A Transcutaneous Electrical Nerve Stimulator, more commonly referre to as a "TENS unit" and pronounced /ˈtɛnz/ tens, is an electronic device that produces electrical signals used to stimulate nerves through unbroken skin. The name was coined by Dr. Charles Burton. The unit is usually connected to the skin using two or more electrodes. A typical battery-operated TENS unit consists of a pulse generator, small transformer, frequency and intensity controls, and a number of electrodes.