15-01-2013, 01:07 PM
SCHOOL/COLLEGE QUIZ BUZZER
[attachment=46962]
Manual buzzers used for quiz
competitions in schools and
colleges create a lot of confusion
in identifying the first respondent.
Although there are circuits using PCs
and discrete ICs, they are either too
expensive or limited to only a few
number of players.
The quiz buzzer circuit given here
can be used for up to eight players,
which is maximum in any quiz com-
GOVINDA RAJU TEKUMUDI
SCHOOL/COLLEGE
QUIZ BUZZER S.C. DWIVEDI
section is IC 74LS373, an octal
latch that is used to transfer
the logic state at data input pins
D0 through D7 to the corresponding
Q0 through Q7 outputs. Data pins D0
through D7 are normally pulled low
by resistors R1 through R8, respectively.
One terminal of push-to-on
switches S1 through S8 is connected
to +5V, while the other terminal is
connected to the respective data input
pins. The switches are to be extended
to the players through cord wire. The
torch bulbs BL1 through BL8 can be
housed in boxes with the front side of
the boxes covered with a white paper
having the name or number of the
contestant written over it for easy
identification. Place the boxes above
the head level so that these can be
seen by the audience also.
When the power is switched on using
switch S9 (provided terminals ‘A’
petition. The circuit uses IC 74LS373
and a few passive components that are
readily available in the market.
The circuit can be divided into two
sections: power supply and quiz
buzzer.
Fig. 1 shows the power supply section.
The regulated 5V power supply
for the quiz buzzer section is derived
from AC mains. The 230V AC mains
is stepped down to 7.5V AC by transformer
X1, rectified by bridge rectifier
BR1, filtered by C1 and regulated
by regulator
IC1. Capacitor
C2 bypasses
ripples in the
regulator output.
Fig. 2
shows the
quiz buzzer
section. At th
[attachment=46962]
Manual buzzers used for quiz
competitions in schools and
colleges create a lot of confusion
in identifying the first respondent.
Although there are circuits using PCs
and discrete ICs, they are either too
expensive or limited to only a few
number of players.
The quiz buzzer circuit given here
can be used for up to eight players,
which is maximum in any quiz com-
GOVINDA RAJU TEKUMUDI
SCHOOL/COLLEGE
QUIZ BUZZER S.C. DWIVEDI
section is IC 74LS373, an octal
latch that is used to transfer
the logic state at data input pins
D0 through D7 to the corresponding
Q0 through Q7 outputs. Data pins D0
through D7 are normally pulled low
by resistors R1 through R8, respectively.
One terminal of push-to-on
switches S1 through S8 is connected
to +5V, while the other terminal is
connected to the respective data input
pins. The switches are to be extended
to the players through cord wire. The
torch bulbs BL1 through BL8 can be
housed in boxes with the front side of
the boxes covered with a white paper
having the name or number of the
contestant written over it for easy
identification. Place the boxes above
the head level so that these can be
seen by the audience also.
When the power is switched on using
switch S9 (provided terminals ‘A’
petition. The circuit uses IC 74LS373
and a few passive components that are
readily available in the market.
The circuit can be divided into two
sections: power supply and quiz
buzzer.
Fig. 1 shows the power supply section.
The regulated 5V power supply
for the quiz buzzer section is derived
from AC mains. The 230V AC mains
is stepped down to 7.5V AC by transformer
X1, rectified by bridge rectifier
BR1, filtered by C1 and regulated
by regulator
IC1. Capacitor
C2 bypasses
ripples in the
regulator output.
Fig. 2
shows the
quiz buzzer
section. At th