In electronics  a mixer or frequency mixer is a nonlinear electrical circuit that creates new frequencies from two signals applied to it. In its most common application, two signals at frequencies f₁ and f₂ are applied to a mixer, and it produces new signals at the sum f₁ + f₂ and difference f₁ - f₂ of the original frequencies, called heterodynes. Other frequency components may also be produced in a practical frequency mixer.