In many situations where people need to make choices, it is pretty common for them to just flip a coin.
However, this simple method can sometimes be unfair leading to biased results.
To solve this problem you can use an electronic coin toss circuit that mimics a random coin flip using digital technology and LED lights.
This Electronic Coin Toss Circuit is made with two main parts the first is IC 555 timer and the second is IC 74LS76 dual JK flip-flop.
IC1 works as an astable multivibrator running at a frequency of 10Hz, while IC2 is set up to toggle making it work the way we want.
Circuit Working:
Parts List:
| Component | Specification | Quantity |
|---|---|---|
| Resistors (1/4W) | 1M | 1 |
| 47k | 2 | |
| 470Ω | 2 | |
| 100Ω | 2 | |
| Capacitors | Ceramic 0.1µF | 1 |
| Electrolytic 1µF 16V | 1 | |
| Semiconductors | IC 555 Timer | 1 |
| IC 74LS76 JK Flip-Flop | 1 | |
| Transistor BC547 | 1 | |
| Switch | Tactile Push Button Switch | 1 |
| LEDs | Heads Red 5mm 20mA | 1 |
| Tails Green 5mm 20mA | 1 |
The IC1 555 Timer is set up to work as an astable multivibrator, which means it creates a square wave signal at a specific frequency.
This timer keeps oscillating, producing a steady stream of pulses.
The BC547 transistor Q1 acts like a switch that turns on the JK flip-flop when the toss button is pressed.
When you push the button S1 it sends a trigger pulse to the JK flip-flop which is IC2 74LS76.
This flip-flop holds the result of the toss and controls the output to the LEDs.
Because the IC1 555 timer oscillates quickly the flip-flop changes its state in a way that seems random.
The output from the flip-flop is crucial for turning on two LEDs (LED1 and LED2) with one LED lighting up based on the final state from the flip-flop.
The push button S1 starts the toss process.
Since the clock pulse frequency is high the LED that lights up seems to do so randomly mimicking the result of a fair coin toss.
Note: LED Placement for Heads and Tails in the circuit diagram:
Red LED (Heads) is connected to pin 14
Green LED (Tails) is connected to pin 15
Formulas with Calculations:
The formulas with calculations for Electronic Coin Toss Circuit using IC 555 and JK Flip-Flop is mentioned below to design your own circuit:
555 Timer Frequency Calculation:
The 555 in astable mode generates a frequency given by:
f = 1.44 / ((R1 + 2R2) * C1)
where,
- R1 is 47k
- R2 is 47k
- C1 is 1μF
Substituting the values:
f = 1.44 / ((47k + 2 * 47k) * 1µF)
f = 1.44 / (141k * 1µF)
f = 1.44 / 0.141
f = 10.2 Hz
The timer sends out signals at about 10.2 times per second, which is quick enough to produce a random result when you press the button.
How to Build:
To build a Electronic Coin Toss Circuit using IC 555 and JK Flip-Flop following steps need to be followed:
- Assemble all the components mentioned in the above circuit diagram:
- Connect pin 1 of IC1 555 to GND.
- Connect pin 2 and pin 6 of IC1
- Connect capacitor C1 positive end from pin 2 and negative end to GND.
- Connect pin 3 of IC1 to base of transistor Q1 through resistor R3
- Connect pin 4 and pin 8 of IC1 to +5V DC supply rail.
- Connect pin 5 of IC1 to GND through capacitor C2.
- Connect a resistor R2 between pin 6 and 7 of IC1.
- Connect resistor R2 between pin 7 and positive supply.
- Connect collector of transistor Q1 to positive supply through resistor R4.
- Connect emitter of transistor Q1 to GND.
- Connect pin 1 of IC2 74LS76 to collector of transistor Q1 through S1 switch.
- Connect a resistor R5 from pin 1of IC2 and GND.
- Connect pin 4, pin 5 and pin 16 of IC2 to positive supply rail.
- Connect pin 13 of IC2 to GND.
- Connect pin 14 of IC2 to positive supply through LED2 (Red heads LED) and resistor R6
- Connect pin 15 of IC2 to positive supply through LED1 (Green tails LED) and resistor R7
Conclusion:
This Electronic Coin Toss Circuit using IC 555 and JK Flip-Flop gets rid of any unfairness in flipping coins and offers a fun and equal way to make choices.
By using the IC 555 timer and JK flip-flop, it guarantees randomness and the LEDs show the final result.
This project is great for students and hobbyists interested in learning about timers and flip-flops in digital circuits.