Un LFO comme pédale d'expression?

Unlike an in line volume pedal, there is no ‘input’ on an expression pedal as it does not connect to the instruments signal chain. There is just the single output that connects to the dedicated expression pedal input on the effect device. The device sends out a control voltage on one conductor of the cable which passes through the potentiometer and then is received back by the device on another conductor. As the pedal is moved up and down, the resistance within the potentiometer changes allowing more or less of the input control voltage to be returned. The amount of returned voltage is continually measured by the device allowing it to determine the position of the pedal and hence vary the effect. Expression pedals are typically passive devices that require no power of their own, with the control voltage being generated by the equipment they are connected to.

Expression pedals and CV pedals are not the same although they are often confused as they perform largely the same function but in a slightly different way. A passive expression pedal does not generate the control voltage itself; it receives it from the connected device, and returns it on a separate conductor along the connecting cable. A CV pedal generates the control voltage itself. A CV pedal requires a battery or external power supply. Some devices can use either, but if a device is not designed to be used with a CV pedal, then it could potentially be damaged by connecting one, so please read the manual before connecting a CV pedal to anything. CV pedals have their origins in analog synthesizers and are commonly, though certainly not exclusively, seen with synths and keyboard related devices. Built in expression pedals that are integrated into certain floor mounted effects units use different proprietary systems.