A Mylar capacitor is a general purpose capacitor used in direct current applications. It derives its name from Mylar, the brand name of dielectric film used to sheath them.
Mylar capacitors have low levels of moisture absorption. They are used on semicritical circuits with maximum voltage loads of 60,000 volts of direct current. They have replaced polystyrene film and metallized paper capacitors in that role. At low frequencies, Mylar capacitors can also be used with alternating current systems. This role is limited by the high levels of power loss that Mylar capacitors experience at temperatures above 257 degrees Fahrenheit. Mylar dielectric film is made from stretched polyethylene terephthalate.