Control System ^ a = 18m and f = 0 6m

A closed loop control system was designed to track the sun around the N-S axis. This system consists of: a DC motor, a speed reduction unit, a photo resistance sensors unit, and a controller as shown in Fig. 6. Two photo resistances are located on both the parabolic

reflector sides. These sensors are used as part of a wheatstone bridge circuit to give zero voltage when radiation plane is normal to the aperture area of the reflector (sun in center of the parabola). If incident angle changes, the sensors give a voltage proportional to it. The controller amplifies this voltage and sends a signal to the motor to track the sun and keeping wheatstone bridge output voltage equal to zero.