till.com  Articles

A collection of my articles on various topics. Some readers may find them interesting.

Business and Economics

38 Startup Ideas
Want to do something different? I am now keeping a collection of my startup ideas. Updated!

Startup Proposal: Intelligent Traffic Signals
Disrupt the century old traffic signal industry, lower fuel consumption and exhaust emissions.

A New Business Model for the Music Industry
How record companies can actually win big in the next couple decades.

Guitar Physics

Pickups Part 1: Response Effects of Guitar Pickup Position and Width
Analysis, equations and plots of pickup response curves.

Pickups Part 2: Response Effects of Guitar Pickup Mixing
Analysis, equations and response plots of mixes of pickups.

Pickups Part 3: Pickup Response Demonstration
Interactive Javascript simulation of the physics of guitar pickups.

These have been referenced in:

Paiva, Pakarinen, Välimäki, Acoustics and Modeling of Pickups, Journal of the Audio Engineering Society, October 2012.

Kirk McDonald, Princeton University, Physics Examples — Electric Guitar Pickups.

Mohamad, Dixon, Harte, Pickup Position and Plucking Point Estimation on an Electric Guitar , Journal of the Acoustical Society of America, 2017

Henri Penttinen, Acoustic Timbre Enhancement of Guitar Pickup Signals with Digitial Filters


Root Locus Demo of Real Poles with Feedback
An interactive Javascript demo shows how feedback liberates the poles of a passive circuit from the tyranny of the real axis. New!

A Palette of Static Audio Waveforms
Bored with audio oscillator waveforms? Me too. Here is a musically powerful palette of waveforms, including two that didn't have names before.

Square Wave Variations
Square Waves may appear uninteresting at first...

"First of all, what the hell have you been smoking?" — Magnus Danielson

The Quadrature Trapezoid Voltage Controlled Oscillator
An original oscillator topology features quadrature waveform outputs and graceful thru-zero FM.

The Doepfer A-100-6 Voltage-Controlled Oscillator is based on this article.

Voltage Controlled Duty Cycle Sawtooth Circuit
Some quick notes on a circuit I came up that can morph from a sawtooth to a triangle to a reverse sawtooth with a control voltage.

Referenced by:

Dr. Edward Kelly, University of the Arts London, Wavefolding: Modulation of Adjustable Symmetry in Sawtooth and Triangular Waveforms, Proceedings of the International Computer Music Conference 2016

Achim Gratz, Triangle / Sawtooth VCO with Voltage Controlled Continously Variable Symmetry

An Interpolating Scanner Circuit
An alternate approach to Juërgen Haible's interpolating scanner.

"I would like to thank Don Tillman. Based on my Interpolating Scanner idea, he created a very brilliant implementation of his own, which is more elegant than my first solution in several ways." — Juërgen Haible

A Discrete FET Guitar Preamp
A popular example circuit for a guitar preamp based on a single FET stage. Now known as the "Tillman Preamp".

An FET Preamp Cable
A phantom-powered preamp built into a 1/4-inch phone plug.

Keyboards and Synthesizers

Triadex Muse in JavaScript
A software simulation of Marvin Minsky's Triadex Muse that runs on a web page.

"Muse in a browser, this is awesome folks!!" — Margaret Minsky

"This is so frigging great - possibly my favorite soft-synth" — numan7/muffwiggler

Psych Tone in JavaScript New!
A software simulation of Don Lancaster's Psych Tone that runs on a web page.

Moog Synthesizers: Moog Patent Reviews
A project to dig up, research, and review all of the patents by Robert Moog and related to Moog synthesizers.

ARP Synthesizers: ARP Patent Reviews
A project to dig up, research, and review all of the patents related to ARP Synthesizers.

ARP/Rhodes Chroma: Upgrading the Power Supply ("Nuclear Powered Chroma")
Replace a Rhodes Chroma power supply with a modern switching unit.

Don's Mellotron Page
Mellotron resources, notes, projects, the Mellotronists mailing list and the tale of a restored M400 with Mike Pinder's autograph.

Mellotron/Chamberlin Patent Reviews
Reviews of the Harry Chamberlin Mellotron Patents, as well as the Birotron patents.

[Outdated] Analog Synthesizer Resources
My favorite synthesizer design links.  General, historical, manufacturers, design, schematics, research.

[Outdated] ARP Synthesizers: ARP Resources
A collection of resources for ARP Synthesizers, including the ARP/Rhodes Chroma.

[Outdated] Moog Synthesizers: Moog Resources
A collection of Moog resources.

[Outdated] Hohner Clavinet Resources
A collection of resources for the Hohner Clavinet.