A '''tuner''' is a circuit module or free-standing equipment which detects Signal (electrical engineering)|electrical signals and converts them to a form suitable for further processing.
The simple tuner consists of a circuit in which a coil and a capacitor are connected in Parallel circuits#Parallel circuits|parallel. The capacitor is usually made to be variable (although the inductor can be made variable, it requires a more complex mechanism and is rarely used). This creates an LC circuit which responds to an alternating current of one frequency.
