A roulette wheel that spins and slows to a stop
Press the button and a ring of ten LEDs spins, slows down and stops on one. A 555 timer, a decade counter and one capacitor.
Free build sheet
The parts, every wire with its length and bend points, a bend guide, both sides of the board and checkboxes to track your progress. Print it or keep it open at the bench.
Open the build sheetWhat you need
20 parts on a perfboard 21 × 42 holes, plus hookup wire.
| Qty | Part | Where to buy |
|---|---|---|
| 1 | Ceramic Cap220nF C1 | Buy Ceramic Cap on Amazon |
| 1 | Electrolytic Cap47uF C2 | Buy Electrolytic Cap on Amazon |
| 1 | Power Input (2-pin) J1 | |
| 1 | LEDGreen LED1 | Buy LED on Amazon |
| 9 | LEDRed LED2, LED3, LED4, LED5, LED6, LED7, LED8, LED9, LED10 | Buy LED on Amazon |
| 1 | Resistor (axial)1k R1 | Buy Resistor (axial) on Amazon |
| 2 | Resistor (axial)100k R2, R3 | Buy Resistor (axial) on Amazon |
| 1 | Resistor (axial)220 R4 | Buy Resistor (axial) on Amazon |
| 1 | DIP-16 U1 | |
| 1 | DIP-8 U2 | |
| 1 | Tactile Button 6mm U3 |
Check every pin against the datasheet of the exact part in your hands before wiring.
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Cut list
40 wires, 1406 mm (55.4 in) in total, in the order the build sheet cuts them. Wire numbers match the build sheet. Each length includes 5 mm per end to go through the hole.
| Wire | Colour and net | Length | ||
|---|---|---|---|---|
| 6 | BlackTIMING N38 → N36 | N38 → N36 | 15mm | Straight |
| 24 | BlackCATHODES J20 → H20 | J20 → H20 | 15mm | Straight |
| 36 | BlackGND R23 → R34 | R23 → R34 | 38mm | Straight |
| 12 | BlackQ8 L19 → P30 | L19 → P30 | 42mm | 19mm (45°) |
| 18 | BlackQ3 L7 → N27 | L7 → N27 | 63mm | 51mm (45°) |
| 30 | Black9V C5 → G30 | C5 → G30 | 84mm | 69mm (90°) |
| 23 | BlueCATHODES N20 → L20 | N20 → L20 | 15mm | Straight |
| 29 | BlueCATHODES E16 → E12 | E16 → E12 | 20mm | Straight |
| 5 | BlueSPIN P33 → K33 | P33 → K33 | 23mm | Straight |
| 35 | BlueGND P29 → K31 | P29 → K31 | 28mm | 10mm (90°) |
| 11 | BlueBUTTON P40 → R32 | P40 → R32 | 35mm | 25mm (90°) |
| 17 | BlueQ2 I8 → K27 | I8 → K27 | 60mm | 48mm (45°) |
| 4 | GreenSPIN R36 → R33 | R36 → R33 | 18mm | Straight |
| 28 | GreenCATHODES G19 → G16 | G19 → G16 | 18mm | Straight |
| 22 | GreenCATHODES S18 → O19 | S18 → O19 | 23mm | 8mm (90°) |
| 10 | GreenDISCH L38 → M33 | L38 → M33 | 25mm | 18mm (90°) |
| 34 | GreenGND Q22 → P28 | Q22 → P28 | 28mm | 20mm (90°) |
| 16 | GreenQ9 G18 → M31 | G18 → M31 | 58mm | 38mm (90°) |
| 40 | GreenGND S22 → D5 | S22 → D5 | 91mm | 48mm (90°) |
| 31 | Red9V H31 → H34 | H31 → H34 | 18mm | Straight |
| 37 | RedGND P34 → P37 | P34 → P37 | 18mm | Straight |
| 25 | RedCATHODES P13 → N10 | P13 → N10 | 23mm | 10mm (90°) |
| 7 | RedTIMING M39 → G38 | M39 → G38 | 28mm | 20mm (90°) |
| 1 | RedQ7 M18 → M27 | M18 → M27 | 33mm | Straight |
| 13 | RedQ0 G15 → J27 | G15 → J27 | 48mm | 35mm (90°) |
| 19 | RedQ5 Q11 → H27 | Q11 → H27 | 74mm | 46mm (90°) |
| 27 | WhiteCATHODES J8 → I9 | J8 → I9 | 14mm | Straight |
| 9 | WhiteDISCH J38 → F38 | J38 → F38 | 20mm | Straight |
| 21 | WhiteCATHODES O16 → O12 | O16 → O12 | 20mm | Straight |
| 3 | WhiteCLOCK G34 → J31 | G34 → J31 | 21mm | Straight |
| 39 | WhiteGND N37 → E34 | N37 → E34 | 40mm | 18mm (90°), 25mm (90°) |
| 33 | White9V D37 → O39 | D37 → O39 | 43mm | 10mm (90°) |
| 15 | WhiteQ1 G11 → I27 | G11 → I27 | 56mm | 10mm (90°) |
| 20 | YellowCATHODES Q18 → Q16 | Q18 → Q16 | 15mm | Straight |
| 26 | YellowCATHODES M9 → K9 | M9 → K9 | 15mm | Straight |
| 32 | Yellow9V I35 → E38 | I35 → E38 | 28mm | 13mm (90°) |
| 8 | YellowTIMING M37 → F34 | M37 → F34 | 31mm | 16mm (45°) |
| 38 | YellowGND Q35 → I31 | Q35 → I31 | 35mm | 15mm (45°) |
| 14 | YellowQ6 O15 → L27 | O15 → L27 | 48mm | 35mm (90°) |
| 2 | YellowQ4 O8 → N31 | O8 → N31 | 81mm | 10mm (90°), 69mm (90°) |
About this build
An LED roulette wheel from two chips. A 555 timer clocks a CD4017 decade counter, and the counter's ten outputs light a ring of ten LEDs one at a time, nine red and one green. Only one LED is ever on, so the whole ring shares a single resistor.
The spin comes from one capacitor. Hold the button and a 47uF capacitor charges to the supply, and the 555's timing resistors are fed from that capacitor instead of the battery. Let go and it drains a little with every step, so each step takes longer than the last.
When the capacitor falls below two thirds of the supply, the 555 can't reach its threshold anymore, and the wheel stops on one LED. It runs on 9V.
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