You can play with your friends to know their reaction time. This is very simple game in this 10 LED's are moving in a random fashion. And you have to hit a particular LED given by your opponent and you will get four chances to hit the right target. And if he or she hit the target correctly 10 points will be given. So at last the person who has scored more points will be declared as winner. Advantage of this circuit is that it will not harm the eyes of children when they play for long duration. As instead of video screen this circuit uses LED for display. It can be easily assembled because of less and easily available components. This circuit also produces a sound when you hit the target like you get in video games. So you will get feel of real video game. You can easily power the circuit with the help of adapter available in market.
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Fig. 1: Prototype of Reaction Timer Game Circuit on Breadboard
How to Play the Game?
Assemble the circuit and provide power supply. All the LED’s are randomly glowing and becoming off. You can vary the speed of LED’s for the period which it on and off with the help of variable resistor VR1. Now give the target that to the contestant playing with you like shoot LED number 5. Then he has to press the shoot button that is switch S2 in such a way that only LED5 will glow. If he presses the button and LED5 glows with a shooting sound than he has given 10 point else no point is given. And LED 11 will start glowing indicates that one chance is over. Now to a start the game again press the start button S1 and again all LED’s start glowing. Repeat the same process till LED14 glows after that one contestant chances are over and in the end who has the highest score will be declare as winner.
To make the game look interesting use sticker of airplane or balloons in front of LED so it will give you a look you are shooting the planes or balloons.
Working of circuit
In this circuit IC2 is wired in bistable mode means it is stable in any one state may be high or low until external pulse is applied. That’s why it is also known as flip flop and can be used to store one bit of data. When you on the circuit voltage at trigger pin 2 of IC2 is less than 2/3 of Vcc, because of this output remain high and remain in that state until voltage at threshold pin 6 of IC2 goes above 2/3 of Vcc. So when you press the switch S2 that is shoot switch this bring the output of IC2 to low and reset the IC3 and IC4.
In this circuit NE555 timer IC3 is wired as an astable oscillator. In this circuit NE555 astable generates a clock for the circuit, which provides an oscillating wave to the output pin 3 of IC4. You can vary the speed of oscillation with the help of R2. The frequency of oscillation of 555 timer can be calculated by-
f=1.44/(R1+2*(VR1)*C1)
Now this clock signals are given to pin 14 of IC4 to start its counter and when ever pin 14 goes high its counter is incremented with one like first we get output from pin 3 that is Q0 and LED1 will glow than from 2 that is Q1, LED2 will glow and so on in sequential manner. As you can see from circuit diagram pin 4 of IC3 is connected to pin 3 of IC2 so whenever shoot switch S2 is pressed it will hold that output and a single LED will glow. And when you again press the start switch S1 it will again start it is counter from 0 to 10.
Sound generation circuit is built around UM3561 IC which is connected to shoot switch S2 so whenever S2 is pressed IC1 gets power supply and provide you the gun sound. While providing the power supply to UM3561 is careful do not provide voltage more than 3.3V as excess voltage may destroy the IC. Or you can use zener diode as we used in our circuit.
You can also UM3561 to produce different sound like fire force, ambulance and police siren. Just make the changes with 1 and 6 as shown in table below to get different sounds.
And the number of changes done this section is build around IC 5 whose counter is incremented every time when you press shoot switch. We have connected a diode between pin 15 (reset pin) and pin 10 so that after fourth chance it will reset the counter.
