Electronic Slot Machine Circuit

  
The slot machine`s realistic action is provided by seven ICs and three displays, as shown. Two 555 CMOS timer ICs generate pulses. IC1 is used to generate the clock pulses for the entire electronic slot machine. The pulses are coupled from the output (pin 3) to the clock inputs of IC4, IC5, and 1C6, the display-driver ICs. The displays are common-cathode 7-segment LED types. They are wired to display three different symbols, an L, a 7, and bar, When all three displays show the same symbols, IC7 (a 4023 triple 3-iriput NAND gate) decodes a winner and sends a signal to pin 5 of IC3.
Electronic Slot Machine Circuit - schematic

That IC is a 4001 CMOS NOR gate and it turns on IC2, a 555 timer IC. IC2 actually produces the winner tone on its output, pin 3. Transistors Q4 through Q12 are used to drive the common-cathode displays. An LED is used to indicate the clock pulses, and a variable resistor is provided for each of these functions. Trimmer resistor PI controls the overall clock rate, P2 controls the winner tone, and P3 controls the display brilliance.




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