● The coin toss circuit is an interesting electronic project which can be used to conduct a toss between two teams or individuals.
● It is a decision maker used at the places where someone is not able to make up the decision. When a button is pressed, the head and tail h and t respectively display on 7 segment display.
● An important feature of this circuit is using a single IC that is CD4049 and displays the h and t on seven segment displays in spite of LED so decision is clearly indicated.
Another feature is it will hold the display if you left the switch S1 also until it will be pressed next time
Fig. 1: Prototype of Coin Toss Circuit on 7 Segment Display Circuit on Breadboard
This simple circuit is based on CD4049 with 7 common cathode seven segment display along with few more components which are readily available in market. So you can make this circuit easily and use in your school and colleges at the time of annual day or spot day.
The circuit is based on NOT gate CD4049 IC in this we are utilizing all gates of IC. To understand the working you should know about the truth table of NOT gate are as follows-
In NOT gate we will get output as logic high when logic zero is provided and we will get logic zero when logic 1 is provided in input.
CD4049 contain six inverter gates in one package as shown in diagram. In this pin 3 is for input and pin 2 is for output for first gate. Similarly pin 5 is input and pin 4 is output for second gate, in the same way we have four more gate. In this 1 is for supply voltage and pin 8 is connected to ground and pin 13 and 16 are unused pin.
Fig. 2: Pin Diagram of CD4049
Seven segment display are common used now a days in place of dot matrix display. This can be used in many places like in microwave or fancy toaster oven or you can find the same on washing machine but in all this you require to interface the 7 segment display with microcontroller or some more hardware will be required.
7 segment display are labelled a to g and decimal point is usually known as DP. DP is the common point. In common cathode display they are connected to ground and rest pin are connected to supply.
Fig. 3: Image Showing 7 Segment Display Numbers
Fig. 4: Pin Diagram of 7 Segment Display
Advantage of 7 segment display-
· It uses low power for its operation less than 2.5V.
· Comes in industry standard size.
· Comes with a industry standard pin out which can be directly refer from datasheet.
· Seven segment display comes different size, user can use according to their requirement like 7.6mm, 10mm, 14.2mm etc.
You can also chose colour of your display. Commonly used- Red, Yellow, Green.
Working of circuit
In this circuit gate N1 and N2 with resistor R1 and R2 and capacitor C1 and C2 are working as a relaxation oscillator. Relaxation oscillator means circuit will not in stable state it will repeatedly change state from low to high and then from high to low depending upon the charging of a capacitor. If we are charging and discharging a capacitor with a constant voltage source with a resistor then capacitor voltage may change exponentially. On the other hand, if we charge and discharge a capacitor at a constant current source than it will change linearly.
And gate N3 just acts like a buffer, which keep apart the oscillator from the load. Gate N6 and N5 are used as a flip flop. When you press the switch S1 corresponding gate output will go high N6 or N5 and head or tail, h or t will be display on 7 segment display.