Using a simple voltage controlled oscillator a 555 timer IC and 4017 counter/divider IC can be designed a very wonderful electronic roulette wheel game.
This 555 timer circuit electronic roulette wheel is a simple version of an electronic roulette game and is based on the 4017 IC which is a 10 stage decade counter/divider. It is driven by another versatile IC 555 configured as a voltage controlled oscillator (VCO).
The 555 timer is connected as an astable multivibrator . When the S1 switch is pressed, the capacitor C3 gets charged, also at this point of time a constant stable clock is fed to the 4017 IC and the LEDs at its outputs light up in a cyclic manner producing a revolving effect. Adjusting the VR1 (variable resistor ) the speed of revolving effect can be varied .
When the S1 switch is released, the main supply is cut-OFF, C3 discharges and forces the freely running astable to gradually stretch and slow down the time period of its output pulses so that eventually the oscillations stop within a stipulated time. In response to these dying pulses the “rotation” of the LEDs connected to the output of IC 4017 also slow down gradually and stops to select a random score marked on the board.
Depending on how long the S1 switch remains depressed score will always be selected in random order .
This electronic roulette wheel game must be powered from a simple 9 volt DC power supply .