This section shows the two versions that have been proposed for the Sun detection.

The first version is shown in FIG. 13 and FIG 14. It consists in an array of eight trios of photodiodes located at the four quadrants formed by a "Greek cross”. This layers cause the photodiodes work in dark or light conditions that are handled by a microcontroller (AT89C2051) like on/off switches so it is possible to control the Altitude and Azimuth position for the 12V DC motors [8].

The design of the second version is based upon the detection of the Sun’s light intensity trough commercial photodiodes located over two small aluminum structures (detection turrets) in a certain way so that it will be possible to locate the Sun even when the oven is totally out of its focal condition, a view of both turrets is shown in FIG. 15 The analog signals provided by the photodiodes, which have proportional linearity to Sun intensity, are driven immediately into a microcontroller having an internal analog to digital converter of a 10 bit resolution. This proceeding in accordance with an algorithm, which considers the diverse positions of the detection photodiodes, will activate two H Bridge circuits to control two electric motors required for, and whose structure is already attached to the oven’s main structure.

The main contributions to be achieved by this tracker are:

a) The existence of two identical detection turrets where the photodiodes are mounted on; it is pretended to provide a redundancy: in the event that due to mechanical reasons one of these detection turrets is out of operation, it will be possible to use the other one to let the

sun tracking be still working. FIG. 15 Redundant Detection Turrets

b) The photodiodes location supplies the tracker three detection sorts: coarse, medium and fine; the first one helps to locate the Sun whenever there are unfavorable conditions, medium and fine detection work together to allow the oven reach its focal condition and once in such condition, it is possible to track the Sun continuously.

c) Due the Solar Oven has been thought to be used within the Tropics, the Sun Tracker must be capable of doing its job in certain Sun paths like its Zenith position and when it goes beyond it, these conditions do not exist outside the tropics.