This circuit uses very basic components. The use of mm74c922 integrated circuit makes it different from other. This hardware based scanning makes the code really simple.
The use of Atmega16 can be avoided but this allows for complex coding structure to be stored. Due to cost associated with the micro controller.
External crystals are avoided as the device will be used for low frequency of up to 100 Hz. Which can be used easily be handled by the internal clock. The deviation of clock timing should be taken into account when programming.
The LM35 series are precision integrated-circuit temperature devices with an output voltage linearly-proportional to the Centigrade temperature