US Patent 7725514 Liquid and plate-based random number generator

A random number generating unit includes an external containment casing and a measurement cone within the external containment casing, to which liquid detection contacts are attached. One or more terminals on a random number generation integrated circuit, which terminals connect to the liquid detection contacts are included, as is a primary reservoir connected to a secondary reservoir containing a pump and a dropper to provide a bead of liquid from the pump, wherein the bead falls on the measurement cone to be detected by the liquid detection contacts and then fall into the primary reservoir.