OR gates are used to detect when one or more parameters exceed safe values, triggering protective measures. An example shows an OR gate detecting high temperature or pressure. AND gates can enable or inhibit data passage. An example shows an AND gate enabling frequency measurement by gating a known frequency pulse. Ex-OR/Ex-NOR gates are used for parity generation and checking. NOT gates, also called inverters, are commonly used to build low-power square wave oscillators for clock signal generation in a ring configuration.

1. Application of OR gate
Wherever the occurrence of any one or more than one event is needed to be detected or some
actions are to be taken after their occurrence, in all those cases OR gates can be used. It can be
explained with an example. Suppose in an industrial plant if one or more than one parameter
exceeds the safe value, some protective measure is needed to be done. In that case OR gate is
used. We are going to show this with the help of a diagram.
The above figure
is a typical schematic diagram where an OR gate is used to detect exceed of temperature or
pressure and produce command signal for the system to take required actions.
Application of AND gate
There are mainly two applications of AND gate as Enable gate and Inhibit gate. Enable gate
means allowance of data through a channel and Inhibit gate is just the reverse of that process i.e.
disallowance of data through a channel. We are going to show an enabling operation to
understand it in an easier way. Suppose in the measurement of frequency of a pulsed waveform.
For measurement of frequency a gating pulse of known frequency is sent to enable the passage of
the waveform whose frequency is to be measured. The diagram below shows the arrangement of
the above explained operation.

2. Application of Ex-OR/Ex-NOR gate
These type of logic gates are used in generation of parity generation and checking units. The two
diagrams below shows the even and odd parity generator circuits respectively for a four data.
With the
help of these gates parity check operation can be also performed. The diagrams below show even
and odd parity check.
Figure (a)
shows the parity check using Ex-OR gates and the figure (b) shows the parity check using Ex-
NOR gates.
Application of NOT gate or Inverters

3. NOT gates are also known as inverter because they invert the output given to them and show the
reverse result. Now the CMOS inverters are commonly used to build square wave oscillators
which are used for generating clock signals. The advantage of using these is they consume low
power and their interfacing is very easy compared to other logic gates.
The above
figure shows the most fundamental circuit made of ring configuration to generate square wave
oscillator. The frequency of this type generator is given by Where n represents the
number of inverters and tp shows the propagation delay per gate.