27-12-2012, 01:02 PM
A PROJECT REPORT ON FASTEST FINGER FIRST INDICATOR
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INTRODUCTION
Quiz-type game shows are increasingly becoming popular on television these days. In such games, fastest finger first indicators (FFFIs) are used to test the player’s reaction time. The player’s designated number is displayed with an audio alarm when the player presses his entry button.
In the buzzer round of quiz contests, the question is thrown open to all the teams. The person who knows the answer hits the buzzer first and then answers the question. Sometimes two or more players hit the buzzer almost simultaneously and it is very difficult to detect which of them has pressed the buzzer first. In television shows, where the whole event is recorded, the actions are replayed in slow motion to detect the first hit. Such slow motions are possible only where huge funds are available to conduct the show. For this reason buzzer rounds are avoided for quiz contests held in colleges.
This project is an electronic quiz buzzer that is affordable by the colleges and even individuals. This project is useful for a 4-team quiz contest, although it can be modified for more number of teams. This system is sensitive. The circuit can detect and record the first hit contestant among all the contestants that may appear to be simultaneous. JK master slave flip flop is the heart of this project. The complimented output of all JK flip flops is given to NAND gate input. The output of the NAND gate is fed to NOT gate. Here in this project, NOT gate is realized from NAND gate.
The output of this NOT gate is fed to CLK pins of all JK flip flops through four Push-to-ON switches. LEDs are connected to output pin of all JK flip flops through a transistor driver. Whenever any switch is pressed first, the corresponding flip flop’s output goes high and makes the LEDs blink.
PROJECT DESCRIPTION
Quiz-type game shows are increasingly becoming popular on television these days. In such games, fastest finger first indicators (FFFIs) are used to test the player’s reaction time. The player’s designated number is displayed with an audio alarm when the player presses his entry button.
The circuit presented above determines as to which of the four contestants first pressed the button and locks out the remaining three entries. Simultaneously, an audio alarm and the correct decimal number display of the corresponding contestant are activated.
When a contestant presses his switch, the corresponding output of latch IC2 (7475) changes its logic state from 1 to 0. The combinational circuitry comprising dual 4-input NAND gates of IC3 (7420) locks out subsequent entries by producing the appropriate latch-disable signal.
Priority encoder IC4 (74147) encodes the active-low input condition into the corresponding binary coded decimal (BCD) number output. The outputs of IC4 after inversion by inverter gates inside hex in-verter74LS04 (IC5) are coupled to BCD-to-7-segment decoder/display driver IC6 (7447). The output of IC6 drives common-Anode 7-segment LED display (DIS.1, FND507 or LT543),
The audio alarm generator comprises clock oscillator IC7 (555), whose output drives a loudspeaker. The oscillator frequency can be varied with the help of preset VR1. Logic 0 state at one of the outputs of IC2 produces logic 1 input condition at pin 4 of IC7, thereby enabling the audio oscillator.
IC7 needs +12V DC supply for sufficient alarm level. The remaining circuit operates on regulated +5V DC supply, which is obtained using IC1 (7805).
Once the organizer identifies the contestant who pressed the switch first, he disables the audio alarm and at the same time forces the digital display to ‘0’ by pressing reset pushbutton S5.
INDUCTORS:
Adding electrical current to a coil of wire produces a magnetic field around itself. This is how the inductor works. It is charged with a magnetic field and when that field collapses it produces current in the opposite direction. Inductors are used in Alternating Current circuits to oppose changes in the existing current.
Most inductors can be identified by the "coil" appearance. Others actually look like a resistor but are usually green in colour.
Antenna Coil:
This consists of several turns of insulated copper wire wound on a plastic tube. It is used in this kit for transmitting radio waves. The coil has four tappings on it. The leads can be identified by the spacing in between.
PCB’s:
PCB stands for printed circuit board which are used for wiring up of the components of
a circuit. PCBs are made of paper phenolic FR2 grade (low cost, for low frequency and
low power circuit assembly) and glass epoxy FR4 grade (for high frequency, high power
circuits) copper clad laminates (available in 1.6mm, 2.4mm and 3.6mm thickness). Singlesided PCBs have copper foil only on one side while double-sided PCBs have copper foil on both side of the laminate. Thickness of copper foil is 35 micrometer minimum on cheaper PCBs and 70 micrometer on slightly costlier PCBs. Tracks (conductive paths) are made by masking (covering) the track part of copper with etch-resist enamel paint (you can even use nail polish) and later dipping the laminate in ferric chloride solutions to dissolve all copper except under the masked part. Holes in PCBs are drilled after etching is over. The tracks on two sides of a PCB are joined using printed through hole (PTH) technique, which is equivalent to using slotted copper rivets for joining tracks on both sides. On cheaper PCBs, PTH are not provided, only Pads (i.e. circular copper land with centre hole) are provided and you have to join the tracks on both sides by soldering a copper wire to the pads with a copper wire. In singlesided PCB components are mounted on the side which has no track (called component side). In a double-sided PCB the component side is defined (marked before hand) or it
will show component outline (also called silk screen) Green masking is the process of applying a layer of green colour insulation varnish on all parts of tracks except near the holes, to protect the tracks from exposure to atmosphere and thus prolong its life and reliability.
IC’s USED IN FFFI
BCD TO 7-SEGMENT DECODER/DRIVER(SN54/74LS47)
The SN54/74LS47 are Low Power Schottky BCD to 7-Segment Decoder/Drivers consisting of NAND gates, input buffers and seven AND-OR-INVERT gates. They offer active LOW, high sink current outputs for driving indicators directly. Seven NAND gates and one driver are connected in pairs to make BCD data and its complement available to the seven decoding AND-OR-INVERT gates. The remaining NAND gate and three input buffers provide lamp test, blanking input / ripple-blanking output and ripple-blanking input. The circuits accept 4-bit binary-coded-decimal (BCD) and, depending on the state of the auxiliary inputs, decodes this data to drive a 7-segment display indicator. The relative positive-logic output levels, as well as conditions required at the auxiliary inputs, are shown in the truth tables. Output configurations of the SN54/ 74LS47 are designed to withstand the relatively high voltages required for 7-segment indicators.
These outputs will withstand 15 V with a maximum reverse current of 250 mA. Indicator segments requiring up to 24 mA of current may be driven directly from the SN74LS47 high performance output transistors. Display patterns for BCD input counts above nine are unique symbols to authenticate input conditions.
WORKING OF FFFI
When a contestant presses his switch, the corresponding output of latch IC2 (7475) changes its logic state from 1 to 0.
The combinational circuitry comprising dual 4-input NAND gates of IC3 (7420) locks out subsequent entries by producing the appropriate latch-disable signal.
Priority encoder IC4 (74147) encodes the active-low input condition into the corresponding binary coded decimal (BCD) number output.
The outputs of IC4 after inversion by inverter gates inside hex inverter 74LS04 (IC5) are coupled to BCDto-7-segment decoder/display driver IC6 (7447).
The output of IC6 drives common anode the active-low input condition into the corresponding binary coded decimal (BCD) number output.
The outputs of IC4 after inversion by inverter gates inside hex inverter 74LS04 (IC5) are coupled to BCD to- 7-segment decoder/display driver IC6 (7447).
The output of IC6 drives common anode 7-segment LED display (DIS.1, FND507 or LT543).
The audio alarm generator comprises clock oscillator IC7 (555), whose output drives a loudspeaker.
The oscillator frequency can be varied with the help of preset VR1. Logic 0 state at one of the outputs of IC2 produces logic 1 input condition at pin 4 of IC7, thereby enabling the audio oscillator.
IC7 needs +12V DC supply for sufficient alarm level. The remaining circuit operates on regulated +5V DC supply, which is obtained using IC1 (7805).
Once the organiser identifies the con contestant who pressed the switch first, he disables the audio alarm and at the same time forces the digital display to ‘0’ by pressing reset pushbutton S5.
With a slight modification, this circuit can accommodate more than four contestants.