When employed in academic competitions, manual buzzers like those found in schools and colleges can lead to a great deal of misunderstanding over the identification of the first reply. Although there exist circuits using PCs and discrete ICs, they are either too expensive or confined to only a tiny number of players. The maximum number of participants allowed in any one quiz tournament is eight people, therefore this circuit for a quiz buzzer can accommodate that many people. The integrated circuit (IC) 74LS373 and a few passive components are used in the circuit. These components are easily obtainable on the market. Fig. 2: Circuit of school/college quiz buzzer

There are two distinct parts of the circuit that may be separated from one another: the power supply and the quiz buzzer. The power supply part is depicted in Figure 1. The AC power lines are the source of the regulated 5V power supply that is used for the quiz buzzer part. The 230V AC mains are reduced to 7.5V AC by transformer X1, which is also responsible for rectifying the current using bridge rectifier BR1, filtering it using capacitor C1, and regulating it using regulator IC1. Capacitor C2 bypasses waves in the regulator output. The quiz buzzer section is depicted in figure 2. The IC 74LS373, an octal latch, is the most important component of this section. Its job is to convert the logic state present at the data input pins D0 through D7 to the outputs Q0 through Q7 that correspond to those pins. Resistors R1 through R8 are responsible for bringing low the data pins D0 through D7 in their typical configuration. The push-to-on switches S1 through S8 each have one of their terminals connected to +5V, while the other terminals are each linked to their corresponding data input pins. The cable wire is going to be used to run the switches all the way up to the players. It is possible to store the torch bulbs BL1 through BL8 in boxes, and the front of the boxes could have a piece of white paper with the contestant's name or number printed on it. This would make it simple to identify who owned each box. Position the boxes

such that they are visible from above the heads of the audience members so that everyone can see what is happening. The circuit is ready for usage after the power is turned on by utilizing switch S9 (assuming that the terminals 'A' and 'B' of both the power supply and quiz buzzer sections are coupled). At this time, all of the switches, from S1 all the way through S8, are open, and the outputs of IC 74LS373 from Q0 all the way through Q7 are low. As a result, the gates of silicon-controlled rectifiers SCR1 through SCR8 are also low. As soon as a competitor momentarily hits his respective switch, the matching output data pin turns high. This causes the associated SCR to be triggered, and as a result, the respective bulb lights. The piezobuzzer (PZ1) emits a sound at the precise moment when the transistor T1 begins to conduct. Concurrently, a high voltage is applied to the base of the transistor T2 in order to make it conduct. In order to latch all of the Q0 through Q7 outputs, pin 11 of IC2's Latch- enable (LE) component is connected to ground. This limits further change in the output state due to any change in the state of switches S1 through S8 by any other participant. Until the on/off switch S9 is used to reset the circuit, just one of the eight torches' bulbs will emit light.