Electronic Toss Circuit

We have seen a coin is tossed before beginning a football match. This electronic version of it comes with a row of 7 LEDs – the middle one is green, and the rest are red.

When you press reset, the probability of the red LEDs next to the green LED to light are the same for all the red LEDs. Thence, a left or right decision is conducted by the circuit based on complete randomness.

How the Circuit Works

The operation is simple. Button S₁ can be activated at any time to preset the counter IC₁.

This component returns a binary value of 0 at Q₀, Q₁ and Q₂ outputs. As a result, the BCD-to-decimal decoder, IC₂, converts the bits to the corresponding green LED (D₄) in the middle of the row.

You can preset the initial state of the circuit by activating P₆ to P₃ while they are connected to the ground. This signals IC₁ to load 0000 as the initiating binary digits when button S₁ is pushed.

When you press the button S₂, switching of N₁ and N₂ happens. As a result, a single pulse transition develops at the clock input of IC₁. Based on the logic at the UP/DOWN input of IC₁, the 1/8 decoder will light up D₅ (on the right) or D₃ (on the left).

This tallies with the counting up sequence from 0000 to the next binary number, 0001. On the other hand, if counting is downwards, a value of 1111 is delivered. When the value is counted down, IC₂ will let D₃ light up at the output of Q₇. This happens because the most significant input bit of D is connected to the ground.

Toss Results are 100% Random

The randomness of the toss-up circuit is guaranteed by the speed of the pulse applied to the counter UP/DOWN input by oscillator N₃-N₄. In theory, the odds are personalised and cannot be tampered with.

7 active-high outputs of IC₂ are attached to their related LEDs. At the same time, Q₄ aids to impede the counter through the CARRY IN terminal. You may notice the counter limitation happens automatically as IC₁ counts up from the state 3 output. If state 5 is concerned, the IC counts down. Both these situations allow Q₄ and the CARRY IN to go HIGH. As a result, the counting will not continue as long as the reset button is not pressed.

In the end, if you continuously press the S₂ button without resetting the circuit, any random LED will illuminate. This is useful when you are playing any other random-based game.