Comparators are classified into several types, such as electronic comparators, electrical, mechanical, optical, sigma, digital and pneumatic, these are used in various applications. Comparators play an essential role in the design of electrical and electronic projects. In electronic circuits, an op-amp is used with negative feedback and can also be used as a comparator. The comparator is designed primarily 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 of analog. Comparator applications mainly involve BLDC operation motors, zero crossing detectors, switching power controllers and peak detectors.
The Sigma Comparator
FIG. Shows the constructive details of Sigma
Mechanical comparator
The vertical beam is mounted in flat steel Springs A connected to fixed elements, which in turn They are screwed to a back plate. The set provides a Movements without friction with a restriction of Springs The rod B at the base of the vertical beam is Ready to take a measuring contact, The range available. The stop C is provided to restrict movement to The lower end of the scale. Mounted on the fixed members, is the article Set D carrying the forked arms E. This assembly It incorporates a hardened fulcrum (provided with Means for adjusting the control of the trans- Moved) on the face of a jeweled insert In the flexible part of the set. The metal tape, attached to the forked arms, It passes around the G-axis that rotates it in Specially designed miniature ball bearings. Dipping The action to the movement is affected by a metal disc, Mounted on spindle, rotating in a magnetic field Between a permanent magnet and a steel plate. the Indicating the pointer H is secured to a protrusion on the disk.
The trigger J (opposite K) is used to protect the measuring contact. At the upper end of The vertical beam provides an adjusting screw for the final zero adjustment of the scale. A new feature is shown in K. This is a magnetic counterweight that serves To neutralize the positive "rate" of springs reaching the measuring tip. In this way, a constant Pressure is reached on the whole scale. The instrument is available with vertical capacities of 150 mm, 300 mm and 600 mm And extensions of 500.1000, 1500, 3000 and 5000. The scales are graded in English And metric systems. The minimum count representing a division of the order of 0.25 microns.
Advantages:
It has a bold scale and a larger indicator.
Disadvantages:
(i) Due to the movement of the parts, there is wear on the moving parts.
(Ii) Not as sensitive as other types of comparators due to friction Present in moving parts.