D. Temperature Control Circuit
The temperature control circuit consists of the following components:
1) Relay – 5 Volt: The temperature control circuit consists of two relays controlled by the microcontroller. The first
relay is used for switching the incandescent lamp to a 230 V supply and a circulating fan to a 12 V supply. The
second relay is used for switching the gear motor for operating the egg turning mechanism. The relay is triggered
using a 2N2222 npn transistor and the microcontroller
2) Incandescent Lamp: A 60W lamp is used for heating the air inside the incubator. The lamp is turned on when the
temperature inside the incubator reaches below 37° C and is turned off when it exceeds 38.5° C using a relay
3) Circulating Fan: The circulating fan is also triggered using a 5 V relay and is turned on at the same time as the
incandescent lamp. It is used for the purpose of circulating the heated air uniformly around the chamber.
4) Gear Motor:A gear motor is used for operating the egg turning mechanism. The gear motor is switched by a 5V
relay and it rotates an elliptical cam connected to the egg holder. A spring is used to return the holder to its initial
position.