THEREMIN

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THEREMIN
Theremin

• PROJECT MEETING II

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Theremin Modular Design
Theremin
V/F Converter
Freq Switch
Audio Out
Tuner Out Signal
Footswitch
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VPO and FPO Circuits
Theremin
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VPO and FPO Outputs
Theremin
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Detector Circuit
Theremin
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Beat Frequency Output Range
Theremin
CMAX 6 pF gives fMAX of 1765.4 Hz
f 1 / T 1765.4 Hz T 0.566 msec
CMIN 2 pF gives fMIN of 109.9 Hz
f 1 / T 109.9 Hz T 9.1 msec
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Lab Results
Theremin
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Beat Frequency Oscillator
Theremin

• Beat frequency oscillator functions fairly well.
• Audio range falls short of design requirement.

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Footswitch
Theremin
Footswitch
Ring
Normally Closed
Tip
-12V
Control Signal
AmplifiedAudio Out
Audio In

• Stepping on footswitch enables antenna volume
  control.
• Releasing footswitch disables Audio Out.

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Discrete Mode Overview
Theremin
110-1760 Hz continuous beat frequency from
detector
0.3-5 V continuous voltage range
Voltage/Frequency Converter
Binary representation of selected output level
Resulting discrete voltage level
Desired note within 0.1 error
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Frequency-to-Voltage Converter
Theremin
LM741
LM239
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F V Converter
Theremin
Simulation
Lab Results
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Microchip Program
Theremin
Flow Chart of the Microchip Program
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V - F Converter
Theremin
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Tuner Out Circuit
Theremin
To
Tuner
Gain -RF / R1 -46k / 13k 3.54 V/V
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Tuner Out Results
Theremin
Gain Vo / Vin 1.4154 / 0.4 3.54 V/V
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Summary
Theremin

• Beat Frequency Oscillator
• Functions well
• Need to increase audio frequency range

• Frequency/Voltage Converter
• Works well and approx. linear

• Micro Controller
• Programming complete
• I/O not functioning

• Volume Control Circuit
• Works properly

• D/A Converter
• Functioning linearly and accurately

• Footswitch Circuit
• Works properly

• Box
• Need to finish constructing box and install
  hardware

• Tuner Out Circuit
• Works properly

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Questions?
Theremin