A device for a self-regulated pneumatic supply from a main reservoir containing product toward at least one auxiliary reservoir according to its filling rate, the supply device including a compressed air supply, a tilted duct connected to pipe connections, a bypass air duct having a first channel emerging near the outlet of the main reservoir and a second channel emerging near the inlet of the pipe connections to bring product to the auxiliary reservoir. At least one of the channels includes a sliding system for adjusting a passage section of air passing through one of the channels. The device can be applied to a seeder including such a supply device.
