Oscillators

Introduction

The repeated backward and forward motion between positions or states of an item is referred to as oscillation. It also can be known as the periodic movement that has the tendency to repeat itself in a regular cycle. For example- a sine wave, with a side-to-side pendulum swing, or the up-down movement with a weight of a spring. The oscillating motion takes place around an equilibrium point or an average value. 

This movement is likewise known as the periodic movement. A single oscillation is taken into consideration to be a finished motion over a time frame whether or not it is a side-to-side motion or an up-down motion.

The movement of an object is stated to be oscillatory or vibratory movement if it moves back and forth (to and fro) about a set position or point after a regular time interval. The fixed point about which an object oscillates is referred to as mean position and equilibrium position. Every oscillatory movement is periodic however each periodic movement isn’t always oscillatory.

Oscillation Motion

In easy terms, we can say that when an object is swinging to and fro in a mechanical device this motion may be termed as oscillation motion. In this sort of movement, the potential energy typically changes to kinetic energy. An oscillation movement includes one full cycle.

Oscillators

A circuit that creates a continuous, repetitive, alternating waveform without any input is known as an oscillator. Oscillators are devices that convert unidirectional current flow from a DC source into an alternating waveform with the required frequency set by the circuit components.

Working of an Oscillator

The behaviour of an LC tank circuit, shown in Figure below, which uses an inductor L and a totally pre-charged capacitor C as its components, can be used to understand the core idea behind the operation of oscillators. Initially, the capacitor discharges via the inductor, converting its electrical energy into an electromagnetic field that may be stored in the inductor. There will be no current in the circuit until the capacitor has discharged fully.

However, by that time, the stored electromagnetic field would have formed a back-emf, causing current to flow in the same direction as previously via the circuit. This current flow through the circuit continues until the electromagnetic field collapses, causing electromagnetic energy to be converted back into electrical form and the cycle to begin again. However, because the capacitor has now been charged with the opposite polarity, the output is an oscillating waveform.

However, the oscillations that result from the interconversion of the two energy forms cannot last permanently since they are prone to energy loss due to the circuit’s resistance. As a result, the amplitude of these oscillations gradually reduces until it reaches zero, indicating that they are damped in nature.

This shows that the energy loss must be compensated for in order to get continuous and constant amplitude oscillations. However, in order to achieve oscillations with constant amplitude, the energy provided must be precisely controlled and equal to the energy lost.

Type of Oscillator

There are many types of oscillators but it can be broadly divided into two types:

• Harmonic Oscillators 
• Relaxation Oscillators

The energy transfer in a harmonic oscillator is always from active to passive components, and the frequency of oscillations is determined by the feedback path.

The energy is exchanged between the active and passive components in a relaxation oscillator, and the frequency of oscillations is decided by the charging and discharging time-constants involved in the process.

In addition, harmonic oscillators generate low-distortion sine-wave outputs, whereas relaxation oscillators generate non-sinusoidal (saw-tooth, triangle, or square) waveforms.

Some major types of Oscillators are:

• RC Phase Shift Oscillator
• Hartley Oscillator
• Voltage Controlled Oscillator
• Colpitts Oscillator
• Clapp Oscillators
• Crystal Oscillators
• Armstrong Oscillator
• Tuned Collector Oscillator
• Gunn Oscillator
• Cross-Coupled Oscillators
• Ring Oscillators

Oscillators can also be divided into several categories based on the parameters that are taken into account, such as the feedback mechanism, the shape of the output waveform, and so on.

They are as follows:

• Positive Feedback Oscillators and Negative Feedback Oscillators are based on feedback mechanisms.
• Sine Wave Oscillators, Square or Rectangular Wave Oscillators, Sweep Oscillators are all based on the shape of the output waveform.
• Low-Frequency Oscillators, Audio Oscillators, Radio Frequency Oscillators, High-Frequency Oscillators, Very High-Frequency Oscillators, Ultra High-Frequency Oscillators, and so on are all based on the frequency of the output signal.
• RC Oscillators, LC Oscillators, Crystal Oscillators, and other types of frequency controls are used.
• Fixed Frequency Oscillators and Variable or Tunable Frequency Oscillators are classified according to the nature of the output waveform’s frequency.

Conclusion

The pendulum of a clock is one of the most regularly utilised oscillators. When you start swinging a pendulum, it will oscillate at a given frequency, swinging back and forth a certain number of times each second. The frequency is mostly controlled by the length of the pendulum.

Energy must flow back and forth between two forms for something to oscillate. Energy is transmitted between potential and kinetic energy in a pendulum, for example. The pendulum’s energy is all potential energy when it reaches one end of its path and is ready to fall.

 When the pendulum is in the middle of its cycle, all of its potential energy is converted to kinetic energy, and it moves as quickly as it can. All of the kinetic energy in the pendulum’s swing is converted to potential energy as it goes toward the opposite end of its swing. The oscillation is caused by the transfer of energy between the two forms.