Jacob's Ladder Bicycle

Overview

A demonstration of how accessible high-voltage effects can be, built for an early Detroit Maker Faire. The concept: pedal a bike fast enough and make lightning.

How It Works

An old exercise bicycle was fitted with a cheap automotive alternator. Rather than using the full rectified output, the AC voltage was tapped directly off two of the alternator’s internal diodes — giving a raw, unregulated AC signal that scales with pedaling speed.

That AC voltage feeds into a salvaged drip oil furnace spark generator coil, which steps it up to the high voltages needed to produce an arc. The output drives two vertically-oriented copper pipes arranged as a Jacob’s Ladder inside a decoratively painted enclosure — so spectators can watch the arc climb without getting anywhere near it.

The 88 MPH Trigger

A bicycle speedometer was wired in and configured so the spark would only ignite once the rider reached 88 MPH — a nod to Back to the Future and the 1.21 gigawatts needed to power the flux capacitor.