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OSCILLATOR

OSCILLATOR. Bollen. What is oscillation Analog oscillation WIEN bridge oscillator High pass and low pass combined Relaxatin oscillator RC circuit 15k and 10 nF Voltage diviver 15k and 15k Comparator Signals and output Charge Discharge. Frequency = 1 / total time Variationa

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OSCILLATOR

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  1. OSCILLATOR Bollen

  2. What is oscillation Analog oscillation WIEN bridge oscillator High pass and low pass combined Relaxatin oscillator RC circuit 15k and 10 nF Voltage diviver 15k and 15k Comparator Signals and output Charge Discharge Frequency = 1 / total time Variationa Summary AGENDA Bollen

  3. What is oscillation Circuit powered by Vcc and Vee No input signal, only output signal Wienbridge Oscillator; output signal is sine wave (used for making radio frequencies) Relaxation Oscillatoer; output signal is a “digital” block signal (used for clock or count circuits) Bollen

  4. Barkhausen criterium: Loopgain = 1 Total phase = 0 or 360 What is analog oscillationWIEN bridge oscillator Bollen

  5. Oscillator for High frequency Sine signals It uses 2 filters; High pass and low pass For one frequency the phase = 0 degrees !!!! WIEN bridge oscillator Bollen

  6. High Pass and Low Pass combinated Bollen

  7. WIEN bridge oscillator Barkhausen criterium: Loopgain = 1 Total phase = 0 or 360 Bollen

  8. WIEN bridge oscillator After “short” mathematics; Bollen

  9. WIEN bridge oscillator Bollen

  10. WIEN bridge oscillator Bollen

  11. WIEN bridge oscillator For phase = o degrees; imaginair part = 0 Bollen

  12. WIEN bridge oscillator For R1 = R2 = R And C1 = C2 = C At oscillation IM = 0 Au = 1/3 so amplificaton should be +3 Rf = 2 Rs Bollen

  13. WIEN bridge oscillator Bollen

  14. RC-circuit 15k and 10nF; charge / discharge Voltage divider 15k and 15k; high treshold / low treshold Comparator Output: block Vcc / Vee What is “digital” oscillationRelaxation oscillator Bollen

  15. Vin = Vcc = +12 for charge And = Vee = -12 for discharge RC-circuit 15k and 10nF Bollen

  16. Vin = +12 volt = opamp output high or Vin = - 12 volt = opamp output low V treshold up = +6 V for +12 opamp output V treshold low = -6 V for – 12 opamp output Voltage divider 15k and 15k Bollen

  17. Inverting input; Uc, capacitor voltage Non inverting input; Treshold voltage, high (+6 Volt) or low (-6 volt) Output: Comparator Bollen

  18. Signals and output Blue = output signal (+12 Volt or – 12 Volt) Green = treshold signal (+6 Volt of – 6 Volt) Red = capacitor signal Bollen

  19. Calculate 2nd charge track! Why? Charge R = 15 k C = 10 nF Vfinal = +12 V Vinitial = -6 V Switch at Vc = +6 Volt Bollen

  20. Discharge R = 15 k C = 10 nF Vfinal = -12 V Vinitial = +6 V Switch at Vc = -6 Volt Bollen

  21. Frequency = 1 / (total time) Bollen

  22. By using diodes; Charge time and Discharge time are different !! Treshold remains the same So … duty cylce is controlable; up time ≠ down time Variations 1 Bollen

  23. Frequency control by changing the voltage divider Vtreshold up Vtreshold low Variations 2 Bollen

  24. Analyse yourself .. .. .. Conclusion? Summary 1 Bollen

  25. Analyse yourself .. .. .. Conclusion? Summary 2 Bollen

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