PHYS 341 Lecture Notes - Lecture 30: Thaddeus Cahill, Laurens Hammond, Tonewheel
Document Summary
1st electric organs starting w/ telharmonium + later w/ early hammond. Organs (1929) used a tone wheel to generate a sinusoidal electrical signal. Rotating iron wheel made sinusoidal disturbance in current flowing through adjacent electromagnet, which could be amplified + heard via speaker. Created instruments sounds by additive synthesis (adding harmonic partials using many tone wheels) Laurens hammond + john m. hanert (invented 1929, production 1935) Originally for small churches, later rnb, progressive rock. Tone generation: tone wheels (up to 1975, electronic oscillators, digital (2002 -) Harmonic (linear) oscillator produces sinusoidal output w/ 1 frequency component. Inductor (coil of wire) behave as mass: capacitor (2 plates separated by tiny gap) behaves as spring. Developed by lev termin (leon theremin in west) as people sensor for. Pitch control: 2 high frequency oscillators tuned to almost same frequency, frequency of 1 is altered slightly by the proximity of a hand to pitch antenna (affects the capacitance)
