Resonators are devices used in electronics to increase the amplitude and frequency of electronic waves. They are typically used when a signal needs to be amplified, such as an RF signal in a radio or cellular phone. Alternatively, they can be used to reduce the amplitude of a signal so it can be heard more clearly. Resonators are typically made of an inductor and capacitor connected in parallel, with the capacitance tuned to the desired frequency. When a current is passed through the circuit, the inductor will resist the current and create an electromagnetic field. This field will cause the capacitor to vibrate at the same frequency, which amplifies the signal. Resonators are essential components in a number of electronic circuits and are used in everything from radios to smart phones.