Exploring Oscillators and Piezoelectric Effect in Modern Electronics - Devashish Negi

This is a brief presentation on Oscillators and Piezoelectric materials.

1. Oscillators and Piezoelectric Effect in Modern Electronics in brief by Devashish Negi

2. Introduction Oscillators: Electronic circuits that produce a periodic, oscillating signal (sine wave, square wave, etc.) Piezoelectric Effect: The ability of certain materials to generate an electric charge in response to applied mechanical stress.

3. Piezoelectric Effect generation of an electric charge in response to mechanical stress , discovered by Jacques and Pierre Curie in 1880.

4. Piezoelectric Sensor when stress is applied – produces a potential difference of some magnitude converting mechanical energy to electrical energy vice-versa is true too when electric energy is supplied, it vibrates, producing mechanical vibrations

5. How it works? non-centrosymmetric crystals ex. Quartz (SiO2) Lead zirconate titanate (PZT) Polyvinylidene Fluoride (PVDF) It’s polarized but stable, but when disturbed , it’s centre shifts net Electric dipole moment is generated

6. Why SiO2 is polarized? oxygen is more electronegative than Silicon further up in periodic table further right in periodic table

7. Polarization in SiO 2 normally net charge is balanced when compressed or elongated , balance shifts hence, crystal gets polarized we get a net + ve and – ve charge from the whole crystal

8. Polarization in SiO 2 we can connect them via. wires to get a spark this is how gas lighters works

9. Real Life Examples Gas lighters Stethoscope Pressure sensor Clocks

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11. Oscillators circuits that convert DC (Direct Current) from a power supply to an AC (Alternating Current) signal. used in Signal Generating Timekeeping

12. Working two main parts Amplifier Feedback Circuit amplifier amplifies feedback, feedbacks Output Signal back to input – to sustain oscillations feedback circuit is Frequency Selective

13. Working

14. Barkhausen Condition important points to keep in mind the total phase shift by amplifier and feedback should be = 0 Loop Gain (A β ) = 1 this is known as Barkhausen Condition

15. Working A β < 1 A β > 1 A β = 1 i nitially A β > 1, as oscillations starts from 0 and we need them to build up to some desired Amplitude/Voltage when reached, we set A β = 1 we need these Sustained Oscillations

16. Importance in Modern Electronics clock generation frequency synthesis – crucial in signal processing and FM signal processing – used in signal manipulation, providing stable reference signal synchronization feedback control system transducers ultrasound applications

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18. Types Harmonic Oscillators produces Sinusoidal Waves LC Oscillators Crystal Oscillators Relaxation Oscillators produces Non-Sinusoidal Waves RC Oscillators Multivibrator 555 Timer

19. LC Oscillator most common type Sustained oscillations condition: at resonance frequency of L and C when inductive reactance and capacitive reactance are same in magnitude and opposite in phase

20. Clock Oscillators generates precise timing signals a square wave – controls how fast a processor runs useful in synchronization of processes Overclocking – Increasing the clock oscillations

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22. CLOCKS

23. How it works? we need something that is periodic earlier there were pendulums then we shifted to spring clocks then piezo crystals were used quartz crystals are highly stable and accurate

24. Clocks with Piezo Crystals quartz crystal is factory calibrated to vibrate at frequency of 32768 Hz reason? it’s above human hearing range it’s = 2 15 , digital counter can easily divide we need to sustain the signals – Oscillators after every 32768 oscillation, 1 second will pass we can rotate the second hand, using gears we can also connect the signal to LCD display

25. Generating Sin wave with 555 Timer astable mode output square wave is converted to sine wave used as clock pulse for digital circuits

26. TinkerCAD Connections

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28. Thank You