One who, or that which, transforms. Specif. (Elec.), an apparatus for producing from a given electrical current another current of different voltage.
A device made of two coils, which converts current of one voltage into current of another voltage. In a step-up transformer, the primary coil has fewer turns than the secondary, thus increasing the voltage. In a step-down transformer, the secondary coil has fewer turns than the primary, thus decreasing the voltage.
A device used to change the voltage, current or impedance of an electronic circuit. The power stays relatively the same both into and out of the transformer. Common uses are for microphone impedance matching, speaker power matching and plug in power supplies.