Abstract—This paper presents a new microcontroller-based egg candling system. The system, which is integrated to a complete automated hatching machine, utilizes an IR transmitter and a highly sensitive TSOP receiver. A 40 KHz signal is passed through a partially incubated egg and received at the other end. Distortion in the frequency of the received signal indicates the presence of a live embryo indicating that the process of hatching should continue. An undistorted signal indicates the absence of life in the egg and the process of hatching is terminated. Two sets of stepper motors are used for the mechanism of the Candler. The system was tested using chick and quail eggs and performance is excellent. Index Terms—Candling, egg, incubation, microcontroller. I. INTRODUCTION Candling refers to the process of transluminating an egg with light to determine the presence or absence of a viable embryo or to look for shell defects [1]. Candling of eggs during incubation a useful tool for quality assurance and determination of poor hatches. Other important parameters during the incubation process are incubator temperature, humidity, shell quality and egg moisture loss. The arteries of the extraembryonic circulation are uniformly distributed throughout the incubating egg structure. This provides the means for detecting change in blood flow photoelectrically, thus providing a means through which the embryonic heartbeat can be detected. .To determine life in an incubating embryo, relatively intense white light is passed through the partially incubated eggs. This process is called candling and the time it is done depends on the type of egg under incubation. For example, chicken, pheasant, partridge and quail eggs should be candled after 5 to 7 days of incubation. Turkey, duck and goose eggs should be candled after 8 to 10 days of incubation due to their longer incubation periods [1]. The embryo at this stage of incubation is about the size of a dime and appears as a small bubble floating on the surface of the yolk. Candling, as the name implies, was originally done with a candle to provide the transluminating light. Later, more powerful light sources like the electric bulb were used. Recently, a number of new methods for determining egg fertility have been reported. For example, Das and Evens [2] used a combination of machine vision and artificial neural network to identify fertile eggs with accuracy of 93.9 % at day 4, 93.5 % at day 3 and 67.6 % at day 2. In [3], machine vision and modified PSO was used with impressive results. Bamiles et al. [4] successfully used a combination of two Manuscript received November 25, 2014; revised March 11, 2015. S. S. Akanji is with the Department of Electrical/Electronics Engineering, Sokoto State Polytechnic, Nigeria (e-mail: talktosunbo2002@yahoo.com). A. U. Jibia is with the Department of Mechatronics Engineering, Bayero University Kano, Nigeria (e-mail: ajumar@buk.edu.ng). light wavelengths (577 and 610 nm) to determine the fertility of an egg after 4.5 to 5 days of development. Other reported methods for determining egg fertility include machine vision and LS estimation [5], magnetic resonance imaging [6], acoustic resonant analysis [7] high frequency ultrasound imaging [8], hyperspectral imaging [9], [10] and acoustic impulse response and supervised pattern recognition [11]. The candling system presented in this paper is part of a complete microcontroller-based multicompartment hatching system whose block diagram is shown in Fig. 1. Each of the four compartments is designed to hold different type of egg. Three compartments labelled A, B and C are for chicken eggs, while the other compartment labelled D is for quail eggs . Fig. 1. Block diagram of a complete hatching machine. II. DESIGN OF THE CANDLING UNIT Fig. 2 shows the circuit diagram of the proposed candling system. On the fifth day of incubation (specifically, after exactly 120 hours), a 5V, 40 kHz signal is generated by pin A0 of the 16F877A microcontroller [12]. The signal is sent to the infrared transmitter in compartment one. The transmitter causes the signal to pulsate; the pulsating signal at 40 kHz is passed through the egg placed between the IR transmitter and the receiver. The receiver circuit consists of TSOP11240 [13] from Vishay Instruments. The output signal at the receiver biases transistor Q61 and amplified by transistor Q62 due to its low magnitude. Whenever the frequency of the transmitted signal is below what is received due to distortion of the signal by the breathing of the life embryo in the incubated egg, the ouput of TSOP11240 is low and the transistor Q61 is switched off. This means the collector is at high potential, thus turning transistor Q62 on. This makes pin C4 low because it is attached to the collector of Q62 which is at low potential. Thus low at pin C4 signifies that the egg is fertile. Whenever pin C4 goes high, it means that the transmitted signal is received at the same frequency as transmitted, because there is no life embryo in the egg whose breathing will distort the signal. The egg is therefore non-fertile. A „BAD EGG‟ is then displayed on the A Microcontroller-Based Egg Candling System Akanji S. Saidu and Abdussamad U. Jibia International Journal of Information and Electronics Engineering, Vol. 5, No. 6, November 2015 433 DOI: 10.7763/IJIEE.2015.V5.573