Three chips, three clocks, a color that never repeats
Three 555 timers blink the red, green and blue of one LED at unrelated rates, so the colour drifts for ages before it repeats.
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 14 × 30 holes, plus hookup wire.
| Qty | Part | Where to buy |
|---|---|---|
| 2 | Ceramic Cap1uF C1, C2 | Buy Ceramic Cap on Amazon |
| 1 | Ceramic Cap2.2uF C3 | Buy Ceramic Cap on Amazon |
| 1 | Power Input (2-pin) J1 | |
| 1 | RGB LED (common anode) Q1 | Buy RGB LED (common anode) on Amazon |
| 1 | Resistor (axial)470k R1 | Buy Resistor (axial) on Amazon |
| 1 | Resistor (axial)820k R2 | Buy Resistor (axial) on Amazon |
| 1 | Resistor (axial)680k R3 | Buy Resistor (axial) on Amazon |
| 1 | Resistor (axial)220 R4 | Buy Resistor (axial) on Amazon |
| 3 | DIP-8 U1, U2, U3 |
Check every pin against the datasheet of the exact part in your hands before wiring.
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Cut list
27 wires, 790 mm (31.1 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 | BlackOSC2 I12 → E12 | I12 → E12 | 20mm | Straight |
| 18 | BlackVCC C23 → B15 | C23 → B15 | 33mm | 8mm (90°) |
| 24 | BlackGND C12 → B20 | C12 → B20 | 33mm | 8mm (90°) |
| 6 | BlackT2 I18 → D12 | I18 → D12 | 38mm | 8mm (90°), 23mm (90°) |
| 5 | BlueT2 J17 → K14 | J17 → K14 | 20mm | 13mm (90°) |
| 17 | BlueVCC F19 → B22 | F19 → B22 | 28mm | 15mm (90°) |
| 23 | BlueGND B6 → B13 | B6 → B13 | 28mm | Straight |
| 11 | BlueOSC3 J20 → M28 | J20 → M28 | 38mm | 13mm (90°) |
| 4 | GreenT2 H17 → E16 | H17 → E16 | 20mm | 13mm (90°) |
| 10 | GreenOSC3 I19 → E19 | I19 → E19 | 20mm | Straight |
| 22 | GreenGND G5 → C5 | G5 → C5 | 20mm | Straight |
| 16 | GreenVCC J22 → G20 | J22 → G20 | 23mm | 13mm (90°) |
| 1 | RedT1 H10 → E9 | H10 → E9 | 20mm | 13mm (90°) |
| 7 | RedT3 H24 → E23 | H24 → E23 | 20mm | 13mm (90°) |
| 19 | RedVCC C16 → G13 | C16 → G13 | 28mm | 15mm (90°) |
| 25 | RedGND H4 → K8 | H4 → K8 | 28mm | 15mm (90°) |
| 13 | RedOSC2 H13 → K29 | H13 → K29 | 58mm | 46mm (90°) |
| 21 | WhiteVCC E4 → B8 | E4 → B8 | 28mm | 13mm (90°) |
| 27 | WhiteGND K15 → K22 | K15 → K22 | 28mm | Straight |
| 9 | WhiteT3 J24 → D19 | J24 → D19 | 35mm | 12mm (45°), 20mm (90°) |
| 3 | WhiteT1 I11 → D5 | I11 → D5 | 38mm | 8mm (90°), 23mm (90°) |
| 15 | WhiteOSC1 H6 → H28 | H6 → H28 | 66mm | Straight |
| 2 | YellowT1 J10 → K7 | J10 → K7 | 20mm | 13mm (90°) |
| 14 | YellowOSC1 I5 → E5 | I5 → E5 | 20mm | Straight |
| 8 | YellowT3 I25 → K21 | I25 → K21 | 25mm | 10mm (90°) |
| 20 | YellowVCC F12 → G6 | F12 → G6 | 28mm | 8mm (90°) |
| 26 | YellowGND M8 → M15 | M8 → M15 | 28mm | Straight |
About this build
A chaos lamp with no microcontroller. Three NE555 timers each run as an astable oscillator, and each one blinks one colour of a common anode RGB LED.
The timing parts are picked so the three rates don't line up: 470k, 820k and 680k resistors on 1uF, 1uF and 2.2uF caps. Because the three clocks are independent, the mixed colour keeps drifting for a very long time before the pattern comes back around.
To fit the board, all three colours share one 220 ohm resistor on the common anode. It works, but the colours won't be evenly bright. If you want them even, give each cathode its own resistor.
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