The comparator plays an important role in the electronic circuit design. Types of comparators are categorized into several kinds, namely electronic, electrical, optical, mechanical, sigma, pneumatic and digital comparators. Comparators play a vital role in making electrical and electronic projects. In electronic circuit design, an operational amplifier is used with negative feedback and it can also be used as a comparator. The designing of the comparator can be done without feedback for open loop formation. These are used widely in analog to digital converters. When the input signal is sampled, then the signal is applied to numerous comparators to change the digital form from the analog form. The comparator applications involve in zero crossing detectors, BLDC operating motors, switching power regulators and also in peak detectors. This article gives an overview of different types of comparators and its applications.
Different Types of Comparators
The comparator is a simple circuit and moves the signals from analog to digital. The comparators are used to compare the two analog signals to produce the one-bit digital signal. It should satisfy some conditions which are like when the positive voltage is greater than the negative voltage, then the output bit should be one or if the positive voltage is smaller than the negative voltage, then the output bit is one. The symbol of the comparator is following. ‘
The different types of comparators are following
- Mechanical Comparator
- Electrical – Electronic Comparator
- Read type Comparator
- Pneumatic Comparator
- Mechanical – optical Comparator
The mechanical comparator is designed in the year 1930 by the “Johnson Company” in Sweden and this comparator is also known as Microcator. In this type of comparator, the magnification is occurred by the mechanical devices and mechanical linkage. The mechanical comparator is a measuring instrument, the mechanism of this instrument is tape spring twisted and it is positioned in the middle part. The rotation of the middle part is fixed angle upon tension which can be observed in the figure. By using relative contact method the comparator is used for linear measurement.
There are different types of mechanical comparators which are following
- Dial Gauge Comparator
- Johansson Mikrokator Comparator
- Reed Type Comparator
- Sigma Comparator
- The prices are very low by comparing with the other devices
- It doesn’t require any external power supply like air, electricity
- The linear scales are present in the mechanical comparators and they are easily understandable
- These comparators are easy to handle and compact
- The range of the instrument is limited as the pointer moves over a fixed scale
- Error due to parallax is possible as the moving pointer moves over a fixed scale
The principle of the electrical comparator is to convert linear displacements into an electric output. In this comparator, we will use the whetstone bridge circuit and the working of this comparator can be done by using the step up and step down transformer. There are three components required for the electrical comparator which is like transducer, amplifier and display device as a meter. The working of the electrical comparator is described below.
The armature is placed center in between the coils, the inductance of both coils is equal and opposite direction with different signs. Hence the bridge stone circuit is balanced, thus the meter will read zero, but it is not possible practically. In the practical cases, the armature will be lifted up and lowered down through the plunger when the measurement is done.
Hence this will be unbalancing the Wheatstone bridge circuit. Due to this effect, there will be changes in current or potential will be induced correspondingly, at this time the meter will indicate some values as a displacement and the indicated value is a small or large component. If the induced current is too small then it should be amplified before displaying in the meter.
- Very less number of moving parts are available in the electrical comparator
- In this comparator there is high magnification and
- The mechanism carrying the pointer is very light and not sensitive to vibrations
- It is more expensive than the mechanical comparator
- Heating of coils in the measuring unit may cause zero drift and alter the calibration
The electronic comparator has a base stand, powering unit, measuring unit, indication unit, and amplification unit. In this, the measuring contact progress is changed into the electrical signal. Hence the signal is recorded by a device which can be adjusted in terms of plunger movement. This comparator compares tough stylus, armature iron to break against W & spring & W1. In between the coils of W & W1 armature is located thus the inductance of this coil is equal. The Wheatstone bridge stands stable from the datum line.
The component size of armature should be raised up or down and it overcomes the circuit of Wheatstone bridge balance and the result will be as unbalanced current flow. The current is directly tuned into the different sizes of the comparators and they are prolonged by an amplifier specified by the galvanometer. The precision of this comparator is 0.001 mm.
- In this comparator, there are no moving parts
- They are sensitivity
- The accuracy period of this comparator is very long
The working principle of the pneumatic comparator is pressure difference is generated by the air flow. The supplied air is at constant pressure from the jaw and air will escape from the jets through a restricted space which is applied from the back pressure. The difference in the back pressure is used to find the dimensions of a component.
The figure shows the air is compressed in the compressor with a high pressure and it is equal to the water head H. The overload air is escaping from the baddies and some specific amount of air passes through the orifice with a constant pressure. Therefore, due to a limited area at the A1 position, the back pressure is generated by the water head displaced at the tube of the manometer.
To mention the rotations of the job, it is rotated along the jet axis and if there is no difference in the pressure reading then the job is said to be as a perfectly circular at the position of A1. Hence the same procedure is repeated at different positions like A2, A3, A4 we can find pot different positions & variations in the pressure reading.
- The operation is very simple and low price
- Indicating & measuring is done at two different places
- The gauging members are direct contact with the work
- These comparators are very sensitive are temperature and humidity.
- For different job, it requires different gauging heads
Applications of Comparators
The applications of comparators are following
- Null detectors
- Zero-crossing detectors
- Relaxation oscillator
- Level shifter
- Analog-to-digital converters
- Window detectors
In this article, we have discussed the different types of the comparator and its applications. I hope by reading this article you have gained some basic information about the comparators and its applications. If you have any queries about this article or to implement electrical projects for engineering students, please feel free to comment in the below section. Here is the question for you, What is a comparator & functions of comparator?