The Fender Stratocaster is an electric guitar that was originally released in 1954. The model has been the flagship model for Fender since then. The tone control uses a capacitor to eliminate high frequency tones from the guitar signal. The vintage Stratocaster models used the same capacitor for this purpose. Some of the newer models use other size tone control capacitors.
Tone Control Capacitor
The role of a capacitor in an electric guitar is to allow the tone control to function properly. The capacitor only allows higher frequency signals to pass through it. The capacitor is connected between the tone control and the ground, removing it from the final sound produced by the guitar. Turning the tone control alters the amount of the signal sent through the capacitor. At the maximum setting, none of the signal is sent to the tone control capacitor. At the minimum setting, all of the high frequency signal is sent through the capacitor to remove it from the electric guitar signal.
Fender Vintage Stratocaster Capacitor
Fender Stratocasters have two tone controls connected to a single capacitor. Vintage Stratocasters use a 0.1 uF 200 V poly film capacitor. The 0.1 uF value refers to the capacitance of the capacitor, the amount of energy it can store. This value determines how much of the higher frequency signals can pass through it. The 200 V value is the amount of voltage that can pass through it without destroying the capacitor. This tone control capacitor was used consistently on Fender Stratocasters produced in the 1950s, 1960s and 1970s. This capacitor is also used on some, but not all modern Stratocasters, as well.
The 0.1 uF 200 V poly film capacitor used by vintage Stratocasters was selected for a few reasons. Poly film capacitors are cheap, which saves money while mass producing Fender Stratocasters. This does not make it a low quality choice, though. The capacitance and voltage requirements for electric guitar pickups is very low compared to most applications that need capacitors. A larger, more expensive capacitor would be completely unnecessary. The 0.1 uF is a larger capacitance value than most tone control capacitors in electric guitars. This allows vintage Stratocasters to remove a larger amount of higher frequency signals with the tone controls than many other electric guitar models with smaller capacitors.