project meeting ii theremi n theremin. variable oscillator fixed oscillator detector pitch control...
TRANSCRIPT
PROJECT MEETING II
Theremin
THEREMIN
VariableOscillator
FixedOscillator
Detector
Pitch Control
VariableOscillator
VolumeTuning
Volume Control
FreqSwitch
Theremin
Tuner Out Signal
Footswitch
Audio Out
Freq-VoltageConverter
PIC controllerwith A/D
Discrete Frequency Controller
14-bit D/AV/F
Converter
VCAProcessor
Voltage ControlledAmplifier
Output Control
Theremin Modular Design
Theremin
VPO and FPO Circuits
Theremin
VPO and FPO Outputs
Theremin
Detector Circuit
Theremin
Beat Frequency Output Range
f = 1 / T = 1765.4 Hz
T = 0.566 msec
CMAX = 6 pF gives
fMAX of 1765.4 Hz
CMIN = 2 pF gives
fMIN of 109.9 Hz
f = 1 / T = 109.9 Hz
T = 9.1 msec
Theremin
Lab Results
VariableOscillator
FixedOscillator
Detector
290 – 288 kHz
292 – 288 kHz
Audio:80 – 850 Hz
Left:
• VPOmax = 291 kHz
Right:
• VPOmin = 288 kHz
Left:
• FPOmax = 292 kHz
Right:
• FPOmin = 288 kHz
Detector Output Waveform
Theremin
Beat Frequency Oscillator
VariableOscillator
FixedOscillator
Detector
290 – 288 kHz
292 – 288 kHz
Audio:
80 – 850 Hz
•Beat frequency oscillator functions fairly well.
•Audio range falls short of design requirement.
Theremin
Footswitch
Footswitch
Tip
Ring
AmplifiedAudio Out
Audio InControl Signal
Normally Closed
• Stepping on footswitch enables antenna volume control.
• Releasing footswitch disables Audio Out.
-12V
Control Voltage:
0V full volume
-12V no output
Theremin
Discrete Mode Overview
Frequency/Voltage
Converter
PIC controller with 10 bit A/D
14 bit
D/A Converter
Voltage/Frequency
Converter
110-1760 Hz continuous beat frequency from detector
0.3-5 V continuous voltage range
Binary representation of selected output level
Resulting discrete voltage level
Desired note within 0.1% error
Theremin
Frequency-to-Voltage ConverterRequirement Current Status
Input frequency 110 – 1760 Hz 110 – 1760
Output voltage 0.3 – 5.0 V 0.27 – 2.51 V
LM741 LM239
Theremin
F –V ConverterFrequency to Voltage Converter
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
0 500 1000 1500 2000
Input Frequency (Hz)
Ou
tpu
t V
olt
ag
e (
V)
Ckt OutputIdealLinear (Ckt Output)
Simulation
Lab Results
Theremin
Microchip Program
Flow Chart of the Microchip Program
Theremin
V - F Converter
Voltage to Frequency Converter
0
200
400
600
800
1000
1200
1400
1600
1800
0 2 4 6 8 10
Vout (V)
Fin
(H
z)
Circuit Output
Linear (Circuit Output)
Requirement Current Status
Input Voltage 0 – 12 V 0.01 – 9.6
Output Frequency 110 – 1760 Hz 156 - 1760 Hz
Theremin
Tuner Out Circuit
Gain = -RF / R1 = -46k / 13k = 3.54 V/V
To
Tuner
Theremin
Tuner Out Results
Gain = Vo / Vin = 1.4154 / 0.4 = 3.54 V/V
Theremin
SummaryBeat Frequency Oscillator:
Functions well
Need to increase audio frequency range
Volume Control Circuit:
Works properly
D/A Converter:
Functioning linearly and accurately
Frequency/Voltage Converter:
Works well and approx. linear
Box:
Need to finish constructing box and install hardware
Micro Controller:
Programming complete
I/O not functioning
Footswitch Circuit:
Works properly
Tuner Out Circuit:
Works properly
Theremin
Questions?