Writing Games in Light on a Quiet Board

Chess Move Lighttrail Journaling
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🎮 Play: Lighttrail Tactics

Thirty-four hobbies in, and the wiring has become automatic. Strip the insulator, tin the pad, solder in dim light because the flux smoke stings. My fingers know this even when my brain has wandered off to calculate exposure times.

Tonight I’m fitting LEDs to chess pieces. Not all thirty-two — just the ones that move most in a rapid game: queens, rooks, knights, and both kings. The goal is to play a game, photograph the trails, and have a visual record that matches the notation afterwards. What follows is a technical walkthrough of the LED wiring, because I spent three hours getting it wrong before I spent one hour getting it right.

The Wiring Problem

A chess piece is small, hollow, and needs to balance on a square without tipping. The LED has to sit inside the piece pointing down through a hole in the base, so the light bleeds onto the board surface rather than glaring at the camera. The wire has to exit without catching on adjacent pieces. And everything has to survive being picked up, moved, and set down forty times in ten minutes.

I’m using 3mm diffused white LEDs rated at 20mA. Not addressable RGB — I tried WS2812Bs first and the wiring bulk was absurd. Single-colour LEDs keep the harness thin. Each piece gets its own LED on a dedicated GPIO pin from an ESP32, which means I can control brightness per piece and, eventually, log which piece moved when.

The wiring topology that works:

ESP32 GPIO → 100Ω resistor → LED anode (+)
LED cathode (−) → common ground rail

The 100Ω resistor limits current to about 15mA at 3.3V, which is slightly under the LED’s rated current but bright enough for photography when the room is dark. I learned during RC Light-Trace Calligraphy that dimmer LEDs write cleaner lines — a trail at full brightness becomes a fat smear that loses information. At 15mA the stroke stays legible.

Each piece has a 1-metre lead of 30 AWG magnet wire, which is thin enough to coil inside the piece’s hollow base without adding noticeable weight. The wires run through a channel carved into the board’s edge, then down to a connector block under the table. The whole assembly looks like a marionette’s rigging, but from the camera’s angle you see only the board.

Drilling the Pieces

The hole matters more than I expected. Too small and the light doesn’t escape; too large and the piece becomes structurally weak at the base. I settled on 2mm holes drilled through the felt pad and into the hollow cavity, then widened the inside with a countersink bit to seat the LED dome.

The process:

  1. Remove the felt pad (it peels off cleanly on most tournament-weight pieces)
  2. Mark centre with a pin
  3. Drill 2mm pilot hole through the base
  4. Countersink the interior to 5mm depth
  5. Hot-glue the LED in place, dome facing down
  6. Route the wire through a notch in the base edge
  7. Replace the felt pad with a slot cut for the wire

The knight was the hardest. Its centre of gravity sits forward of the geometric centre, so the hole has to be offset to hit the hollow cavity. I drilled two knights before I got the angle right.

Exposure Calculation

A rapid game at 5+0 time control runs about ten minutes for both players combined. Forty to fifty moves per side is typical. If I want a single exposure to capture the entire game, that’s 600 seconds — impossible without stacking.

So I shoot in segments: one 30-second exposure per phase of the game. Opening (moves 1-10), middlegame (moves 11-25), endgame (the rest). Three exposures, composited later. The camera sits on a tripod directly above the board, pointed straight down. Settings: f/8, ISO 100, 30 seconds. The room is dark except for a dim red safelight that doesn’t register on the sensor.

The composite in post-processing uses lighten blend mode — whichever pixel is brighter wins. The trails accumulate without overwriting each other. If I play the same opening I’ve played 30,000 times, the first ten moves appear as a confident, unbroken set of arcs. The middlegame chaos is visible. The endgame simplifies again.

What the Trails Actually Show

After the first complete game — a Sicilian that I won on time in a messy rook ending — I compared the photo composite to the PGN notation. The trails matched. Every move was visible as a distinct arc from origin square to destination square. Captures showed as bright points where a piece paused before being lifted off; the stationary moment accumulates light.

The knights drew the most interesting paths. They don’t slide — they jump. The trail shows a vertical lift, a lateral arc, and a descent. It looks like handwriting. The rooks, by contrast, drew long straight lines that occasionally crossed the entire board. The king, when it castled, produced a paired motion with the rook that’s immediately recognizable.

I made one error visible only in the photograph: on move 23, I picked up my queen, hesitated, and set it back down on the same square before playing a different move. The notation doesn’t record this — it’s not a move until you release the piece. But the photograph shows a small bright loop, a moment of doubt burned into the exposure.