Harmonic distortion and phase meters are instruments that measure harmonic distortion or phase position

Harmonic filters isolate harmonic current to protect electrical equipment from damage due to harmonic voltage distortion.

Differential amplifier chips are designed to amplify the difference between two input signals.

Amplifier and comparator chips are board-level components for amplifying voltage, current, or power.

Audio analyzers measure the noise and audio spectrum of output from an amplifier or a stereo.

Harmonic Mitigating Transformers are transformers used to reduce harmonics in electrical systems

Form gages and form gaging systems are used to inspect parameters such as roundness, angularity, squareness, straightness, flatness, runout, taper and concentricity.