14 DAY TRIAL // Oscillators are extremely important for both electronic and mechanical devices. Quartz watches, computers, radios, clocks would be rendered inoperable without the help of oscillators. The basic idea is that oscillators are required to provide with a constant clock at a given moment. The clock of an oscillator is measured in cycles per second, most commonly known as Hertz.
Mechanical oscillators
The oldest and best known oscillator is the pendulum, of course. A clock with a pendulum oscillator, for example, is able to keep time with a certain accuracy by measuring the number of cycles per second made by the pendulum, meaning the frequency at which the pendulum is swinging back and forth. The frequency that the pendulum is oscillating at is determined by its length.
In order to work, an oscillatory device must switch between two energy states in a given amount of time. The pendulum of a clock oscillates between potential energy and kinetic energy. When the pendulum reaches one of the ends of a cycle, all its energy is potential energy and it is ready to fall towards the other end of the cycle. However, between the two ends, all the energy is converted into kinetic energy, thus reaching the highest speed in its travel between the two ends of the cycle.
In an ideal universe, an oscillator would continue to function for an infinite amount of time without any supplemental energy input. However, real oscillators, such as the pendulum, are affected by energy loss which eventually decreases the amplitude of the oscillation until the pendulum no longer switches between energy states. In order to compensate for the energy loss, oscillators must be provided with extra energy input.
Electronic oscillators
The same is available for electronic oscillators. The simplest electronic oscillator is a parallel circuit formed by a capacitor and an induction coil. If the capacitor is charged up and inserted in the circuit, then it will discharge into the induction coil, thus generating a magnetic field. However, once the capacitor has fully discharged, the induction coil will try to keep the current flowing through the circuit and the magnetic field will generate an electric current that will recharge the capacitor.
As you already know, each conductor experiences an electrical resistance, no matter how small. As the circuit oscillates, electrical resistance converts part of the electrical current into heat, until some point in time when the circuit will no longer have enough energy to oscillate.
Resonance
An oscillator reaches resonance when its frequency matches that of a particular signal. By matching the frequency, the signal is boosted in amplitude and all other frequencies are being ignored. For example, when you turn the knob of your car radio, you actually change the frequency of the oscillator inside your radio. When the oscillating frequency matches that of a radio station, the oscillator reaches resonance and boosts the carrier signal.