This repository documents the full reconstruction of Albert A. Michelson’s 20-element harmonic analyzer—an analog mechanical computer that performs Fourier synthesis and analysis via a system of gears, springs, levers, and cams.
This is a high-fidelity, didactic recreation of the original machine described in:
- Albert Michelson’s Harmonic Analyzer: A Visual Tour of a Nineteenth Century Machine that Performs Fourier Analysis by Bill Hammack, Steve Kranz, and Bruce Carpenter.
- EngineerGuy YouTube video series: "A Machine That Uses Gears to Add Sines and Cosines"
The project is designed as an advanced, hands-on learning experience in mechanical engineering, digital fabrication, and precision machining.
The analyzer is composed of 20 mechanical channels operating in parallel, each contributing one sinusoidal term. Key subsystems include:
- Crank and translational gearing
- Cone gear set (variable frequency generation)
- Cylinder gear set (frequency transmission)
- Rocker arms and amplitude bars
- Summing lever and spring systems
- Magnifying and pen mechanism
- Platen (paper transport)
See docs/components/ for engineering drawings and CAD assemblies.
The implementation follows a structured seven-phase process:
| Phase | Duration | Description |
|---|---|---|
| 1. Research & Documentation | 2 weeks | Study source materials, identify mechanical principles |
| 2. Preliminary Design | 3 weeks | Create core CAD assemblies of gears, linkages |
| 3. Detailed CAD Modeling | 4 weeks | Full-featured models with tolerances and annotations |
| 4. Manufacturing | 6 weeks | CNC machining, lathe work, and parts procurement |
| 5. Assembly & Calibration | 4 weeks | Physical build-up and iterative tuning |
| 6. Testing & Validation | 3 weeks | Compare machine output with known Fourier series |
| 7. Publication | 2 weeks | Prepare final documentation and make it open-source |
Full plan: Study and Implementation Plan.md
This project is built using:
- CAD: SOLIDWORKS xDesign for Makers
- Machinery:
- Mill: PM-30MV (1 HP, R8, 4000 RPM)
- Lathe: JET BD-920N (9″ × 20″)
- Manufacturing Methods: Manual milling/turning, custom jigs, DROs, hand finishing.
- Hammack, Kranz, Carpenter. Albert Michelson’s Harmonic Analyzer. Articulate Noise Books, 2014.
- Michelson & Stratton. "A New Harmonic Analyzer", American Journal of Science, 1898.
- EngineerGuy YouTube Series Playlist
All original documentation, code, and CAD files are released under the MIT License. Reuse of book content or video transcripts must respect original copyright.