Wien Bridge Oscillator

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Wien Bridge Oscillator

• Merlin Perry
• Travis Vollmer
• Mohamed Elsayed

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Specifications to Meet

• Adjustable 10kHz Oscillation frequency
• Using - 15 volts
• Close to 1 THD
• Using Linear and Non-Linear Components
• At room temperature

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Wien Bridge Oscillator

• Wien Bridge was invented in 1891 by a German
  Physicist Max Wien.
• At first the Wien Bridge was designed as a
  measuring device for AC circuits.
• It was impractical as an Oscillator because it
  required amplification, and vacuum tubes where
  not yet invited.
• Hewlett Packard made the Wien Bridge oscillator
  practical by solving the problem of varying the
  gain by using a lamp.

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P-spice Schematic
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Hardware Schematic
1.6nF Capacitors
5.6K?
10K?
823 Diodes
29.2K?
10K?
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Gain of Wien Bridge Oscillator

• Gain Of A Non-Inverting Amplifier
• - Rf/Rg 1
• For Wien Bridge To Oscillator Gain Must Be
  Greater Than 3
• In Our Pspice Schematic The Gain Is
• 30k/10k 1 4
• In Testing The Gain Was
• 29.2k/10k 1 3.92

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Varying R3
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10kHz Wave Form
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10kHz Sine Wave
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Frequency Analysis
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Bench Spectrum Analysis
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Oscilloscope Reading
2V/Div
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Varying the Frequency

• To vary the oscillation frequency our group
  changed the values of the capacitors.
• From 1.6nF to 1.8nF to get an Oscillation of 9kHz
• From 1.6nF to 1.3nF to get an Oscillation of
  11.7kHz

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Varied Frequency (1.8nF)
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Varied Frequency (1.8nF)
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Varying Frequency (1.3nF)
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Varied Frequency (1.3nF)
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Lamp

• 52 Lamp Used
• Specs
• -14.4 V
• -100mA

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P-spice Schematic
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Hardware Schematic
1.8nF
1.8nF
5.6k?
10k?
52 lamp
741op-amp
28?
47?
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Warm up Frequency
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10kHz Frequency
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Warm Frequency Analysis
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Frequency Analysis
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Diode Vs. Lamp

• Less THD Using Lamp Than Diodes
• -0.76 Vs. 1.71
• Higher Oscillation Voltage Using Diodes
• -5.56 Vrms Vs. 1.45 Vrms
• No Warm Up Period With Diodes
• Lamp cost1.59 for 2 bulbs. Diode cost1.00 for
  4

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Gantt Chart
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Budget Report
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References

• http//www.scoon.co.uk/Electrotherapy/Rife/BeamRay
  /Analysis/hewlett.htm
• http//www.engr.uky.edu/radun/EE603
• http//www.ece.utep.edu/courses/ee3329
• http//www.ti.com/sc/amplifiers
• http//www.ecircuitcenter.com/circuits/opwien/opwi
  en.html
• Electronic Circuit Design Comer and Comer, 2003