Device for cleaning the guides of travelling flats in a flat carding machine, to eliminate from these deposits of foreign material found in the carded fibrous material, consisting in fitting the travelling flats assembly with flats provided with scraping or cleaning elements which come into contact with the surfaces of the guides on which the elements on which the flats rest are pulled. 1, measured with Illuminant C for a glass thickness of 4 mm, and a coating deposited by pyrolysis on the colored glass substrate. The first one-way valve is openable in response to a first, selected differential pressure acting upward across the first one-way valve. A seam joins the opposite ends of the belt. The first RF element is operably coupled to the memory element to receive the at least one parameter therefrom, and is operable to modulate a parameter signal containing the at least one parameter onto an RF signal for transmission. The plurality of active devices comprise at least two active devices coupled in a common base arrangement and arranged to receive the radio frequency signal with the voltage variable element coupling the emitter contacts or source contacts of the at least two active devices, such that a variable control voltage applied to the voltage variable element adjusts a phase of the radio frequency signal.