Diagonal Light-Up Board

Select any node to complete the circuit and discover its diagonals.

Selected Polygon None
Number of Sides (n) -
Formula (n - 3) -
Total Diagonals Lit -
Awaiting circuit completion...

DIY Cardboard Setup Guide

Want to build this physically for your exhibition? Here is how to construct the real-life board using cardboard, copper tape, and LEDs.

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Step 1: The Base

The Base & Shapes

Cut a sturdy piece of cardboard and paint it dark blue or black. Draw the five polygons (Triangle to Octagon) using a silver marker.

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Step 2: Placing the Nodes

Placing the Nodes

Push conductive brass fasteners (or metal thumbtacks) into every corner (vertex) of the polygons. These act as your circuit nodes.

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Step 3: Wiring the Diagonals

Wiring the Diagonals

On the back, connect the fasteners using copper tape and LEDs. Crucial: Only connect a vertex to non-adjacent vertices (the n-3 rule!).

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Step 4: Common Ground

Common Ground

Connect the negative (short) leg of all LEDs to a single common ground wire on the back, connected to a battery pack's negative terminal.

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Step 5: The Probe

The Probe

Attach a loose wire to the positive terminal of the battery pack. Attach a metal probe (like a large nail or stylus) to the end of this wire.

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Step 6: Complete the Circuit

Complete the Circuit

Touch the probe to any fastener on the front. Power flows through the specific diagonal LEDs connected to that node, proving the formula!