Transcript The Theremin - College of Charleston

THE THEREMIN
Marco A. Rodriguez
Department of Physics & Astronomy, College of Charleston, Charleston, SC
WAVES / SOUND
Resistor-R
Capacitor-C
Inductor-L
555 IC
PARALLEL-PLATE CAPACITOR MODEL
A
C = ereo
d
LÉON THEREMIN
• Born 1896
• Russian research 1920
• The high frequency
oscillator
OPERATION: HETERODYNING
• High to Low frequency conversion
• Non-linear signal processing device
• Heterodynes
• Filtering to audible frequency range
OPERATION: HETERODYNING
OPERATION: THE VARIABLE OSCILLATOR
• LC circuit-based
f =
1
2p LC
• Capacitor: Antenna + Hand
OPERATION: THE FIXED OSCILLATOR
• Initially tuned at high frequency
• Change in capacitance = change in voltage
• Voltage-controlled amplifier
CHALLENGES
• Complexity/construction of circuit
• Frequency mixing
• Cost of materials
OPTICAL THEREMIN
• Varying resistance vs. capacitance
1
f =
2pRC
• No need for RF oscillators
• No need for heterodyning
THE 555 TIMER
• Astable mode
1
f =
ln(2)C(R1 + 2R2 )
• Light-dependent resistance
CHALLENGES
• IC sensitivity
• Soldering work
(12 hours of my life I will never get back)
• Resistor/Capacitor Tuning
Demonstration