Sensors and Control Systems (Electrical and Electronic Engineering) - Lab Report Example

Rotating a DC electric motor’s rotor like tacho generators will produce electricity and voice-coil speaker can also act as microphones. It consist of a nickel wire of 0.5-1 mm diameter kept stretched between the poles of a permanent magnet and having a small stylus rigidly attached to it at the mid-point. The wire is prestressed by twisting it, before being installed into the position. Two pick-up coils of fine wire are wound round the wire on either side of the mid-point. Any displacement of the stylus to one side or the other increases the torsion on the side and decreases it by an equal amount on the other side.

This results in an increase of magnetic flux in one-half and a decrease in the other half. The corresponding induced emfs are in phase opposition and are processed by suitable networks as in the case of linear variable differential transformer. It is used as phonograph pick-up and is designed to have flat frequency response over 150 Hz- 15 kHz frequency range. Due to the nonlinearity and hysteresis in the performance, it is normally limited for use when time- varying torsions of small amplitude are to be measured.

It was discovered in 1879 and belongs to one of the galvanomagnetic phenomena in which the interaction between the magnetic field and the moving electrical charges results in the development of forces that alter the motion of the charge. When an external magnetic field is applied to the current carrying hall element perpendicular to the current flow a Lorentz force acts on the current due to which a voltage called hall voltage is generated perpendicular to both the current and the magnetic field.

This voltage is so small and needs amplification. If an electric current flows through a conductor in a magnetic field, the magnetic field exerts a transverse force on the moving charge carriers which tends to push them to one side of the