Digital Roulette Circuit with 7-Segment Display

Figure 1 

The circuit was designed to produce a digital roulette that will display the result using a 7-segment LED display.

• Roulette – refers to a game of chance played at a table where a small ball is made to move around rapidly on a circle marked off into numbered red and black spaces where the one which it stops indicates a mixture of wagers allowed by the game
• BC550 – an NPN general purpose transistor with low current and low voltage used for low noise stages in audio frequency equipment
• 4011 – a quad 2-input NAND gate integrated circuit, generally characterized by small fluctuation in voltage supply, very high impedance, outputs that can sink and source, one output can drive up to 50 inputs, high speed gate propagation time, high frequency, and low power consumption
• 4026 – a decade counter where the count advances as the clock input becomes high and has a maximum current of about 1 mA with a 4.5 V supply and 4 mA with a 9 V supply, which can light the appropriate segments of a common cathode 7-segment display
• 7 Segment LED – is a form of electronic display device for displaying decimal numerals that is an alternative to the more complex dot-matrix displays also known as seven-segment indicator

The operation of the circuit is represented by the functionality of the IC1 CMOS oscillator 4011 which produces a time varying or repetitive electronic signal, sine wave or square wave, without an external input signal using positive feedback. The model 4011 contains circuitry that protects the inputs against damage due to high static voltages or electric fields since its primary use is where low power dissipation and/or high noise immunity is desired. The frequency of oscillation of IC1 can be modified by changing the value of the capacitor C1 which is connected to the trimmer TR1. This would regulate the frequency to the range of 10 Hz or slightly higher. Higher frequency would result to faster speed in spinning or rolling that is indicated in the LED display. A potentiometer can be used in place of trimmers TR1 and TR2 depending on the compatibility.

A binary-coded decimal counter 4026 IC2 is used in the circuit to drive the 7-segment LED display. This 16-pin CMOS operates by counting the clock pulses and then returns the output in a form that can be displayed on a 7-segment display. A counter may be defined as a device used for storing the number of times a specific process or event has occurred. The transistor BC550 is used in the circuit provides aid in driving the display. The type of supply can be from a 9 V battery or a dedicated power supply.

Switch S1 is used to release the alteration of time from the last measurement while S2 functions as the RESET to the display. Switch S1 is responsible for decoupling the output circuit from the RESET, after a round. The release of S1 would signify the meter to stop in a number while pressing S1 again would start another round of game. If the meter stops at zero, the player that makes the “mother” or banker wins all the bets from other players. The players can reach from 2 to 9 persons.

Figure 2 

Roulettes are mainly used as a gambling game where bets are placed against the casino bank or the house. It can also be used by people of any age for enjoying the hours of playing the game where it includes pop out chips with unique designs of different values. Digital roulettes can also be found in mobile phones and computers for the purpose of mastering the game, analyzing the bets, creating own strategies, and monitoring all chance in playing the real game.

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