This project is a slot machine that uses 15 colored LEDs to create three reels. It operates with a single push button that powers the device and starts reel movement; pressing the button resets the operation each time. The machine automatically shuts off after about eight minutes of inactivity. The project uses colored LEDs from an assortment kit available on Amazon, including red, yellow, green, blue, and white. All colors were used except for white; orange LEDs were ordered separately to replace the white ones. Alternatively, the project can be assembled with LEDs of just one color.

Three CD4017 counters control the LED reels, while a resistor-capacitor combination connected to the clock enable pin of each CD4017 manages the duration the reels spin. A CD40106B CMOS Hex Schmitt-Trigger generates three separate clock circuits, one for each reel. The reels begin spinning when power is supplied to the circuit, and restarting requires cycling the power.

The PC board includes a mounting hole for the push button switch, designed to be affixed to the board itself. The recommended switch type is a NO/NC SPST momentary push button, connected via wires to the COM, NO, and NC terminals. The edge of the PC board provides connections for a 9-volt battery clip.

In this design, the normally closed side of the push button links the positive battery terminal to the circuit, while the battery's negative terminal connects to a MOSFET's source, and the slot machine ground is attached to the MOSFET drain. Activating the push button temporarily disconnects the power and charges a 1000 μF capacitor, which triggers the MOSFET to remain on until the capacitor discharges.

The tab of the MOSFET should be oriented toward the outer edge of the printed circuit board. The RFP30N06LE MOSFET was sourced from Amazon; it may not be readily available from suppliers such as Digikey or Mouser, although equivalent substitutes are accessible. Any N-channel MOSFET with a matching pin configuration is expected to function appropriately.

For manual power control, a latching push button may be connected between the COM and NC terminals on the PC board. In this setup, the reels activate upon switching on; restarting involves turning the unit off and back on. A momentary normally closed push button can be wired in series as a start mechanism. Using this approach, C1, Q1, R1, R2, and R3 components are unnecessary; instead, a jumper wire replaces Q1 between the S and D terminals, labeled on the PCB as S and D.

LEDs are positioned on one side of the board, while other components are located on the opposite side. To accommodate the LEDs and the push button switch, holes need to be drilled in the enclosure. The SlotMachine.zip file provides KiCad project files and a PDF template to guide the drilling process. The template can be printed, trimmed to match the size of the PCB, laminated, and used for marking the hole locations for both the LEDs and the switch. The enclosure, supplied by Vetco Electronics, has dimensions of 4.37” L x 3.25” W x 1.5”, featuring a battery compartment suitable for a 9-volt battery. The switch functions to secure the PC board inside the case.

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