measurement of speed of the shaft by photo electric transducer.

AIM: - measurement of speed of the shaft by photo electric transducer.

APPARATUS: - DC motor, CRO, photo electric pick up connecting wires.

THEORY:-
In this method on the shaft of DC motor, a disc with opaque and transparent segment is mounted. Above the disc a photo conductor of high sensitivity is placed & source of light is placed below the disc. Output is connected is CRO. When the motor rotate, the disc connected to its shaft rotates, this disrupts the path of light coming below the limit interval that depends upon rotation speed & photo conductor responds for interruption on CRO. We get a square wave.
Shaft of DC motor:-  ( frequency diameter of disc  no. of segments )
  Where   D = 56.5mm
                 S =60 

PROCEDURE:-
Connect the circuit according to the diagram & switch on the power supply.
Adjust the speed of DC motor by the knob & wait until it attains maximum speed at corresponding knob position.
Measure the frequency from output wave on CRO.
Find the speed of DC motor by the given formula.

RESULT: - Thus we have measured speed of shaft using photo electric transducer.