The signal amplifier interfaces to the "Provaset", and serves to drive from 1 to 5 of our air extractors equipped with inverter (ES 1500IN ES 5000IN ES 12500IN) by modulating the speed of the extractors with digital controls. The minimum and maximum depression required for the confined area and the equipment is defined on the Provaset, Provaset plus the signal amplifier provide for modulating the speed of the extractors, guaranteeing a constant depression in the confined area.