Jack-o'-lantern eyes that flicker, from one 555
Two orange LEDs that flutter like jack-o'-lantern eyes, one brightening as the other dims. One 555 timer.
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
12 parts on a perfboard 15 × 28 holes, plus hookup wire.
| Qty | Part | Where to buy |
|---|---|---|
| 1 | Ceramic Cap100nF C1 | Buy Ceramic Cap on Amazon |
| 1 | Electrolytic Cap10uF C2 | Buy Electrolytic Cap on Amazon |
| 1 | Electrolytic Cap220uF C3 | Buy Electrolytic Cap on Amazon |
| 1 | Power Input (2-pin) J1 | |
| 2 | LED LED1, LED2 | Buy LED on Amazon |
| 1 | Resistor (axial)1k R1 | Buy Resistor (axial) on Amazon |
| 1 | Resistor (axial)10k R2 | Buy Resistor (axial) on Amazon |
| 1 | Resistor (axial)220 R3 | Buy Resistor (axial) on Amazon |
| 2 | Resistor (axial)680 R4, R5 | Buy Resistor (axial) on Amazon |
| 1 | DIP-8 U1 |
Check every pin against the datasheet of the exact part in your hands before wiring.
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Cut list
18 wires, 502 mm (19.8 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 | ||
|---|---|---|---|---|
| 12 | BlackVCC G15 → K12 | G15 → K12 | 28mm | 15mm (90°) |
| 6 | BlackDISCH C12 → H15 | C12 → H15 | 30mm | 8mm (90°), 15mm (90°) |
| 18 | BlackGND B16 → M20 | B16 → M20 | 48mm | 15mm (90°) |
| 5 | BlueDISCH D11 → E6 | D11 → E6 | 25mm | 18mm (90°) |
| 11 | BlueVCC F4 → F14 | F4 → F14 | 35mm | Straight |
| 17 | BlueGND C17 → D26 | C17 → D26 | 35mm | 28mm (90°) |
| 10 | GreenVCC G3 → L3 | G3 → L3 | 23mm | Straight |
| 16 | GreenGND F12 → D16 | F12 → D16 | 25mm | 15mm (90°) |
| 4 | GreenTIMING E10 → I15 | E10 → I15 | 33mm | 8mm (90°), 20mm (90°) |
| 1 | RedOUT L11 → I11 | L11 → I11 | 18mm | Straight |
| 7 | RedFLICKER L18 → E18 | L18 → E18 | 28mm | Straight |
| 13 | RedVCC J11 → K19 | J11 → K19 | 33mm | 8mm (90°) |
| 3 | WhiteTIMING E12 → C14 | E12 → C14 | 17mm | Straight |
| 9 | WhiteVCC C6 → G5 | C6 → G5 | 23mm | 15mm (90°) |
| 15 | WhiteGND I4 → G11 | I4 → G11 | 30mm | 18mm (45°) |
| 2 | YellowTIMING F11 → H11 | F11 → H11 | 15mm | Straight |
| 14 | YellowGND H5 → K5 | H5 → K5 | 18mm | Straight |
| 8 | YellowFLICKER M17 → K26 | M17 → K26 | 38mm | 10mm (90°) |
About this build
Two orange LEDs become jack-o'-lantern eyes, driven by one NE555 timer. The 555 runs at about seven pulses a second, and a 220uF capacitor rounds every pulse off.
The eyes hang on opposite sides of that capacitor. One runs from the capacitor down to ground, the other from the supply down into the capacitor, so as the voltage rises one eye brightens and the other dims. It's a steady, rhythmic flutter rather than a random candle flame, and it looks alive through a carved pumpkin.
It runs on 9V, laid out from the input at the top down to the eyes at the bottom, and each eye gets a 680 ohm resistor.
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