Angular velocity is measured using devices called tachometers.Tachometers are instruments that measure angular speed by registering anyone of the following
Number of rotations during the contact period (or)
● Number of rotations per minute (rpm)
● Tachometers are classified as follows:
Mechanical Tachometers
1. Revolution counter and timer
2. Tacho Scope
3. Hand speed indicator
4. Slipping clutch tachometer
5. Centrifugal force tachometer
6. Vibration reed tachometer
Electrical tachometers
● Drag cup tachometer
● Commutated capacitor tachometer
● Tachogenerators
● DC – Tachogenerator
● AC – Tachogenerator
Contact Less Electrical Tachometers
1. Inductive pick up tachometer
2. Stroboscope tachometer
3. Photoelectric tachometer
4. Capacitor tachometer