KITT's scanner from two chips
The sweeping eye from KITT in Knight Rider, from a 555 timer, a decade counter and two steering diodes.
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 17 × 30 holes, plus hookup wire.
| Qty | Part | Where to buy |
|---|---|---|
| 1 | Electrolytic Cap10uF C1 | Buy Electrolytic Cap on Amazon |
| 2 | Diode (axial) D1, D2 | |
| 1 | Power Input (2-pin) J1 | |
| 3 | LED LED1, LED2, LED3 | Buy LED on Amazon |
| 1 | Resistor (axial)10k R1 | Buy Resistor (axial) on Amazon |
| 1 | Resistor (axial)68k R2 | Buy Resistor (axial) on Amazon |
| 1 | Resistor (axial)330 R3 | Buy Resistor (axial) on Amazon |
| 1 | DIP-8 U1 | |
| 1 | DIP-16 U2 |
Check every pin against the datasheet of the exact part in your hands before wiring.
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Cut list
25 wires, 766 mm (30.2 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 | ||
|---|---|---|---|---|
| 18 | BlackVCC G7 → C10 | G7 → C10 | 28mm | 13mm (90°) |
| 12 | BlackTIMING K9 → D6 | K9 → D6 | 35mm | 13mm (90°) |
| 24 | BlackGND M8 → C6 | M8 → C6 | 40mm | 10mm (90°) |
| 6 | BlackCLK E6 → F16 | E6 → F16 | 53mm | 13mm (90°), 38mm (90°) |
| 17 | BlueVCC H5 → F6 | H5 → F6 | 18mm | 10mm (90°) |
| 5 | BlueLED2A F23 → J23 | F23 → J23 | 20mm | Straight |
| 11 | BlueTIMING L10 → E10 | L10 → E10 | 28mm | Straight |
| 23 | BlueGND P28 → N9 | P28 → N9 | 63mm | 53mm (90°) |
| 4 | GreenLED2A G22 → G24 | G22 → G24 | 15mm | Straight |
| 10 | GreenTIMING M9 → M7 | M9 → M7 | 15mm | Straight |
| 22 | GreenGND K12 → G16 | K12 → G16 | 34mm | 9mm (45°), 16mm (90°) |
| 16 | GreenSCAN3 M24 → G12 | M24 → G12 | 56mm | 35mm (90°) |
| 7 | RedLEDK N24 → M25 | N24 → M25 | 14mm | Straight |
| 25 | RedGND B7 → D5 | B7 → D5 | 17mm | Straight |
| 1 | RedRST E16 → J16 | E16 → J16 | 23mm | Straight |
| 19 | RedVCC B9 → B4 | B9 → B4 | 23mm | Straight |
| 13 | RedSCAN1 C24 → F12 | C24 → F12 | 47mm | 33mm (45°), 37mm (45°) |
| 9 | WhiteLEDK G25 → E25 | G25 → E25 | 15mm | Straight |
| 15 | WhiteDISCH J9 → K5 | J9 → K5 | 23mm | 15mm (90°) |
| 3 | WhiteQ1D E18 → E12 | E18 → E12 | 35mm | 10mm (90°), 25mm (90°) |
| 21 | WhiteGND N28 → L13 | N28 → L13 | 53mm | 43mm (90°) |
| 8 | YellowLEDK K25 → I25 | K25 → I25 | 15mm | Straight |
| 14 | YellowDISCH I10 → D10 | I10 → D10 | 23mm | Straight |
| 2 | YellowQ3D K18 → J12 | K18 → J12 | 33mm | 8mm (90°), 23mm (90°) |
| 20 | YellowVCC C5 → C15 | C5 → C15 | 40mm | 8mm (90°), 33mm (90°) |
About this build
A Larson scanner, the bouncing eye from KITT in Knight Rider, built from two chips. A 555 timer clocks a CD4017 decade counter, and steering diodes fold the count back so the light sweeps across the LEDs and returns.
This compact version uses three LEDs. The middle LED gets two of the counter's outputs through two diodes, so the light goes left, middle, right, middle, and then the counter resets and does it again. The same idea scales to six LEDs with eight diodes for the full KITT sweep.
The 555 runs on a 10k and a 68k resistor with a 10uF cap, and since only one LED is lit at a time they share one 330 ohm resistor.
Knight Rider and KITT are trademarks of their owners. PerfBoard is not affiliated with or endorsed by them.
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