The process of hooking up a foot switch to a guitar will depend on the type of foot switch used. Foot switches supplied with your amplifier plug into the designated foot switch plug on the amp, and control particular amplifier functions. Other types of foot switches (also called "stomp boxes," "foot pedals" or "effects pedals") are connected differently. Effects pedals produce sound-enhancing guitar effects, and are turned off and on with built-in foot switches. Effects pedals have input and output jacks, internal circuitry and usually have external controls. Amplifier foot switches have no circuitry, connection jacks or controls, and use a built-in cable for amplifier connection.
Locate the foot switch jack on the guitar amplifier. This will be clearly marked with the printed words "Foot switch" in the immediate vicinity of the jack, and will be on the front or back amplifier panel depending on brand and model.
Insert the plug of the cable connected to the foot switch into the foot switch jack on the amplifier. Most foot switches have built-in cables. If yours does not, plug one end of a guitar cable into the foot switch jack, and the other end into the amplifier foot switch jack. Always consult your amplifier owner's manual, as foot switches require a stereo guitar cable or another type of connector.
Turn the amplifier on and test for operation. Your amplifier owner's manual will provide information on which features are controlled by the foot switch.
Provide power to the effects pedal by installing a 9-volt battery or plugging in a 9-volt AC adaptor connected to an electrical socket. Consult the effects pedal owner's manual for battery installation procedures and recommended AC adaptor type, as they differ from brand to brand.
Plug one end of a guitar cord into the guitar and the other end into the effects pedal "input" jack. The input jack will be clearly marked with the words "Input" or "In" printed on the pedal.
Plug one end of another guitar cable into the effects pedal "output" jack, and plug the other end into the guitar amplifier input. The output jack on the pedal will be clearly marked with the words "Output" or "Out" printed on the pedal.
Turn the guitar amplifier on and test the effects pedal for operation.
When using batteries to power effects pedals, unplug the guitar cable from the input when not in use to conserve battery power. Use amplifier foot switches designed for your amplifier for best results.
If an effects pedal will not be used for a long period of time, remove the battery (if installed) to prevent possible battery leakage and possible damage to circuitry. Using an AC adaptor that is not compatible with your effects pedal may cause damage to the pedal. AC adaptor specifications can be found in the owner's manual, and are sometimes printed on the bottom of the pedal. Alternatively, music store personnel can advise you of the proper adaptor for your pedal.