Tachometer is a device used for rotational speed monitoring. This instrument is used widely for measuring rotational speed of disks or shafts found in motors and other machines. Earlier, the market only had analog tachometers; however now, the majority of the stores selling this equipment also offer different kinds of digital units. You will come across these machines in aircraft and cars; a tachometer installed in these vehicles is also often referred to as the revolution counter. The units found in a rail vehicle, on the other hand, is commonly called wheel impulsive generator. In short, it can be said that manufacturers have come up with different kinds of products for different kinds of applications. The section below will educate you about different types of tachometers and their features.
Electronic units: This measuring equipment has been designed for measuring frequency of pulse waves or sine-waves. These units are known for possessing discriminating circuits, which clips and shapes the input sine waves. The resultant waves are then passed through a gate circuit to meet the decade counters. The device’s crystal oscillator performs the job of controlling this gate’s open time. The decade counters, on the other hand, remain responsive to all the pulses the gate passes at a particular moment.
Electric-generator units: This highly flexible electric tachometer includes an indicator and electric generator. The market houses two types of electric-generator units; the first type comes equipped with DC voltmeters and DC generators and the second type possesses AC voltmeters (or DC voltmeters with rectifiers) and AC generators.
Direct-current units: Experts refer to these units as DC tachometer. These are petite permanent-magnet generators with output ranging between 2 and 10 V/1,000revolutions/minute. This measuring equipment has low running and starting torque; this feature makes it a perfect tool for gauging wind velocity. Other than being used for measuring speed, this device also often plays the role of stabilizing components in velocity servomechanism of different kinds.
Alternate-current units: The most significant feature of these devices is that they can be built using stationary field winding and permanent-magnet fields that revolve. An AC tachometer works by generating frequency and voltage keeping pace with the rotational speed. Here, the term “rotational speed” refers to the speed in which the shaft or disk of the machine the tachometer needs to measure is rotating.
Eddy-current units: The majority of the people using this instrument refer to it as the “drag type” tachometer. The most common application of the eddy current units is in automobile speedometers. They are also used for gauging the speed of aircraft engines.