal into a digital signal of either high or low. The hystereses makes inputs more immune to noise. The input must surpass a low threshold voltage before the output goes low, and likewise the input must exceed a high level threshold before the output goes high.

LM386 is a low voltage audio amplifier and frequently used in battery powered music devices like radios, guitars, toys etc. The gain range is 20 to 200, gain is internally set to 20 (without using external component) but can be increased to 200 by using resistor and capacitor between PIN 1 and 8, or just with a capacitor.

H-bridge is the circuit in which voltage can be applied across the load, in either of the direction. These circuits are frequently used in robotics, especially for the DC motor. Voltage can be applied in either direction to rotate the DC motor forward or backward

This gate is mainly used in applications where there is a need for mathematical calculations. So calculators, computers and many digital applications use this gate.

IR Transmitter and receiver are used to control any device wirelessly, means remotely. TV remote and TV are the best example of IR transmitter and receiver. TV generally consist TSOP1738 as the IR receiver, which senses modulated IR pulses and convert them into electrical signal.