different types comparators and it's working

What is a Comparator? Types of Comparators

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Introduction


Comparators play an essential role in designing electrical and electronic projects. In electronic circuits, an op-amp is used with negative feedback and it can also be used as a comparator. The comparator is mainly designed without feedback for open loop configuration. These are widely used in A/D converters. When the i/p signal is sampled, then this signal is applied to multiple comparators to convert the digital form from analog.

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What is a Comparator?

A comparator is defined as, a device which includes two i/p terminals namely inverting and non inverting terminals.

One input terminal is fed with reference i/p signal and the remaining i/p is fed with the actual values of the signal.

The o/p signal can be generated based on the difference between two i/p signals either high or low.

Here low and high signals are denoted by 0 and 1.







What is a Comparator? The main purpose of the comparator is to compare two currents or voltages.

It fed to the two i/p signals and generates binary digital o/p signal that specifies which is greater is called as a comparator.

The two i/p terminals of the comparators are V+ and V- and the digital o/p is V0.

This o/p signal can be defined as

If V+ is greater than V- then V0 = 1and

If V+ is less than V- then V0 = 0,







Types of Comparators

Comparators are classified into different types such as

• Mechanical Comparator

• Mechanical-Optical Comparator

• Reed Type Comparator

• Electrical-Electronic Comparator

• Pneumatic Comparator







Mechanical Comparator







The mechanical comparator comprises the following parts


• Spring

• Pointer

• Pointer Attachment Fitting

• Damping Lever

• Measurement Spindle







Mechanical Comparator The mechanical comparator is also called as “microcator”.

In mechanical comparators, magnification is achieved by various mechanical devices and mechanical linkages.

Mechanical comparator is a measuring instrument.

The mechanism of this instrument is in the form of tape spring twisted, and that is positioned in the middle part.

The middle part of the mechanical comparator rotates through a fixed angle upon tension.








Mechanical comparators are classified into four types such as

• Dial Gauge Comparator

• Johansson Mikrokator Comparator

• Reed Type Comparator

• Sigma Comparator.







Advantage

Mechanical Comparator Less costly as compared to other devices.

Instrument do not require any external agency like air or electricity.

Usually mechanical Comparators have linear scales.

They are compact in design They are easily portable







Mechanical-Optical Comparator

In this comparator a small dislocation of the measuring plunger is first amplified by a mechanical system comprising of pivoted levers.

The mechanical movement which is amplified by an optical system connecting the outcrop an image.

The general arrangement of mechanical system causes a reflector to angle near the image

An axis of an index estimated on a scale on the inner glass screen.

Optical magnification offers a high degree of precision measuring.








In this system, the mechanical amplification is multiplied by optical amplification.

if the mirror is sloped by an angle 60, then the image will be sloped by 2×66.

Therefore, the total magnification of the system is 2 x (Z^i) (J4//3).

The optical comparators are proficient of giving a high degree of calculating accuracy.

It is because of high magnification & the discount off moving members to a minimum.








In this type of comparator, front reflection type mirror is used instead of normal back reflection type mirror.

In normal back reflection mirror type, there are two reflected images such as front and back.

One image is bright and other one is blurred both are observed.

The main advantage of this comparator is that deliver of an illumined scale allows readings to be taken without favour to the conditions of room lighting.







Reed Type Comparator






What Is a Comparator? Types of Comparators


This is a frictionless device for expanding small motions of the spindle.

It comprises of a static block A, which is strictly attached to the gauge head case.

The floating block B carries the gauging spindle & is connected horizontally to the static block by reeds C.

A perpendicular reed is attached to every block with the higher ends combined together







A linear motion of the spindle travels the free block perpendicularly causing the perpendicular reed to slide.

This effort roots the target to swing through an arc over the scale related to the distance moved by the spindle.

This type of comparators may have the compassions of the order of 0.25 micro/scale division.








Electric Comparators

In this comparator, the measuring contact movement is changed into an electrical signal.

Then this signal is recorded by a device that can be adjusted in terms of plunger movement.

For this, an AC Wheatstone bridge circuit including a galvanometer is used.

This electric comparator comprises of a tough stylus, an iron armature.








It breaks against the W and spring and W1.

If the armature is located between the coils W & W1, then the inductance of these coils is equal.

The Wheatstone bridge is stable and forms the datum line.

When the work piece is located under the stylus for the measurement purpose due to the difference in datum.

The armature, component size would either be raised up or down.








It defeats the Wheatstone bridge balance that results the unbalanced current flow.

This current is directly adjusted into difference in size of the component which is expanded by an amplifier specified by the galvanometer.

This current is directly adjusted into difference in size of the component which is expanded by an amplifier specified by the galvanometer.

The main advantages of these comparators are no moving parts, sensitivity and accuracy over long periods.








An electrical comparator consists of as follows

• Base a stand.

• Power unit.

• Measuring unit.

• Indication unit.

• Amplification unit.







Pneumatic Comparator








The working principle of pneumatic comparator

When the air under constant pressure discharges by passing through two openings.

If one of the hole is kept uniform, the pressure will change according to the size of the other.

The tube 1is connected to an air supply & via restriction jets2 to pipe 11.

Which dips into water in a deep vessel open to the atmosphere.







Pneumatic Comparator Air flowing at tube 1 increases in pipe 11 and keeps a fixed head of water-

H and extra of air outflows as bubbles.

Air from pipe11 flows through control jet3 & finally outflows through the measuring jet at 6.

The pressure in the tube b/n control jet 3 and calculating jet6 will depend on the orifice size at 6.

It is controlled by the distance b/n the measuring table and face.

It is replicated by the height of a liquid in the manometer pipe8.








The scale 9 is also adjusted that a head difference h specifies changes in the gap d enlarged various hundred times.

The main advantages of this comparator is, easy to operate, cheap, independent of the constant pressure.

It is free from mechanical wear and magnification is high as 10,000 times.







Applications of Comparators

Mainly involve in BLDC operating motors.

Zero crossing detectors.

Switching power regulators.

Peak detectors.

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Conclusion

This is all about a comparator and the types of comparators and its wide applications. A comparator compares two analog signals and produces a one bit digital signal.

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different types comparators and it's working

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